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All,
Car is my wife's 1994 945t. It is around 230k miles. Beyond a new turbo last year, the engine has had only normal maintenance.
At the 90 mile mark of a 100 mile trip yesterday I heard a rattle start from the car. Sounded like a fan blade just tapping plastic/metal. There was no power loss, drivability issues, or anything out of the ordinary.
Later that day I started the car to drive back the 100 miles. The most awful wail came from the engine compartment. Sounded like metal on metal, but I don't know if that's what it was. It changed tone with RPM, but not in a consistent way. The change in the RPM was what changed the tone... once it reached steady state RPM, the tone settled. Turning the AC on and off did nothing. Turning the steering did nothing. Thought that it might have been the alternator bearings.
Belts were tensioned fine, timing belt seemed OK, and temperature seemed fine. Instead of towing it 100 miles, I chose to drive it. (I had a screwdriver and no other tools)
Noise got worse driving home. It was intermittent at first. At about 30 miles it became constant. At 50 miles it became louder. At 70 miles there was a "bang" and the engine shut off. I pulled over to the side of the road. The engine would turn over without problem and there was no bad noise. (whatever was rubbing must have broken off) But, I couldn't get the engine to start. Temp was fine, oil was fine, as were the belts and timing belt. Nothing was leaking or out of the ordinary. Got a tow home (only 30 miles).
I've been guessing and checking to see if I could find/fix the problem fast. But, no luck. The sound was definitely rotary in nature. I pulled the timing cover and the belt looks pristine (25k old). The tensioner shows no wear. (don't know when I changed it last though) The timing is spot on.
The distributor and cap looked fine. (cleaned them up while I had them off, but it was just normal wear)
The turbo spins freely with no issues.
Compression is 124,128,135,136 on cylinders 1-4. I haven't done much internal engine diagnostics, but I would guess that most head issues would show up on a compression test? Cam turns when the crank turns.
The PS pump spins with no grinding noises.
So, here is where I'm at. The engine cranks over with no problem. But, it isn't starting. Still no nasty noises. I haven't checked for spark, fuel, or air specifically. Though, even if I did find something, I'm guessing it would be a side effect. I have not pulled the AC or Alternator belt to check those devices. My next step will be to pull those belts and check for spark.
Anybody have any other suggestions?
Thanks for your help!
-simon
simon.dodd at alum.mit.edu
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