Porsche Newbie Buying Question: When to rebuild engine/transmission?
 

Am looking to buy a 1983-1990 used 911, probably with high (100K) miles to keep the price down around $10-18K for use as an autocross and fun car.

My question is: at what mileage do 911's typically require their engine and transmission rebuilt, and how much does this typically cost?

Hey, Welcome to the forums,
The '84-'89 Carrera engine is pretty much indestrucatlbe with the exception of one issue. Valve guides. Once the engine starts burning a quart of oil every 500 miles(new engine burns roughly 1 quart per 1k), chances are the valve guides are worn. A top end rebuild is roughly $3500-$4000. Many suggest to rebuild the entire engine if it has well over 150k miles or so. Personally, I believe that the bottom ends are strong enough to go for at least 200-250k miles due to a local club racer's '81 911SC that went over 330k miles without a bottom end rebuild. The gentleman who owns this vehicle also owns the most reputable Porsche shop in Las Vegas(Carl's Place) so you know the car was serviced correctly. A full engine rebuild done by someone who knows, is upwards of $7-$8k depending on what is replaced but, it can be as low as $4-$5k.

The 84-86 cars had the less robust 915 transaxle which people seem to either love or hate. I own a 915 and it is great. 915's do not shift 1st to 2nd as fast as the later g50 box but, it is a much more raw and positive feel. The clutch in the 84-86 cars is a cable operated clutch , opposed to the hydraulic g50 in the 87-89 cars. The cable is a much more positive feel and undoubtedly allows the driver to feel more in control of when the clutch is grabbing. The 915 transaxle rebuild cost if done correctly, usually runs about $2k if you have a pro do it for you. The later g50 box rarely needs any attention other than the normal clutch related wear parts(disc, pressure plate) which are roughly double the cost to that of the 915.

All in all, my '86 targa is the most reliable sports car I have ever owned and have never had any significant issues with it. Make sure to perform the regular services on the car ($400-$500 if a pro does the work) and it will provide years of fun.

good luck

When will engine rebuild be neccesary on 180K mile 1992 Carrera?
 

Actually I'm now looking at a 1992 Carrera in great physical shape from an older Porsche fanatic who seems to have taken meticulous care of his car, and is asking $15K for it, after having fixed the items listed on the PPI. It does not leak oil. He uses it as his daily driver, and has played with it autocrossing. He owns several Porsches, and is a reputable person.

My questions are: is this a good buy, and when will I most likely have to rebuild the engine, and at what cost?

Grateful for your responses...

Welcome. Mil? Sounds you found a good buy. Experienced eyes underneath, and leakdown give the necessary assurances. Be safe!

Regards,

1992s are fine. Some 90-91 964s had head gasket issues, most of them are fixed by now...especially after ~90k miles.

You should get 200k miles out of most higher-mileage 911s without too much issue...when to rebuild really depends on whether the car a) got up to operating temperature when it was driven, b) got the crap revved out of it after warm-up and c) had frequent oil changes. If one maintains a 911 well, and really uses it like it was designed to be used (racing, basically), it will last forever. Well-maintained 911s after 1978 will easily go 300k miles without bottom end work. A top end job will cost around $3-4k (I can't charge that much) but a full rebuild is usually $6-8k.

cheers.
scott