water pump replacement + overheat

[gary_lucas]

So, my water pump is probably going. It seems to be bleeding out of the weep hole. About 1-2 tablespoons everytime it warms up and cools down. Nothing substantial. I always keep the overflow tank pretty full.

Wondering if it's worth getting the 'welded impeller' water pumps that seem to be all over the place. Has anyone had a quick failure? I guess for $100 it's a deal.

Also, truck overheated pretty badly on the highway with the trailer... Twice...

I'm not sure if that's related to the water pump or not, could well be.

I saw 250f on the edge insight once, after the DIC chimed I pulled over immediately and let it idle for about 15 minutes and it dropped back down to 210. That was on what was mostly a flat highway with a few dips, rises and curves.

I figured I'd be ok if I drove slowly and carefully... However, the next chunk of highway was longer and steeper (still not more then 3 or 4 degrees, but fairly long) and that killed it, 260 before I could pull over... Ended up calling BCAA to tow me out as I didn't want to risk trashing the engine.

Truck does seem to run hot, I hit 230 today going up a 4 block, but steep hill... No load...

I'm doing the thermostats in a few days, I know I need to get the water pump done but I'm wondering if I should be replacing the rad as well. May as well while everything is exposed and then I hopefully wouldn't have to worry about overheating any more.

Thoughts?

[Kennedy]

Thermostats-OE only

Water pump-welded to prevent spin

Fan clutch-if you don't hear yours roar

Radiator-clean the air side thoroughly including the rest of the coolers. The coolant side will be like new as the Dex Cool keeps it that way.

Coolant-Dex cool 50/50

[a5150nut]

Gary,

I have been towing heavy with my 2006 (21500 lbs) and I have seen the engine temps start to spike, But most of the time if I keep pyro temps in check there is no problem. You can't rely on the speedometer but must watch the pyro. It is surprising how little you can back off the throttle or as Robyn refers to it as the loud peddle, and the temps will drop. Dropping down a gear doesn't always help but got to love the Allison.

I know my radiator stack is clean but have you checked yours? Remove radiator and clean ac condenser and oil cooler from the back side and clean out the radiator while out. Might want to check your air filter too.

On the highway if you can tuck in behind a semi it helps too. At least with my fifth wheel I have a very large sail that catches a lot of wind.

The main thing is to learn what your truck is capable of and work within those limits. You can work it hard, just don't over work it.

[gary_lucas]

That all makes sense, it never occurred to me that you could / should hose out the cooling stack.

My AC also goes warm when I'm idling so that's probably in need of a cleaning.

I'm going to do the fan clutch and thermostat and get the water cooler done by someone who is more competent (and do the fan clutch at hte same time).

I ordered a welded waterpump.

Hopefully between all this the overheating will be done with.

G

[gary_lucas]

Thermostats done.

I brought the trailer to my camping spot again this long weekend, truck started heating up again on pretty moderate hills.

The dealer near my spot (gardner GM in hope, BC) is known for having a good service department. I asked them to take a peak.

They confirmed the leak is in the water pump, refused to say if it was ok to drive back to Vancouver, however I made it and it's more down than up on the way back.

They could not find a definite cause for the overheating so they suspect air in the coolant and stated that I needed to get the water pump resolved before spending time on doing anything else.

They also checked the compression and said there's nothing wrong with the head gaskets so I'm good there.

Now I just need to either get back up there so they do the water pump or find somewhere nearer to home to get it done. I'm in Port Moody BC if anyone has a recommendation that's more local than hope (150km)

Also, with the weeping water pump (and they said it was leaking a reasonable amount, which sounds like it's worse than when we first found the problem)... Is there any point in trying to bleed the system until it's resolved?

Thanks much

Gary

[DmaxMaverick]

I agree with the dealer. It should replaced at your soonest convenience. I can't help with a local shop. Good hunting. If it's leaking a "reasonable amount", it may be significant, but not much volume. You made a loaded trip and didn't dry it up, and that speaks volumes, so to speak.

If you must drive it, avoid loading it or driving hard or far enough to get the temp up. Fill the reservoir, leave the cap loose about 1/2 turn, and place a container below the water pump overnight. This will show if it has a static leak, and how much. If it doesn't leak, or much at all, then keep it full with the cap loose. Don't overload/heat it, during short-ish, local trips only. Keep it topped off and it should be OK for a short period until you get it fixed. Keep in mind, it will "push" coolant out at a much lower temp with the cap loose, so it's important to keep it as cool as possible, and keep the reservoir full to prevent air in the system.

[gary_lucas]

Thanks, I don't understand why I would want to keep the cap loose. Is that to prevent pressure build up?

I'm kind of torn, that dealer is an hour or so drive, and it's an 8 hour job. However, I've heard good things about them and I've brought my truck there a couple of times. They charge $54 for diagnosis (that included a compression check) and the last time I brought it in for work they estimated $700 and billed me $430.

Generally around here it's a minimum $100 to put a vehicle on the scan tool and I've never in my life heard of a mechanic's shop bill coming in at below the estimate. Their quoting me about $800 to do the water pump. I've already bought a kennedy pump...

It's basically that or a specialty / duramax shop as my local mechanic doesn't feel comfortable charging 8 hours for something he knows is going to take at least twice as long (don't blame him, he's not a diesel mechanic).

I did top up the coolant before I got on the road this morning, I was seeing flat ground temps @ 200-212 and on very moderate, short hills it would spike to 230... so definitly not normal.

I'm probably going to drive up there in the next 2 weeks.

Gary


I agree with the dealer. It should replaced at your soonest convenience. I can't help with a local shop. Good hunting. If it's leaking a "reasonable amount", it may be significant, but not much volume. You made a loaded trip and didn't dry it up, and that speaks volumes, so to speak.

If you must drive it, avoid loading it or driving hard or far enough to get the temp up. Fill the reservoir, leave the cap loose about 1/2 turn, and place a container below the water pump overnight. This will show if it has a static leak, and how much. If it doesn't leak, or much at all, then keep it full with the cap loose. Don't overload/heat it, during short-ish, local trips only. Keep it topped off and it should be OK for a short period until you get it fixed. Keep in mind, it will "push" coolant out at a much lower temp with the cap loose, so it's important to keep it as cool as possible, and keep the reservoir full to prevent air in the system.

[rapidoxidationman]

They did a compression check on a diesel for $54???
How? Does the tech II scanner do it?

[DmaxMaverick]

Yes, loose cap to prevent pressure. If it leaks, it will still leak, just a lot slower. As I said, keep the conditions controlled and the tank full, and it'll be OK.

Good price for the services. If you get good work from them, they're a keeper.

[DmaxMaverick]

They did a compression check on a diesel for $54???
How? Does the tech II scanner do it?

That's what I thought. The Duramax isn't at all difficult, but it's still 8 cylinders and wrench time.

The Tech II can't do a compression test, but can do a balance test. Results will usually tell the same story. It isn't the same as "balance rates".

[Kennedy]

Maybe what they did was a cooling system pressure check?

[gary_lucas]

They stated they put a pressure check on the cooling system and said it was "Leaking pretty good".

They also explicitly stated that they checked the compression (didn't say how) and that it had no problems in that area... The service manager said: "Your head gaskets are good"

I'm inclined to head back there, just trying to decide the best way to spend a nite in hope :p

G

[DmaxMaverick]

You just may have found yourself a "no bs" dealer. The holy grail. If their service is good, it's worth the trip, and lodging.

[Kennedy]

I don't see a compression test as a positive test of a seeping head gasket. The head gaskets tend to "seep" small amounts of combustion gasses at higher cylinder pressures.

At this point it is probably best to fix the external leak(s) and see what happens.

[More Power]

They stated they put a pressure check on the cooling system and said it was "Leaking pretty good".

They also explicitly stated that they checked the compression (didn't say how) and that it had no problems in that area... The service manager said: "Your head gaskets are good"

I'm inclined to head back there, just trying to decide the best way to spend a nite in hope :p

G

While I hate looking for problems, I'd consider doing a cooling system pressure test on my own. A head gasket or injector cup compression leak can cause excessive pressure in the cooling system, which causes the pressure to ride up against the relief pressure setting of the surge tank cap (theoretically 15-psi). Normal cooling system pressure at operating temperature should be 8-10 psi. Excessive cooling system pressure can produce short water pump seal life.

Jim

[gary_lucas]

While I hate looking for problems, I'd consider doing a cooling system pressure test on my own. A head gasket or injector cup compression leak can cause excessive pressure in the cooling system, which causes the pressure to ride up against the relief pressure setting of the surge tank cap (theoretically 15-psi). Normal cooling system pressure at operating temperature should be 8-10 psi. Excessive cooling system pressure can produce short water pump seal life.

Jim

Good idea, well I need the water pump done regardless. And with the leak right now I don't think I'll get much in the way of helpful information... IE if the pressure was super high it would just piss out of the water pump and the PSI would read normal.

Once I get the leak fixed I'll run a pressure test.

G

[gary_lucas]

Hi all, long time since last update.

We finally pulled the pump out.

The water pump housing had substantial wear on it.

There was a 1-3 mm deep wear in the water pump housing starting about 3cm from the outflow on the housing... All the way up to the outflow.

Can anyone comment on what kind of impact that would have on pulling under heavy load uphill? I assume it would impact the cooling efficiency substantially but no idea really.

The water pump was definitely leaking, the seal was cooked.

Obviously that's been changed, we also did the serpentine belt and the bottom rad hose monstrosity...

Should be back on the road this week.

Hopefully that's the last of the overheat problems. I'll get another pressure test done on the cooling system and see if we've got anything showing as abnormal and hope for the best.

G

[rapidoxidationman]

The water pump housing had substantial wear on it.

There was a 1-3 mm deep wear in the water pump housing starting about 3cm from the outflow on the housing... All the way up to the outflow.

What was causing the wear? Was the impeller touching the pump housing (worn seal or bearingcausing the impeller to lean)? Or does it look like something solid was stuck inside the pump and being scrubbed around by the impeller?

The pump is driven directly off the engine so it isn't going to turn any slower and lose efficiency unless the impeller was actually not bound tightly to the shaft of the pump. Given that it's only a press fit (no key, no D shape to the shaft) then if there's something stuck in the pump that would cause the impeller to bind up then that could be a cause of low/no coolant flow.

Can you turn the pump impeller by hand and not have the drive gear and shaft turn? Been there, done that...:(

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=40784

[gary_lucas]

What was causing the wear? Was the impeller touching the pump housing (worn seal or bearingcausing the impeller to lean)? Or does it look like something solid was stuck inside the pump and being scrubbed around by the impeller?

The pump is driven directly off the engine so it isn't going to turn any slower and lose efficiency unless the impeller was actually not bound tightly to the shaft of the pump. Given that it's only a press fit (no key, no D shape to the shaft) then if there's something stuck in the pump that would cause the impeller to bind up then that could be a cause of low/no coolant flow.

Can you turn the pump impeller by hand and not have the drive gear and shaft turn? Been there, done that...:(

http://www.thedieselpageforums.com/tdpforum/showthread.php?t=40784

Interesting read, I'll take a closer look at the old pump. Could be a worn seal / bearing... Given we had a leak too.

I don't think the shaft is turning without the pump but could be I'll have a closer look.

We did put a pump in that's had it's shaft welded... So that will never be an issue now.

G

[Kennedy]

We weld them all now. Thought we could get away with not welding them for street use, but the combination of the heavy cast impeller with a gear drive (no slip) can cause issues with the replacement pumps.

[gary_lucas]

got my truck back, time will tell if the issue is reoccurring.

Link to photo of the worn housing:
https://plus.google.com/103645652808911426825/posts/VQEHwLchqcm

Also replaced the various rad hoses and the actual pump was bleeding at the weep hole.

I couldn't find any play in the actual water pump, the bearings are fine... All that... The pump and the gear appear to be solid...

G

[rapidoxidationman]

That looks more like corrosion/erosion/cavitation from coolant being peeled off the impeller by the volute. I doubt any actual contact occurred.

You did replace the two thermostats, right? That cavitation could be caused by low/no coolant flow at high rpm/temp, and that could also overpressurize the system and pop otherwise good pump seals.

Edit: Good hi resolution pic! You can really zoom in and see that there's no sign of scuffing, but it looks like it's been sandblasted. My bet is cavitation at the point in the pump that sees the greatest difference between pressure and vacuum. Literally, tiny steam implosions that will pit the metal they occur on. If you're interested: http://en.wikipedia.org/wiki/Cavitation

Edit again:
The relevant entry from the article:

Discharge cavitation[edit]
Discharge cavitation occurs when the pump discharge pressure is extremely high, normally occurring in a pump that is running at less than 10% of its best efficiency point. The high discharge pressure causes the majority of the fluid to circulate inside the pump instead of being allowed to flow out the discharge. As the liquid flows around the impeller, it must pass through the small clearance between the impeller and the pump housing at extremely high flow velocity. This flow velocity causes a vacuum to develop at the housing wall (similar to what occurs in a venturi), which turns the liquid into a vapor. A pump that has been operating under these conditions shows premature wear of the impeller vane tips and the pump housing. In addition, due to the high pressure conditions, premature failure of the pump's mechanical seal and bearings can be expected. Under extreme conditions, this can break the impeller shaft.

[gary_lucas]

That looks more like corrosion/erosion/cavitation from coolant being peeled off the impeller by the volute. I doubt any actual contact occurred.

You did replace the two thermostats, right? That cavitation could be caused by low/no coolant flow at high rpm/temp, and that could also overpressurize the system and pop otherwise good pump seals.

Edit: Good hi resolution pic! You can really zoom in and see that there's no sign of scuffing, but it looks like it's been sandblasted. My bet is cavitation at the point in the pump that sees the greatest difference between pressure and vacuum. Literally, tiny steam implosions that will pit the metal they occur on. If you're interested: http://en.wikipedia.org/wiki/Cavitation

Edit again:
The relevant entry from the article:

The thermostats got replaced first thing, also I don't get pressure on my coolant tank anymore. Used to get allot of steam and pressure when I opened it up hot.

I'll be loading it up with the 5th wheel sometime in the next 5 weeks and i'll find out pretty fast if this was the problem.

G

[gary_lucas]

So finally got it out on a real hill.. Still overheats. I was climbing sisikyou pass today and I had to pull over 4-5 times to let it cool down. 15-30 mph in 1st or 2nd and the ect was still cresting 240 and the tranny was hitting 235.

Had to pull off let it run for 30-45 minutes with the hood up. Rinse repeat.

The thermostats both got replaced last year. The ****ty kn filter box gives no isolation so when the engine heats up the filter sucks in hot air. I verified by watching on the edge insight. When I pop the hood the intake trmp drops by 20degrees instantly.

I'm in San Fran tomorrow.

Can anyone recommend a good diesel tech nearby.

That airbox has to go and I need someone to check the cooling system and possibly make some tweaks.

G

[rapidoxidationman]

Which brings us back to head gaskets:(

When you turn the truck off for the evening, is there still any pressure in the upper radiator hose in the morning?

[Kennedy]

Is your fan clutch engaging?

[rapidoxidationman]

Have you verified that your truck is actually overheating?
The guage or the sending unit could be lying to you...

[gary_lucas]

Sorry for not responding sooner. Been busy getting stuff sorted. Working in SF for a few days and needed to get my ducks in order while helping to get the little girls ducks in order with the wife too...

In order:
1) The upper rad hose is soft in the morning. We've had 2 gm techs and an experienced mechanic say that there's no problems with head gaskets so far... Of course that doesn't mean it's true... Just that there's no indication of that issue yet.
2) The fan is definitely running, but I've never been able to hear it engage, the truck is quite loud, modified exhaust, no muffler just 2 tips. So if the fan is fully engaging i may not be able to hear it. When I open the hood it's definitely running, but doesn't seem to be making much noise. so that could be an issue.

3) Both the stock indicators we're looking very hot (not quite overheat, but it's a 9500lb trailer and I shouldn't see significant heat issues under these situations). I was seeing 240+ on insight ECT (confirmed on the dash as well as can be). I've seen the Insight and the dash working together previously when the truck went into limp mode. And I was seeing some very hot transmission temperatures. Another 5 minutes would have definitely put me into limp mode and I had to pick a safe place to pull over before that happened.

In any case I left it at Left Coast Diesel in Livermore for a more thorough diagnosis, I'm working here and won't have time to really investigate it + I'm not anythign approaching an expert. There was a dealership but it wasn't appreciably closer than the diesel specialist. I'm going to have hte air box replaced with something more effective at cold air intake no matter what. The mechanics opinion was a bunk fan clutch or thermostat, but he also said the air filter mechanism was not suitable for my purposes as well (KN airbox + filter).

Thoughts, suggestions? Anyone know Left Coast Diesel? They had no BBB complaints which I'm taking as a good thing.

G

[DmaxMaverick]

If you're running under load above 2,000 RPM's, you should hear the fan when it's engaged. If you're running next to a locomotive, you'll hear it, if it's working properly. Loud exhaust won't hide it. You should also hear it for a few minutes after a cold start, especially when it's really cold (winter). The cold start noise is for comparison, as it is no indication of health when the engine is hot. If you don't hear it after a cold start, the clutch is bad. If you're getting up to 240 and don't notice it, it isn't working properly. If the thermostats are not working properly, neither is the fan clutch. Radiator heat is what causes the clutch to engage, NOT direct engine heat. So if the stats aren't opening (enough), the clutch isn't seeing the heat and won't engage.

[Kennedy]

Suggest start here: http://www.kennedydiesel.com/detail.cfm?ID=692

[gary_lucas]

Hi Kennedy, that's the fan clutch currently installed.

G

[Kennedy]

If that is the case then you will have to look at air flow characteristics, cleanliness of the cooling stack etc. That or you are missing the fact that it is engaged.

The LLY overheat can be a chronic issue for some. There has only been one sure fix that I have ever seen for the really bad ones. The second radiator addition. I don't recall ever hearing from anybody with a LLY overheating after doing this mod.

[More Power]

A week or so ago we had several days of higher than normal temperatures here in Montana - above 100 degrees F. The engine driven fan could be heard a lot more of the time, while motoring around town.

[gary_lucas]

If you're running under load above 2,000 RPM's, you should hear the fan when it's engaged. If you're running next to a locomotive, you'll hear it, if it's working properly. Loud exhaust won't hide it. You should also hear it for a few minutes after a cold start, especially when it's really cold (winter). The cold start noise is for comparison, as it is no indication of health when the engine is hot. If you don't hear it after a cold start, the clutch is bad. If you're getting up to 240 and don't notice it, it isn't working properly. If the thermostats are not working properly, neither is the fan clutch. Radiator heat is what causes the clutch to engage, NOT direct engine heat. So if the stats aren't opening (enough), the clutch isn't seeing the heat and won't engage.


That's really interesting. I would have assumed the fan clutch would work independently of the thermostats.

The diesel guy also suggested an SB cold air intake + a scoop below the bumper as a cheaper alternative to buying a lbz air intake kit.

[DmaxMaverick]

That's really interesting. I would have assumed the fan clutch would work independently of the thermostats.

Common misconception. The fan clutch is air-heat-engaged. With little or no (hot) coolant flowing through the radiator, the air passing to the clutch isn't hot enough to engage the clutch. Once the thermostats open enough, it will heat the air passing to the clutch to engage it, progressively depending on the air temperature. At 240, the stats should be full open, and the air passing to the clutch should be hot enough to cause full engagement. This isn't happening if you don't hear the fan when it's that hot.


The diesel guy also suggested an SB cold air intake + a scoop below the bumper as a cheaper alternative to buying a lbz air intake kit.

Cheaper? That's a relative term. How much cheaper is it, if it doesn't work, or doesn't work well enough? It's only a small piece of the puzzle, anyhow. You should be able to source a 2006+ intake system from a wreck for near or below that of an aftermarket kit. The 2006+ OEM system works very well, with little to no improvement from aftermarkets. An added benefit is the filter element required will be for your truck (although for a different M/Y) and commonly available, even if someone replacing it doesn't know of the upgrade. Many of them were upgraded by GM under warranty, so all or most dealerships would be familiar. If you upgrade, you can have the GM vehicle history reflect that, which may add to the trade/sell value.

[gary_lucas]

Common misconception. The fan clutch is air-heat-engaged. With little or no (hot) coolant flowing through the radiator, the air passing to the clutch isn't hot enough to engage the clutch. Once the thermostats open enough, it will heat the air passing to the clutch to engage it, progressively depending on the air temperature. At 240, the stats should be full open, and the air passing to the clutch should be hot enough to cause full engagement. This isn't happening if you don't hear the fan when it's that hot.



Cheaper? That's a relative term. How much cheaper is it, if it doesn't work, or doesn't work well enough? It's only a small piece of the puzzle, anyhow. You should be able to source a 2006+ intake system from a wreck for near or below that of an aftermarket kit. The 2006+ OEM system works very well, with little to no improvement from aftermarkets. An added benefit is the filter element required will be for your truck (although for a different M/Y) and commonly available, even if someone replacing it doesn't know of the upgrade. Many of them were upgraded by GM under warranty, so all or most dealerships would be familiar. If you upgrade, you can have the GM vehicle history reflect that, which may add to the trade/sell value.

Fair points, I'm going to try shopping around to find a stock LBZ airbox, but my initial searches we're not looking good.

WHen I looked in Vancouver, BC I never found anything at the junkyards, not too many of these vehicles end up in junk yards, or at least not quite yet out here.

I just found the price on a full replacement for the LBZ airbox and it's quite expensive... But on the same general price point of the S and B + scoop (withing a couple hundred). Generally speaking I Don't trust aftermarket so I'd prefer to have OEM stuff.

Based on what you've described I'm thinking the fan clutch (newish though it is) or the t-stats are bunk... And I'm fairly sure that the crappy K+N air box is exasperating the problem. Engine gets hot, then feeds itself hot air stays hot... etc. Fix the t-stat / fan clutch and get some cold air and it's probably ok. Possibly even cheaper to just replace all 3 and see what happens.

Does anyone know of method for testing for restrictions in the cooling system? Some way to test total flow?

Gary

[DmaxMaverick]

I know of no simple or inexpensive way to test coolant system flow. If the components are healthy, then the system should operate as designed. Unfortunately, the design didn't take a turn for the worst until the LLY. The LB7's are generally cooler than they should be, but I think that was overkill from the start. Not that I mind, but it takes a LOT to get it close to hot. I've flogged it, pedal to the metal, for 7 miles of 6%+ grade at 122 degrees ambient with 14K+ in tow, and it got "hot". Hot, at that time, was 230-ish, with the A/C on. Turned off the A/C and it settled down to 220 and stayed there. The drawback is, it's not a barn-burner in the winter, which means less heat in the cab. As with previous discussions on the matter, it isn't the heat that's the problem. The problem is the heat you can't manage. The LLY's have a issue the LB7 and LBZ's don't. We'll work the problem as best we can. I have installed a "cold air intake" system that's not really improved over OEM, but it overcomes an issue that was an issue with the original OEM system. The "Swiss cheese airbox" and snorkel removal was a solution to one problem that led to another, which I think is, at least, part of the issue with the LLY.

[Kennedy]

That's really interesting. I would have assumed the fan clutch would work independently of the thermostats.

The diesel guy also suggested an SB cold air intake + a scoop below the bumper as a cheaper alternative to buying a lbz air intake kit.

Not a fan of the gauze type intakes be it dry, oiled, or whatever. Even more I really HATE the street sweeper design of those scoops. Just watch the dust curls off shoulder from the vehicle in front of you. Your intake will be in or near this flow ready to suck it up.

I think what I might suggest is the LBZ mouthpiece and then use the Volant intake kit (without the snorkel)with the Donaldson Power core filter:

http://www.kennedydiesel.com/detail.cfm?ID=690

If you feel the need to snorkel I would add a nylon prefilter.

As for used air boxes they are so commonly destroyed in a wreck that you will seldom find one in salvage. Unfortunately, many LBZ owners throw theirs away after throwing away their money on a fancy aftermarket intake kit.

[gary_lucas]

Hrm, I'm restricted to whatever they have in stock at this point need to head back on Friday or Monday. Will give them a call today and see where there at.

WHat a massive pain in the ass, the crazy part is I did pull all those hills before the water pump started to fail. So something has gone south since then or the t-stats / fan clutch that got replaced we're defective.

I don't think it's possible to screw up a water pump install in a way that's not obvious.

[Kennedy]

Refresh my memory has the cooling stack been removed and cleaned?

Thermostats replaced? and if so GM or aftermarket?

[gary_lucas]

I blew it out with a light pressure washing and visual inspection.

Thermostats are definitely OEM / GM.

G

[DmaxMaverick]

....Or, perhaps, the condition that (may have) caused the initial WP failure is still at work.

[rapidoxidationman]

pretty easy to tell if the fan clutch is engaged just by trying to spin the fan. Like already stated, when it is cold or when it is HOT the fan should be bound to the serpentine belt and spinning in time with the engine. When the clutch is not engaged, the fan will spin more easily. Not freewheel easy, but easier than when it is engaged.

So... What does YOUR fan feel like when it's hot/lukewarm/cold?

[gary_lucas]

For the fan clutch, can't tell right now, but I'll be checking when I get the truck back. Didn't know that was how you tested it.

For DMaxMaverick: Yah, that's my real fear.

I don't think I've got a gasket issue, none of the the signs I've seen so far point in that direction. But who knows.

Oil looks good, coolant looks good. No abnormal smoke, compression tested properly coolant system pressure tested properly.

truck worked until the water pump cacked out. Confounding variables are:
* New thermostats - Are they bunk?
* New fan clutch - is it bunk?
* Hard to isolate issue, only appears pulling 9500+lbs on 6% grades 2+ miles long.
** One thing to note, the initial overheat issue from before the WP fix took much, much less time to materialize. I essentially overheated on a gentle incline. Whatever's going on now is at least 2 orders of magnitude less severe.
* I did put a couple water wetters in near the beginning of this trip when I saw some warmer temperatures on more gentle climbs.

Things that may be causing problems, but have been on the truck since it last pulled the trailer up a severe grade:
* Air box is not stock and it's garbage.
* Tuned ECM

Things that are potential unknowns:
* Non stock exhaust.

Additional info:
* Not empirical data but the truck does seem to run alternately hot and cold... Sometimes when i"m on a long gentle slope it runs 190ish... Sometimes on what feels like the same slope or just slightly steeper it seems to hit 225 - 230 pretty quickly. Take this with a grain of salt, there's no data to back this up.

[Kennedy]

I blew it out with a light pressure washing and visual inspection.




Was it in vehicle or removed? In order to get all the chaff and junk out you really need to remove the rad and IC and clean independently.

The fan clutch only knows what it sees for coil temp and if the air in that area does not get it to that temp it will not engage.

[gary_lucas]

Was it in vehicle or removed? In order to get all the chaff and junk out you really need to remove the rad and IC and clean independently.

The fan clutch only knows what it sees for coil temp and if the air in that area does not get it to that temp it will not engage.

In vehicle, I'll get it out and cleaned. Didn't look gunked up, but worth the check.

G

[gary_lucas]

So Left Coast Diesel called me back, they can't find an issue. Thermostats seem to be functioning... fan clutch is operating as expected.

Everything is looking good to them, they're going to try a pressure test and then try and reproduce the issue by hooking up a trailer and dragging it up a mountain to see what the truck does.

I've asked them to examine the cooling stack and see if it's crudded up, but he thinks the mechanic has already done that.

He warned me about the cavitation issue that I did originally have that's since been resolved.

I've definitly never heard the fan engage in the way that is described. So i'm wondering if perhaps something else in the grill is interfering with the air flow. Or maybe the radiators really are crudded up.

G

[gary_lucas]

This is the airbox currently on the truck

http://www.knfilters.com/search/product.aspx?prod=57-3047

As the ECT heats up the air intake heats up.

Even stopped on the side of the road I don't see any appreciable cooling until I pop the hood, then the intake cools down almost immediately and the ECT also cools down.

Eventually the transmission follows, but there's quite a bit of lag there.

A scoop is probably not a great idea, I see where Kennedy is going there. But at the very least that box shouldn't be open to air in an already hot engine compartment.

Other than a plugged up cooling stack (possible, but not likely) or aforementioned head gasket issue that we've ruled out at every turn I have literally no other idea.

Hopefully the shop can repro the issue on a long haul up a steep grade and get some better ideas of what's going on.

Gary

[Kennedy]

For years the LLY has been problematic for some and many factors and fixes have come out. I still say that if the cooling stack has not come out it needs to. The stuff that blocks it is in the areas that you cannot see, particularly the area of the clutch etc.

With all the fixes, the only one that I have ever seen work on a problem truck was at one time called the Rad mod V2 by TXChristopher. Chris did not have the greatest business skills and has not built these in years, but www.coolertowing.com is now doing them.

I'm not a fan of replacing the OE radiator, I've seen that proven over time to not work. Adding the second rad and electric fan seems to be the way to go.

[gary_lucas]

For years the LLY has been problematic for some and many factors and fixes have come out. I still say that if the cooling stack has not come out it needs to. The stuff that blocks it is in the areas that you cannot see, particularly the area of the clutch etc.

With all the fixes, the only one that I have ever seen work on a problem truck was at one time called the Rad mod V2 by TXChristopher. Chris did not have the greatest business skills and has not built these in years, but www.coolertowing.com is now doing them.

I'm not a fan of replacing the OE radiator, I've seen that proven over time to not work. Adding the second rad and electric fan seems to be the way to go.

I'm definitely going to blast out the cooling stack as well as put on a more effective cold air intake. Not sure what else I can do other than bring it into a GM dealership and replace the whole shebang with the LBZ cooling system as per GM's spec. I may also have a larger capacity trans / oil pan put on with cooling fins as a way of improving the overall heat characteristics of the vehicle.

Any thoughts on those 2 items (larger fluid capacity components)

Gary

[gary_lucas]

So some good news, Left Coast Diesel said they were able to at least partially recreate the issue on a really brutal hill with a vehicle trailer and a couple of cars.

They pulled and inspected the radiator and determined that there is debris in the radiator and that the radiator itself was in need of external cleaning. Their recommending replacing the radiator and I'm having them do that + power wash the rest of the cooling stack and replace the K+N air intake with a cold air intake.

Obviously the cooling system is in need of flushing too. That needed too happen as I didn't want to leave the water wetter additive in there in any case.

So progress on that front.

I will call my local wrecking yards and see what I can do about being alerted when an intact LBZ air box comes in / monitor ebay and replace that when I can do so economically.

I will post my results when I get back into Vancouver, hopefully without overheating.

[Kennedy]

The "water" side of these cooling systems tends to remain clean as a whistle. The air side plugs up with debris, but is very easily cleaned with some TLC so there is really no need to replace the rad.

Water wetter is just fine in any cooling system so I'd not worry about that.

[gary_lucas]

Yah that's my understanding. But they did say they apparently found some foreign debris.... Which is definitely not normal at all.

Who knows what the previous owner put in his cooling system though. I'll be taking a look myself later today.

[gary_lucas]

Kennedy was right. The radiator had a family of starlings living in it.

Will post pictures when I have a chance.

G

[Kennedy]

tumbleweeds, butterflies, bees, and birdfeathers I would expect depending on the operating environment.

[gary_lucas]

Problem solved.

I drove back over the Oregon i5 mountain passes with 9500 lbs of 5th wheel.

The whole run was at or above the speed limit and the main assent was about 6% for 4 or 5 miles where I kept it floored the whole time. Hit the top at about 65 mph and the outside temp was about 35.C (95f)

Ect on the insite never went above 224. The fan clutch did not noticeably engage.

Overall I'm comfortable saying the problem is solved.

G

[gary_lucas]

The offending radiator:
https://goo.gl/photos/TocR9AC9FvJUynqh8

[Kennedy]

That'll do it. I'm reasonably certain that this rad would work just fine with the air side cleaned and there's nothing wrong with the wet side.

[ToddMeister]

Yeah clean it up and put it on craigslist (hee hee)

[rapidoxidationman]

Do you have this item for sale?
I would like to pay full price for this item if you kindly will forward me your paypal address and contact informations. I am currently overseas and will have a representative of mine contact you for shipping of this item upon your satisfactory receipt of my payments.
Best regards,
Norton B Schwackingham

[gary_lucas]

Lol, I got allot of that when I was listing my DSLR camera a few years back.

G