Why is there a grease nipple on my tensioner

LM3929 · 11-09-2010, 03:20 PM

I am currently putting in a Carrera tensioner upgrade when I noticed that one tensioner had a "grease nipple" on it.

Can anyone tell me why is it there? maybe to bleed the tensioners?

any help would be appreciated.

Thanks Lorne M.

hcoles · 11-09-2010, 03:56 PM

interesting, I don't recall they looked like that - my memory isn't too good.
Someone will know. All I remember is it was a PITA to get them bled and installed.
You can use a drill bit of proper size to stick in and hold the piston down. You might want to install Jerry Woods slugs at the bottom of the cylinders, might was well at this point. Easy to make from OSH bushing.

Flat6pac · 11-09-2010, 04:00 PM

The one on the right appears to be defective as I pulled a set last week and one had the nipple broke off and wouldnt hold pressure causing chain rattle and fingers could compress it against the spring. I collapse them in a vice slowly because the oil is cold and the relief is slow.
Bruce

sailchef · sailchef's Garage

I had just the opposite experience. They went in very easy, and, I don't remember bleeding them. There were two grenade type pins that you had to pull after the install. Don't see them on the ones above, the holes are there tho.

daniel911T · daniel911T's Garage

Just wanted to share a nifty little fact: possibly even useful!

When installing mine, I didn't have the little grenade pin either, and that was a real issue. While looking for something to fill the need, I came across the perfect tool for the job: the shank of any dremel bit.

Just pull out any old dremel bit, and it fits the hole perfectly.

Also, I just did this job last weekend, it takes a lot of force, slowly applied, to get them to compress enough to get the pins in. I had to use a large C clamp. Not ideal, but it worked. Expect to have some oil come out as you compress it.

Good luck!

Dan

preston_brown · preston_brown's Garage

Quote:

Originally Posted by Flat6pac

The one on the right appears to be defective as I pulled a set last week and one had the nipple broke off and wouldnt hold pressure causing chain rattle and fingers could compress it against the spring. I collapse them in a vice slowly because the oil is cold and the relief is slow.
Bruce

The right one might be defective, but then so again, the left one could be too! Why does the left one have the piston completely retracted (with no pin in place) while the one on the right one is completely extended??

Completely agree about the grenade pin being standard from the factory...my replacements had them 3 years ago. Were these purchased new or did they come from someone?

snbush67 · snbush67's Garage

I had a broke nipple like the one on the right as well, I do not think it is repairable I tried but ended up getting an exchange. It seems that the aftermarket tensioner are prone to this type of failure. The Porsche OEM tensioner are a better product.

Trackrash · Trackrash's Garage

The one on the right looks to be missing the circlip that keeps the piston from coming out of the bore.

4sd911 · 11-09-2010, 10:20 PM

Did you buy these used? As stated above the right one is damaged, the grease nipple on the right one is not like mine, I haven't seen one like that before. Look at the picture of a new one on this site. If these are used I'd think about returning them.

RWebb · RWebb's Garage

I bet a PO used that to pre-fill the thing with oil

LM3929 · 11-11-2010, 03:13 PM

I have to check my setting, I haven't been getting any responses to this post.

the tensioner on the right was an old spare unit that took apart to see what makes it tic.

I was going to do the Jerry woods mod to two used units that I bought from the site

I came across a descent pic of a hydraulic tensioner and mine are different.

neither of the two used tensioners have the cage over the bleed hole.

does anyone know if the cage is needed?

Lorne M.

gtihop · gtihop's Garage

I'm pretty sure the cage on the bleed hole also holds in a spring and a ball, whicj if the cage is gone, so are those parts. I did the Woods mod to my tensioners two years ago, after having a new tensioner fail. So far they have been working well.

Walt Fricke · 11-11-2010, 09:47 PM

Lorne

If your tensioner does not have the sheet metal cap the green arrow points to, it won't work. The cap holds one end of a spring. The spring presses on a ball, which closes a hole. If the ball is missing, oil just squirts out the hole and the tensioner won't work.

The grease nipple is one of two things.

A. Someone carefully threaded the hole in the tensioner, and modified the nipple to serve the function of holding the spring (and thus ball) in place and under more or less the right spring pressure. In which case he is a master mechanic, and I'd like to know more about how he modified the grease fitting.

B. He is a dunce, and a scoundrel for selling them to you.

I had a cap pop off on the track. All the standard sounds of a failed tensioner.

Carrera tensioners don't need any prefilling or the like. After all, they are pressure fed.

LM3929 · 11-12-2010, 09:37 AM

I took a more careful look at the tensioner with the "grease nipple" or cage modification and from what I can see it's a darn good modification for the stamped cage/spring problem that came with the original units.

There is another thread here on Carrera tensioners, where the problem of the cage falling off has come up, I am going to see if I can find it to see if anyone else has "fixed" the problem.

Lorne M.

gregwils · gregwils's Garage

I can't really comment on the grease fitting, but here are what mine looked like when opened the chain covers. The piston is compressed on both, but that doesn't change the appearance of the oil relief.

LM3929 · 12:32 PM

I think that the cage/ball and spring must only be there to keep the dirt from falling into the bleed hole because the way that the ball and spring are positioned they would only let the air out not keep any oil under pressure in and dirt from falling in, they dont really look that they do alot?

Lorne M.

Walt Fricke · 11-14-2010, 07:23 PM

Lorne, you go ahead and take these off and see how your car runs.

Parts inside the case don't need screens or whatnot to keep dirt out. Dirt isn't supposed to be there, and when it is, you have bigger issues. Consider, if you will, how the tensioner arm is lubricated: through the trough on its top side. Ditto the rocker arms.

From memory here's how things work: Look at Greg's picture of a tensioner. Oil under pump pressure enters the tensioner through the O ringed part. It goes into the right side chamber - the one with the hat and spring on top. It then goes through an orfice on the bottom to the bottom of the left chamber. It then goes through another ball and spring device up into the upper left chamber, where it pushes up against the piston. A stout spring also pushes up against the piston.

When you compress the piston in a vice, you will note that oil slowly flows out of the very top of the piston - the working end, as it were. From a very small area under the hardened (at least it looks hardened) cap piece. You can see that in the picture. Which is why it is so hard to compress, but also why eventually it does compress. The valve at the bottom of that chamber is one way, and oil can't go backward past it. So it comes out the top, but slowly.

The hat, spring, and ball valve on top of the right chamber just release excess engine oil pressure. When the left chamber is full enough, it doesn't need any more pressure than it has. If the engine is trying to pump more in, it bleeds out the top through the hat.

No hat, spring, and ball? Well, then the engine pressurized oil just runs out the top. Never gets to the left chamber. Which eventually pumps enough of its own oil out that it doesn't work properly.

After all, the tensioners act like shock absorbers, dampening the rather wild jumping around of the chains. I am told that you can remove a cover to watch what the chain does, and not get all splattered with oil. Some day maybe I'll try that, but several have said they have, and, unlike those who tried that with a valve cover and regretted it, said it was worth the look.

Anyway, a shock absorber with no oil in it doesn't work. No damping action. Which is what happens to a chain tensioner if it looses its oil.

Flieger · Flieger's Garage

Right, the oil is mostly for dampening, the spring is what really does the tensioning part.

Walt Fricke · 11-14-2010, 08:23 PM

I had always heard that damping was pretty important. Blah Blah Blah. Then I had an old VW which I was going to flat tow to a shop to have a roll cage installed. I had first stripped it of a lot, including the shocks front and rear. They were to be replaced, and what do I need those for for the tow.

Well, I got half a block. The car was jumping up and down even at those slow speeds. Undamped oscillations can be wicked.

Flieger · Flieger's Garage

I had the rear damper (coil-over) somehow unscrew from the Heim joint that connected it to the swing arm on my mountain bike. The geometry and spring settings were such that the spring stayed in place if I was sitting on it. That was the worst, bouncy-est ride down the mountain and back home I ever had. Pedalling setup a weird harmonic. I re-attached it that afternoon and the ride was immeasurably better.

You truly only know the value of dampers when you don't have them.