Randyb

The car I am looking at has 158k milles, so about how long can they go on average before they need to be rebuilt?

Guy

300k is not unreasonable on the bottom end.

Randyb

Thanks Guy, that is really good to know.

NoVector

157K actual mileage doesn't sound unreasonable at all, but know that the odometer gear frequently fails on the older models so true mileage can be way off. Compounded by a lot of people putting bigger rims/tires and that also makes odometer show less than it actually is. Not sure about AL registration, but a Carfax with steady increase of miles through the years would be comforting.

I wouldn't lose too much sleep about a rebuild, but a top-end refresh or new head gaskets could be in your future. Put it through the PPI wringer with compression test, leak-down test, flex plate TBF movement, etc., if you have doubts.

GregBBRD

....but since most don't get close to this, I would not call this the "average".

I think 150,000 is probably closer to the actual average.

The Forgotten On

Definitely head gaskets at this age. They are all ready to fail.

The soft parts like seals and gaskets are all drying out and failing now as most are over 30 years old at this point and could warrant a rebuild if they are all leaking.

The bearings are probably fine though if the engine has had a nice life filled with good oil.

C531XHO

Just done my 16v engine which has an indicated 88k miles on it. Mains were acceptable apart from the ring bearing at the front which showed some signs of wear, I suspect from aged damper not doing it's job. Big ends ok ish but I changed them as they are affordable. Also changed rings as they are affordable too. Crank was very good. At the top the valves were ok but guides worn. Most of the rubber parts were past their usefull life plus my head gaskets were poor although only one side had a slight leak.Would the engine have gone to 300k miles, yes apart from the HG i think but now I have something that will hopefully not leak and run well for as long as I am around.
D

928FIXER

Endless,as long as maintenance is done and not overheated.My 79 has 350K,if not more miles on it,as the car already had its 1st replacement speedo in it.

z driver 88t

In agreement with most of these posts. Lots of things on 928s break, but the engines are good just about forever with proper oil changes and reasonable maintenance. Rod bearings may occasionally need replacement, but that can be done dropping the oil pan with the engine in the car. Pretty much all the oil seals and gaskets can be done with the engine in the car during a timing belt service. The killer on these cars is all the other stuff that can be neglected. There's a common saying on Rennlist that any 928 is only $10K away from being a $5K car. While values are starting to increase, these are hardly collectible right now (barring a pristine GT or GTS).

Head gaskets are starting to fail and are a PITA on 16V cars and although some have successfully done them with the engine in the car, it's one of those jobs I'd hate to do. I did mine when the engine was out.

As long as it checks out and passes a PPI, no outstanding repairs and you have a decent maintenance history, I would not worry about the mileage. DO NOT BUY ONE without having it thoroughly checked by someone that knows 928s. You can easily buy one that will be a money pit. Pay a little more for one that is well sorted.