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Most folks don't seem to replace them with a rebuild as they are a bit spendy. Having said that, one of mine (passenger side) gave out shortly after top end rebuild at around 125k miles. Made a weird kind of slapping sound at about 3000 rpm, probably the loose chain slapping the housing. Replacement solved the problem. No issues with the left side one so far.
Sonnen has them for $253.73 a side, so just over $500 for both. They are relatively easy to access - especially the right side - so not strictly a "while you're in there" item.
While the hydraulics on mine failed, the spring still kept enough tension on the chain to prevent catastrophic slipping of chain / sprockets. It took a while to figure out where the noise was coming from, eventually narrowed it down with a mechanics stethoscope and second opinion from Trophy aka Steven.
It seems to me inspecting or even bench testing a chain tensioner may be a good way to come to a decision. I assume one could pressure test one with a little oil and an air compressor and see how much/ if they are leaking.
I am sure there is a procedure for this if someone would chime in on the subject.
If not, developing your own procedure or buying a new one to compare leak rates, if there is any, would be a good evaluation as long as you can return the purchased one if not needed.
Those tensioners are designed to have some leakage-a small flat on the side of the piston.
I usually install limiters if for no other reason than to prevent the cold start noise when they've
collapsed after sitting.
Those tensioners are designed to have some leakage-a small flat on the side of the piston.
I usually install limiters if for no other reason than to prevent the cold start noise when they've
collapsed after sitting.
Does this suggest a rate of leakage compared to a new one at a given pressure would be a good functional test?
Sonnen has them for $253.73 a side, so just over $500 for both. They are relatively easy to access - especially the right side - so not strictly a "while you're in there" item.
While the hydraulics on mine failed, the spring still kept enough tension on the chain to prevent catastrophic slipping of chain / sprockets. It took a while to figure out where the noise was coming from, eventually narrowed it down with a mechanics stethoscope and second opinion from Trophy aka Steven.
Brian,
I was thinking while the motor is out and there is no obstructions what so ever, and while the car is in the air...
IMHO, money and time well spent.
Those tensioners are designed to have some leakage-a small flat on the side of the piston.
I usually install limiters if for no other reason than to prevent the cold start noise when they've
collapsed after sitting.
Are these limiters readily available or are they a special motorsports item?
I would suppose you could makea fixture to do a kind of leakdown test-apply pressure into the oil feed
end but I haven't tried it. Other than the flat on the piston and wear/scratches on it or in the bore there shouldn't be much leakage-there's a ballcheck to prevent backfeed towards the fill end of the piston which wouldn't show in the kind of test i described though.
As far as I know-which isn't that far you need to make the limiters on an engine by engine basis.
These tensioners are superior to the old "turbo tentioners" used on the older 911 motors. When I rebuilt my 3.6 at 107k miles, I gave them a visual inspection and then reinstalled them. I have not seen in any of the write-ups any chronic issues mentioned with this design. If the motor had 200k miles on it, I would think that replacing them should happen.
Having said that, one of mine (passenger side) gave out shortly after top end rebuild at around 125k miles.
This is the first I've heard of a tensioner failure in a decade of working on 993's. Completely different design than the earlier cars. I've never known anyone to replace tensioners during a routine rebuild. Lotta armchair "experts" in this thread, including two of the forum's bad advice legends, who know little and have even less experience.
This is the first I've heard of a tensioner failure in a decade of working on 993's. Completely different design than the earlier cars. I've never known anyone to replace tensioners during a routine rebuild. Lotta armchair "experts" in this thread, including two of the forum's bad advice legends, who know little and have even less experience.
IIRC, the tensioners can be disassembled & cleaned. the RH one might be more susceptible to collecting grit due to its inverted position.
I had a chain tensioner fail this summer at 62k miles. I had a similar "slapping"/growling sound at about 3,000 RPM that bcameron59 . If I revved the engine in neutral and let the RPMs fall, I could hear that sound at about 3,000 RPM, too. My tech said don't drive the car unnecessarily until he could inspect it. He replaced both (the second one as a precautionary item) and the issue has been remedied.
11-21-2016, 06:29 PM
To Replace or Not: Chain Tensioners
