Meissen's LT1 Rebuild Thread

[PoorMan]

Suxs about the motor dude.

I took a used cam and had the journals polished at a machine shop for $10.00. Made me "feel" better and its been working fine so far.

[98blackbeauty]

So Larry, If I understand this correctly you are saying no problem with a roller cam as long as it isn't scratched or worn bad. All the hupla is over flat tappet cams. I'm tring to understand all the stuff everyone is saying about the cam and it don't make sense to me. Its just a hunk or steel and as long as lobes are ok there is no issue? correct. I have not pulled the cam and the lifters yet, but will be doing that tomorrow. Then need to check cam bearings also. All the damage at this point has been to the main bearings #3, #4, seized and turned. # 1, 2, 5, didn't turn but are worn bad. Only 2 rod bearing look bad, #4 turned and #8 real bad turned and really wore the crank. Cylinder walls, pistons and rings look fine. There are some circular scratches from top to an inch down, I think we did this honing the top of the cylinder walls, #8 has 1 verticle scratch.
To the touch I don't feel any wear ridge at top or bottom of cylinder walls. Sorry for the lengthy write up but I think you can picture what I am discribing.
I am still trying to logically figure out what went wrong. The puzzle I think started with #8 rod bearing the wear is .020 to .025 in the crank journal. Interestingly the same journal for #7 looks like new. ???? Kinda thinking all this might have been there when we bought the engine. I would really be interested in hearing your opinion.

[Kwazrollinz28]

Wow this sucks major donkey dick.

can't believe all that hard work for nothing.

[bigjon88]

i cant believe 100 miles and all this happen i wanna believe it had some damagebefore..... the install...

[meissen]

Honestly, the more people we talk to the more it sounds like this engine was damaged prior to us purchasing it. People on CamaroZ28 were even saying that the 26# to 30# injector is only a 15% difference and the MAF should have been able to make up for almost all of that - the difference would have been burned out. So it sounds like the piston rings were just too worn? I don't know. There was definitely gas in the oil, no doubt about that, it's just trying to explain how the gas got there that's been our issue...

[bigjon88]

ya but your plugs were loaded with gas to maybe your spark wasnt good enough????

[Kwazrollinz28]

Hope i don't run into crap like this when i go with the 306 cam and 30# injectalators.

But should be fine, my car runs like a champ. doesnt look it though hahaha
you never really heard or seen that motor you bought run before which sucks.

[WMCC Doug]

If I understand this correctly you are saying no problem with a roller cam as long as it isn't scratched or worn bad. All the hupla is over flat tappet cams. I'm tring to understand all the stuff everyone is saying about the cam and it don't make sense to me. Its just a hunk or steel and as long as lobes are ok there is no issue?

While it is true that flat tappet cams have a different (higher) wear characteristic than roller cams, this only applies under "NORMAL" conditions. The hoopla is, should be, about the highly contaminated, metal filled oil that circulated through this engine.

That throws a whole new wrinkle into the mix. The rollers on the lifters crushed tiny metal particles between the rollers and the cam lobes. Those same fine metal particles were forced between the cam bearing surfaces and the (soft) cam bearings (as well as everywhere else inside the engine and other bearings - like the rockers).

I would make darn sure that a qualified expert examines the cam before using it again. Both the LOBES and the BEARING surfaces.

The hoopla is about the highly abrasive contaminated oil and the damage it COULD have done. (or did do.)

[1BADAIR]

the maf doesn't really compensate for much.it just tells how much air is entering. the 02's tell how the the engine is running. while the pcm can compensate some its actually not very much. The 02's are really just along for the ride at WOT . The pcm barely does anything at WOT. thats pretty much a set parameter and it doesn't take much to fuel wash a ring.
an engine with injector changes shouldn't be started or even keyed on with fuel pressure until the injector flow rate has been set.
most shops have you bring the new injectors to be installed right before tuning or your pcm is given to them to get a precal before start up

[WMCCjames]

Honestly, the more people we talk to the more it sounds like this engine was damaged prior to us purchasing it. People on CamaroZ28 were even saying that the 26# to 30# injector is only a 15% difference and the MAF should have been able to make up for almost all of that - the difference would have been burned out. So it sounds like the piston rings were just too worn? I don't know. There was definitely gas in the oil, no doubt about that, it's just trying to explain how the gas got there that's been our issue...

Exactly....I knew you'd come around

Running those injectors and a stock tune will not hurt the engine. There is enough compensation in the PCM to pull out the excess fuel....unless you were doing WOT runs from stop light to stop light.

I tuned a 383 super ram motor that had fuel running out the tailpipes and black sooty smoke from running so rich......never washed a ring, never hurt the motor.

[meissen]

Hope i don't run into crap like this when i go with the 306 cam and 30# injectalators.

But should be fine, my car runs like a champ. doesnt look it though hahaha
you never really heard or seen that motor you bought run before which sucks.

Mine literally was running like a champ when I data logged driving around for 5-10 minutes. Then I drove to woodward and it all went to shit. That's what has been the hardest thing to get over - on the way to Woodward it was running freaking AWESOME... it's amazing how fast it went downhill.

[meissen]

the maf doesn't really compensate for much.it just tells how much air is entering. the 02's tell how the the engine is running. while the pcm can compensate some its actually not very much. The 02's are really just along for the ride at WOT . The pcm barely does anything at WOT. thats pretty much a set parameter and it doesn't take much to fuel wash a ring.
an engine with injector changes shouldn't be started or even keyed on with fuel pressure until the injector flow rate has been set.
most shops have you bring the new injectors to be installed right before tuning or your pcm is given to them to get a precal before start up

Exactly....I knew you'd come around

Running those injectors and a stock tune will not hurt the engine. There is enough compensation in the PCM to pull out the excess fuel....unless you were doing WOT runs from stop light to stop light.

I tuned a 383 super ram motor that had fuel running out the tailpipes and black sooty smoke from running so rich......never washed a ring, never hurt the motor.

Haha and there's that polar opposite opinions. I don't think I ever went WOT - maybe give it 1/2 to 3/4 but never WOT.. not sure how much of a difference that would make.

[Transamsfast]

ill say this...i lost ton of power when my LT1 went.. it was soo slow it was not funny. but my engine had no shavings like yours at all.
did you ever do a compression test?

[98blackbeauty]

While it is true that flat tappet cams have a different (higher) wear characteristic than roller cams, this only applies under "NORMAL" conditions. The hoopla is, should be, about the highly contaminated, metal filled oil that circulated through this engine.

That throws a whole new wrinkle into the mix. The rollers on the lifters crushed tiny metal particles between the rollers and the cam lobes. Those same fine metal particles were forced between the cam bearing surfaces and the (soft) cam bearings (as well as everywhere else inside the engine and other bearings - like the rockers).

I would make darn sure that a qualified expert examines the cam before using it again. Both the LOBES and the BEARING surfaces.

The hoopla is about the highly abrasive contaminated oil and the damage it COULD have done. (or did do.)

OK! Thanks WMCC Doug, that clearifies or explains the issue. I was mystified by statements to "throw away the cam", "trash the cam" and had a hard time understanding where these statements were come from. We figured on replacing the roller lifters, on this rebuild. We used the original lifters on 1st rebuild. I am still trying to assess the failure as to not make same mistake again. I am still leaning towards the 1st startup and not having the tune for the injectors. excess gas thined the oil (10w30) and started the wear. That being said I am still open for ideas and assesment of damage.

[WMCC Doug]

Larry,

Ya, I agree, you need to try and figure out exactly what caused this failure, if at all possible. Otherwise, how can you be sure to avoid the same situation again?

I spent nearly 30 years as a Skilled Trades - Machine Repairman at GM/Delphi and much of my time was spent repairing/replacing damaged bearings and other components caused by contaminated lubricants or lack of lubrication. There is nothing good that come out of oil that is filled with metal particles.

Not replacing the old lifters when you installed the new cam would be an area of concern for me, however, if that was the cause, I would expect to see a much more damaged cam shaft. So that's probably not the initial source of this failure.

It sounds like the main bearings are the worst, which would make one think the failure started there. Obviously the oil wasn't contaminated with metal particles until the bearings started to let go. As they started to wear, that's when the oil contamination started to become an issue for the rest of the engine.

Therefore, there's really two questions to be answered here. One, what caused the initial failure, and two, how much collateral damage was caused by the contaminated oil in other areas of the engine.

Like James, I'm a bit skeptical that the lack of a tune caused the problem. But Fuel Injection is not an area that I consider myself to be any kind of expert in. James is much more knowledgeable in that area than I am.

On the bearing issue. Once you have the crank turned and replace the bearing inserts (both the mains and the rod bearings) you have essentially "new" components and should be fine there. If you bore out the engine, you'll be getting new pistons and piston pins. Again, new parts and elimination of old potentially damaged components. Unless a rod bearing insert was completely destroyed and damaged the actual connecting rod itself, and there is no measurable wear in the piston pin end of the rod, you should be able to clean and reuse the connecting rods without any issues. I think I would consider replacing the oil pump, just to be safe. With the crank and rod bearing damage, there was definitely a lubrication issue of some sort.

So then it's time to asses the condition of the remaining components (mostly valve train parts). You are already planning to replace the lifters, so again, new components, should be good to go. That only leaves a few parts that could have been damaged by the contamination. One, the cam shaft. As stated before, if you are not willing to replace this, it needs to be inspected very carefully, even under magnification. You want make sure that there is no degradation of the surfaces of the lobes and bearing areas. Having the machine shop polish the bearing surfaces might be a good idea.

Now, what about the rocker arms? They have needle bearings where they pivot. Needle bearings are a great place for metal contamination to get trapped, as well as the roller on the tip. I would be very careful about using these again. Have an engine building expert examine these too when he looks at the cam.

That only leaves the push rods, and they should be able to be cleaned and reused, providing there is no visible damage to the ends and are not bent. Another area here contamination could collect is the timing chain and gears. Again, very careful cleaning and inspection should do the trick.

This is just my opinion on these things, so take it as just that. You guys will need to make the final call on what direction to go. Here's hoping for the best.

I'm so sorry this happened. I sure hope things go OK this time around.