Hi everybody,

I went to inspect a 1990 928S4 here in Belgium. The car has 279,000km (173,000 miles) but is cosmetically in a very nice and original condition. The car is Forest Green with a tan full leather interior. It is not an everyday color you see for a 928, but I kind of like it.

There were three issues with the car about which I would need expert advice. Hence my request to this forum.

1. The engine sounded kind of "noisy" at idle. I do not know for sure, but it sounded like the valvetrain having a slight rattle in it. If it were a car with mechanical valve lifters, I would have suspected the valves needed to be adjusted. But I suppose the 928 S4 has hydraulic valve lifters, right? Any ideas on this?

2. Secondly the OBD gave an "ABS disengaged" warning and the ABS red telltale light would not go out. We checked the ABS fuse but it was OK. According to the seller the car had had its battery disconnected for a couple of months (he had taken it off the road and sent in the registration plates). Could it be that the system just needs to be reset?

3. And finally, the OBD gave also a "PSD disengaged" warning. I suppose this is the limited slip differential? Same question as above? How worrying is this warning?

Thanks for the feedback,
Rik Gruwez
Brugge, Belgium

 

About the ABS problem...
Just read from another forum that one of the local PCS members have the exact same problem with his ABS-system. His is a Euro spec 928 S4 aut, 1990.

The ABS sensors and the PSD sensors are the same ones...
Therefore if for example the ABS-Sensor on one of the wheels stop working the warning light for the PSD will also lit up. So, symptom 2 and 3 most likely from the same error..

First of all, check the sensors. Finding a good workshop with a Bosh "Hammer" will make this easy.
Second, check signal from/to the ABS/PSD control unit.

 

Hi Rik:

Generally you should NEVER buy a 928 without having a pre-purchase inspection done by a mechanic who is very much familiar with the 928. It is hard to diagnose an engine noise from afar, and there are lots of other potential and costly to repair trouble areas on a car with this mileage, or a car that has been sitting for a prolonged time. Spend 200 Euros or whatever it costs to have the car inspected thoroughly - it is well worth the peace of mind (and possible the money you save in the long run.

In regards to your ABS and PSD problems - I think that Adam is on the right track... maybe there is corrosion somewhere from the car sitting too long? Not sure - again this is something a pre-purchase insepction could answer in more detail.

I have seen a '90 GT here recently in this same color combo you describe. I agree that it it a nice combination - the 928 usually looks very elegant in darker colors.

Best of luck!

 

I agree as well to having a PPI performed; however, re. valve train noises, it will really help if you can listen to a good running S4 to establish a reference point as to what is 'normal'. Also, be advised that the fuel injectors often click and clatter away and are confused with valve/lifter noises.
With a stethoscope, a long screwdriver, or a length of ~9mm hose stuck in your ear - move along the valve covers and each injector: soon you will understand the 'symphony' of sounds - you are listening for one that is 'out-of-tune', for if they all sound alike over 8 cylinders, it is reasonable to assume the engine is OK.
First check for good oil level and pressure: some engines experience lifter noise on start up due to dirt in the two check valves in the heads (oil pressure is then lost in the hydraulic lifters when sitting, and must be reestablished before the lifter noise subsides - not a big problem!). Good luck

 

Rik,

The 32 valve engine has a chain that drives one of the cams off the other driven cam and an oil-pressure fed tensioner. There is no specified service interval, so the chain or tensioner could need servicing. It will be noisy if things are loose. Worse yet, if the chain is damaged there could be damage to the cam sprockets and new cams, chains and tensioners could be in order.

A PPI should report if the noise comes from this area, but only a full inspection of the top end would confirm the condition of these components.

BTW, I once visited Brugge and found it a very charming city, the canal tour is very nice.

 

on my 87 during start up it makes a strange shrieking noise like a squeaky fanbelt but it seems to go away after it warms up. Still can't diagnose it

Andy

 

Mine 944 did that just before the timing belt blew some teeth. Just a thought.

 

Not to hijack the thread, Boyeee...... but I imported this USA spec 928 and am having a speedo problem, too. The rest of the traffic seems to be going awful slow when I set the cruise at 100 !!

 

Rik
The control systems for the ABS and PSD (Porsche electronically controlled limited slip diff) are combined into a single unit in the PSD-equipped cars so the two faults are almost certainly related. It may be a single fix but could mean an expensive replacement control box. Try to reduce the asking price by about Eur 3000. If the battery has been disconnected the various control 'brains' will all reset themselves automatically within about 10 minutes of engine-running time.

Colin. 89GT

 

Thanks to everyone who has posted feedback on my questions. My search for the "perfect" 928 continues...

Rik Gruwez
Brugge, Belgium