Chain Tensioners, when do you worry??

[J.HK]

I have a 72 911T. The engine had the top end rebuilt around 37k ago. The rebuild was over 12 years ago. I have full receipts for the rebuild and the receipts show that the tensioners and ramps were re-placed when the motor was rebuilt. I obviously don't have the updated oil fed tensioners, I wouldn't be writing this if I did.....

So, when do I start to worry??? Mileage? Time?

J

[Superman]

Start worrying any time. Stop worrying when the pressure fed tensioners are installed. It's like roulette. No one can tell you when the stock tensioners will fail.

If you stay with the stock tensioners, at least install the little collars that can potentially help yoru engine survive a tensioner failure.

[rstoll]

Mixed emotions here. As I was updating to pressure fed tensioners, I thought about how well the 18 yr old stock tensioners had held up. Actually had a broken chain ramp generating all the noise.

[J.HK]

I talked to several different mechanics on the issue and the verdict I came to was that they had very very rarely seen them fail. And when they did fail, they made a lot of noise before they failed. Obviously when they do it's real bad.

Not 100% sure where I stand on the issue...... Just trying to take in all of the info....

[Doug Zielke]

Originally posted by Superman
Start worrying any time. Stop worrying when the pressure fed tensioners are installed.

Agreed.
When I opened up the virgin chaincases on my '81SC (with around 70k miles at the time), I was met with a potential horror show.
The left-side tensioner was totally collapsed; the right-side seized up solid. I still can't believe there was no damage to the cases, chains, or ramps. I may have been lucky in that the PO of the Blue Bomber was a lady who babied the car, and consistently avoided the redline.

Bite the bullet, and replace, or at least inspect the tensioners now.
BTW....I'm not a fan of the "collars". If they ever come loose inside the cases, they can do more damage than a malfunctioning tensioner. My local wrench showed me an example of that occurance. What a mess! They are a "band-aid"; don't trust them.

[Ottawa911]

Sounds familiar....my '70T had a complete engine rebuild about 6 years ago. According to the receipts, the tensioners were replaced at that time. I bought the car last year and it only had about 5000 miles on it since the rebuild.

Last year, I started hearing a horrific noise when the car was idling but the problem seemed to come and go. I didn't know what the noise was until I consulted the bright lads on this board. I opened up the chain cases and sure enough, the left tensioner had failed. I ended up putting in new oil-fed tensioners (and changing the ramps at the same time!)

Moral to the story......it's a real crap shoot!! If I were you, I would at least install the collars on the tensioners and keep your ears tuned for strange noises!
Good luck

[MBAtarga]

BTDT. My 83 targa purchased in May '01 had 87k miles with no update. I talked around and decided that $375 was cheap insurance for the possibility of catastrophic damage ..not if, but when .. the original tensioner(s) failed. I can now sleep at night.
Ditto on the comment from Doug on the collars - one of the mechanics I talked to also knew of several failures.

[tight as a bull's ass]

Mechanical tensioners don't rely on hydraulic pressure...

I would replace tensioners with original mechanical type.
You'll be set for the next 100K + miles.

With hydr. type, if you ever lose oil pressure, you're screwed.

concurrent systems dont always have the advantage.

[911nut]

The mechanic of the PO of my '82 SC told me the following story when we were discussing the upgrade to Carrera tensioners: a customer who drove his '77 S over 100 miles round trip to work every day brought his car in due to a rattling noise he heard at idle. The mechanic diagnosed the problem as a possible tensioner failure. Due to the shop's backlog of work he couldn't repair it until the following week. The customer dutifully returned with the car the following week and the mechanic learned that the customer had continued to drive the S to work since the last visit! The mechanic found no damage caused by driving with the failed tensioner. However had the customer decided to do a DE or trackday the previous weekend the outcome may not have been as favorable.

[KTL]

Originally posted by les paul guy

.....With hydr. type, if you ever lose oil pressure, you're screwed.......

If you ever lose oil pressure, you'll have more worries than just your chain tensioners!!!

Porsche continually improves on their designs, year after year, model after model. If Porsche decided to forego the mechanical design for the pressure-fed design, i'd have to believe that the engineers at Porsche felt it to be a better design.

I know full-on race setups don't use the pressure-fed style, but that's a different animal altogether.

[Superman]

I'd agree that if you lose oil pressure you'll have more problems than just tensioners or bent valves. I'd also add that hydraulic tensioners are actually kind of "hydraulic assist" tensioners. They are very much spring loaded and they keep my chains quiet during the roughloy 1-2 seconds between startup and full oil pressure to the cam oil lines. I can hear them growl during that brief time. I timed my cams with only the spring tension of the PF tensioners because these internal springs held my chains TIGHT. So no, they don't rely entirely on hydraulic pressure.

[CraigD]

There was a very interesting discussion re tensioners on the Early S Board some time ago. None other than Roland Kunz was a major contributor. Here is the link