I've read ina a couple of places that TBF is not an issue on early MY, specifically 16v engines. Searching the archives is inconclusive...reminds me of the interference/non-interference issue on 16v. Can anyone confirm whether there is a possibilty of TBF on early models? Tks

TBF is possible on any model, whether failure will affect the valves, depends on whether the car is interference or non-interference. Yours and mine are non-interference, so a TBF should not bend valves unless there is excessive carbon build up in there.

My P.O. said after a specialty Porsche shop serviced the car, the crank bolt spun loose while he was doing 85 mhp. The shop did rebuild the engine, I think more based on principal then actually determining bent valves.

I believe Al was asking about thrust bearing failure which I have NOT seen in an early engine , only 4 speed automatic cars . I believe you could improperly install a transmission and cause failure in a three speed . The later 4 speed cars have the ability to create a preload condition and push the crankshaft forward several theories abound as to how but all we know is they CAN ! .

I'm assuming the TBF you are referring to is Thrust Bearing Failure, rather than Timing Belt Failure?

Yes Randy, thrust bearing failure is what I'm inquiring about. I was merely using the timing belt as an example of conflicting info on early MY cars, sorry for confusion!!