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Calling out to 6.2 Diesel gurus, need help

As others mentioned, the military injection pump is the same as the civilian pump so there was no reason to open it up. Most diesel mechanics won't open up the governor assembly because there's no reason to and it's easy to cause this. Thankfully it's only going to high idle (max governed RPM).

If the throttle linkage is letting the pump act like it should, then pull the pump and have it rebuilt to the 4911 specs and it will be good to go.

Also, there are no actual performance injectors for a 6.2/6.5. The ones that are marketed as "performance" are actually the ones from boat applications and do flow some more fuel but the engine can't move enough air to make use of it. Even those who have pushed the absolute limits and cranked up a 6.2/6.5 above 500ft/lbs of torque are doing it with the stock injectors.


Coming from a naturally aspirated 6.2 it probably has the original tiny pre-combustion chambers. The stock Banks turbo is a good match for that with lower boost pressures (low teens) but if he wants to go higher than that he will have to pull the heads and swap out those pre-cups to later model ones such as the 'diamond' pre-cups.
 
friend of mine who was a diesel mech for years did stuff from farm / on road / off road / rock trucks with 12v 2stroke detroits .

he use to turn up 6.2 engines for guys all the time . after the 2 or 3rd one chasing his tail on a laggy flat spot he learned any 6.2 with miles on it needs a timing chain set . after he started doing this with the pump turn up they were rocket ships from stock .

so keep this in mind timing chain stretch .
 
sweetk30 said:
friend of mine who was a diesel mech for years did stuff from farm / on road / off road / rock trucks with 12v 2stroke detroits .

he use to turn up 6.2 engines for guys all the time . after the 2 or 3rd one chasing his tail on a laggy flat spot he learned any 6.2 with miles on it needs a timing chain set . after he started doing this with the pump turn up they were rocket ships from stock .

so keep this in mind timing chain stretch .
Click to expand...

Some people are going to timing gear sets rather than the chains since they stretch so quickly on these engines. Can't hear the gear whine over the engine clatter anyways haha.
 
More good info. I'm pretty sure this engine was fresh when he started on it, but it's interesting to know the chain stretches easy on these engines.

I've passed on the info so far and found a couple Stanadyne facilities in Denver.
 
even the factory sbc/bbc gas engine oem chains stretch out . and most is in the first 5k miles or so .

thats why aftermarket say pre-stretched chain .
 
Funny,I've read just the opposite about the factory double roller timing chain & gears GM put on 6.2's,that they stretch very little and last up to 200,000 miles before they get sloppy enough to affect timing and advancing the injector pump timing helps compensate for the stretch..

I guess it boils down to which thing you believe after reading it..:dunno:

I find it strange GM designed the 6.2 with some desirable features like the double roller timing chain & gears,a 4 bolt main block,roller lifters,shaft mounted rocker arms--then put a weak non forged cast crankshaft in them..just doesn't make sense..:screwy:
 
diesel4me said:
Funny,I've read just the opposite about the factory double roller timing chain & gears GM put on 6.2's,that they stretch very little and last up to 200,000 miles before they get sloppy enough to affect timing and advancing the injector pump timing helps compensate for the stretch..

I guess it boils down to which thing you believe after reading it..:dunno:

I find it strange GM designed the 6.2 with some desirable features like the double roller timing chain & gears,a 4 bolt main block,roller lifters,shaft mounted rocker arms--then put a weak non forged cast crankshaft in them..just doesn't make sense..:screwy:
Click to expand...

That was the bean counters. When GM tasked Detroit Diesel to design the 6.2 they built a stout engine that would of been better then the 6.9 IH ford used. But it was thought to be too costly so GM cheapened it up.
 
The crank itself isn't really a weak point on these, it's neglecting to replace the harmonic balancer when it's worn out that causes most crank failures in the 6.2/6.5. Original blocks however, heh, flip a coin. Cracks in the main webs are extremely common. Not an issue with the Optimizer and P400 versions.

Oh and make sure he has that little starter brace that mounts on the front of it. It's a dinky little piece of angle iron that looks unimportant but if it aint there the starter will decide it needs a divorce from the engine, and take part of the block with it.
 
red EOD said:
The crank itself isn't really a weak point on these, it's neglecting to replace the harmonic balancer when it's worn out that causes most crank failures in the 6.2/6.5. Original blocks however, heh, flip a coin. Cracks in the main webs are extremely common. Not an issue with the Optimizer and P400 versions.

Oh and make sure he has that little starter brace that mounts on the front of it. It's a dinky little piece of angle iron that looks unimportant but if it aint there the starter will decide it needs a divorce from the engine, and take part of the block with it.
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Fluidampr harmonic balancer.
First mod i made when i got my m1009.
(Balancer, water pump, ip pump, lift pump, radiator all at once)
Incidentally, my 6.2 had 93,000 onnit and pretty sure the timing set was original.
Timing chain was pristine and showed very little slack.
So i left it alone.

But that harmonic balancer is really important for the survival of the crankshaft.
Lee Swanger of the diesel page goes into depth on the subject.
 
I'm terminally late here, but if you put the IP cover on straight the shutoff solenoid linkage won't engage (problem #1), and being in the wrong spot can cause it to push against the throttle linkage (problem #2). Seems straightforward to me. But I've been staring at mine a little too much lately. :rolleyes:

You set the cover down behind where it goes, and then slide it forward until the three holes line up. This will compress the spring on the solenoid linkage so it pushes on the right lever inside. If you push it straight down it sits behind the lever and locks it in the running position.
 
I strongly recommend the CUCV manuals to anyone owning a 6.2 or 6.5 truck. Almost everything is directly applicable to civilian trucks, too. Not sure if IP rebuilds are covered by the factory manual.
 
Ok gents...Here's an update back from my buddy with the problem child. Got a little more detail that might help going back to the beginning.

The engine in question was pulled from a 90 military Humvee. Since he knew the 84 pump and injectors worked, he put them in the 90 engine. The performance was doggy and he did some research to find the 90 injectors and pump were higher psi (again what he found) so he put the 90 injectors and pump back in while swapping the parts off of the top of the pump (electrical connections and shut off solenoid) since the 90 was 24v. That's when he restarted it the engine rev'd and would not shut down.

He did go on to say that whatever shop he sent it to said they checked the parts he swapped on and said they were ok. He didn't say it was a Stanadyne shop though.

I still can't help but think the move to swap the 84 parts onto the 90 pump is the root of the problem as the 84 pump never caused a runaway. I'm not sure the shop that checked out the pump this last time may not have even checked what he did there.
 
Assuming that he has the throttle linkage installed correctly, he needs to take it to a different pump shop that will test more than just maximum flow. The governor was put back together incorrectly on the injection pump.

Swapping the injectors can't cause this problem.
 
red EOD said:
Assuming that he has the throttle linkage installed correctly, he needs to take it to a different pump shop that will test more than just maximum flow. The governor was put back together incorrectly on the injection pump.

Swapping the injectors can't cause this problem.
Click to expand...
10-4. Time for a new pump.
 
ZooMad75 said:
Ok gents...Here's an update back from my buddy with the problem child. Got a little more detail that might help going back to the beginning.

The engine in question was pulled from a 90 military Humvee. Since he knew the 84 pump and injectors worked, he put them in the 90 engine. The performance was doggy and he did some research to find the 90 injectors and pump were higher psi (again what he found) so he put the 90 injectors and pump back in while swapping the parts off of the top of the pump (electrical connections and shut off solenoid) since the 90 was 24v. That's when he restarted it the engine rev'd and would not shut down.

He did go on to say that whatever shop he sent it to said they checked the parts he swapped on and said they were ok. He didn't say it was a Stanadyne shop though.

I still can't help but think the move to swap the 84 parts onto the 90 pump is the root of the problem as the 84 pump never caused a runaway. I'm not sure the shop that checked out the pump this last time may not have even checked what he did there.
Click to expand...

Having 100% good parts doesn't prevent him from jamming the linkage when he puts the cover on incorrectly. Did you ask him about his installation technique?

Bench-checking the shutoff solenoid is just a matter of seeing that it cycles when power is applied. Pretty easy to do at home.
 
campfire said:
Having 100% good parts doesn't prevent him from jamming the linkage when he puts the cover on incorrectly. Did you ask him about his installation technique?

Bench-checking the shutoff solenoid is just a matter of seeing that it cycles when power is applied. Pretty easy to do at home.
Click to expand...
Yep, there should be a very audible click.
But would an improperly installed shut off solenoid alone, cause the engine to race up to governed speed?
 
ZooMad75 said:
10-4. Time for a new pump.
Click to expand...
100% agree.

The beauty of diesel is that when you've got compression, the problem is either fuel or fuel. Working backward from the combustion chamber, the injector is only a poppet valve and relies on the pressure spike from the IP at the appointed moment in the pump's cam ring rotation. The IP modulates flow and pressure to the injectors, and it's the only component in the system to perform this function. The filter is a flow restriction, and a lift pump is really just a low pressure fuel supply to the IP, and as Ethan as proved a handful of times, the IP is capable of drawing its own fuel supply.

The basic mechanical workings internal to the current IP are not operating correctly. Aside from being able to return the 90 pump to its original condition (if he took notes and photos, it's feasible), the test is to either install and test a known good pump, or to have his malfunctioning pump evaluated by a Stanadyne authorized diesel shop. Since both of these require removal of the IP, I'd favor the latter and save on FelPro gaskets. I suspect they'll discover the governor assembly is not according to Hoyle, and they won't have to do a full rebuild to correct it. Also, that 90 pump is a good one for NA operation.

David
 
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K5wrench said:
Yep, there should be a very audible click.
But would an improperly installed shut off solenoid alone, cause the engine to race up to governed speed?
Click to expand...

Governed speed? Not necessarily. If it jammed against the adjacent linkage it would bump up the throttle, which could produce those symptoms. It doesn't take much of an advance to get an unloaded 6.2 to its rev limit.

I have no guarantee that this is what happened, but it's feasible. I can be reasonably sure the cover wasn't installed correctly if a perfectly working pump suddenly stuck in run mode. That's a really easy mistake to make, and one that gets a special warning in both the CUCV and Stanadyne manuals.
 
Counterintuitively, the linkage in the fuel bowl defaults to run position. The only thing pushing it closed is the return spring on the shutoff solenoid. The solenoid is actually just pulling against its own spring, it doesn't push the linkage to the run position. So if the cover isn't in the right place, with the right lever engagement, it will stay in the run position.
 
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