Follow up on Chain Tensioner thread

[Jack K]

Abt a week ago I posted a thread asking for opinions regarding upgrading the chain tensioner in my 82 SC. The responses were mixed and I decided to have it done - for peace of mind if nothing else. It sounded like an idea which, at worst, would be an insurance against damage due to failure and at best, it sounded like a sensibel upgrade with a superior kit being installed which would be there for the life of the car.

When I went to fetch the car and drove it away, I immediately noticed that the timing was out and the dial on the tachometer bounced around before returning to 800 rpm idling speed. Changing gears, therefore, occurred with the revs higher than usual. Concerned, I took the car back to the mechanic.

After a lengthly investigation, my mechanic told me that one of the new tensioners that he fitted had failed and needed to be replaced - which he did at no extra cost. What that has to do with what I found wrong with the car beats me!

I went to pick up the car for the second time to be told that it still wasn't any good as it now had a rattling noise which he said he would investigate the next day.

He phoned to tell me that it was the new tensioner that he had installed which wa faulty. He then put in a 2nd chain tensioner kit which also failed. After that he phoned the Porchse agents and they investigated his complaint and told him that they, too found that the tensioner they tried also failed !! He was also told that when they checked their remaining stock, they too were faulty....a bad batch !!

Again, according to the mechanic, I was lucky that the parts failed when they did because had I been driving at high revs, the resulting damage to my engine could have been catastrophic .... the same as if the old tensioners had broken.

I am not mechanically minded....but I find it hard to believe that an entire batch of Porsche tensioner kits is faulty.

Does anyone have an opinion on this ?

[GB83SC]

As of late there has been alot of complaints around about problem's after tensioner upgrades.
I also thought that the ones out on the market where new and improved?
Maybe Wayne knows what is going on?

[911nut]

There have been reports of new oil-fed tensioners failing on this bb from time to time.
Keep in mind that the purpose of the oil on an oil-fed tensioner is to damp the motion of the spring due to resonance and not suspension of the tensioner sprocket. Since springs resonate and that resonance causes motion, the oil that's being pumped into the tensioner is damping that motion. Additionally, this damping extends the fatigue life of the spring.
There were issues with the idler arm pivot bushings which Porsche corrected during the introduction of the SC which also led to premature failure.
If there is a manufacturing issue with the chemistry of the steel of the spring or a heat treating problem the spring will break, oil or no oil. Since parts are usually produced in batches, it's possible that Porsche's supplier of tensioners had some junk slip into the supply base.

[Jack K]

Tx for the replies.

Do you think that these tensioners could be pirate parts and, therefore, problematical or are they more likely to be genuine Porsche parts? It's hard to believe that Porsche would not have the quality control that we would all absolutely rely on.

[emcon5]

There is a thread on bad tensioners here:
Alert - 911 Carrera Chain Tensioner Installation!!!

I just installed them after Thanksgiving last year. One of the new tensioners in the kit was good, one wasn't. The replacement for the bad one was bad. The replacement for the replacement was also bad. I currently am running a good used tensioner my wrench had laying around.

All the bad tensioners would leak oil out of the pressure relief valve with the pressure of a small oil can (small thumb pump).

I didn't get them from Wayne, so it isn't his fault.

Tom

[Jim Sims]

I also had a new (out of the kit box) oil fed tensioner with a bad oil pressure relief valve. It was installed in a crooked manner and just flipped out (retainer, ball and spring) of its mounting recess with frighteningly little finger pressure. QA went across the River Styx somewhere in Germany. Jim

[Wayne 962]

Read the previous thread...

While there have indeed been reports of this pressure relief valve not working properly, most people who install the tensioners don't use the method that was given to us recently by the manufacturer (see the post).

As for the oil only dampening the spring, I don't believe that to be correct. It is my understanding that the tensioners have both oil pressure and spring pressure to support the idler. It was my understanding that the spring was there merely to hold it into place until oil pressure builds up...

-Wayne

[Jim Sims]

If the pressure relief valve blows or falls off the end it doesn't matter how one prepares or installs the tensioner. A bad bunch of these were made; there seem to be too many reports of failures for it just to be an installation problem. Cheers, Jim