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Mechanical tensioners VS. oil fed carrera tensioners

I have the car in the shop for some work and the mechanic found that the left timing chain housing is leaking so they are gong to fix that. well my next question is "while you are in there" should I do the other side and he mentioned the chain tensioners. The car is a 84 turbo with 35K miles on it. he is a a bigger fan of the mechanical tensioners but understands the arguments for both types. what are your guys thoughts? anything else I should have him look at?

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Old 11-06-2010, 11:24 AM
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put the locking collars on and keep it exactly as your mechanic wants
Old 11-06-2010, 11:27 AM
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I thought Wayne ('Mr.Pelican') proffered up the Carrera tensioners. (My car had them when I bought it.)
Old 11-06-2010, 04:00 PM
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I may be wrong, but don't all 930's come with hydraulic tensioners? Back in the day of earlier 911's they were considerd the wise upgrade, since the mechanicals can fail without notice and bend lots of valves and break lots of piston crowns in the process. Yes, you probably get more accurate valve timing with mechanical and with the safety locking collars you can at least prevent catastrophic damage in the event of a tensioner collapse. My personal opinion FWIW is hydraulic over mechanical.
My old '73 911T had mechanical without locking collars. One failed; luckily it only bent one exhaust valve...sodium filled at something like $75 if I remember (this was WAY back and my memory is fogged over the years). Did the work myself, but had I kept the car I would have converted over to hydraulic.
Can locking collars be installed on hydraulic tensioners (might be a redunant)?
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Old 11-06-2010, 04:50 PM
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I think that the oil pressure-fed tensioners were introduced in 1984, along with the 3.2 carrera. Cars built before that, like my '79, had mechanical tensioners from the factory. Mine still had the factory tensioners when I purchased it back in 2007.

I'm pretty sure I've read somewhere that its possible to modify the oil-fed tensioners and install safety collars. It seems that either type of tensioner can fail. I do believe that the 930 mechanical tensioners are different than the NA cars and are considered superior if you choose to run mechanicals.
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Old 11-06-2010, 05:30 PM
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Quote:
Originally Posted by jwasbury View Post
I think that the oil pressure-fed tensioners were introduced in 1984, along with the 3.2 carrera. Cars built before that, like my '79, had mechanical tensioners from the factory. Mine still had the factory tensioners when I purchased it back in 2007.

I'm pretty sure I've read somewhere that its possible to modify the oil-fed tensioners and install safety collars. It seems that either type of tensioner can fail. I do believe that the 930 mechanical tensioners are different than the NA cars and are considered superior if you choose to run mechanicals.
Jacob, thanks for the education. You learn something new every day. Just one more thing to add to my mod wish list. Will it ever end.....
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Old 11-06-2010, 06:55 PM
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All Porsche cam chain tensioners are hydraulic. They all use oil to dampen the spring. The spring is what does the actual tensioning. The difference is in where the oil comes from. Some just have a one-time fill of oil while Carrera style get a constant feed of pressurized oil.

"Mechanical" tensioners commonly refer to the solid metal ones used for setting timing.

The safetry collars only work on non-pressure fed tensioners. There is a mod that involves cutting a length of rod to fit inside the pressure-fed ones so that it acts as an internal stop. "Jerry Woods mod" would be a good term for searching.
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Old 11-07-2010, 09:44 AM
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Quote:
Originally Posted by Flieger View Post
All Porsche cam chain tensioners are hydraulic. They all use oil to dampen the spring. The spring is what does the actual tensioning. The difference is in where the oil comes from. Some just have a one-time fill of oil while Carrera style get a constant feed of pressurized oil.

"Mechanical" tensioners commonly refer to the solid metal ones used for setting timing.

The safetry collars only work on non-pressure fed tensioners. There is a mod that involves cutting a length of rod to fit inside the pressure-fed ones so that it acts as an internal stop. "Jerry Woods mod" would be a good term for searching.
So true. I guess the reason that the "mechanical" (misnomer) tensioners...although they are sealed hydraulic/spring units...is that when the seal fails and the oil leaks out, then all you have is the tension of the internal spring, which isn't sufficient to keep the proper tension. I guess that's the attraction of the pressure fed system.

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Old 11-07-2010, 03:10 PM
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