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

[shortboxin]

I'm just going to point out that 130psi on a 2002 5.3 is not OK compression. That should be 150-185psi AT LEAST.


You need to verify everything. Run compression on all cylinders. When you go to get a new motor, run compression test on all cylinders BEFORE you try to run it in the truck. You should be cranking the engine for ~30 seconds with the coils unplugged and full throttle before you start up the new engine anyways. The motor could have been sitting for years and have bone dry oil galleys. You want to pump fresh oil everywhere before starting it for real. Unplugging the coils and full throttle will put it into flood clear mode and shouldn't fire the injectors so that you can crank the engine to prime it with fresh oil.

I would also be inspecting the inside of all cylinders with a bore scope on a junkyard engine before installation and do the initial prime cranking with the valve covers off so you can see the valves move normally as well. I always send injectors to my guy on any major top end service or before putting a new motor in. It runs about $10-20 per injector to have them cleaned, flow checked, new seals and filter, and shipped back to me.

The second engine and this third engine were both running when I bought them. I drove them onto the trailers. The second one only sat for two weeks between me buying and installing. I've done a ton of Ford small blocks in Mustangs over the years and never had an issue like this. Even without doing much of anything to them most of them had 130-150k and I only ever had one injector problem and that GT sat in a field outside of Phoenix for 8 years. All 8 injectors were frozen shut. Sprayed them with Gumout carb spray and applied power to eventually clean them. Car ran great!

You guys make it sound like these LS engines are very susceptible to all kinds of issues. I'm hoping they're better than that.

 

[Camar068]

I've learned from others on the web to replace the oil pump on a used LS engine.

I'd pull it from the top down to diagnose. From the sound of it in the video, it's going to be pretty obvious.

 

[shortboxin]

I've learned from others on the web to replace the oil pump on a used LS engine.

I'd pull it from the top down to diagnose. From the sound of it in the video, it's going to be pretty obvious.

I was planning on oil pump and timing chain/gears on this motor.

 

[edgephoto]

Doing a compression check on a junk yard motor is not possible but you can do a leak down.

On your failed engine you should do a leak down so you know what the failure is. These engines are in a junk yard for a reason but two used engines failing the same way? Whatever you swapped between them is the cause.

 

[Ricko1966]

Doing a compression check on a junk yard motor is not possible but you can do a leak down.

On your failed engine you should do a leak down so you know what the failure is. These engines are in a junk yard for a reason but two used engines failing the same way? Whatever you swapped between them is the cause.

You absolutely can do a compression test on a junkyard motor,sitting on the ground at the junkyard. I've run SBCs sitting on the ground propped up with 4x4s. To compression test a junk yard engine you'll need a plug wrench a starter a battery,jumper cables,a starter and something to short the solenoid.

 

[Vbb199]

I saw somewhere the same injectors/rail is being used. Thats what im blaming.
Try a new set of them or test them!

 

[shortboxin]

Doing a compression check on a junk yard motor is not possible but you can do a leak down.

On your failed engine you should do a leak down so you know what the failure is. These engines are in a junk yard for a reason but two used engines failing the same way? Whatever you swapped between them is the cause.

It's looking that way. Only common items are fuel system, PCM, wiring harness, and throttle body.

Only the first engine was from a yard. 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. The most recent I bought complete and it was driving when wrecked, so same story. I've been using motors from scrap Mustangs for ages and I never had one problem (probably at least 20), so thinking that cars can't provide good donor engines is like saying you should never buy a used car.

 

[shortboxin]

I saw somewhere the same injectors/rail is being used. Thats what im blaming.
Try a new set of them or test them!

That's the direction I'm going courtesy of TotalyHucked. Might be the harness causing the injector to stay open though as I mentioned because it's a Chinese harness and I found a whole lot of miswires.

I hope it's actually not an injector because I ran 5.0 Mustangs with Bosch injectors for 3 decades and never had anything like this happen.

​

 

[edgephoto]

It's looking that way. Only common items are fuel system, PCM, wiring harness, and throttle body.

Only the first engine was from a yard. 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. The most recent I bought complete and it was driving when wrecked, so same story. I've been using motors from scrap Mustangs for ages and I never had one problem (probably at least 20), so thinking that cars can't provide good donor engines is like saying you should never buy a used car.

Used engines are fine. I didn't mean to insinuate all junk yard motors are no good. I meant the engine was in the junk yard so don't be surprised when one has an issue.

 

[Vbb199]

I had a guy that went thru 3, maybe 4 LS motors in a short span, some brand new; the common culprit was cheap, chinese deka 80s, but hes in denial about it for whatever reason haha

 

[Bextreme04]

The second engine and this third engine were both running when I bought them. I drove them onto the trailers. The second one only sat for two weeks between me buying and installing. I've done a ton of Ford small blocks in Mustangs over the years and never had an issue like this. Even without doing much of anything to them most of them had 130-150k and I only ever had one injector problem and that GT sat in a field outside of Phoenix for 8 years. All 8 injectors were frozen shut. Sprayed them with Gumout carb spray and applied power to eventually clean them. Car ran great!

You guys make it sound like these LS engines are very susceptible to all kinds of issues. I'm hoping they're better than that.

No one is suggesting that LS motors have all kinds of problems. We are all suggesting that when using a used engine, it is prudent to do 5 minutes of diagnostic data collection before you just slap it into a truck and drive it around. I would never try to start an engine that I didn't know how long it had been since it ran without priming first. It sounds like you drove this one, so no issue there. It also sounds like you didn't ring out the whole chinese swap harness? I'd be highly suspect of all wiring on that and make sure you track every pin back to where it is supposed to go. You can find the entire blue/green(P59) PCM pinout on LT1swap.com. It's MAYBE a 30 minute job to pull out the mulimeter and ring every single wire from the PCM connectors to the sensor it is supposed to run to.

 

[TotalyHucked]

Okay, I'm going to put the starter and flywheel back on it and run a compression test on the rest of the cylinders and post that up next week. Additionally, when I put the next engine in, I think I will remove the fuel pump fuse and check for signal on the injector on cylinder #2 to make sure it's not constantly on. I will also be running the fuel injectors and fuel rail from the replacement engine to alleviate the possibility of the injector on cylinder two being stuck open mechanically.

That doesn't guarantee success either, get one of the sets of injectors flowed/checked/cleaned before firing. I didn't do it on mine and got lucky, I've since seen enough people hydro a motor, I won't fire one without known good injectors in it

 

[TotalyHucked]

The second engine and this third engine were both running when I bought them. I drove them onto the trailers. The second one only sat for two weeks between me buying and installing. I've done a ton of Ford small blocks in Mustangs over the years and never had an issue like this. Even without doing much of anything to them most of them had 130-150k and I only ever had one injector problem and that GT sat in a field outside of Phoenix for 8 years. All 8 injectors were frozen shut. Sprayed them with Gumout carb spray and applied power to eventually clean them. Car ran great!

You guys make it sound like these LS engines are very susceptible to all kinds of issues. I'm hoping they're better than that.

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.

 

[shortboxin]

I had a guy that went thru 3, maybe 4 LS motors in a short span, some brand new; the common culprit was cheap, chinese deka 80s, but hes in denial about it for whatever reason haha

What are deka 80s?

 

[shortboxin]

No one is suggesting that LS motors have all kinds of problems. We are all suggesting that when using a used engine, it is prudent to do 5 minutes of diagnostic data collection before you just slap it into a truck and drive it around. I would never try to start an engine that I didn't know how long it had been since it ran without priming first. It sounds like you drove this one, so no issue there. It also sounds like you didn't ring out the whole chinese swap harness? I'd be highly suspect of all wiring on that and make sure you track every pin back to where it is supposed to go. You can find the entire blue/green(P59) PCM pinout on LT1swap.com. It's MAYBE a 30 minute job to pull out the mulimeter and ring every single wire from the PCM connectors to the sensor it is supposed to run to.

Actually, I did ring out the whole harness which took 8 hours for shorts every point to every point and for continuity. Never know if one short got missed. I found like 8 or 9 problems which is why I wonder if I missed one.