I have now owned my '89 928 S4 for about three years and must state I love this vehicle. I bought it with 114,000 miles on it and it is now just at 170,000. I have bought the service manuals and learned that this vehicle is not hard to work on at all if you aren't dealing with the wiring that is. Replacement of the timing belt and WP for example is not to difficult for the do-it-yourself person. A basic metric tool set and a set of ramps and it isn't quite that hard to get done yet it is time consuming. I have replaced my TB/WP twice now and can get the front of the motor apart in about 3-4 hours... and back together in about the same.
The vehicle is special and takes time to learn to work on as all vehicles do. This isn't a '66 Mustang with a 289 ci... it is a vehicle made to travel safely at higher than normal speeds the American public aren't accustomed to. Treat it with repsect, and the vehicle will reward you with great satisfaction and not to mention many on-lookers will constantly ask you for a ride... happy motoring...Patrick.
I run three Porsche 928 S4 cars (1987 @ 1988 vintage) for a tourist venture here in Australia, and they are a beautiful machines to own. I have never understood why they stopped production, when they were so popular.
It is a very worthwhile exercise to learn all you can about the machines, as this will save a lot of money. If you don't learn to do some or most repairs, you had better have a big wallet.
I have fitted the Porken timing belt tensioner on all of the cars, and this has proven to be a good long term move. The tensioner ensures that the timing belt is never too tight or loose, thus extending water pump life and increasing timing belt life.
Into the future I shall be fitting the new Gates Kevlar timing belts, as timing belt failure on these engines is very expensive, as they are an interference engine.
Overall, these cars are quite reliable I have found. It is worthwhile to keep fuel and oil filters, and spare fuel pumps and especially fuel pump relays.
In closing, ensure that all earths on the car are grounded well; this I have found can cause a lot of headaches otherwise. Also ensure you change those oil filters regularly, and the engine should run for a long time provided you check on the cam chain tensioner wear pads. I have these checked every year just to ensure they look okay. If these wear beyond a certain point and break, they will cause the timing chain to bind in the engine, and the rebuild cost will be in the thousands of dollars.
Hope you enjoy them as much as I do.
I am a proud owner of an 89 928S4 and as those of you who know, well it's the s#%@. I am in need of the complete shop manuals, if anyone has for sale, let me know, it will come in handy for many years to follow. Thanks H hcombest2010@gmail
The 928 is a rocket ship. A bad ass German auto Bond super car. Third gear is amazing, and the euro cam sounds awesome at 6gs. Best sports car for the money bar none. The resale will continue to increase; could be a car to watch over the next ten to twenty years.
P.S. find a mechanic that loves the 928, and you will have a friend for life.