Carrera chain tensioners?

[Mr9146]

Lars - the later, wider arms would be the optimal way to go. However, I doubt the failing is due to the galling of shaft/arm(s); rather, I would attribute failing Carerra tensioners to poor engine maintenance. Because the Carrera tensioners use engine oil, if the oil is not changed at regular intervals the chances that dirt, grime and slime from the dirty oil could contaminate the tensioners' internals thus leading to failures. It's rare, but it does happen.

As for a faulty brand-new tensioner, well, even production robots make mistakes. Again, extremely rare but it does happen.

[KlaasyT]

John, I am beginning the process of this update as well. I haven't tried bleeding my tensioners yet. The left side chain housing needs to have the two upper studs changed. Everything I have read said longer studs are needed. Mine are currently short M6 studs.The replacement studs are M8? So the housing needs to drilled and tapped to accept the larger/longer stud? Did you have to do this? Or can longer M6 studs be used?

Clarence

[Zithlord]

Clarence; I used longer M6 studs(as they should be), I made them myselves out of some very long M6 studs, just shortened them down to the correct length. Use two nuts on the old stud to remove and two nuts on the new one to insert(two nuts just for this prosess).

I contacted www.autotuning.no in Norway(independent Porsche specialist) today and they had a bhunch of NOS tensioners at 500 Norwegian Kroner a piece!!! Lucky me.

And Lars, I will not drive this car very hard, and the old idler arms and the shaft look very nice with no scratches, so I will go with the old setup, with the pressure fed tensioner. A trip across Hardangervidda is beautiful, 1000-1500 meter platau with Raindeer and Moscus ox's. I have been there many times as a kid fishing with my father.

BTW; can any of you guys repair the used failed pressure fed tensioners I now have as "spares"?

John

[911pcars]

Try squirting some air pressure into the oil inlet. Sometimes the ball check sticks and this can dislodge it. I did this out of frustration with a new pressure-fed tensioner that was soft. I stuck the rubber end of an air nozzle into the oil hole, gave it a shot and heard the ball "click". Tested it once again and it was and has been fine ever since.

FWIW,
Sherwood

[KlaasyT]

How is it going John? Did you get another set of tensioners? I have run in to the same situation.At first mine seemed to be good and solid in the oil. I slowly compressed them in the vise and installed the pin. After installing in the car and releasing the pin I found that though they snapped against the idlers, I could compress them by hand. I removed the tensioner and tried to bleed it but now it would not. I tried Sherwood's suggestion with air and my result was that while I applied air the bleed valve let some air by intermittently and the tensioner would go solid. When I stopped with the air the tensioner stays solid for about 3 seconds and then has only spring pressure.If I submerge it Immediatly after applying air,I noticed the air seem to escape just below the top of the pistom where there is a small indent on both sides.
Pumping the tensioner in oil seems to have no effect.It doesn't seem to push out air or suck in oil. I am unsure how to proceed. I would think that oil pressure would keep them solid, but what about initial start up? Mine were also a used set from a dismantler that came off a 3.2.

Any more ideas would be great!
Thanks
Clarence

[911pcars]

Clarence,
I should add that I applied air (as I recall) with the guts removed from the tensioner, and it was just some quick bursts of 90 psi air, not a constant flow. I wanted to see if it would dislodge something that might be stuck. Not sure if the empty tensioner makes any difference, but at least it's worth a try to see if this can be salvaged.

And just to clarify. The pressure-fed tensioners receive its oil supply from the pressurized lube system, not from oil splash. If the supply port is blocked or otherwise restricted, it doesn't matter if the tensioner is primed prior to installation. This type tensioner relies on a constant source of pressurized oil to maintain proper tension. During normal operation, oil forces the piston upward to remove slack in the system. At the same, oil bleeds past the piston in a controlled leakdown rate; not unlike how a hydraulic lifter operates in a pushrod engine.

The self-contained (Turbo) tensioners produce tension from the sealed oil supply and from the quantity of splashed oil in the chain box. Normal movement of the chain components causes the piston to move up and down. Oil can enter through the check valve to maintain the desired upward piston tension. However, if the piston O-ring fails, the oil and tension loss is immediate.

Hope it works out.

Sherwood

[Zithlord]

After reading several treads at Pelican and the answers I got here, I decided not to take the chance on using the used set I had. I could not get them to firm up when I submerged them in oil and primed them. I bought a set of new ones and received them yesterday.

Its the internal valve in the tensioners that keeps them firm, and not the oil pressure from the engine. The oil supply from the engine is just to keep a constant supply for the tensioner. Without the oil supply from the engine the tensioner would weep out oil through the internal valve and would lose its firmness when working in a running engine. I will dismantle the old set and see if I can get them working and keep them as spares.

John

[Frank-J]

I had the same problem a few years ago priming the oil fed tensioners. I even bought a new set, and had the saem problem.

I finally figured out to get the air out of the tiny bleed orifice, the oil needed to be thin enough to let the bubble form, and let it out. Try 5-30 oil, or thinner!

Once I changed oil in my setup, they worked fine. BTW I used a small C-Clamp and fully imersed the units in oil.

[KlaasyT]

Thanks guys, Because these were used they had oil in them when I received them (also no grenade pin)so when I first primed them they were hard. While I compressed them to insert a pin (nail) oil slowly came out. When I released the pin in the car they snapped in place but then felt softer. When the pin released the piston you could hear air getting sucked in through the feed port. I think this is why the felt soft. After removing and trying to reprime with no luck I came to the conclusion that whatever oil was in there I removed much of it when I compressed it the first time. After reading posts for many hours on this subject I came across one post http://forums.pelicanparts.com/showt...=top+ten+myths
from Wayne at PP.
This was posted at a later date than the one that explains the process of priming the tensioner before installation.
I decided to install as they were believing that to be filled they would have to be pressurized with oil. (releasing the pin would always fill it with air again as the piston extends to the idler).
I cranked the engine first with the fuel pump disconnected to build up oil pressure, reconnected and started the engine.
No problems! All is well. The very slight clatter I had at Idle with the old setup is gone.
It seems to me to actually prime these things you should have a small pump that can be threaded into the feed port after the installation and pump oil into them till they bleed before installation of the covers and the feed line.

This has been my experience with this project. Thanks for all the responses!

Clarence