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MYSTERY SOLVED - not oil over-pressure.
For a quick review, the engine in my '87 5K TQ died just before
Christmas. No apparent reason, but the valves and pistons had intimate
contact, to the detriment of all parties concerned.
I finally figured out what caused the valves and pistons to get together.
Up to this point the only observation that was even remotely possible was Phil
Payne's quote from the Audi text regarding oil-overpressure. This is a rare
instance, but was within the realm of possibility. BUT, for this to have
happened, the oil relief valve should have been stuck, it was as free as it
could be. I had been assuming that it must have freed itself while I was
removing the engine from the car.
Now I know better. I am in the process of completely disassembling the
thing for possible overhaul and reuse. (And I did not want to rebuild it
without knowing the source of the problem. Why rebuild if the problem is
still there?) I took the four small bolts out of the harmonic balancer and
removed the timing belt gear. That's when I found the incrimnating evidence.
The key stock had been chewed up! So the engine must have gotten out of time,
thus allowing the valves to impact the pistons.
The engine APPEARED to be in time since the t-belt gear and harmonic
balancer were still in the same physical relationship. I don't think I
checked the location of the timing mark on the flywheel - just the
distributor, cam gear, and balancer. So I completely missed it up front.
I am assuming we didn't get the torque right when we changed the timing
belt last spring. Every one of you can rest assured that I won't UNDER
tighten this bolt again. We have three of these cars now and I'm negotiating
for a 4KQ with an I-5 as well, so the lesson is very well learned.
Later this evening I'll check the crank to see if it was damaged. If
not, I'll be making plans to rebuild the engine.
Many thanks to all of you who sent suggestions. Add this one to the
Imperial Potentate, Bucksnort Quattro Club (Un-Inc.)