Jbws86928

I am getting the error code or tensioner light on the dash. This will go out after a few seconds. This is my first 928, 86 928S

Maleficio

Sounds like the monitoring system is doing it's job.

Probably should look at the timing belt tension/condition.

antsmands

Check the belt and tensioner asap. If you belt breaks on your 86 you will have big trouble with valves hitting the pistons! Do not wait on this!

Jbws86928

Where is this located? I have heard of inference engines that if this belt breaks while driving, I would be in big trouble. A friends Audi is the same way. Can I fix or should I find a mechanic. Any mechanic or ???

Rick Carter

Don't drive the car until this is fixed it can be a multi-thousand dollar mistake. Post your location and ask for local help, get the manuals now.

Jbws86928

Thanks Rick and the location is Decatur Illinois. I will do a new post for mechanic help. Thanks Again

linderpat

jb - definitely get the car to a place that knows 928s - I had an 86, and the timing belt job is not for the faint of heart. If you are an experienced wrench, you can do it, but you'll need to study the tutorials found here and on other sites.
Here's a link to a thread with lots of recommended 928 experienced mechanics (Not sure if any are close to you): https://rennlist.com/forums/928-foru...-our-list.html

Here's are some good timing belt tutorials:
- http://members.rennlist.org/v1uhoh/checking.htm
- http://members.rennlist.org/v1uhoh/timing.htm
- http://www.dwaynesgarage.norcal928.o...0Procedure.htm

Good luck and keep us posted.

antsmands

In Decatur this weekend. More that happy to stop by and take a look at it with you. I am pretty new but have gain lots of info from this forum. Just do a search and a ton of references and detailed write up with step by step photos will come up. Looks at Dwayne's Garage. I think he as a write up on this.

Jbws86928

With the tensioner light on sporadically, does this mean the timing belt needs to be done or maybe the tensioner?? What is the difference between the two?? Is there a timing belt kit?

Mike Frye

There are kits for it. You can check any of the normal vendors: 929International, 928sRus, 928Specialist...

It could just be the tensioner warning circuit (you're lucky it hasn't just been bypassed by now, mine was originally) but until you know, you shouldn't run it and definitely don't rev it up (to check out that idle situation in the other thread).

The tensioner warning circuit just goes to ground when it's fine and goes open when the tensioner is 'triggered' (belt too loose). You can use a digital VOM to test it easily, even with the car off. If it's intermittent it might be something that is temperature sensitive and only occurs when the car warms up.

There are special washers (bimetalic belden washers I think they're called) inside the tensioner and also oil in there. Or at least there is supposed to be some oil in there.

The tensioner system is pretty archaic and is designed in such a way that when it's warm, it's supposed to increase the tension on the roller slightly because the heat of the engine warms up the washers and that pushes the tensioner rod out, which pushes the roller closer to take up more slack in the 'return' side of the belt.*

You might want to get in touch with Roger at 928sRus and get an aftermarket kit called the 'Porkensioner' designed by our resident inventor. It uses an Audi tensioner for a much more modern and reliable system.

Anyway, whether it's just the indicator circuit or the actual tensioner, you should replace the belt and either rebuild or replace your tensioner while you're in there. It's the only way to sleep peacefully at night now that you know a broken belt could grenade your engine (or just the valves).

It's also a right of passage.

Plenty of support on here whichever way you go, but I would definitely deal with it sooner rather than later.

Also, if your car is an auto, you should do some searches on TBF or 'Thrust Bearing Failure'. Just one more little 'quirk' about these cars that you'll need to prevent.

Good luck and keep us posted.


*I might have the direction backward, meaning the washers heat up and relax, allowing the plunger to move back into the tensioner to account for engine expansion, I forget which. Either way, the washers and oil are to deal with the temperature change of a warm engine over a cold one. For this reason the tensioner light also has a 'grace period' of several minutes during which it won't trip when you first start the car. It's supposed to account for the fact that a cold engine might trigger the circuit, but warmed up it never should.

M. Requin

You'll get lots of good advice on this forum about this question. Mine is, regard that warning light as a "Please do not drive me!" light. I am sure you will get offers from experienced owners to help you check this out- the check itself is pretty easy. The timing belt and tensioner are part of a system, and you (or your mechanic) will be doing them together. It is within the capabilities of a DIY job, as has been pointed out already there is a lot of info here on this, and there is one very good manual for our model year available, see https://rennlist.com/forums/928-foru...lt-manual.html I used it when I did mine, which was the first thing I did on my 86.5, thanks to finding this list before I bought the car.

Landseer

Should light with other bulbs during starting, then go out immediately.

There is a about a 2 minute delay on the light triggering as a warning.

Once that happens, you have to restart the car in order to cancel the light.

Of course, that means ignoring the warnring its giving, assuming its correctly wired and functioning.

What exactly is it doing?

I've had new timing belt installations trigger the warning. Reason: I tightened the belts on the 85 and 86 cars to the lower indicator mark on the kempf gauge. One car triggered the light on a rapid acceleration out of a traffic light. The other car triggered the light during heavy kickdown passing on the highway. Both were fixed by retensioning the new belts and no damage was done fortunately. So, if a new belt is somewhat loose, heavy acceleration will trigger it in my experience.

Loose old belt --- less certain the outcome. But be assured that heavy acceleration causes more movement and stress on the apparatus.

Avoid until you solidify your belt / gear / tensioner situation.

Jbws86928

I start the 86, all dash lights go on, then dash lights go out, tensioner light stays on for a few seconds then goes out with me pushing the pedal. Now, with the idling issue, I did not press on the pedal and the tensioner light went out automatically. The light does not come back on when driving or idling. I am checking on mechanics here and I myself am a wrench turner and need lots of reading to complete projects. What is involved in retensioning?

pcar928fan

Is you "Belt Ten" light and your "!" light mixed up???? The "Brake Blub" (or whatever it says) and "!" should be on when you start your car and STAY on till you hit the brake pedal... Normally the belt ten light comes on after a few seconds if it is immediately a problem and then it SHOULD NOT go out...

mj1pate

It should also be mentioned that an increasingly common reason for belt tension lights is a waterpump failing so as to give up belt tension. In instances where a waterpump steel impeller begins to wallow during a failure and impacts the block, some block repair is necessary.

It should be mentioned at this tender stage....DON'T PANIC. There are quite a lot of possibilities and what-ifs. More than likely you need a belt tension adjustment or maybe belt replacement. Even if the water pump impeller failed and scraped the block, there are engine-in-car repairs for this, as identified in detail in this forum. At this point, take your time and do a bit more reading than driving. get your car sorted out a bit and you should then find it a reliable vehicle for which maintenance can be planned in between road trips.