matthewclaxton

Hello, on my way to work tonight a new light lit up on my dash, it said 'belt tension' in red , I assume this means that my timing belt is not tight? when I shut the car off and turned it back on drove around the block no light? is it ok to drive it home? 1988 928S4.
Thanks

leperboy

The warning light won't come on until something like three minutes after start up, so if your trip around the block was short, it wouldn't come on. I wouldn't drive it until you've had the belt tension checked and tightened, if necessary.

Do you know when it was last replaced or checked, or how many miles are on the current belt?

Matt

blown 87

Your car is not safe to drive, IMHO.

matthewclaxton

Thanks for the replies, not sure when the belt was replaced last will have to go throught original owners receipts at home, I have had the car a year but other than start it once a month not much driving! what needs to be done when the belt is changed, I have a 944 and when I replaced the belt on it I updated the water pump and the pulleys etc...

Mike Frye

Hey Mathew,

I don't know how much you know about these cars, so if this sounds condescending I apologize.

Your 1988 S4 is an 'interference' engine, which means that if the belt goes or even slips a few cogs on either cam gear you could end with with a nice little collection of bent valves. The valves are expensive and replacing them is much more if you pay someone to do it.

You can find lots of information by searching on here. There are two sides to the TB/WP job, some say to do the WP while you're in there, others say don't fix it if it aint broke. You'll have to be the judge of that. There is also a new tensioner system available from 928sRus that was designed and developed by our local mad scientist Porken. It updates the tensioner (more accurately called a de-tensioner) to a more modern and dependable design than the original.

The fact that you bought it a year ago and haven't researched the maintenance leads me to believe you don't plan to do the work yourself, so you may want to try to find someone you can trust that knows these cars to do it. Not sure if there's anyone up in your neck of the woods, but there are some in PA and northern NJ that you might try.

Drop me a PM if you need anything, my brother lives up in that area and I go up there from time to time.

OH, and I wouldn't start it again until after you've replaced the TB.

Landseer

Needs definite checking, especially the condition of all the belt guide rollers.

S4 guys chime in, but the earlier 32V pre-S4 cars have a single terminal plug near the oil fill tube that is the sensor wire. I've knocked mine loose twice checking oil, resulting in the toothed belt warning light.

To Mikes overriding point about researching, if this S4 is an automatic car, then you have another immediate go-do: flex plate pressure release and crankshaft end play check.

WallyP

Matthew,

As you have seen here, the timing belt is a critical part of your 928. The belt tension warning light is a serious warning, and should not be ignored.

First: According to Porsche, the timing belt should be replaced every 50,000 miles. Since Porsche expected the cars to actually be driven, they did not see any reason to put a time limit on expected life. Most owners feel that five years is a reasonable limit, as the rubber deteriorates with time as well as with mileage.

If the belt is less than five years or or so, and appears to be perfect, the problem may just be a false warning light, or the belt may need tensioning. If the belt needs tensioning, you need to keep an eye on it in the future. The tension doesn't continue to change unless something is wrong, such as a failing roller bearing or water pump.

Check the belt warning light connection, a small black wire located just behind the oil dipstick tube.

Remove the large black air inlet tubes, and use a good light to examine the belt thru the vent holes in the top of the belt cover. ANY deterioration of the belt is serious! The belt should appear new, and should be very near the center of the cam sprockets. Any fuzz is a serious warning sign.

Let us know in detail what you find, and we will try to help.

dprantl

No one should EVER start up a 32-valve 928 unless they know *for sure* when the timing belt was last changed.

Dan
'91 928GT S/C 475hp/460lb.ft

Giovanni

LOL, the timing belt light saved my engine from a possible catastrophic destruction. See pics of my timing belt: https://rennlist.com/forums/928-foru...placement.html

Lionel S4 - 88

Hi ,

May I have the view ?
Having no records , but no alerts either , I decided to go for the WP and TB replaced , job done by Porsche .
Just after I got the car back , exactely 15km after leaving the shop , the alert light came up .
Stopping the engine and restart , the light alerts after 1 minute when driving or 3 mn when not driving and engine at iddle .

First the shop told me there is no issue , but on my seconf call , theey suggested to come back .

After re-inspection , they say the tensionner is weakening and has to be replaced .
Does it make sense to you ?
Had no alert alert before ,but immediately after the WP&TB are replaced .

From above posts , I understand it is logic that the light goes on after few minutes and not immediately when starting the engine ( when something is wrong , what ? ) ?

Is that logic to replace the expensive tensionner ?

What can it be they did wrong for the WP&TB job ?

Thanks

Bill Ball

No. The tensioner does not "weaken." It has a simple adjustment bolt.

Judging from their statement about the tensioner weakening, they could have done a lot of things wrong. Somebody here who lives in PA should be able to recommend a better shop in your area.

Lionel S4 - 88

Bill

Am in France .
They answer looks actually weared ,
btw , see a the pic at took immediately aftre the job , might be ok but seems to me the belt is not well centered ?

WallyP

It can get to be REALLY expensive to train a shop to work on 928s, using your car and your money...

The tensioner very rarely needs replacing (and is very expensive), but rebuilding the tensioner should be a standard part of changing the timing belt. This is a very simple job, taking less than thirty minutes and needing only a few simple parts (O-ring, boot and gasket). The tensioner must then be filled with oil after installation. I seriously doubt that your shop did any of this.

The timing belt must be correctly tensioned upon installation, and again after about a few hundred KM.

Good luck with your shop.

Mrmerlin

This belt job should be done again and any parts that have not been replaced on the run should be.
The tensioner is not a replaceable part it is a rebuildable part that has about 40 dollars worth of parts needed to rebuild it (Small O ring , Gasket, Rubber Boot , Boot Clamp, tensioner bolt).
It could be possible that the Tensioner wasnt filled with oil, or better that the rollers were not replaced or better that the tensioner arm bushings and its pivot were not replaced.
Its also possible that the Belville washers inside the Tensioner were not replaced in the correct order se WSM for proper fittment.
If all of these parts have been replaced then its possible that its a wire connection.
That said i have had the light come on in my 1988 S4 and after a few times of checking the belt i found the tenzioner pivot bushings ( dark grey) were slightly loose on the pivot bolt, i replaced them with the TAN colored bushings and also installed a new pivot bolt

Lionel S4 - 88

Thanks for your view .
This is an official Porsche shop dealer so far considered as okay in the area and recommended by other 928 owners ... Will have a call then