New hydraulic tensioner won't pump up

[ChrisBennet]

I've got 2 brand new hydraulic tensioners that I cannot get them to firm up. I've exercised them until they sucked in oil and pressurized them with air until they squirted oil out the little pressure relief valve but I can still compress them with my bare hands.

I'll ask the client where he got them but it's been a few months so we may be out of luck returning them.

Does anyone know of any tricks for making them work?

-Chris

[1meansc]

Hi Chris,
I normaly pump them up with a small oil can. Just place the nozzle of the oil can over the oil inlet of the tensioner, and slowly pump the tensioner up in its correct orientation, so that the air can be released.
This should work.

[ChrisBennet]

Originally posted by 1meansc
Hi Chris,
I normaly pump them up with a small oil can. Just place the nozzle of the oil can over the oil inlet of the tensioner, and slowly pump the tensioner up in its correct orientation, so that the air can be released.
This should work.

Yes, of course it should work - but it isn't with this pair for some reason.
-Chris

[john walker's workshop]

i use the pump can method too, but i cut the banjo end off a metal line and use a short length of hose between the pump can and banjo, which attaches to the tensioner with the normal banjo bolt. i've had a couple lately that didn't pump up, so the supplier just sent another kit. if they don't pump up, they ain't going in.

[ChrisBennet]

Thanks John!
-Chris

[hcoles]

I submerged mine and started pumping the piston up and down with a big set of channel locks. At first the bleed opening at the top of the piston bubbles out air after compressing the piston...you may have to wait for a few seconds and the pressure of the air should be pretty high. This assumes you have some oil on the piston so that air doesn't just come up the sides. If this doesn't happen my guess is that the check valve at the bottom of the piston is not holding. I would try shooting some brake cleaner in there and see if you can clear out some debris. Where the debris goes is another issue, it may bet back into the check valve. I don't know if this helps....I don't like these things but they are better than no hydraulics at all.

[ChrisBennet]

Dang, I left one tensioner in last night to keep the idler sprocket and chain from flopping around and tonight when I went to remove it, it was pumped up. Go figure. Guess I'll try it with the other one tonight.
-Chris

[hcoles]

if your not kidding....it could be that the oil in the resevoir section leaked passed the check valve and then made the main chamber feel pumped up or more pumped up than it did before....assuming I understand how these work this doesn't seem good to me...oil should not move forward past the check valve without any pressure or piston movement....just thinking, others may understand these better

[ChrisBennet]

I'm not kidding. I don't know if sitting compressed made a difference or if it unplugged itself when it snapped open during removal.
-Chris

[hcoles]

Have you or are you going to install the JWE spacers inside the tensioner? I made some for my engine..the dimensions came out fairly small....2.5 to 3mm long. You can make these out of a 5/8" (I think that is the size) bronze bushing you can get at OSH and a hack saw and sanding/etc. I talked to Jerry Woods and he suggested to even push the recommended .128" of remaining play I went for 2mm. This is good insurance in case the tensioner fails. I think this was the thing that saved Jim's 3.2 start up when his tensioner failed.
-h

[ChrisBennet]

Originally posted by hcoles
Have you or are you going to install the JWE spacers inside the tensioner? I made some for my engine..the dimensions came out fairly small....2.5 to 3mm long. You can make these out of a 5/8" (I think that is the size) bronze bushing you can get at OSH and a hack saw and sanding/etc. I talked to Jerry Woods and he suggested to even push the recommended .128" of remaining play I went for 2mm. This is good insurance in case the tensioner fails. I think this was the thing that saved Jim's 3.2 start up when his tensioner failed.
-h

I have considered it. I even went so far as to disassemble an old (failed) hyd. tensioner to practice on.
-C

[hcoles]

Chris,
Another thing I discovered....the tensioner O ring comes from the factory as size 1.8mm x 12.5mm - that's the closest metric size I could measure to. Two sources (Victor Rense kit and local Porsche mechanic) of replacement O rings came in at a size of 1.7mm x 12mm. In my humble opinion this is not the correct replacement but it may still work. I went down to my local O ring supplier company and the guy was very nice and found some Viton 1.8mm x 12.5mm rings and gave me a hand full for free. I also got replacement O rings for my Weltmeister collapseable return tubes. BTW - O rings are sized by CS (cross section) and ID. Again, I want to encourage you to make and install JWE tensioner spacers, cheap and easy to make and install. Your story of the tensioner fixing itself overnight worries me...I think it will unfix it self when you start the engine.

[ChrisBennet]

To wrap things up, thhe supplier sent me another tensioner update kit and the new tensioners pumped up fine. The supplier is sending me a call tag to return the kit w/the bad tensioner.
-Chris

[hcoles]

Chris,
OK, that's good news.....if it was me I would still make and install internal "JWE" spacers. The needed remaining play in the chain is only for differential expansion of the engine relative to the chain,... so you don't need much after the engine is installed and bolted together. The wide range of travel is to accomodate the large variances in engine parts and head fly cuts/etc. Remember that some racers use solid tensioners. Don't take my word as for sure just my thoughts on the subject. If you have good working hydraulic tensioners you will likely be fine for a long time to come. Remember I come from the if it ain't broke fix it camp.
-Henry