Tensioner rebuild: when to?
 

When would you recommend rebuilding the spring loaded tensioner? I have a set that have a few thousand miles on them, then they were removed and bagged for 12 years. Would the O rings go bad from age? One tensioner's piston can be moved about 2mm by hand pushing against a block of wood before stiffening, the other cannot be moved by hand.

Also determining the type that can be rebuilt. The part no. on mine looks like 930.105.501.OR the book states "only tensioner with part no. 930.105.049.00". Mine seem to have identifying features, Chamfer on upper housing, total height 78.2mm & mounting boss stop, but doesn't show the trade mark like the book. Attached is pictures of one.
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I wouldnt rebuild them, I d put guards on them. If they fail then, rebuild consideration but there is always some sitting on the shelf that are holding good pressure.
The guards are the important thing to be there if the tensioner fail.
Bruce

The one's you have are the one's you can rebuild. If you can move one by hand, then at least a bleed is necessary but would advise you to rebuild them. Rebuild kits are cheap compared to the potential for engine damage.

I installed them yesterday. The one that moves about 2mm with hand pressure I believe was like that new purchased new. Could not use the collars, there's not enough room for the collar and the gauge block.

How do you bleed them? Open bleeder screw, submerge in oil and pump the piston rod? How hard is it to compress the piston with bleeder screw open?

I have the two that were on the engine when I bought the car they are the same type but with the thick flange. I tried to disassemble one to see how it comes apart. I got the top C ring off with the spring retainer and spring but I couldn't get the aluminum piston out. Also I removed the bleeder screw and the piston is still hard to move, although this tensioner, before working on it, the piston will move with hand pressure about half way before harding. Oil coming out of the bleeder has metal flakes in it.

It is common to not have enough room with new chains. I would try again in 6 months. One good thing about this lack of room is that you do not need a collar sice there is little room if a failure should happen.

That procedure is a bit involved. You would have to remove the piston without damage. there is a check valve that has to be depressed with a very thin wire. The amount of oil in the reservoir is important as well. Feel free to PM me if you are not up to tackling the procedure.


Some flakes can be in the oil after the seal failure. You would have to inspect the piston and bore of the reservoir for damage.

The important thing to remember when you use the older style tensioners is to replace the tensioner arms with new Carrera style units.
The new style arms are wider and have a bushing for smoother operation.
Supertec makes an improved arm that has proven to be superior to even the factory models.
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On a related note... How do you check the carerra tensioners? do they ever need rebuilt?

They are not servicable.

Is there a change interval? just clean them and reinstall?

Has anyone else noticed the outrageous cost of tensioner lately?

I would replace around 100,000 miles or so.

I'm just glad they are still available. Our ability to get replacement parts in the future will be a challenge.