2000 C2 Dying Engine Problem, Next Steps

[brwilson]

Ran a second track day this Saturday. I am a novice, but I could tell the car did not seem to have its normal power after the first session. Second session, check engine light flashed several times when I was coming down the straights. I pulled off track but the light was off. Durametric said code was for misfire on cylinders 4 and 6 (I think) and a warning about damaging the cats, but still, no lights. I cleared the codes, decided quit for the day and to drive into town for lunch.

 

Engine was driving very rough for about a mile, seemed to be delayed coming off the revs and throttle—would spin for a moment coming off throttle, and really started to loose power. I slowed way down and tried to limp it back to the track for some help.

 

Then I noticed some grinding and knocking noises—knocking like ping/rattle of a diesel luging in a way-too-high gear. I pulled over, and things just got worse, really loud mechanical knocking, then it died.

 

I tow-strapped it to a track shop and started it up, but it really started to knock LOUD, more like something hitting. I killed the ignition after about a second an decided to not start it again.

 

Got the car home, no water in oil (dipstick?), no oil in water (at overflow?), no CEL and no codes stored in memory per Durametric. Dual-row IMS bearing was replaced with LN bearing 45k miles ago.

 

I’m not sure what to do next. I am too afraid to run the motor to diagnose. Drop oil pan? Drop motor? Tow to a shop? Punt?

 

 

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[JFP in PA]

Pull the oil filter and check it for debris.  If you find any, check to see if it is ferrous (attracted to a magnet).  If you find ferrous debris, you have a major issue, if there is none, I would start investigating the noise further.

[wizard]

If you Google 'sound of knocking con rod', that should enable you to rule that in or out .... without starting your engine, of course.

 

[brwilson]

At first the sound was more of a misfire, then the grinding (like road noise or but with engine speed) then the diesel ping/rattle, then the loud knocking—like the rod knock or piston slap examples. This all developed in less than a minute over the course of a half mile, and I couldn’t hear from outside. When I started it at the shop near track the owner/mechanic (a BMW guy) was shocked at the sound.

I can repair most things on my car, but I don’t have the time, tools, or space to do much regarding the engine at this level. This is the one thing I worried about.


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[wizard]

Firstly, my apologies to JFP for butting in. I really must read before positing.

 

As he says, what is in the oil filter will provide an indication as to how serious it is. 

[brwilson]

Filter will be first. I have the magnetic drain plug, which I may check next, and probably even drop the sump plate.

In the past, I have found a few tiny pieces of plastic in the sump, and a few specks of aluminum or other non-ferrous metal in the filter. They never concerned me before as they were very few and tiny.

My fear is that it may have lost part of a chain ramp or some other vital in the timing chain path that caused the misfire codes in bank 2 and engine knock, then a chain slackened and skipped teeth allowing the pistons and valves collide. But I am making this stuff up and have no idea what I’m talking about.


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[JFP in PA]

36 minutes ago, wizard said:

Firstly, my apologies to JFP for butting in. I really must read before positing.

 

As he says, what is in the oil filter will provide an indication as to how serious it is. 

 

No apologies necessary

[brwilson]

Someone might find this interesting...

[Ahsai]

Sorry to see that. There are a few options but none of them are pleasant :(

 

If you plan to keep the car forever, you can rebuild and upgrade the engine to 3.6L. It makes no sense if you just repair/rebuild it and then sell it. May as well sell it as a roller.

 

You can roll the dice again with a used engine but the risk is high that same thing may happen again.

[brwilson]

I am investigating rebuilding, but as you say, unless I plan on keeping the car for a while it is not worth it. The car really only has value to me at that point since it isn’t a perfect car. Honestly, I didn’t pay much for the car, but have spent a lot of time and effort fixing little things that probably don’t matter, but I would just have to start over with a different car. Maybe my car, with a solid rebuilt motor would ok for a few more years.


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[Ahsai]

The problem with a solid rebuild motor is it's $15-20k so unless the car has sentimental value to you or you plan to keep it for a long time...

[brwilson]

I could probably find a rebuild I could live with, but having had the taste of the track I would be on a slippery slope to necessary replacements and upgrades that would definitely exceed my budget.  I may not be comfortable pushing the car again which would completely defeat the purpose of ownership.

[Ahsai]

I can see that. The price I mentioned was just for a reliable build for DD. A track-ready engine will be more $$$.

[brwilson]

Talking with a local engine builder here in town over the phone, it looks like the gold flakes are a failed connecting rod bearing.  It most likely failed due to high cornering Gs that starved the engine of oil, probably damaging the rod and crank.  I guess an upgraded baffle may have prevented this. The earlier misfire codes were troubling, but may have been the AOS being overwhelmed and spraying oil into the intake, momentarily fouling the plugs on that bank. I guess can happen if the car is topped-off with oil while tracking, which I did--he recommends running the oil on the low side when at the track.

 

Makes sense to me, but we would have to pull apart the engine to fully diagnose.

Edited October 31, 2017 by brwilson

[brwilson]

A second opinion from another builder confirms that the AOS probably failed, but he disputes that there was starvation.  He says the engine has weakness in the rod bearings that does not allow enough oil at high rpm, and the AOS failure probably caused some hydro lock that exerted too much pressure on the pistons. Lots of opinions.