PHIL928

Bill,
The car wasn't really driven for that period of 3 years, probably had only done about 2500KM which is 1553.42 miles (thanks google), but I only bought the car in March and he had never had it rechecked.
It happened while the car was idling in the driveway one morning. It wasn't too loose either, it was on the border of the loose side on the little square cutout on the tool and a quarter turn of the tensioner bolt brought it back to the middle. So I assume the belt is still alright, right? Let me know what you think as I'll have it changed immediately if it's bad news.

Bill Ball

You'd have to assume it was installed a bit on the loose side. From my experience, the settling maybe drops the tension 1/3rd of the tension tool window. So, I hate to see the warning at all as it usually means a lot more tension loss than that. It's a judgment call. I'm not as paranoid as others about the belt. I'd probably check the tension again in a month or so to make sure it is stable - don't wait for the tension warning again. If it stays stable, great. Oh, and drive the car more!

FredR

These issues about the timing belt are a recurring theme. A warning light is just that- a warning! It is telling the owner to take note and do something but it does not tell the owner to "abandon ship".

That the alarm has functioned is a good sign in and of itself. To my knowledge the system cannot diagnose whether the belt tension alarm is functional or indeed if the belt tensioner is working correctly - someone correct me if I am wrong.

Before panic sets in you have to rationalise what may be going on. We all know that belts can snap but I have not read of anyone getting a warning light and a few seconds later -snap. It could happen that way but does it?

These sort of things tend to happen to owners who know relatively little or nothing about their 928's or the belt history. Most do not know if the warning system is functioning correctly. Little or no mileage is not a performance indicator-indeed it may be quite the opposite if the rubber in the belt is not flexxed regulararly.

If you have a tensioner that is working correctly, if the idlers are in good condition, if you have a factory OEM belt fitted and the cam and crank teeth are clean and you know this, the chances are nothing will happen.

The belt needs a settling in check after a 1000 miles or so and you might reasonably expect a "mid life" tension adjustment or two of 1 flat on the adjuster but that is about it. If you do not know how long the belt has been on the car change it. If it has been on the car 5 years or it has seen 40k miles- I change it.

If these criteria are met, then paranoia over a single one off alarm is not justified assuming it clears and does not re-appear immediately.

False alarms occur in any instrumented system - fact.

If I see an alarm, I might pull the belt covers and take a visual at the belt in its entirity amd check the tension. If get were to get an alarm when I am near the end of life cycle criteria I set, I would probably change the belt immediately.

If a tensioner has failed and the belt is sloppy, if you get a resultant alarm [system working] do you really think it is going to be cancelled and not come back on?

Regards

Fred

Podguy

There is no belt warning light on a 16 valve car.

Podguy

Ok in reading the replies there seems to be some misinformation.

1. The belt system is checked when the ignition is turned on as are the other warning systems. All the lights come on to show the light bulbs are working.

2. The belt warning system can be and should be checked when adjusting the belt. The belt should be loosened and then tightened while measuring the contacts to determine at what point the light comes on. Somewhere around the 4.5 level is probably as low as it should go.

3. The 32 valve engine is set to 5.0 and the GTS motor set to 5.5. I have found that the 90 S4 at least needed to be set to 5. Not sure why this was.

4. Over tightening the belt - like without the gauge - until the light goes off is bad policy. Some shops have been known to do this. Over tightening the belt will cause the cam pulleys to wear excessively. On the 16 valve engines can cause the left cam to break.

5. Belts can fail in different ways. Age is a factor and will cause teeth to strip. But it is also possible that a new belt installed without new tension arm bushing will cause the belt to rub against the damper and wear thin eventually failing. When checking the tension tracking should be observed and the interior of the covers checked for belt particles.

6. The belt check system can give false errors. The system works by gounding the light circuit. A short in the system like a bare wire can cause a short and turn the light on.

FredR

Dan,

With respect, I believe your first point is in error- I suspect that what you have written and what you meant are different -I agree the bulbs are checked but the tension system cannot be checked for functionality on start up - kindly correct me if you know something different.

Regards

Fred

FredR

Let me correct my post slightly- I meant to say I cannot understand how functionality can be checked by switching the ignition on.

Regards

Fred

SeanR

Wholly cow, I don't even know what to say to a couple of the comments in here, some shouldn't work on cars with the advice they are giving. Fred you are correct.

Bill Ball

It might be more useful if you noted that with which you disagree or is Fred the only one who is correct?

dcrasta

Thanks for the correction.

I think the OP needs to get the car towed and replace the belt. IMHO if you dont know the history of the timing belt, and you have a 32valve car, its in your best interest to treat the belt as if it was 1 rotation from breaking. At the very least, inspection is in order.

PorKen

'85-'86 ROW 16V do.

SeanR

Some days I am just floored by somethings people say.

This time it is Podguy, once again.

I'd like him to explain to us how you can go about loosening and tightening a belt to check to see exactly where the point is where the system goes off. Does he accomplish this while the engine is running for 3 mintues? LOL

How the ignition on tests the system.

Tight belts cause water pump bearings and cams to break, loose belts cause excessive wear on the gears.

There can not be any shorts in the warning system, it's a grounded circuit or if it is failing, its opens.

Porken is right on the Euro 16v cars have warning systems. Etc.

If I came across as an *******, well, that's just me. No sugar coating and I'm going to call it as I see it. You would think that someone who has been in the industry for 25 years would try and get it right before giving advice. But what do I know, I"m a noob.

WallyP

"6. The belt check system can give false errors. The system works by grounding the light circuit. A short in the system like a bare wire can cause a short and turn the light on. "

The system works the other way...

Proper tension keeps a spring on the tensioner push rod compressed, maintaining a connection to ground on the warning computer input lead. When tension is lost, the connection to ground is broken, and if it is more than three minutes after engine start, the belt warning is set.

The system can and does give false warnings. These can be caused by:
- Belt flutter due to slightly low tension and lack of oil in the tensioner.
- A broken connector strip on the tensioner arm.
- A poor connection anywhere in the electrical lead to the warning computer.

davek9

# 6
the red light comes on when the ground is broken, if the wire to the tensioner is grounded the light will never come on, ask me how I know.

Also the correct tracking of the belt can be seen in the vent holes on top of the cam gear covers. If it is running close to the gear edges that is not good, and also if it is not tracking true (wobbling) both are signs of part failure in the belt system.

hopes this helps,

Dave

PorKen

'86-up.

'78-early '85 can't see the front of the gears. Late '85, left side only.