Lost Two Gen 3 LS Engines in my 1986 C10 2WD

[Edelbrock]

The second I bought a complete vehicle from a friend which is a long story involving a broken relationship, so it was a good runner.

Lets hear more about this.

 

[shortboxin]

Saw this after my last response. If you drove them on the trailer, the injectors may not be hung wide open, but there's certainly the possibility of them having a leak that could fill up the cylinder while it's not running.

Let me clarify. The first engine was from a yard which I didn't not drive until it was in the truck. The second was driven onto the trailer, but I used the fuel system from the yard motor on the one that I drove on the trailer.

 

[shortboxin]

Saw this after my last response. If you drove them on the trailer, the injectors may not be hung wide open, but there's certainly the possibility of them having a leak that could fill up the cylinder while it's not running.

These injectors must be questionable if you've heard of this before. I never experienced this or heard of this on the Ford/Bosch injectors.

 

[TotalyHucked]

Yeah, one of my good buddies is one of 3 main tuners in my area. Unfortunately it's all too common. Not just in LS engines but anything that's sat for a while and been neglected or had trash get through the fuel system. You've just been very lucky

 

[Bextreme04]

These injectors must be questionable if you've heard of this before. I never experienced this or heard of this on the Ford/Bosch injectors.

LS injectors ARE bosch injectors. For most years volvo, GM, Ford, etc.. all used the same or similar Bosch injectors. The main issue you see with injectors is from junkyards or from aftermarket suppliers of higher flowing injectors for performance applications.

 

[Camar068]

if for some reason you pull the engine or get another one, get a cheap test stand so you can run it prior to installing. Nothing meant, just saying for the future. Test it before you install to save time/hassle.

test stand

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[shortboxin]

if for some reason you pull the engine or get another one, get a cheap test stand so you can run it prior to installing. Nothing meant, just saying for the future. Test it before you install to save time/hassle.

test stand

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That's a nice idea for having a spare engine lying around. I've got them for 5.0 Mustang motors. I did that for storage when I was parting Mustangs out. I had as many as 5 engines at a time and needed to constantly move things around.

Thing is that both engines ran fine at idle for an hour or more on multiple occasions. No indications of anything unsavory. They only had problems after I drove them. Besides, if it's a harness issue, I wouldn't be using the harness from the truck, so I wouldn't be testing it as it's going to be run when installed.

 

[Tommy L]

I have seen when an injector is stuck open, it washes down the cylinder wall to the point of hardly any compression. Sounds like a possibility here!

 

[mlparkey]

If you used the same fuel rail and injectors and are experiencing the same issue, it's possible that a couple of injectors are leaking down after shutoff. That gasoline will wash all of the oil out of the cylinder and lose the compression. Timing is either on or not.

 

[shortboxin]

Got a chance to do the compression on the engine. Definitely many cylinders affected with whatever the cause is.

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[Ricko1966]

Got a chance to do the compression on the engine. Definitely many cylinders affected with whatever the cause is.

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Are sure neither of these engines are DOD? I'm seeing or imagining I'm seeing a pattern in compression between DOD cylinders.

 

[shortboxin]

Are sure neither of these engines are DOD? I'm seeing or imagining I'm seeing a pattern in compression between DOD cylinders.

I'm buying old donor vehicles that may or may not have original engines. I will say that neither of them had the heat tabs on the freeze plugs which most wrecking yards use.

The 2004 4.8 had 706 heads and the 2002 5.3 had 862 heads. Were those used on DOD engines?

Additionally, that still doesn't explain the running great, shut off, next day turning over like no compression (really fast) and definite impact in the motor each couple of rotations. The 5.3 clatter went away after a handful of attempts.

 

[83Stepper]

Are sure neither of these engines are DOD? I'm seeing or imagining I'm seeing a pattern in compression between DOD cylinders.

Don't think DOD/AFM/VVT was available on the gen IV's until 05 iirc on the 5.3, 6.0 or 6.2L. By 07 think they were pretty much in everything, cars and trucks.

Buddy of mine is rebuilding an 03 LS 4.8L for his track car and pulled the motor apart first before dropping in into his car. Save himself a lot of money by doing this because we found cylinder #7 had a smoked piston and cylinder #5 had some ring issues on the piston. A few extra hours and about another $600 and this kid knows he's got a solid motor for when he drops it into the car.

But for both engines to be doing this, there is definitely a pattern that is being repeated here. Assume that the common denominator is going to be the use of the same parts on both engines. Start there and dive deeper once that has been either cleared or tested good. But I've never heard of an engine slipping timing and then going back into time with gear driven motors. Best of luck with the truck and the new engine bud.

 

[Ricko1966]

I'm buying old donor vehicles that may or may not have original engines. I will say that neither of them had the heat tabs on the freeze plugs which most wrecking yards use.

The 2004 4.8 had 706 heads and the 2002 5.3 had 862 heads. Were those used on DOD engines?

Additionally, that still doesn't explain the running great, shut off, next day turning over like no compression (really fast) and definite impact in the motor each couple of rotations. The 5.3 clatter went away after a handful of attempts.

This the first I've read of definite impact that went away,okay my bet is you did hydroloc it and bent rods the impact especially that went away was the piston skirts hitting the rods