Timing Belt light Question
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From: Bloomfield, MI
My timing belt light came on for the first time in 10 years about 5 months ago. Stopped driving immediately, had it towed to the shop. (The belt/wp pump - whole timing belt system was changed about 2 years ago and the belt was retensioned after 1,500 miles. Less than 10,000 miles driven since the belt change) The shop checked the tension this time, said everything looked good: belt/tensioner/etc and said the tension was within spec. I did have a problem with the light 10 years ago when I first got the car with the light not working at all but had it fixed.
The other day, just driving at 20 mph the belt light came on again. No load on it. At other times, passing someone on the freeway, downshifting, etc., I get no light. I know you're going to say I'm taking a chance driving it with the light coming on at times but I really don't think it's a problem with the tension, I think it's an electrical problem. Anyone have that type of problem?
The other day, just driving at 20 mph the belt light came on again. No load on it. At other times, passing someone on the freeway, downshifting, etc., I get no light. I know you're going to say I'm taking a chance driving it with the light coming on at times but I really don't think it's a problem with the tension, I think it's an electrical problem. Anyone have that type of problem?
Just wondering how often you checked the oil in the Stock tensioner ?
Other than the other issues mentioned (elect, mech failure) if the stock tensioner is not maintained by checking for full oil and flushing some fresh through), it can stick and will not de-tension the belt when the eng is hot.
When this happens, belts stretch, things like gears wear out fast, others parts just break
Dave K
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There is a test procedure included in the Technical CD from Jim Moorehouse and it is contained in one of the Techniical Bulletingnumber 9010.
In addition I check and add oil to the tensioner at each yearly service when I check the cambelt tension.
Tails 1990 928S4 Auto
In addition I check and add oil to the tensioner at each yearly service when I check the cambelt tension.
Tails 1990 928S4 Auto
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Thanks for all the replies. I asked about oil in the tensioner and they said it was good. I may take Bill up on his offer and have him take a look at it. The car has been fairly trouble free for the lat 10 years as I've kept the maintenance up but I hate seeing the light come on even if it's an electrical issue. Just not something a good 928 owner should put up with.
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Joe........the warning light for the tbelt is catastrophic if the belt failure/timing slips. The engine is an interference design meaning the valve timing has to be exact or the pistons will hit them bending valves, cracking guides etc etc.
DO NOT start the engine under this condition. If possible have Bill come to you.....it will save you $KKKKs
DO NOT start the engine under this condition. If possible have Bill come to you.....it will save you $KKKKs
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The test procedures are great if the belt light is coming on consistently after the 3 minute delay. One car I dealt with would trip the warning only once in a long while. And until the loose crimp (wiggle, wiggle) was found, it would pass all the tests.
So, the system was examined (by Devon at Hi Tech in San Rafael, Joe informs me) and he found nothing wrong. So, it's unlikely that it is unsafe. If the warning only comes on very sporadically, it's likely a wire break/bad connection issue. I'd be happy to go over to Joe's place and take a look.
So, the system was examined (by Devon at Hi Tech in San Rafael, Joe informs me) and he found nothing wrong. So, it's unlikely that it is unsafe. If the warning only comes on very sporadically, it's likely a wire break/bad connection issue. I'd be happy to go over to Joe's place and take a look.
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From: Fresno, CA (summer in Calgary)
It DOES.....absolutely correct.
Sean....if you have a Porkensioner installed and the tbelt light comes on at high rpms theres other issues with your car as well as the fuse/relay panel (other thread).
My first response to the OP was to encourage him to seek out an experienced Rennlister rather than take it back to a $$$$ shop and presto Bill offers his services as I would have done if nearer.
Bottom line......get this issue fixed asap by someone who knows what they are doing.....good luck
Sean....if you have a Porkensioner installed and the tbelt light comes on at high rpms theres other issues with your car as well as the fuse/relay panel (other thread).
My first response to the OP was to encourage him to seek out an experienced Rennlister rather than take it back to a $$$$ shop and presto Bill offers his services as I would have done if nearer.
Bottom line......get this issue fixed asap by someone who knows what they are doing.....good luck
-Sean
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There was no mention about the status of the bearings of the tensioner pully - if they are worn out the tension will vary. If the cam gears are worn, they'll also cause cam belts to wear at an accelerated pace. There is more to check than just belt tension!
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From: Southern Alberta, Canada
I believe the PO had it installed at Greg Brown's shop in Anaheim, he warned me that the light went off all the time and it is supposedly no big deal. Ken (Porken) told me a while ago that this issue is known to arise from a bad ground connection somewhere, which would fit right in with the weird electricals on my car. It cannot possibly be due to loose belts, because the warning system is in fact not connected, so I'm not concerned about a major problem. But I will try to get it addressed with all the other electrical stuff in the near future. It might end up being one of those gremlins.
-Sean
-Sean
Given your engine is 'upgraded' with the Porkensioner system, which IMHO is a far superior to the OEM, there is a bad ground probably one of the main engine grounds which should be removed and cleaned. Good to know you're addressing the other issues you have, hopefully it all works out soon.
Bill, good to know theres confidence in the mechanic and the issue will be resolved asap. Its hard to know on internet chats whether the OP was getting the message in regard to the seriousness of the problem. Please complete this thread by letting us know what is found
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Bill, good to know theres confidence in the mechanic and the issue will be resolved asap. Its hard to know on internet chats whether the OP was getting the message in regard to the seriousness of the problem. Please complete this thread by letting us know what is found
if the belt goes. I trust the mechanic that did the work and checked it, they know 928s well and I'd take it back to them and have them sort through it again but that's a bit of a logistics problem at the moment. Sure, any time the belt warning is in question, I'm taking a risk driving it but I'm ok with that. Worst case scenario is there may be a lot of nice parts for sale on here next Saturday as I'm parting it out. hahaha ( I shouldn't laugh at that 
) I'm just happy that Bill is willing to take a look at it and we'll go from there. Thanks for all the replies.
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It is probably missing the ground wire from the 6mm dipstick stud to the 8mm belt cover bolt (included in the PKT hardware kit). The dipstick loses ground contact with the block at higher rpms. I can send you the wire if it is missing.
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From: Fresno, CA (summer in Calgary)
Ken, thanks for the detail there. I will add it to list of electrical bits for my shop to play around with, I will let you know if I need any parts. I think my shop may be unfamiliar with your aftermarket stuff on this car, can you let me know where I can tell them to look for documentation about the tensioner and clamp if they need any? There are a couple of old-time 928 mechanics at this shop, but here in Fresno they don't get a chance to work on one but once every few months. I know the owner cut his teeth doing 928 work at the local Porsche dealer years ago.
-Sean
-Sean