Lost a Cam Chain Tensioner (3.2). What else should I do?
 

As I mentioned in my post in the thread http://forums.pelicanparts.com/porsche-911-technical-forum/1014445-chain-tensioner-questions-carrera-vs-930-a.html I lost the drivers side cam chain tensioner in Anni (‘89 3.2 Anniversary Ed). We are going to replace both while we are in there. It looks like the only part number is a 930 number, which in the little reading I have done is a good thing as the 930 tensioners are better??? I would think they were the same, but that’s just me.

The question is what else should we do? The car has less than 3k miles after a fresh top-end rebuild. No, we did not replaced the tensioners. They hardly ever fail so we left them. In hindsite they should have been replaced, but hindsite is 20/20. We are doing this by dropping the motor a little and will leave the engine in the car. All of the oil lines on the motor etc were replaced when the top end was done.

For future reference, I will say that after the rebuild I did notice a “funny knock.” I mentioned it to the guy who did the rebuild and he agreed it was a little strange but it was very faint. So we ran the engine and wanted to see if it would go away (sometimes they do) or get worse. It never really changed, though my nervous ear would tell you it got a little worse then stabilized. As mentioned by Bob Kontak in the thread http://forums.pelicanparts.com/porsche-911-technical-forum/1010461-loud-ticking-lower-left-side-engine.html, it was not a rod knock and not a ticking like a sloppy valve lash, but some where in between. It is my believe now that this was a partially failed tensioner, but I wont know for sure until I get them fixed. If that knock is gone....nailed it. I will try to report back here those results. Regardless, knowing what I know now, I am sure I would have said “let’s wait until it fails and then do both,” vs having it replaced based on that sound. The car went over 3k miles with that noise, and these really don’t fail very often. Also, since its a topic in another thread (first one I mentioned above) I will also say here I am not going to worry AT ALL about the hydraulic tensioners, their failure rate, etc. This experience showed me they don’t fail often (esp in a street car), and when they do the car is drivable and will get you home. Had I done track days or was flogging the car to redline al the time with a bad tensioner, yes bad things could have happened I am sure (skipped chain, etc). It was making a very obvious racket though, so I took it easy on her and she got me home just fine. Once this fails you wont miss it. In the drive weary rev the car up to say 3.500 and let it come back down to idle, as it passes through 2,200-2,000 the rattle REALLY comes on. Or hold it at that range and it will just rattle away. Very obvious.

930 is the lead parts number on all of our cars...the engine in my 911SC is a 930-10...US models 930-16.

Just replace what is defective
Low miles on a top end all nuts are fresh
Left side is way easier than right
Did you replace chain guides as they were 30 years old
Bruce

Yes the guides etc were all done at the rebuild.

As for the driverside being easier, we are doing both. The PAX side is harder......but is it not doable with the engine in the car?

Once you pull the muffler,motor mount and some a/c support pieces it free to do in the. Car
Bruce

Change the oil and filter and slap it back together and tell us whether the faint knock is gone.

I agree that failed tensioners make an unmistakable noise. It's unbearable to listen to. Somewhere between hitting a steel garbage can with a bike chain and rattling a jar full of marbles. Yes it is loudest off-throttle and quieter on-throttle.

http://www.pbase.com/mrcjb60290/image/168533623.jpg

Well here is the culprit. Notice the parts in the palm of my hand? Not good. That is all we found too. Hmmm....


My knock did not go away, though it may be more subtle than I was. Car runs great, so I am not sweating it at all!

I would replace the chains as well if they are 30 years old. May be why the tensioner failed....too much slack. Easy enough to do with a master link chain.

Chris

My thought when I first read this thread was a damaged tensioner. Those MM check ball cages can be easily knocked loose when working on them.

What did your mechanic say? They just fall off sometimes....?

My motor also makes a subtle knocking sound, when cold, that comes from the right cam housing. I started a thread on it a while back. I also had a tensioner failure on that side of the motor.

I could find nothing wrong when I opened up that cam housing again to look. EXCEPT the idler pulley had noticeable SIDE play on its shaft. If I wiggled the sprocket back and forth it would make a similar knocking noise. Lately I don't notice the sound as much.... Porsche does not, to my knowledge, have a spec for side clearance of the idler sprocket.

BTW, to answer your question, about while you are in there, I assume your motor has the idler arms with the brass bushings.