16V-replc tensioner or just rails?

[GostRidr]

I've been reading up on the tensioner that we need to be wary of in the 16v in addition to the usual belts. Zims (any others?) started selling the replacement plastic guide rails for the top of the tensioner. This becomes a $30 repair instead of $400. However, some were arguing that, if the rail has been worn down that much that the hydraulics in the tensioner aren't far behind. I'm wondering what has been the experience of anyone trying this. Or, maybe everyone is just replacing the whole $400 tensioner? Any experience thoughts would be great.

Thanks!

[rmconner80]

Risk management = assessing IMPACT and PROBABILITY of the risk.

In this case, a tensioner failure has a low but unkwown probability... but a known HUGE impact. Probability of the failure goes up with mileage / age... and goes down depending on what parts you replace.

I replaced the J tube and the whole tensioner, not just the pads. I left the chain because pulling the cams and retiming can be a big job.

Then my headgasket blew 500 miles later, at which point they replaced the chain while because it was an obvious "while you're in there".

So it's up to you to manage your risk. In this case you can't lower impact. You can lower probability of a failure. Each step decreases your probability of failure, but incurs incrementally more cost / time:

1) Replace Pads
2) Replace J tube oil supply
3) Replace whole tensioner
4) Replace chain

When I pulled the cam cover, I also replaced the gasket as well as the funky long and short bolts. These bolts are reported to break very easily as they give a lot under only 6 ft lbs of torque. If one breaks it could be a pain in the ass, so I didn't take a chance. Rennbay has replacements for under $100 that are superior. You need to be sure that you do not exceed 6 ft lbs torquing on this stuff though or you'll strip the mounting in that purty, expensive aluminum head.

[Dave L]

I bought the pad from Zims and gave it to my mechanic to install along with a timing belt, roller and water pump. He worked at Porsche for 17years during the late 80's and 90's and had seen the chain tensioner destroy heads. He inspected the tensioner, the chain, J tube and said that everything really really good (the head was rebuilt by the PO). Even the pad wasnt really worn too badly but was replaced anyway. This was 2 years ago and the car currently has about 100,000 miles on it. I will probably check it out this year to see how the Zims pad is holding up.

If your car has high miles I would consider replacing the whole lot as rmconner80 suggested as it will ensure that you are good for another 130,000 miles.

[Jeff Laurence]

When my belt stripped a few teeth( and bent 8 exhaust valves) I replaced the pads and the chain- timing the cams is not hard at all (once you realize the picture in the Porsche manual is looking at the rear of the engine!). I realize that I probably should have replaced the copper pipe-because copper work hardens when you bend it repeatedly. I would like to know what fails in the tensioner and is it rebuildable?

[rickharrison]

I got the Zims pads for my tensioner too...my car had only 122,000 kms on it, and everything looked like it had minimal wear, so I opted for the cheaper route.

As long as the tensioner functions smoothly, you should be ok. Just make sure the oil feed tube isn't broken.

Ian at 944online sells a brand new tensioner/pads for a good price, and in your case that might be a good option.

That's where I'll get mine when the time comes.

[mistertate]

I thought the only failure mode was deterioration of the pads. Does the tensioner itself ever fail?

[GostRidr]

Great info all. Thanks guys. I always have a tough decision about when to replace something due to age-not mileage. Neither of my cars are driven very much so I'm always way under the mileage but, since I live in the desert where rubber and other materials dry out MUCH faster I tend to change out earlier. Good to know the pads are a, potentially, reliable alternative for the short term.

John, I've never done this before but the little bit of reading I did said that, yes, the tensioner itself DOES fail after awhile. RM alludes to this above as does Clark in the 16v section about the belts....

[kdjones2000]

There is an S2 car in the Phx area with 80k miles on it with the dreaded broken tensioner. Took the head and cams with it.

Let's hope YMMV.....

[mistertate]

So does the tensioner just break or does the piston fail? The piston fails and there's slack in the chain to break the camsprockets? I always thought it was just the pad..
I'm rolling with 230k on my chain tensioner, just replacing the pads

[kdjones2000]

I think it depends on what version of the oil tube you have. If yours is the "J" tube, then I think you are OK. If it is the earlier straight type, those are prone to failure, and I would recommend replacing with the newer tube design.

Other than that, pad tensioner is the major failure mode, as far as I know.

Cheers,

Keith

[Arizona_928]

Originally Posted by kdjones2000

There is an S2 car in the Phx area with 80k miles on it with the dreaded broken tensioner. Took the head and cams with it.

Let's hope YMMV.....

yeah that one looks like a good find. if I had room I would jump on it.

[rickharrison]

I'd bet that 90% or more of the tensioner failures are the results of a plastic pad that is brittle, and comes apart.