Compressing Mechanical Tensioners

[MarkMW]

I am currently trying to replace an early type tensioner in a 3.0 SC engine , and am having problems with compressing the unit.
I have done several hydraulic tensioners in the past , with no dramas - but I think I am doing something wrong here!

I bought the bent metal clip from our host here , as I understand this is the best method to keep it in the closed position , and duly compressed the tensioner in a vice - there was a lot of resistance , but it did close up sufficiently to get the clip on.

Returning to the bench a couple of hours later , I found the tensioner sitting in a pool of oil , and on removing the clip , was able to compress the piston with finger pressure only - obviously I have wrecked it

Can anyone tell me what I might be doing wrong before I destroy another one?

Many thanks
Mark

[1982911SCTarga]

Bump for some qualified thoughts about this.

Brian

[safe]

compress it very slowly, if you didn't.

[cgarr]

I could be all wrong here but, if you keep a steady pressure on them they should compress, the oil is only a buffer to keep them from quickly collapsing, I believe the screw in the side will release the pressure? I have pumped them back up with a supply of oil on top and I guess thats how they stay full when in use, there is a check ball inside which will let oil in but not out when pumped up.

[MarkMW]

Originally Posted by safe

compress it very slowly, if you didn't.

Thanks !!! - I didn't ! - now I have , and it works perfectly.

Where would we all be without this board - Thanks again

[1982911SCTarga]

I'm not sure the route to recovery/repressurizing is through the check ball. If you depress the check ball, oil escapes. On the other hand, I don't think it will naturally allow oil back in.

You can depress the check ball by removing the uppermost retainer and seal. From there, you can slip a paper clip down the plunger to depress the check ball. That's as far as I've gotten in messing around with one out of a pair of spare tensioners I have (I carry them in my spares kit when I travel). It was leaking oil, so I disassembled the top part and found a shot O-ring. I plan on rebuilding both, but I haven't gotten around to ordering the rebuild kits for them.

Compare a properly filled 930-type tensioner to one that has lost a portion of its oil -- it highlights the incompressibility of a fluid to the compressibility of a gas. There shouldn't be any air inside a properly functioning tensioner.

The workshop manual and Haynes have procedures about re-filling and bleeding while mounting the tensioner at a 20-degree angle in a vice (working from memory here).

Brian

[1982911SCTarga]

Thanks !!! - I didn't ! - now I have , and it works perfectly.

How did you replace the lost oil?

Brian

[thesey914]

Compress it in a vice - see my sig for a "how to"

[equality72521]

Originally Posted by thesey914

Compress it in a vice - see my sig for a "how to"

You don't have a sig.

[notmytarga]

http://www.thesey.com/tensioner.html

I found the link in his profile - nice write up with lots of clear pictures.

[equality72521]

Originally Posted by notmytarga

http://www.thesey.com/tensioner.html

I found the link in his profile - nice write up with lots of clear pictures.

Ok, got it.

[thesey914]

whoops forgot to tick sig box