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Discussion Starter · #1 ·
Hello all first post here
I have a 6.2l in a k3500
I've added the inj. Pump and manifolds and turbo to it.

Seems to run fine slight miss at varying rpm.
I've notice fuel will dilute my oil in short order.
I notice little smoke on start up but almost none any other time.
I'm looking to diagnose the different scenarios that will allow fuel into oil.
Roughly a qt of fuel per 100 miles drive time...

Could it be injector or multiple?
Or could it possibly be valvetrain issue?

The 6.2 sat for a number of years before running again.
And upon first start I had a thumping through intake...I assume was a lifter/valve issue...
I treated it to a engine flush and developed a light tick I believe
The thumping is gone now but I have that random miss and fuel diluting oil too quickly resulting in low oil pressure and saturation of rubber oil cooler hoses to the point one got soggy and blew out..

Sorry for the long thread but I'm scratching my head as to where to start digging...any thoughts?
Thanks in advance
 

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Welcome to DieselPlace

What year is your k3500?
Any other mods?

The issue could be related to the injector(s) leaking or it could be that a piston(s) may have a crack.

Any excessive blow-by?
 

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Discussion Starter · #3 ·
It is in a 2000 year classic body truck...
Only mod is vacuum pump delete and a turbo master..
I didn't notice any cracks in pistons when I had oil pan off but did not remove the heads..
Almost no blow by when I pull the oil filler cap off.
And I thought injectors but there almost never any smoke other than after a long drive and going to park it will have unburnt fuel until the engine catches up then back to no smoke.
Wondering about front inj pump seal leaking into timing cover? Or a valve train issue as I noticed upon initial start up I had that thumping like a partially open valve....noise is gone now but I developed a tick some where I believe....(hard to tell over the normal diesel engine "rattles")
 

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Discussion Starter · #4 ·
Also should add that I'm unsure of valve issue because the oil stays super clean throughout all this run time until it thins enough I change it in fear of further damages....seems it would be sooty oil if combustion gas was pushing fuel back into system?
 

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It is in a 2000 year classic body truck...
Only mod is vacuum pump delete and a turbo master..
I didn't notice any cracks in pistons when I had oil pan off but did not remove the heads..
Almost no blow by when I pull the oil filler cap off.
And I thought injectors but there almost never any smoke other than after a long drive and going to park it will have unburnt fuel until the engine catches up then back to no smoke.
Wondering about front inj pump seal leaking into timing cover? Or a valve train issue as I noticed upon initial start up I had that thumping like a partially open valve....noise is gone now but I developed a tick some where I believe....(hard to tell over the normal diesel engine "rattles")
So you have a 6.2L engine in a 2000 k3500 that would normally have been equipped with a 6.5L engine ?
 

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Discussion Starter · #6 ·
Yes I added the crank trigger wheel /timing cover/ds4 injection pump/ turbo to accommodate computer
 

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The injection pump has 3 seals between the diesel fuel side and the timing gear. Between the two fuel seals is a weep hole to indicate a primary seal leak. This weep hole could be plugged with insect debris.

If the engine oil has a quart of diesel after 100 miles, it is probably the injection pump drive shaft seals. That is far too much for injector leak down, if you pull the glow plugs, a leaky injector will show soot wetted with diesel.
 

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Discussion Starter · #8 ·
Ok I will try and pull glow plugs today...it should be all of them being wet correct?
And what if there isn't much soot
It's a recently built engine...not much soot anywhere else so far.
Also if those seals were leaking wouldn't I have air in system after sitting or maybe only leaking when running?
I measured exhaust temp yesterday #7 cylinder seems to be about 25-30 degree colder than the rest.
Is this any kind of clue to a valve train problem
I.e. Is it possible a intake valve isn't closing all the way and also in op due to some lifter/pushrod/arm issue?
Could that blow enough fuel back?

I'd suspect alot of blow by in that case wich I have almost none.

Thanks for the tip I was thinking the pump but being high pressure wouldn't it fill crank case full rather quickly?

Thanks in advance
Joe
 

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Glow plugs should be dry, if wet with diesel, it means improper timing, compression or injection.
Pull #7 first, it might be that injector
 

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Discussion Starter · #10 ·
Ok I was wondering about if timing was too far off to the point it let's residual fuel in oil ?
I manually adjusted pump until it ran best..
Borrowing a tech 2 from a friend when I get back to working on it...
And is it possible that one injector could dump that much fuel with little to no smoking?
I'm fairly familiar with diesels and this one's got me scratching my head lol.
 

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Discussion Starter · #11 ·
Also is there a way to tell if that injector is bad without sending it off or maybe just swap it with another used one?
 

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Also is there a way to tell if that injector is bad without sending it off or maybe just swap it with another used one?
You can make a pop tester out of a bottle jack and test them yourself. Look on Youtube for a "How to" video
 

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Discussion Starter · #13 ·
Hmm I'll have to look into that I wonder how many psi they pop at...
They are the 6.2 injectors
 

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Mech fuel pump leaking by if still installed?
 

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Discussion Starter · #17 ·
Ok I think I'll start with #7 investigation as it does have a miss sometimes once the torque converter locks up its most noticable
 

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Discussion Starter · #18 ·
Also...macdaddyof9
Would one or 2 cylinders misfiring be enough to let fuel by or more the inj. Pump timing?
 

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1997 GMC K3500 dually 4L80 4x4
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Also...macdaddyof9
Would one or 2 cylinders misfiring be enough to let fuel by or more the inj. Pump timing?
One cylinder misfiring would be enough to put that much fuel in the oil. If you ever run the motor with a glow plug out ( wear hearing protection) you'll see how much fuel each cylinder gets.
 

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Discussion Starter · #20 ·
Ah I see I think I'll investigate my valve train first because of the popping noise upon first start up I suspect a lifter /pushrod/rocker arm issue causing a total misfire or partial?
I have a set of injectors spare too with unknown miles is there a good way to clean them prior to throwing them in lol?
 
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