How to Avoid Maintainence Air Bleeding [Archive]

56Nomad

06-06-2003, 12:45

Victory Red wrote in part:

I vehemently refuse to become a person that has to bleed on a regular basis. JK wrote in part:

but even if I were to do a quick bleed at fill up, is that so bad? Yes John, that is bad. The sole purpose of secondary filteration is
to filter............ nothing else. It should not be a maintainence issue.

I know that I'm beating my dead horse, but to my knowledge there
have been no air or vapor issues with those of us using the Racor
assemblies post-OEM. Also, those folks who have mounted their filters
(MEGA, Stanadyne, or Racor) pre-OEM are not having problems.
If you don't want to do maintainence bleeding...... I think these are
the choices we have. Have I missed anything?

There are lots of new members on TDP since we started experimenting
with secondary filtration. Since there has been so much written on this topic, unless you have kept up with it, the information is overwhelming.

Based on the information that we have, additonal fuel filtration on our
trucks is highly recommended. We have some good options, but I think
if makes sense to simplify and summarize every once in a while for the
benefit of those who are just reading this stuff for the first time.

[ 06-06-2003, 01:02 PM: Message edited by: 56Nomad ]

Kennedy

06-06-2003, 12:52

I give up...

6.6L&94ImpalaSS

06-06-2003, 13:24

I have had my mega filter on for 2,500 miles with absolutely (knock on wood) no problems. dmaxallitech (Eric) installed mine and he is not having any problems that I know off.

Eric and I spoke about this and it has to be his installation technique. I will let him tell you.

dmaxallitech?

Mike

hoot

06-06-2003, 13:58

I agree with summarizing but it still seems like the gremlins are still at large. We don't have an answer for why some Mega Filters need to be bled and some do not. Probably cause some trucks are passing more gas than others or maybe the ones with more air are seeing warmer temps this time of year. There are also reports of CAT filters accumulating air.

Heat may be an aggrivator.

It's possible the Racor head is nice and straight through and the fact that it's only 88% efficient at 2 microns is why it does not have air issues.

Finally, I think the lift pump may become a future cure all.

I find it interesting that BROKERS puts hundreds of thousands of miles on his Dmaxes with no injector, air or fuel issues. I have yet to find out what filter he uses though.

a bear

06-06-2003, 14:17

56Nomad,
So you don't have air. I guess you've put that little clear hose on and didn't see anything. Or maybe your truck magicly doesn't experience outgassing (assuming you don't have a leak). Well I got news for you my friend. (WE ALL HAVE AIR/GAS to some point.) Is the system set up to handle this past 100K miles, beats me. Your just not collecting it in quantity enough for a no start. As hard as it may be to accept we all have the same design in our trucks. No where in the Helms manual does it say (Crack the bleeder to check for air.....) Why do you think the OEM only gets dirty on the bottom. Hmmmmmm.
From my previous experiences Ive had with Racor (That no longer exist by the way by orders from above me) they do indeed last a long time and pass air and things quite easily. Like our OEM for example. Like Todd said in reference to the Stanadyne if its plugging it's probably working. I agree 100%. Has the thought even crossed your mind that the pre OEM setups along the rail don't have air because they are not being subjected to vac as long as they are below the level of the fuel on board. I would be willing to bet good money that the air we see in the Mega is mostly coming from that high mounted OEM that is seeing the higher vac and temps. There are a lot of things to consider when determining IF or WHY you have air. Only the guys that have been through their systems know what I'm talking about. The Mega and some Cat filters collect air based on head design, period... The Cat usually a little less because of the smaller trapping volume.
To shed a little light on the words (My filter is doing great) Only two filters have proven good filtering capabilities on our trucks by analysis. Again those being the Mega and the Cat.
In our case the results we see with your eyes mean nothing. If we listen to all the hype manufacturers say about their products we would be wondering how can all their products be the best.
I wonder how the added vac and resulting air/gas increases we have by adding filters (Especially when they start to plug) will affect our systems in the long run. Thats why a large filter is good. And sometimes compensating for increased vac is good.
Flame Away :rolleyes:

56Nomad

06-06-2003, 14:19

Racor head is nice and straight through and the fact that it's only 88% efficient at 2 microns Hoot, are you talking about the OEM, correct?

If my memory serves me correct, George Morrision's test of a fuel sample from the
2 micron Racor was 98% efficient.

[ 06-06-2003, 02:34 PM: Message edited by: 56Nomad ]

hoot

06-06-2003, 14:41

The 2 micron filter (R90S) that you have is 98% efficient at 4 microns. It
is 88% efficient at 2 microns. I hope this information is of help to you.

Best regards,
**** *****
Technical Support Representative
Racor
Nomad,

Between the two Racors, you can be sure we're getting the fuel plenty clean enough. Some guys are happy with a 5 or 10 micron pre-OEM. Not me.

Nobody here can attest to the level of damage if any 2 micron or less particles will do to our system so there is no arguement except.... the cleaner the better.... except too big/good of a filter could spell trouble if it's not executed properly.

Our fuel system was designed and tested as delivered. If we alter it, we need to retest, which is kinda what is happening now. If Isuzu tried bigger and better filters, they may have experienced the same problems.

I personally believe the air is normal and aggrivated by heat. No filter setup should be designed in a manner as to collect air unless it was on purpose. Even our Izusu designed setup is suspect. I find it interesting that it is placed higher than anything in the fuel system. I wonder if that was on purpose to allow bleeding?

I would also challange the Helms "Bible". Just because some technician writes up a clear hose test doesn't mean that test proves anything. Suppose you do a clear hose test on all other diesel engines. Will we see bubbles? Does that mean they are defective or have air problems? This is the suction side of the system. You would expect to see some bubbles. Ever notice how diesel foams so easily?
The question is how to deal with it in a system like ours. Did Isuzu/Bosch design the system well enough to deal with this air?

I like the contraptions being tried that try to capture this air. Good stuff but these are just experiments to see what gives. I think air will accumulate at high points along the way to the HP pump. It can still flow due to common flow physics but sooner or later what happens? Does the air stop accumulating and just start passing as these areas get loaded?

I do like the idea of some kind of air accumulater/bleeder at a high point but one that is simple and transparent. I don't think the pumps will remove the air, just help the dissolved stuff stay that way. I think the Mega will still have air even with a pump. Maybe the stalling will stop because of the flow but a pump does not magically remove larger volumes of air.

[ 06-06-2003, 03:06 PM: Message edited by: hoot ]

56Nomad

06-06-2003, 15:17

Tommy,

I'm not into flaming and I'd rather deal with observable repeatable
results. There must be 5 or more theories why some of the secondary
filters are trapping vapor and others are not. We can speculate till the
cows come home........ but what most of the folks who are interested
in putting on added filtration to their trucks is a piece of equipment that
hopefully will do no harm, requires no maintenance (other than changing
filters) and filters fuel efficiently.

There is no question that the MEGA filter assembly is a fantastic filter.......
but for the fact that a good percentage of those who install them post OEM
have to bleed air. Once that issue is solved, then we all can rejoice.

My point with this string is that we have good options if we want to filter
our fuel to a better standard than OEM. The tenor of many of the previous
posting about adding filtration deals with solving all the problems
that result after you do it. If one system does not work for you,
it is not that expensive to try another or move it to a different location
if it becomes a problem.

"Only two filters have proven good filtering capabilities on our trucks by
analysis. Again those being the Mega and the Cat. "
If I am not mistaken, I think George Morrison did the tests and the Racor
2 micron absolute ranked with the CAT numbers.

I think is the natural tendency to defend and praise what we do to our
respective trucks, however, no one learns anything if we become a
mutual admiration society. One of the reasons why I love this forum
is the wealth of knowledge and experience that is shared freely
by both weekend mechanics and the pros.

dmaxalliTech

06-06-2003, 17:25

hoot says

Heat may be an aggrivator.

Thats possible, but have you ever looked for the fuel filter on a 6.5, its in the oven...

hoot again
I would also challange the Helms "Bible". Just because some technician writes up a clear hose test doesn't mean that test proves anything. Unfortunatly, the 'bible' from Helms is the same one I/techs use every day. If your diagnosing a fuel system concern on a truck and you have to call Tech assist for diag help, they are gonna ask you if you have done the clear hose test. Field engineer is gonna do the same thing.. It may not tell you the future, but its a very important test...

Somebody wrote in another thread about the quality of a product that was 'backwoods engineered' referring to the MEGA base. I dont know about ya'll but my hats off to anyone who would attempt it. Its designer does not have the millions of dollars available to research its design like CAT and Racor and others do. Its a common sinario for all products. Look at the trucks we drive, the 01 models were good, but have some issues, GM is fixing them and now 03 models seem to be better. This is the second largest company in the world and they have a product that was proven to the bone on their lab tests etc but still needs refinement after its in the public. If its determined that the problem is in the filter base ( which I highly doubt) then it will be refined to give peak performance....

So how many more threads are we gonna start to bash filters? Its hard to keep up on them all.

hoot

06-06-2003, 17:36

The 6.5 fuel isn't compressed to high pressures and held in fuel rails directly over the engine for significant amounts of time. There is no doubt in my mind the Duramax systems makes hotter fuel.

dmaxalliTech

06-06-2003, 17:42

true, but the fuel is not under much pressure in either setup, fuel is pressureized and in hot comomon rails AFTER filters and, if the system is doing its job, is considerably cooler when it makes it back to the filter

56Nomad

06-06-2003, 17:46

So how many more threads are we gonna start to bash filters? Its hard to keep up on them all. dmaxalliTech

My intent was not to bash any filter, only to highlight the fact
that we have good options if we want to better filter our fuel
without worrying about priming issues. Yes, It has
been hard to keep up because of all of the
posting.

dmaxalliTech

06-06-2003, 17:52

56, I wasnt pointing the finger at you, dont take it negatively.. It just seems to be a lot of overall bashing or flaming or whatever you want to call it on filter versions. Its getting boring.

Victory Red

06-06-2003, 18:11

First of all I'd like to say that I would let John Kennedy under the hood of my truck anyday of the week. As I'm sure 99.9% of us here would were he an available tech at our disposal. I've missed two opportunities to personally meet him to talk trucks and bikes. He's a diesel enthusiast and a businessman. In both ways we win as consumers.

The Mega didn't create the air issue, it only exacerbated it. I don't fault him at all for the non start issues, nor since the nature of this mod if I wouldn't be screaming for a refund had I used his setup. I'd be pointing fingers at GM/Isuzu/Bosch/Racor for dropping the ball with the quality and performance of the OEM, instilling the fears in us that we need better filtration if we want our injectors to have long and fruitful lives.

I don't think he deserves some of the bashing he's gotten over his Mega.

That said I can happily say I've gone 2 1/2 days with only mild stumbles at startup and only when I leave work, never at home, never at the grocery store. Bleeding isn't a big deal, just a PITA to wonder whether or not each time I go to my truck if it'll start without a kick. Hell I don't even need to bleed, 3 quick pumps on the primer and away I go.

My issue with the lift pump is that I'd need the additional parts I don't have, additional tools i don't have and additional time THAT I REALLY DON'T HAVE. Plus the additional risk of pump failure, other possible leaking, or any other unknown variables. I love my truck, but not so much to want to spend each free moment, modifying my modification to fix the problems that it caused. I just see a daisy chain effect coming on.

On Edit:
I work in the robotics industry. While we use servo driven arms, our machines also need air pressure and vacuum for part removal. I'll have to see if I can rig a setup to test effects on the filter head when it changes from a positive to a negative pressure. I may also spend some time with Mechanical Desktop and a filter head and make up a new replacement primer cap. I can have our in house machinist mill one up with either a flatter head/and or a recessed head to fill in the ports we cap off. I'm off to florida for next week but this seems to be a viable option to try when I get back. I'll also have to enlist one of our engineers to assist me.

[ 06-06-2003, 06:37 PM: Message edited by: Victory Red ]

Tsckey

06-06-2003, 20:09

Wilbur and Orville were back yard mechanics, too. They did alright. JK will eventually figure out the drivebility issues with his filter. All the same, I'm not convinced that air or vapor is as big an issue as some suggest. No doubt we'd all be happier without it, but I don't think cavitation has been satisfactorily demonstrated as the greatest risk to our injectors. I can accept that little bits of crud can do them in, so I intend to address that soon, but if Brokers can get 400+k out of his injectors just filtering the fuel and letting the gas take care of itself, then there is hope for those of us too lazy to take it on.

Good luck luck to you air trappers. We'll all be better off when you've solved that riddle.

TC

hoot

06-06-2003, 22:44

It's kinda like choosing between a PSD 6.0, Duramax and a Cummins.

They all are good but some need service more than others. :D :D

So far nobody with the Racor has had any problems whatsoever.

We're not bashing people, we're questioning products that are questionable. If we can't do that here than there is a conflict of interest as far as I'm concerned.

I have to thank More Power for putting all the rumours of "Big Brother" to rest by simply letting things fall as they have and not getting involved.

Overall we have all kept our cool throughout this filter fiasco. Good going everybody.

Racor rules. tongue.gif

pinehill

06-06-2003, 23:27

Amen, Hoot. Axe Grinder, R.I.P. smile.gif

NWDmax

06-07-2003, 00:10

Ditto

Kennedy

06-07-2003, 08:05

Originally posted by hoot:
The 6.5 fuel isn't compressed to high pressures and held in fuel rails directly over the engine for significant amounts of time. There is no doubt in my mind the Duramax systems makes hotter fuel. Actually, the return fuel temps are quite similar. 150

a bear

06-07-2003, 08:29

Isn't it great when we can just get along. :D :D
I'm not sure anymore if heat plays a role. If so it would be very minor. Removing the vac seems to have done the trick here. I can't wait to cut open another OEM filter to see if the vapor fuel interface mark is still there. It appears that I am utilizing all surface area of both elements now. If the vapors we are seeing are gas instead of air it would be a plus for fuel quality to keep it in a solution instead of venting. As fuel outgasses or evaporates the good stuff leaves first. May explain my increase in mileage and quicker starts. Just recieved a fuel sampling kit from George Morrison. Hope to have results soon.

Hoot,
Enjoy your time on the throne. Although the Mega may prove more costly it will be taking names shortly. :D tongue.gif :D tongue.gif

James S

06-07-2003, 11:04

Hey There,

This might push some of you over the edge, but I need an explanation and summary. I am TOTALLY confused!!!!!! I have not read about bleeding air in the manual. I don't mean to sound ignorant, but please CALMLY explain, what this is for clarification. I GATHER it is when you put bigger fuel filters in, and steer away from factory filters, and then you have problems filtering well enough?????? I feel stupid asking this, but I am confused as I said. I am starting to be afraid to upgrade the exhaust, air filter, oil filter, tranny filter, fuel filter, for fear of having problems. I have gone through the MILLIONS of filter posts, and cannot find specific, and CONFIDENT recommendations. PLEASE, quickly restate, the BEST fuel, oil, air, and tranny filters to use, which will NOT cause any problems, and have the least chance of voiding my waranty. If I improve horse power and torque, even better. If you know by how much my increase will be, PLEASE tell me that as well. Please also specify whether the filters are high performance or not. I will certainly use high performance filters, if they are affective. For the air filters, I don't want alot more turbo whistle, but a LITTLE is fine. QUALITY AND EFFICIENCY, are my main concerns. Sorry to ask for repeats, but I am getting vary confused and frustrated by this whole damn filter issue. I look forward to replies ASAP as my filters need changing soon. Thanks again all of you. I'm sorry if I am getting on some people's nerves, but this is my first diesel, and I don't want to hurt it, and want it to last me for many, many, years. [I only put about ten thousand kilometres a year on it.] Thanks again.

James

Tsckey

06-07-2003, 11:57

It can be confusing, alright. But, I suspect that if you fix your priorities you can sort through the options pretty well. The main controversy in the fuel filter arena appears to be whether you want a filter that addresses BOTH vapor/air and impurities or just impurities. Hoot, Nomad, Ndamico, Trace and others (apologies to those I've not mentioned) have opted successfully for systems that don't require periodic bleeding. Others have chosen to take on the more complex task of removing both impurities AND air/vapor. We may all owe these intrepid souls a debt of gratitude one day.

Air intakes systems are pretty settled, though some insist that K&N only filters down to the small boulder size. Amsoil air filters seem to please many and oil analysis results appear to bear out their effectiveness. Dyno runs don't seem to favor one air filter over another.

Oil bypass filter questions seem to revolve around which, not whether. Amsoil, Oilguard, and others all appear to deliver as promised, though some members question whether any supplemental oil filtration is really necessary for engine longevity. Again the oil analysis results bear out the effectiveness of these accessories.

Exhaust systems appear to provide the greatest benefits to those with chipped engines. But TST's dyno results surprisingly revealed benefits to stock engines as well. There are questions regarding whether the benefits are from freer mufflers or bigger pipes or both. Some suggest the catalyst is a problem in the emssion controlled trucks, though I doubt it. Which aftermarket system is best is for you to decide. JK is a supporter of the Diesel Page and extraordinarily highly regarded both as a supplier of parts and accessories and as a general resource for just about anything to do with our trucks. His systems are uniformly praised. Banks has a solid reputation both for the quality of its products and for overstating their performance benefits.

The chips situation is wide open and getting wider all the time. The Juice still seems to deliver the best power numbers and provides the best protection against zinging the transmission into limp land. The Predator, TST, and recently the Hypermax chips all are finding happy followers.

Shock absorbers have fallen into two principal camps: Bilsteins and Rancho. The Bilsteins are non-adjustable, guaranteed forever and very popular. The Ranchos, particularly the 9000 series offer adjustability and good performance, though from my experience they tail off near 100k miles, though that doesn't seem unreasonable, really.

Tires: I have no idea. Round, black and not made by Firestone seems to be the key.

I hope this is some help. It's really just a survey of the reports from the membership.

TC

Tsckey

06-07-2003, 11:59

Victory Red

06-07-2003, 12:49

JK(or anyone else) in your best opinion can you explain to me why if I park level or engine uphill I have no issues, but downhill is where I have to pop the hood and prime??

hoot

06-07-2003, 15:29

Originally posted by a bear:
Hoot,
Enjoy your time on the throne. Although the Mega may prove more costly it will be taking names shortly. :D tongue.gif :D tongue.gif More costly? Does that mean existing Mega owners will have to add a lift pump so it works?

I don't think the lift pump is removing any air at all. I think it's just helping to keep it in solution so the Mega filter with it's one micron restriction doesn't extract and accumulate it.

Leave it in solution like all the other billions of diesel fuel systems that have been on the road since Rudolph invented the diesel. For those with tempermental filters like the Mega, somebody ;) will soon be selling you a lift pump
:eek:

a bear

06-07-2003, 16:32

Exactly right about keeping it in solution. Especially if its fuel vapors.
Economical-Burn instead of vent
Possible cavitation - Eliminated
Particals - Even less
Element life - More
Lift pump life - Probably long if set at 0 psi.
Furure leaks in lines - Not to worry with no vac.
Quicker starts - Seems that way ?
Filter priming - Flip a switch
Fail safe - Yes for flow through type.
Added vac by adding another filter - none
Added outgassing by adding secondary filter - none
Emergency back up if OEM LP pump fails - Yes
Pump a load of bad fuel out the tank - Yes
Taking fuel samples - a definite plus
Adverse affects on LP pump - none
Warm Fuzzy about those injectors and pump - :D
Ok, I promise to quit.

hoot

06-07-2003, 17:43

Originally posted by a bear:
Exactly right about keeping it in solution. Especially if its fuel vapors.
Economical-Burn instead of vent
Possible cavitation - Eliminated
Particals - Even less
Element life - More
Lift pump life - Probably long if set at 0 psi.
Furure leaks in lines - Not to worry with no vac.
Quicker starts - Seems that way ?
Filter priming - Flip a switch
Fail safe - Yes for flow through type.
Added vac by adding another filter - none
Added outgassing by adding secondary filter - none
Emergency back up if OEM LP pump fails - Yes
Pump a load of bad fuel out the tank - Yes
Taking fuel samples - a definite plus
Adverse affects on LP pump - none
Warm Fuzzy about those injectors and pump - :D
Ok, I promise to quit. Racor post OEM....

Bleed once at install.
Drive.

PROS:
Not required....
Lift pump.
Lift pump oil pressure switch.
Additional control wiring.
Additional plumbing.

Initial cost substantially lower
Recurring costs 50% lower
Filter availablity
Filters available with multiple size and micron levels. Optional heat, water and vacuum sensing.
Warm Fuzzy about non-backwoods design ;)

CONS:

Manual bleeding requires 2 extra minutes.

[ 06-07-2003, 06:02 PM: Message edited by: hoot ]

a bear

06-07-2003, 18:16

nyunk - nyunk - nyunk :D :D :D

Lone Eagle

06-07-2003, 18:54

a bear, Would you please define "outgasing" for me? Thanks. Later! Lone Eagle

hoot

06-07-2003, 19:06

I won't rule out a lift pump in my future if you guys come up with a good reason why I would need one or I start having prime problems.

Mean time, keep up the good work.

I guess I should get a sample done. I figure with two filters running, both in the 2 micron range, I should be into some pretty darn clean fuel.

I haven't touched my truck since I put the filter in. Just driving. Before that it was just wheels and tires at 52,000 miles and regular lubes.

a bear

06-07-2003, 20:11

Hoot,
No doubt we are all doing some good to our fuel systems with additional filtration. What ever route a person desides to go will surely help. Thanks for being a good sport. Saw you was here and thought I would have a little fun with your Racor rules sig. Like Dmaxalitech said the wars are getting old.

Lone Eagle,
Vapors flash off of liquids that are subject to pressure drops, increased temps, and retention time. I deal with this type of outgassing in my line of work as the Government requires accurate measurement of this for their royalties. All liquid hydrocarbons we deal with comply with volume corrections to an API standard of 60 degrees/0 PSIA. It is not unusual to see a fluid loose 50% of its volume from outgassing at pressure drops of 6000 PSIA. The facility I just left was flashing approx. 17 million Cubic feet of gas off of 34000 barrels of oil requiring the HP of two Cats and 3 stages to compress to sales pressure.
If you do a search (Fuel outgassing)there is some interesting information relating to outgassing caused by certain filters that are experiencing vacs as little 1-2" Hg. ;)

dmaxalliTech

06-07-2003, 20:26

6.6l, I am glad to see you still are not having any trouble with that filter. You have been racking the mileage up on the puppy!.. Its gettin close to injector time I bet. Of course, they are probably getting better with all that filtration ;)

I have a MEGA kit sitting here on the shelf that I will sell to somebody for the going price. ( 206.00) I will install it for you for next to nothing, I will put it on anybodys truck, I am intersted if I can go 3 for 3 here. :D

Lone Eagle

06-07-2003, 21:26

a bear, It is possible that we have added too much suction head to our system and have a partial vapor lock. (what you call outgassing)I know that diesels aren't suppose to vapor lock because diesel fuel has a vapor pressure of 8 PSI. This is a little out of my line. I spent more time correcting the causes of cavitation, airation etc. You might look at a web page I found. I really think it applies to our problem. I don't know how to sort it out. Maybe you can.www.bennettusa.com/bookserv/mchysr17.htm (http://www.bennettusa.com/bookserv/mchysr17.htm)
Later! Lone Eagle

[ 06-07-2003, 09:31 PM: Message edited by: Lone Eagle ]

a bear

06-07-2003, 23:08

Lone Eagle,
You have hit the nail square on the head. This is exactly related to our system. Just for calculation purposes lets assume our fuel is 110 degrees with 2.5 feet of suction head.(Roughly from the height of fuel in the tank to the highest point in the system) With a fuel vapor pressure of 10 PSIA @ 60 degrees the correction to 110 degrees would yield a vapor pressure of roughly 13.3 PSIA. With a atomspheric pressure of 14.7 PSIA this would give us a working pressure of 1.4 PSIA. 1.4 x 2 = 2.8" HG max suction head the LP pump can see before outgassing occurs. With 2.86" HG suction head required to lift the fuel 2.5 feet we have already exceeded the max suction head of 2.8" HG where outgassing (vapors) begin. Probably why we see the vapor to fuel interface marks on the OEM filter dirty side. Anything added to the system at this point would increase vac/outgassing slightly. I think the add on filters have been adding about 1" of suction head. Doesn't seem to leave much room for filter plugging. We shouldn't be able to increase the suction head enough to cause vapor lock though.

hoot

06-08-2003, 06:28

Great article Lone Eagle.

Like a bear said, notice how the design is based on a normal working fuel temperature? It also mentioned the unlikeliness of vacuum related outgassing of diesel at normal temps because it's vapor pressure is 2 psi less than gas.

I noticed JK mentioned the fuel temps between the older 6.5TD's and the Duramax are similar coming into the hp pump. Is this verified?

What is the peak temp anywhere in the system? Is it higher in the Dmax? I would think so.

And if so, it's still possible that the higher heat rise associated with the Dmax fuel system (even though it does get cooled back down) could be building vapors that don't get chance to get back into solution. We know the little fuel cooler is just a simple attempt to keep the temp down.

Right out of the article...
"The only real cure for vapor lock in hot climates is to keep the installation and pump cool."

One fellow I talked to with the Mega has more problems in hotter and low fuel situations.

I still believe additional fuel cooling might be benificial.

a bear

06-08-2003, 07:04

Hoot,
Although cooling the fuel further could play somewhat of a role it would be hard to cool the fuel below the available air temp for cooling. Roughly 95 degree summer heat where I live. In my conditions here in the south I can more easily place myself below the threshold of outgassing by removing some of the vac needed to lift the fuel. I'm not sure what average summer time heat runs where you guys are but you may be able to obtain sugnificant cooling. I'm curious to see what summer heat will bring.

I often wondered if it would be beneficial to provide a gasket between the OEM filter and mount. This assuming the heating of the filter is from direct contact and not convection. We all know how quickly aluminum transfers heat. Just a thought.

[ 06-08-2003, 07:10 AM: Message edited by: a bear ]

56Nomad

06-08-2003, 09:47

Victory Red wrote:

I also just stumbled across this site: Racor Specs (http://www.maesco.com/products/racor/r_spn_intro/r_spn_specs/r_spn_specs.html)
it seems that the Racors are good for both a pressure and vacuum system. Maybe the Mega/Cat are designed for pressure only that's why we have issues while the Racor guys don't? I thought this was covered before :confused:

Victory Red

06-08-2003, 10:13

Good chance that it was Nomad, this situation has been going on for a long long time. If it was, my bad, I can't remember everything ;)

56Nomad

06-08-2003, 10:40

Victory Red,

I don't remember either... you may have hit
upon something smile.gif

Just waiting for the experts to reply :D

technician

06-08-2003, 12:11

I really don't know what I am talking about.

However it seems that the Mega-Filters large volume and holding capacity would cause the fuel to stay longer and thus cool. Could this slowing of fuel travel cause cooling of vapor thus sperating fuel from air??? :confused:

I don't know, just thought I'd throw the thought out for all you engineer types :D

Victory Red

06-08-2003, 13:37

Technician,

General consensus is that heating the fuel is what causes the vapor burnoff. Although the larger elements, will have a slower flow through. If it works that way, since the small factory element would seemingly pass through quickly, there's a good possibility that there's no time for it to gather. But, in a large element is would take longer to pass through henceforth a pocket being able to establish.

What we really need is to see a running complete model w/see through everything on a bench setup. Then we could see exactly what is going on.

Now I don't know of anyone here that has that capability. So it's back to the old speculation, trial, error and repeat.

With enough of us bumping our heads on this, sooner or later someone will stumble across the solution or a fix(shy of adding more hardware).

Kennedy

06-08-2003, 15:50

A couple of points I'd like to clarify:

1) Peak fuel temp is not so much an issue as the majority of the heat is introduced AFTER filtration. The EDU and a bit of radiant heat are the only key contributing factors here.

2) Restriction (suction head) is ONLY increased between the pump and the added filter element. Since we see an accumulation of free gasses on the dirty side of the element, the gasses are seperating/entering/whatever before the fuel hits the element.

Please feel free to correct me if I am wrong about the restriction. My statement is based on common sense, but sometimes science/physics can trump common sense...

That said, I'll make another statement:

I have yet to see any factual data on added restriction imposed by adding another filter. We have tested this, and to the best of my recollection, it was .75-ish inches hg. I should have a sample of my test gauge at the Rendezvous to show. Production units will have much finer graduations for increased resolution.

As to where this gas/air is coming from, the most common thing that I have seen is MANY small bubbles in continuos flow from the EDU. This may be a result of heat on the fuel, but this can be a LOT of gas. A little bit of this may not be such a big deal, but in continuous form, it sure cannot be beneficial...

hoot

06-08-2003, 18:22

Yes the heating is occurring after the filters but I would like to know what this post heating does to the fuel as it returns to the tank. GM/Isuzu obviously felt it to be an issue or they would not have installed a fuel cooler.

Take a two circulating systems.
One raises temperatures significantly higher than the other but has a radiator cooler.
On both systems, the fuel is the same temp entering the filters but the one system had the fuel much hotter elswhere in the loop.
Will the fuel/vapor tendancies be identical?

I personally thought it was the dumbest thing to put the cooler where they did, somewhat in harms way and certainly more exposed to dirt accumulation. Was this a late engineering change? I think it belongs up front behind the grill but I guess the plumbing and safety issues nullified that.

Maybe someone with vapor issues should try an additional cooler or a fan added to the existing one. No other changes. Seems like an easy experiment especially for a vendor that has access to these things. Although it won't change the peak heated temp, it might make just enough difference to minimize vapor outgassing prior to entering the filters.

I know the Racor seems to be working but I'm with all of you who are concerned about vapors accumulating and lowering the wetted area of the filters.

a bear

06-08-2003, 19:00

I have about a 3 hr trip tomorrow. As soon as I return I will check the temp of the fuel in the tank. The outlet side of the cooler seems warm while sitting still. It's possible it may be working ok while driving with air being exchanged across the coils. I allways check it while sitting still but the fuel in the tank never seems that warm.
If this doesn't work I can allways build a little platform under there to lay on while the wife takes me out on the interstate. This Mega filter is working so good I ran out of things to do. :D

dmaxalliTech

06-08-2003, 19:32

The cooler is mounted in the rear of the truck for a few reasons..
</font> Have you ever seen all the coolers in fron of the truck?? Radiator, Intercooler, Condenser, Tranny cooler. No room

[LIST] By mounting it close to the tank, they can take advantage off the travel it must make in the fuel lines before it gets to cooler, helps cool it before the cooler for maximum effect. Yes, its prone to trapping debris there.</font>
abear, I have been bored myself lately :( . Dont have to touch the MEGA, gives me more time to post :D

mark45678

06-08-2003, 20:44

I have to agree with HOOT! I cannt stand opening the hood for every tank of fuel.... I fill up 2~3 time a week ! and lately in raining all the time! I check my oil every 5000 mile like clock work (the drain pan holds 2.5 gallons so I spill some) most of the time I drain out 8~9 qts. I could see looking into a lift pump maybe even a gas truck in tank type pump would be the best. but for me my 01 has only a few more months left in my drive way so Its just a dream for me.... I am thinkin of ordering a New 04 with the new turbo set up! :D I think a good parts guy/gm tec could tell us how to put a gas pump in a diesel tank...the only problem is how to blead off the extra pressure ,I dont know much about the bosch FI system but I am sure that some smart SOB could tell us! that would end all the filter problems!

Victory Red

06-09-2003, 02:37

Dmaxallitech,

If I didn't already have my Cat in, I'd be jumping the pond between us and sitting in your service department taking you up on your Mega install offer.

Anyhow next time I need to go visit the guys over at Plastech in your town, expect me to be knocking on your door.

Manfred

06-09-2003, 08:13

Victory Red - I share your thoughts that initiated this post. To test the theory, I have a Racor 660 set-up on order. It should arrive in about two weeks and will be installed in the same place, where the Mega filter hangs now, trapping vapors and/or gases.
The truck has 11K miles on it, had no history of stalling before the Mega filter, which has been used for just under 1K miles. I seem to have had more problems than others, because I run the tank nearly dry on one 600 mile trip during hot weather and about 7000 feet altitude change. I'll keep the Forum posted of the results.

Hoot - Another reason for not having a fuel cooler up front would be thee safety issue. Most accident damages are caused in the front. GM is still smarting from law suits and settlements on truck fuel tank fires which were mounted outside the frame.

hoot

06-09-2003, 08:35

Manfred,

It's not cut and dry so changing from the Mega to the Racor doesn't mean there will be no problems when doing the extremes like you described.

Good luck and if you have any questions, let us Racor guys know ;)

Here are the instructions again....

Install filter.
Drive truck. :D

BTW: I just ordered a fuel analysis kit. I'm really curious how clean my fuel is.

[ 06-09-2003, 08:52 AM: Message edited by: hoot ]

Manfred

06-09-2003, 09:34

Hoot -

I think my driving out here was well within vehicle specifications. I do live in a hot part of the coutry where diesel is expensive, a bad word and -stations are hard to find. Any after market product should meet the overall vehicle specifications, or the supplier will have to deal sooner or later with reliability issues. For this reason, every vehicle manufacturer I know (except for the YUGO0), spends time and tests the hell out of new vehicles, not only in cold and hot chambers, but also in the real world, be it the hootest desert, or the artic climate in the deepest winter.
The Mega filter was developed with good intenetions by knowledgible folks with good reputation on this forum, in the cold weather season. The problems we see may only developmental teathing problems, which may be overcome? For this reason I have not returned my filter. I cross my fingers on the Racor test.

dmaxalliTech - You live in a much more temperate climate, may be this helps the Mega to perform better?

a bear

06-09-2003, 19:31

I previously stated that I didn't think the fuel temp played a large part in outgassing but I may have to change my position on this some. After returning from a 165 mile trip today I dropped the old probe into the tank and this is what I found.
Temp in the tank 111 degrees with an outside temp of 91 (20 degree increase) This was taken with mostly interstate driving with max air flow across the cooling coils. I would expect city driving to raise the temps even higher. (See the temperature pic. below.) Although I presently have any outgassing in check by removing my fuel system vacumm I just wanted to put the results out there for all that was interested to see.
I would definitely knock the bugs off of the coils in the spring. As someone previously stated this was no doubt a GM issue. ;)

dmaxalliTech

06-09-2003, 19:53

Rick, looking forward to your visit.

Manfred, what are you gonna do with your MEGA? Send it to me if you dont want it. I will pay shipping. You can keep the filter.

hoot

06-10-2003, 07:46

Originally posted by a bear:
I previously stated that I didn't think the fuel temp played a large part in outgassing but I may have to change my position on this some. After returning from a 165 mile trip today I dropped the old probe into the tank and this is what I found.
Temp in the tank 111 degrees with an outside temp of 91 (20 degree increase) This was taken with mostly interstate driving with max air flow across the cooling coils. I would expect city driving to raise the temps even higher. (See the temperature pic. below.) Although I presently have any outgassing in check by removing my fuel system vacumm I just wanted to put the results out there for all that was interested to see.
I would definitely knock the bugs off of the coils in the spring. As someone previously stated this was no doubt a GM issue. ;) I see a fuel cooling mod in your future. ;)