possible severe engine damage - would appreciate diagnostic advice

[Maxodus]

Originally Posted by seningen

I'm all for more knowledge -- my questions are not questioning your opinion
just seeking more information:

What experiences have you had with broken valve springs?

What is the sound like on an M96 engine?

Why is the "S" a factor in your decision.

thanks,

mike

Yeah sorry i forgot to elaborate - it's a friend of mine, who has a 2003 S model that exhibited the same symptoms. It's definitely weak having only one data point, but sometimes i just go with my gut feelings~

[seningen]

Originally Posted by Maxodus

Yeah sorry i forgot to elaborate - it's a friend of mine, who has a 2003 S model that exhibited the same symptoms. It's definitely weak having only one data point, but sometimes i just go with my gut feelings~

My mech/shop partner is deaf but is very skilled rebuilding M96 engines

I help out by being his ears, i have not had the chance to hear a broken valve spring before.

Mike

[Lil bastard]

If I'm reading this correctly, the OP has now turned the motor over a 3rd time at least.

If you keep doing that, the sympathy quotient is going to rapidly drop to ZERO!

These are expensive motors. Until you have a competent, qualified person look it over, leave it be. For your own sake!

Good luck!

Cheers!

[Fluellen]

Another update.

Spark plugs looked okay, albeit a bit sooty for my taste. 19 Kmi / 3.5 years on the plugs. Perhaps I need to look into the O2 sensors...

Plug #1 was noticeably loose, perhaps barely hand tight. My hypothesis is that this plug was never installed tight enough and loosened due the recent extremely cold outdoor temperatures around here. This perhaps could explain the clattering.

Compression test yielded good consistent numbers (>140) across all cylinders.

I installed new spark plugs and started the car. Smooth idle. Slowly reving up to 2500 rpm, there were no noises.

I can't do a road test at this time, because I discovered that my rear axle boots are torn and need to be replaced. They were fine four months ago; perhaps also a victim of the cold temperatures.

For now, I am hopeful that this could be the happy ending to this story... we'll see.

Thank you, everyone, for your helpful advice and suggestions!

[Fluellen]

Originally Posted by Lil bastard

If I'm reading this correctly, the OP has now turned the motor over a 3rd time at least.

If you keep doing that, the sympathy quotient is going to rapidly drop to ZERO!

These are expensive motors. Until you have a competent, qualified person look it over, leave it be. For your own sake!

Good luck!

Cheers!

I agree that the first restart after the noise was reckless. No doubt about it. Subsequently, however, I think I took reasonable, calculated risks.

But it perhaps doesn't make much sense to discuss individual risk perceptions. I started this thread to ask for diagnostic advice. What would have been the diagnostic plan that a competent, qualified person would have followed?

[Dale_K]

The compression numbers certainly seem to be a good sign. Kind of rules out piston/valve contact. Did you figure out where the oil leak is coming from?

[Jake Raby]

The M96 is known for broken valve springs.. That could be the issue. A compression test and leakdown test would be the first diagnostic that I'd carry out.

[Gilles]

Originally Posted by Jake Raby

The M96 is known for broken valve springs.. That could be the issue. A compression test and leakdown test would be the first diagnostic that I'd carry out.

Jake,
Since a broken spring will affect the leakdown test, does this means that the M96 heads have a single valve spring on each valve?
.