sudden onset problem

[mobilevet]

** 94, 6.5, suburban, mods in sig, 275K, remote mount FSD, ***

Ok, I've searched the forum and don't really see my problem, so here goes:

Truck has been running fine for several months, so nothing to suggest that I was about to have this problem.

Was driving home from town about 30 min interstate drive cruising at 65, stopped at the end of the off-ramp and as I began to pull out noticed that the truck was vibrating badly - like when a U joint goes out. Pulled over and noticed that the vibration did not improve (apparently not due to the drive train). Drove home slowly for 5 miles and vibration did not improve. Got home, turned motor off and re-started - started fine but still vibration. (no smoke, no other outside indicators). Vibration changes little with rpm increase or decrease... maybe a little smoother with higher.

I have a mechanic that will help over phone (because he doesn't like to work on 6.5's) so called him these are the steps that he suggested and we've done so far:

1. check belt for slack (to r/o harmonic dampner) - no slack normal tension
2. remove belt and start (to r/o other belt driven problems) - no change in the vibration

(at this point he came over to my house to listen to the engine... he thought he heard a cylinder "missing", I believe he said there was a "putt").. said to crack each injector line to dtm which one.

3. crack each injector line - every injector line was cracked and a discernible drop in rpm (then rise when tightened) was heard except on the first cylinder toward front driver side (#2?) - However, even this cylinder it is possible that there was a very, very slight change - but for sure much less than the others... the cylinder beside it also sounded a little different than all the other but not as discernible.

*** disclaimer: this was an amateur listening to this ****

4. So, based on this he recommended removing the valve cover (again, driver side) to look for a valve/rocker/etc problem. This was done and nothing seemed out of the ordinary. The engine was turned over (injector lines off) and all the valves moved [strangely the engine hit once also], so the injector lines were reinstalled and the motor cranked to watch the action which seemed fine (everything moving smoothly in relation to each other etc)

5. As an after thought (and since nothing looked wrong) the top of the intake manifold was removed to view for any back-blow... again, amateur looking here, but there MIGHT have been some back-blow - but from the passenger side and from both the front and back ducts... so I'm not sure if this means anything - also the valve cover was still off of the driver side when I did this...

So this is where we are with this... still have the engine torn down and my mechanic is out of ideas....don't know what to do next to figure this out....

thanks.

[DmaxMaverick]

Good initial diagnosis. Next, determine if the problem is an injector, or a cylinder. Swap the injector that had little change during your loose-nut test with one on the other bank (#2 or #4). This is the quickest, easiest, and most telling test you can do at this point. The front/driver side is cylinder #1, and rear/driver side is #7. If you have the same result, then the problem is the cylinder, and you'll have to continue diagnosis from there (new chapter). If the problem follows the injector, then a set of injectors is in your future. If they have more than 100K on them, they may be suspect.

[mobilevet]

Well, I've been to school on this.. got a friend that works on equipment to come by and take a look:

1.) I now realize that the cylinders are numbered on the intake manifold (duh), so the previous number (#2) was wrong.. it was #1 that I was talking about..

2.) He was able to view the intake and it turns out that #8 is blowing back

So, I've gone from the easiest to get to to the hardest, but that's that... now on to pulling the other valve cover...

any tips? (I know I"ll have to pull the turbo - hope there's a trick to that...)

PS: thanks Dmax... didn't see your post earlier... sorry I got side tracked on the #1.. guess that injector could still be having a problem, so after I figure out what's up with #8 I'll have to go back and see about #1....

[Robyn]

The bottom bolts on the turbo and the manifold bolts can be reached easily by removing the RH front tire/wheel and then the rubber inner fender flap.

With the rig blocked up you can sit on your Butt and access all the goodies in there that you may need to.

This is far better than trying to fight it over the top.

Also unhook the air cleaner box, the air inlet hose and other goodies and get that stuff out of the way.

You will then have a great shot at the turbo, manifold and then the injectors or the head.

You may have lost a lifter (read this as collapsed)

Good luck and keep us posted.

Missy

[JohnC]

Go for the easy stuff first. Swap the injector to another cylinder and see if the lack of drop follows the injector or stays with #1 cylinder. The "blow back" could be a red herring.

[Burning Oil]

The symtoms actualy sound like a classic Flight systems problem they were having with a "batch" on PMDs they put out. The problem is fixed now.
I would have tried a new PMD before tearing into it. You need a spare anyway right:)

So with that said what PMD are you running and were is it mounted?

[mobilevet]

has two remote mount FSD's, both put on before I bought the truck in 08, one mounted on a heat sink and then bolted to the intake cover, the other on a heat sink with an electric fan mounted on the fire wall... have been using the one on the intake with no problems for most of the time I have owned it.

[DmaxMaverick]

If the PMD/FSD is to be left in the engine compartment, it is best to be left on the pump. Either get it out of the oven, or leave it where it was designed to operate. The intake or firewall is the absolute worst place to mount it, and the heatsink does nothing good for it. The FSD by itself can heat up to about 140° at the heat transfer. The pump, with fuel flowing, can get up to about 110°. Underhood air temps, on a summer day during a drive can exceed 150°, and more during heavy work. The heatsink will help to lower your underhood temps a little, by pushing it into the driver.

Your FSD(s) may be bad or failing, but not because of any symptom you've posted here. Look elsewhere.

[Burning Oil]

Dmaxmaverick took the words out of my mouth.
Im not saying for sure your problem was/is a PMD but the symtoms sure acted like alot of those I have heard about failing. I actually stop sell the Flight Systems PMD because of it. They are now supossedly fixed so have started selling them again.

What brand are your PMDs?

[mobilevet]

Okay, new update. Valve cover off of passenger side and no visual problems.. turned the motor over a few times and all the valves moved in rhythm. So, next we did a pressure test to check for valve leaks. Loosened the rocker arms so that both valves should have been seated, then replaced the glow plug with an old G-plug that had been drilled out in the center. Compressed air was then put into the cylinder via the modified G-plug to check for improper valve seating... no leak. The air just pushed the piston down which could be seen as the dampener turning a bit. Since #8 tested fine, I went ahead and did every cylinder - all of them tested fine (a couple were already at the bottom of the stroke so I had to do a different one first to be sure that was why the dampener didn't move initially, but even so none of them produced air via the intake or exhaust).

Sooooooo... now I'm going to pull the injectors and have them tested.

any other thoughts??

[DmaxMaverick]

Don't bother having the injectors tested. Unless they are relatively new (80K or less), complete the diagnosis as described above, or just toss them. Anything else is a waste of time and money. Your problem is most likely a LOT more simple than you are trying to make it. You are surrounded by a lot of folks with 20-30 years of experience with these things. One bad injector, and a couple others nearing life's end, can cause everything you've described, so far. Why not start looking at the most likely suspect?

[mobilevet]

hmm... okay, I am certainly appreciative for the experience and help that the board has given.. correct me if I'm wrong, but what you're saying is that the symptoms could easily be injector problems and that there is no value in testing them; instead I should just replace them.

Best I can tell the injectors were replaced at about 220k (275k now) so that would only be about 55k on them... also, I have a mechanic that will test them for free.... that's why I was going to have them tested... of course, I'm getting the impression that the testing will just confirm that they are the problem then I should replace them all around...

.. what about having the reworked? There is a place in Meridian MS that was recommended...Meridian Fuel Injection, I believe

I'm not exactly sure what you meant by "complete the diagnosis as described above"... I thought I was done.. I air tested all the cylinders and they all seemed to have good seating of the valves. Of course, we got off on the valve tangent because the mechanics that listened to the engine thought they 1) heard a valve problem and 2) saw blow-back from #8 (or the one beside it)... agreed that it could have been an error all the time...

also I agree that would be easier if I'd known the for sure problem (injectors?) to start with rather than jumping through all the hoops I've done thus far... although I have learned a lot through this..

[mobilevet]

Also, in reference to the FSD... I can see how moving it out of the engine compartment would significantly reduce the temps... can I just clip the wiring harness and splice in an extension so it can be mounted in the cab?

of course, I'll not do anything until I get it running well again first...

[Burning Oil]

Also, in reference to the FSD... I can see how moving it out of the engine compartment would significantly reduce the temps... can I just clip the wiring harness and splice in an extension so it can be mounted in the cab?

of course, I'll not do anything until I get it running well again first...

I suggest behind the front bumper using one of the licence mounting bracket holes. I would not cut the cable, just another source for potential problems later.
What brand PMD's do you have.

[Burning Oil]

hmm... okay, I am certainly appreciative for the experience and help that the board has given.. correct me if I'm wrong, but what you're saying is that the symptoms could easily be injector problems and that there is no value in testing them; instead I should just replace them.

Best I can tell the injectors were replaced at about 220k (275k now) so that would only be about 55k on them... also, I have a mechanic that will test them for free.... that's why I was going to have them tested... of course, I'm getting the impression that the testing will just confirm that they are the problem then I should replace them all around...

.. what about having the reworked? There is a place in Meridian MS that was recommended...Meridian Fuel Injection, I believe

I'm not exactly sure what you meant by "complete the diagnosis as described above"... I thought I was done.. I air tested all the cylinders and they all seemed to have good seating of the valves. Of course, we got off on the valve tangent because the mechanics that listened to the engine thought they 1) heard a valve problem and 2) saw blow-back from #8 (or the one beside it)... agreed that it could have been an error all the time...

also I agree that would be easier if I'd known the for sure problem (injectors?) to start with rather than jumping through all the hoops I've done thus far... although I have learned a lot through this..

Free injector testing! go for that, can't hurt. They can be rebuilt with German bosch nozzles and pop tested.
IMveryHO it seems like you went way to fast and dismissed checking the simple stuff first, please don't be offended. Its hard to advise you now as we would only be guessing.

[DmaxMaverick]

The "above" diagnosis was simple. Remove the "suspect" injector (#1, that indicated little RPM change during your line-loosening test), and install it in a cylinder on the opposite bank (such as #2 or #4), and install that injector in #1. Repeat the line-loosening test. If the results are the same as before, with #1 with little RPM change, then the problem is at cylinder #1. If the condition follows the injector (now at another location), then the problem is, without a doubt, the injector. The "80K mile injector" recommendation is assuming a known history of the injectors, and their condition when installed. If they "may" have been installed about 55K ago, and they are of unknown origin or quality, I would consider them a candidate for replacement. New OEM injectors have failed in less time/miles under known, good conditions. If your current injectors are OEM or Bosch (new or reman), they can be reconditioned reliably, by a good injection shop. Or, they can be exchanged for reman's from a good supplier (such as a TDP Vendor), for a little more than the cost of a local shop (most of the time, but some locals are more). If you can have your current injectors tested for free, go ahead, but after you do the "swap" test. The injector(s) may or may not be the cause, but not taking the time to do the easiest and least expensive diagnostic process may prove futile.

As far as the FSD goes, leaving it on the pump is as good or better than moving it to the cab. I know of several attempts at this, and they all ended up the same. More hassle than it was worth, and less than expected results. Unless you mount it in the A/C duct (still, on a heatsink, or fry it without), run the A/C all the time (even in the winter), and never use the heater, it might work. Maybe. Unless you live in the tropics, this isn't ideal. It's gonna get cold, sometime, and you'll want to take away that cool air in favor of warming your butt. Keep it simple..... Either leave it where it was designed to operate, or get it away from the engine compartment. Splicing the harness is hit/miss, as well. Sometimes it works, more often it doesn't. If you need to extend the harness, get an extension harness. Mount it where it can get fresh ambient air, on a good heatsink (buy one, or make one). Keep it simple.

[mobilevet]

well guys I can see the wisdom in your thinking and I appreciate the advice... in fact, both the mechanics here have already basically said that if all the injectors test "good" the only thing left is to reassemble and "start over"... I think they are hoping that there was a piece of carbon or something causing the valves "noise" that may have "self corrected".. seems like a long shot and I expect the injectors to reveal a problem tomorrow, but it's hard to second guess a guy - actually two - that work on diesels all day every day and is standing right there looking and listening to the motor.. oh, well, so far I'm just out time and I did learn a lot... I don't mean that to discount all the advice from the board, I really appreciate it... sometimes it came in just after something was already done, but even then it was good to know...

about the injectors.. anyway to tell if they are OEM or Bosch? like I said, I was just told when I got the truck that the injectors were replaced around 220k... come to think of it I may have the paperwork.. I'll look and see if it says what kind were used.

Interesting about the FSD and front bumper... I guess weather - like getting wet? - is not a big issue... I thought that the little electric fan that was put on the one on the firewall (with a heat sink also) was a novel idea to keep the air flowing and it's on the far side of the engine compartment which I guess could get some air circulation from underneath as well..??.. doesn't matter much I guess since that's not the one that has been in use. Have no idea what brand.

I guess tomorrow will tell... test the injectors, if all test well put it all back together and start over... hopefully a little smarter.

thanks again for the help

[DmaxMaverick]

OK. You got one thing right. You, and others, are standing right there, seeing and hearing what's going on. If I were there, I might agree with your current local advise. But I'm not, and am only available to offer an objective opinion according to the symptoms described.

That said.....
A failing/failed injector can make any number of noises, depending on what has failed. It can sound like a slight tick (lifter noise, exhaust leak), rattle (more lifter noise, wrist pin, timing set), slight knock (wrist pin, piston slap, broken ring, valve stem), average knock (mis-timed, vacuum pump, accessory), loud knock (broken piston, rod), to "Katy bar the door, she's about to scatter" knock. They can truly be a master of disguise.

Unless your mechanic friends have extensive experience with light duty Diesels, they may be off the mark. Maybe not. It's your truck, your time, and your money. You obviously have no sanity remaining, or you wouldn't be here, associating yourself with this bunch of GM Diesel freaks.

[Burning Oil]

well guys I can see the wisdom in your thinking and I appreciate the advice... in fact, both the mechanics here have already basically said that if all the injectors test "good" the only thing left is to reassemble and "start over"... I think they are hoping that there was a piece of carbon or something causing the valves "noise" that may have "self corrected".. seems like a long shot and I expect the injectors to reveal a problem tomorrow, but it's hard to second guess a guy - actually two - that work on diesels all day every day and is standing right there looking and listening to the motor.. oh, well, so far I'm just out time and I did learn a lot... I don't mean that to discount all the advice from the board, I really appreciate it... sometimes it came in just after something was already done, but even then it was good to know...

about the injectors.. anyway to tell if they are OEM or Bosch? like I said, I was just told when I got the truck that the injectors were replaced around 220k... come to think of it I may have the paperwork.. I'll look and see if it says what kind were used.

Interesting about the FSD and front bumper... I guess weather - like getting wet? - is not a big issue... I thought that the little electric fan that was put on the one on the firewall (with a heat sink also) was a novel idea to keep the air flowing and it's on the far side of the engine compartment which I guess could get some air circulation from underneath as well..??.. doesn't matter much I guess since that's not the one that has been in use. Have no idea what brand.

I guess tomorrow will tell... test the injectors, if all test well put it all back together and start over... hopefully a little smarter.

thanks again for the help

The PMD is made to be waterproof, so you should not have a problem. I've never had one returned because of a leak. As far as mounting fans on the heat sink it won't help when it surrounded by 190* temps, the heat has nowhere to go. Think of it like it was in a bucket of 190* water.
If you wind up needing a new PMD let me Know, check my web site if you get a chance, its all new with many more products.

I hope you find a problem with your injector/s:D
Leroy

[mobilevet]

Ha! Mav. your pretty funny... I really do appreciate the advice I've gotten off this board over the years... usually pretty spot on and looks like it may be again in this case...

my guys kept talking about the sound that they were hearing as a "putt" and associated it with something like a "burnt valve".. whatever...

interesting you mentioned the timing... I have been wondering if it could be a pump timing issue???

Also I wanted to ask the board what they considered would be a good "health checkup" for the 6.5? What sort of maintenance checks would be good to do periodically?: check injection timing? check turbo boost? etc. and maybe how often would be recommended... in my case, I have never done these things, just always started trouble shooting when there was an issue.

[mobilevet]

Ok, back from injector testing... since I don't know what an "appropriate" tester is like I'll just describe the one used: basically a manual lever pumps up pressure through a fuel line on which the injector has been mounted.. the pump has a gauge to read the pressure required to open the injector. Watching the process, the injectors would initially squirt out a fine stream of fuel and then a big mist type spray. The tech doing the test seemed to read the pressure as the mist escaped... all the injectors were about the same in the 16-1700 range. (I suppose that it is possible that the peak was higher than this as he was having to watch the injector and the gauge at the same time?)

The mechanic thought that those pressures were adequate and since all the injectors were about the same recommended putting the motor back together and seeing what it sounded like now.

More injector info: The injectors say Bosch on them and have other numbers

I also found the invoice of when the injectors were installed - although it does not specify the type of injectors, they were installed 11/2006, about a year before I bought the truck with 235k miles. At that time they cost $516 for the set.

I searched the forum and found where Robyn says that they ought to be in the 1900 psi range... what do you all think?

These are the numbers on the injectors, all BOSCH brand:

362-3 0430211054 974 [inscribed with "5" at top]
472-2 0430211054 974
862-4 0430211097 973 [has corrosion/pitting along where the word BOSCH is located]
265-4 0430211054 974 [inscribed with "8" at top]
272-3 0430211054 974 [inscribed with "3" at top]
167-3 0430211054 974 [has more corrosion/pitting along the area where the socket would engage, none below the threads
065-2 0430211054 (there was no number at this spot)
361-4 0430211054 974

I also called the guy at Meridian Fuel Injectors and he said that 2100 psi was the spec pressure and that a rebuild would run $20-$25 each... that sound right??

Thanks

[DmaxMaverick]

If his gage is somewhat accurate, those injectors are toast. 1900-2100 PSI (all within 1% of average) is the range, with 1900 being the minimum. And, they shouldn't "pee" a stream or dribble, at any time. They should "pop" and spray a fine mist, 100% of the time. They are shot. Don't spend $500+ on a set of injectors. You can do them for about 1/2 that from our Vendors (http://www.thedieselpage.com/vendors/main.htm), with unbeatable service. Stay with OEM types (No "marine" or "hi-pops", etc.). Your injectors are Bosch housings, which says nothing of what's inside.

If all the injectors were popping the same, worn out or not, they should not cause a favoring of only one cylinder. You should see some indication of a bias.

Don't worry about your timing. Unless something broke, it's right where you left it. A worn timing set can cause it to vary over time on mechanicals, but the EFI's stay timed with the crank. By the time it's an issue, it's time for a timing set. Periodic adjustment is neither required or recommended.

Get the thing fixed, then worry about periodic service.

[mobilevet]

That's what I thought... they'll all be getting R&R'd

Thanks

[JohnC]

If the injector doesn't close properly then the pump does not control the timing of that cylinder. It fires as soon as the heat of compression is sufficient to ignite the fuel already there.

[mobilevet]

Ok... injectors are done.. guy at Merdian Fuel Injection, said that the nozzles were okay and they just needed cleaning and resetting??? He said he took them apart and then reset the pressures to 2200 psi.? I can see a difference when looking at the nozzle ends - the parts up inside look nice and shinny silver again - not black... he said that he did not pay much attention to if one was worse than another.. said something about some "sticking".. not much personality so it was hard to get much info out of him.

Anyway, injectors are in an torqued... now putting everything back to give it a try...

question: on #8, it is easier to put the return line cap on the front side and push the return line on the "back" (firewall) side of the injector.... any problem with this?

Thanks.. will update again once we've fired it up.

[mobilevet]

injectors in, spun the motor to bleed the lines and it hit and ran for a second so I shut it down and remounted all the brackets and injector line stabilizers, reinstalled the turbo and now it doesn't want to start... guess there is air in the lines again... having to re-charge the batteries after today's try... guess I'll try again tomorrow..

[rameye]

search the posts for starting an airbound 6.5...plenty of procedures

[mobilevet]

Well, it has been a while (vacations and work had to be done) but some progress has been made here.. and still no answers:

Finally got all the air out of the lines (thanks Rameye for the tips)... turns out the PDM currently in use is mounted to a heatsink and the ground is also attached to the heatsink... so, since the PDM heatsink was removed from the intake top it was not grounded anymore!!! No ground no fuel pumping... however it must have been grounded occasionally because fuel was flowing intermittently.. anyway, stupid problem, easy solution.

So, put everything back together (most was already back) except the airbox and she starts fine, but still shakes.

Here is a recap of what has been done:

1. check belt for slack (to r/o harmonic dampner) - no slack normal tension
2. remove belt and start (to r/o other belt driven problems) - no change in the vibration

(at this point a local mechanic came over to my house to listen to the engine... he thought he heard a cylinder "missing", I believe he said there was a "putt").. said to crack each injector line to dtm which one.

3. crack each injector line - every injector line was cracked and a discernible drop in rpm (then rise when tightened) was heard except on #1, however, even this cylinder it is possible that there was a very, very slight change - but for sure much less than the others... the cylinder beside it also sounded a little different than all the other but not as discernible.

*** disclaimer: this was an amateur listening to this ****

4. So, based on this he recommended removing the valve cover (again, driver side) to look for a valve/rocker/etc problem. This was done and nothing seemed out of the ordinary. The engine was turned over (injector lines off) and all the valves moved [strangely the engine hit once also], so the injector lines were reinstalled and the motor started to watch the action which seemed fine (everything moving smoothly in relation to each other etc)

5. As an after thought (and since nothing looked wrong) the top of the intake manifold was removed to view for any back-blow... again, amateur looking here, but there MIGHT have been some back-blow - but from the passenger side and from both the front and back ducts... so I'm not sure if this means anything - also the valve cover was still off of the driver side when I did this...

6. Pulled valve cover off passenger side and repeated inspection process as #4 - nothing seen.

7. pressure test to check for valve leaks. Loosened the rocker arms (initially just at #6-8, then all around) so that both valves should have been seated, then replaced the glow plug with an old G-plug that had been drilled out in the center. Compressed air was then put into the cylinder via the modified G-plug to check for improper valve seating... no leak. The air just pushed the piston down which could be seen as the dampener turning a bit. After #8 tested fine, I went ahead and did every cylinder - all of them tested fine (a couple were already at the bottom of the stroke so I had to do a different one first to be sure that was why the dampener didn't move initially, but even so none of them produced air via the intake or exhaust).

And the latest tries:

8. R&R (rebuilt) injectors all around - no change

9. (for BurningOil) plugged into my backup PMD - no change.

So, after all this failed to change anything, I once again did test #3. Cylinder #1 STILL does not produce any change, while #5 (only other one I checked) does.

Doesn't this seem to point to a problem with cylinder#1?? The injectors were all redone, and even so, it is unlikely that the same one was put back in #1 anyway since I didn't label them when I took the out...doesn't that rule out an injector problem? I can see fuel coming out of the line when I crack it - that seems to r/o a pump problem????

I'm not sure what to do next.

any ideas?

[DmaxMaverick]

The ground wire from the harness MUST be firmly attached to the PUMP. Anywhere else almost always causes a problem, sooner or later. The FSD and/or heatsink requires NO ground. The PMD is internally grounded and completely isolated.

[mobilevet]

hmmm... ok, guess I mis-spoke about what that ground was to... just guessed the PMD because it was in the harness with the plug... something else to do later I suppose.. after I figure out what's giving it the shakes... I'm sure this won't be my last mistake in regard to this whole ordeal.

[mobilevet]

Since it looks like I'm in need of starting over in this diagnosis process, I'm wondering if it's time to revisit some areas that I might have breezed by too quickly on....

Is is possible that the balancer could still be the problem even if the shake still occurs without the belt on??

Also, when I first got the truck the flywheel busted - and I mean busted, it was in several pieces when it was R&R'd. That was about 40k ago... any chance this could be a problem with that old repair??

Again, I'm not a professional, but this sure feels like something is out of balance...