rgs944

After researching TB failures I have noticed a common theme. It seems about 1/2 fo them have been shortly after doing the job. Whether it be not using correct parts, not replacing everything, or just plain doing something wrong. Does not seem to matter if it was done at a so called reputable shop or not. It also seems quite a few of them have been done by rennlisters who should have all the right information. What I am wondering is that maybe the old rule, "if it ain'nt broke, don't fix it" should be followed a little more often. When you compare the cost of the TB kit at $600 compared to the cost of good used NA engine, is it really cost savings in the long run. I drive my cars very few miles and give everything a close inspection at least every 1000 miles. I know there are some things you can not see, but there are also some things you can see in advance to increase your odds of survival. Of course I am kind of a gambler by nature anyway.

V2Rocket

i would bet most are do to improper tension on eithre the tb or the balance belt, which snaps and destroys the tb at 13000rpm

DLarsen

Porsche dealership.............2 yr warranty on parts and service. I don't use them much....but for replacing and adjusting the timing belt; it gives me peace of mind.

Hollywood D

What do they charge to do the belts?

Tom M'Guinn

How did you come to the conclusion that half TB failures occur shortly after installation? In any event, if a TB fails shortly after install, then in most cases I'd suspect it's due to installation errors, non-factory tensioning techniques, or re-using worn parts (lock-nuts, tension stud, rollers, etc.). This is one area where the "if it aint broke don't fix it" approach is not a good idea. Eventually, even good looking belts will break...

Dean924s

I have done my share of belts and in my opinion the re tensioning after 1500-2K is critical and is many times over looked (after all I have a new belt it should not brake). Many just don't do it / forget about it and if the belt was set a little on the loose side. Things go bad fast.

I had one where the owner called me and said that there car had stopped running. After talking with him for a while they fessed up to hearing belt slap for several weeks (more like a month) when the motor was cold but since it went away when it warmed up they just ignored it.

Mighty Shilling

a small fortune. but they do quality work. Hollywood, if you decide to take it to the dealer, go to Stevinson, and have Justin Underwood as your writer. He's an awesome guy, knows these cars well. Also, request either Todd or Jesse work on it. they're some of the few Gold meister techs in the USA (and the only two in Colorado). Porsche factory certified to work on ANY car from 356, to 959, to CGT.

However, Hollywood, I personally have done over a dozen timing belts, and I have the special tools to do it. If you'd like, I'll replace your timing belt for $300 (you supply parts) and tension them for $150 PM me if you're interested.

Hollywood D

I still have about another 10k miles before they need to be replaced. I'm still a timing belt virgin. Will keep you in mind for when it needs it. I dont mind spending the money to have someone show me how to do it right.

rgs944

Just by reading the post it really seems like a large # do fail shortly after replacement, the "1/2 of them", is just a guestimate of mine by studying all I could find on TB failure. I guess I am just nervous about doing a big job only to have it not last as long as it would have if I would have just left it alone. I am sure that scenario does happen, just how often it happens is the question.

DLarsen

Porsche dealer labor to replace the Timing Belt, balance belt, drive belts and the water pump...$800. I purchased the belts and water pump from Sunset Porsche and had my local Porsche dealer install.

Mark944na86

"Almost never" is the correct answer. Indeed, "timing belt failures" are rarely failures of the belt itself. Much more likely is that a related component such as a roller or waterpump seizes due to a lack of proper inspection and maintenance, or the belts are not tensioned correctly, as already mentioned. Keep the car maintained according to the factory guidelines, and you have nothing to worry about. Really.

Tom M'Guinn

I actually did a poll a long time ago, linked below. Not scientific, but interesting to note that only 23% of the reported failures were on engines that were tensioned with the factory tool in the last 30k miles. Of those, you wonder how many were in fact attributable to some other installation error or worn parts.

https://rennlist.com/forums/924-931-...lure-poll.html

rgs944

Do reputable parts dealers keep build dates on the belts. I am worried about buying a belt that is actually NOS, and could be 15 years old.

Mike C.

I've been doing them since '89 on my car with no issues. I do use the 'gold-plated' tension tool but I wouldn't give it all of the credit. Also, I've used a few different (non-OEM) belts with no problems and no obvious wear with a 30K replacement interval. My guess is that very few failures are due to defective (or over-aged) belts. YMMV...

hacker-pschorr

I would estimate less than 10% - 15% of all 944 owners are Rennlist members and an even smaller percentage post anything.

So 50% of 15% of all 944's is not very many IMO

As a 944S owner since 1996 & PCA member since 1991 I know a lot of 944 owners who have owned their cars longer than me.
Not one has ever experienced a broken timing belt and almost none of them are on Rennlist. I'd say about half do their own maintenance.

How many people start threads like: "My timing belt hasn't broken yet??"
It's a case of bad news receiving more press than good news.

Every five years on an interference engine & replace everything the belt touches. I would also be leery of rebuilt water pumps from any non-Rennlist associated vendor.

How many DIY'ers have access to a proper tension tool?