Hopefully these images won't scar anybody too badly, or give them nightmares, but I'm hoping to get some thoughts on what may have caused this.

I'll save everybody the lengthy history, but basically after experiencing some issues with the engine (smoke out of valve cover breather, and eventually a REALLY rough idle) and doing compression & leak down tests, I decided to pull the thing out and have a look. I was pretty certain that it was a ring problem and with 100K+ miles on the engine figured I'd probably need to have it bored, so I just yanked the engine out instead of screwing with in while in the car.

Anyway, here's what I found in #1 (?) cylinder (by the timing end of the block):









One thing worth mentioning is that when disassembling the engine I found the bottom half of the intake to turbo coupling had slipped off. I'm pretty sure this had happened fairly recently as I had also done a boost leak test not long before the compression test.
I had also changed the plugs around the same time. And finally, I was having some issues with my MAF around then as well and had taken it off to clean, etc. The HKS air filter had not been doing it's job (no huge surprise, I guess) and some fine dirt was definitely getting in there. Kind of random bits of info, but may be related. Oh, and my turbo, intake pipes and IC all had oil in them. ouch....

So, I'd love to hear any thoughts on what may have caused this. I'm guessing the combination of dirt getting into the engine, and the massive amount of blow by that was being recirculated into the intake were major factors (duh). This, along with the MAF problems would make it run extremely lean I'm guessing, possibly causing the cylinder to get really hot and melt? Or perhaps debris got caught up in the upper ring, breaking it and then combustion actually took place in the ring groove itself?

On a positive note, I now have the excuse I need to build the engine. I don;t know how much it matters at this point, as I plan to replace most things that could be the cause of this, but I'd like to know if there is anything in particular I should look for to make sure I avoid a repeat of this once I get the new internals in.

Oh, it looks like I'm going to have to sleeve the cylinder, so if anybody has experience or advice on this, I'd love to hear your thoughts.

Thanks!

 

I just got a little sick in the stomach.

Now you'll have the opportunity to build that stroker you always wanted

 

Yep, pretty hard for my wife to argue with this one.

I plan on going with a 2.3 but am just starting to look into the 2.2 option with the 94mm stroke. Don;t see many of them but it seems like it may be a nice compromise. Look for a build thread in the near future.

 

did you check the turbo? does it have any excessive shaft play?

 

Stock tune, pump gas?

 

damn ur motor mustve had like no compression lol. it looks like the crank had a little play somewere in there. or watever was in your oil really did some damage

 

I haven't measured against spec, but there is definitely some play there. If I had to wager I would say it's excessive. Are you thinking of this as a cause or just something to check on?

Running on 91 (yuck). The original owner (friend of mine) had it tuned at a shop years ago. After I finally got a look at the maps I wasn't impressed. It may have "pruven" to be the downfall of the engine.

Actually, there was quite a bit of knock across the top half of the power band, but I was never sure if it was real or not. I had installed a solid hub clutch before I started logging, so I half convinced myself it was vibrations being transferred from the tranny showing up as knock. I've been planning to retune after some new bolts ons, but apparently planning to do something won't stop bad things from happening.

Yeah, that cylinder was at about 100-110psi. Funny thing is that it was still running "ok" at the time of the test. It got MUCH worse about a day or two later.

When I did the compression test and finally poured a little oil in to make sure ti was a ring problem, I may have poured a little too much in. Is it possible that that on the compression stroke the compressed oil could bust a ring?

 

i dont think it would build to much compression. if anything it would maybe stop ur spark to the cylinder iff there was to much oil

 

Oil is bad to have in the chamber, lowers octane considerably. Most will burn away after warmed up.. but it probably left a carbon deposit in the ring that got hot enough to preignite. You see how it was blown out.


Is that the worst bearing shown on the bigend pic, doesn't look more than scuffed

 

That would make sense. Fits well with the sequences of events. Hard lesson to learn.

That's not the worst. Just included it because it was the same cylinder. Here's a few others:















You can see some pretty good lines in some of them. Don't have pics but the thrust bearings looked ok & the crank seemed pretty tight in there.. no obvious play.

 

That piston is rough bro.

 

Well my theory, take it or leave it is this; you probably ran lean causing detonation leading to that cracked top in the piston. When you ran lean you could have cracked the top ring allowing oil/fuel and air to get into the ring landing there and ignite. Especially if the oil got in there, then got hot enough to burn or detonate then you could have had the issues with the mini combustions in the ring landing shown here:

and


After seeing all of this, you had two major problems, the detonation in the piston ring landings and the destruction of the piston, but also the bearings. What is up with this picture:

At the top of that cylinder, is that a deep gash in the wall or just some discoloration? Almost all of your cross hatching is gone and you have serious cylinder scoring from the piston moving and the rings being toast. This most likely led to the bearings damage, also. It could also account for the crappy idle, with that much free play in the piston traveling through the cylinder you 1) scored the walls and 2) destroyed the bearings.

I hope that isn't a gash because you would have to put a larger bore on the piston to just try and get to unmolested metal. If it is a gash, then you could also consider a foreign object got in there and led to some of the damage, but I think my previous guess was correct.

How did the head look? You have some overhaul to do on this bad boy.

 

First off, thanks for the comments guys... I appreciate it.

buchnerj, you're story sounds about right on. The intake/turbo coupling coming off would be allowing much more air into the engine than the ECU thinks is there, giving a very lean mixture I guess? As C6C6CH3vo says, the oil in there may have compounded the problem.

As for the cylinder wall, yes that's a deep gash. A quick measure has it about a mm deep. It was located in the same area as the crack/blowout in the ring landing, so I assume it was from the combustion that took place in the landing.

So, I think 86mm is about the limit for bore diameter on these engines, giving me .5mm to recover a smooth wall, which I don't think will cut it. Looks like a new block or sleeving it are the only options. My bank account tells me a new block is probably not going to happen, so I guess a sleeve it is. I'd love to hear from anybody who's had experience with doing this.

Probably a stupid question, but is it not possible to just build up the gash with a weld and then work it down even with the wall?

 

I have never heard of anyone using a weld or anything to fill in the holes as a measure. With all of that heat and compression going on in there the last thing you want is that weld breaking loose and then bouncing around in the cylinder. You could take that block from new to screwed in no time flat.

I have never sleeved a block either, so I wouldn't know about the prep or needs. You could also do a stroker motor and switch it up to a 4g64 and save a little money. That way you have a new core, fresh internals and are ready to rock. On a side note, you weren't using meth or anything, were you? How was the tune (if it had one)?

I'm sorry to say, but most of this probably could have been prevented with a wideband and just even taking a look at it. It would have shown your AFRs were really lean and alerted you to the problem most likely before the cylinder wall damage took place. For your new setup, I would invest in a WBO2.

Hope this helps. Let us know how it turns out!

 

Yeah, I didn't figure the weld would be a smart idea. Wishful thinking.... I have a machine shop here who says they can sleeve it for me, but I may still look into the 4g64. Seems to be a popular option.

As for the tune, the previous owner had it tuned at a shop. Like I mention above, when I finally pulled the maps, they weren't that well done. And no meth or any of that craziness. Was fairly lightly modded actually. Intake, IC pipes, walboro & boost controller.

And yes, a wideband will definitely be a part of the build. I think I may hook it up to some flashing lights and an air-raid siren so this doesn;t happen again.