Chain tensioner advice for a newbie please
 

1979 SC

In the middle of my restoration project. Car has been sent off to the painter and now I am turning my attention to the engine while it is gone. Total newbie to 911 builds and learning as I go.

I am in the process of evaluating all my components and coming up with a list of what needs to be accomplished. History of the car is unknown and the odometer shows 171k.

Below are pictures of the chain tensioners. I am reading in the 101 projects book and it talks about safety collars. Are those the red collars in my photos? Can anyone tell by looking at the ramps is those have been upgraded or if they are original? Anything else stand out in the pictures?

Looking for advice on how best to proceed. Is it a no brainer to just order the upgraded tensioners? How hard of an install is that for a newbie? I am mechanically inclined and have automotive experience. Just new to these cars and motors.

Thank you for any feedback.

http://forums.pelicanparts.com/uploa...1551815383.jpg

http://forums.pelicanparts.com/uploa...1551815383.jpg

If you're going to rebuild, replace the chains,ramps and possibly the gears. The gear teeth wear out. You should install the hydraulic tensioners. Get ready to open your wallet.

Yes those reds parts are the collars. IMO, there is nothing wrong with rebuilding these tensioner but you will get varied opinion on that. Definitely check the chain and idler wheels. I am however more concerned with all that sludge, when I opened mine it was like new.

That engine was a victim of very infrequent oil changes, hence the sludge. As for the tensioners, I am not a big fan of $2,000 chain tensioner update kits. I would be absolutely OK with the older tensioners, rebuilt, and safety collars like you have. Save your money for something else like seats, carpet, or paint.

Well already spent the money for seats, carpet and paint! haha

What is the process for rebuilding the existing tensioners?

Thanks
What specifically would you check on the chain and idler wheels?

There’s a theory that the tensioner issues are actually due to binding on the picot shaft. Henry Schmidt (at Supertec) installed a larger bronze bushing to provide a better surface and would be cheaper than installing pressure fed tensioner. The collars do a good job of protecting from a collapsed tensioner.

Chain, look for stretch. Unfortunately most guys can tell by the left hand side spacing between the lever and casing. You have so much crud I can’t tell. Idler wheels, look for wear. Tensioners, rebuild, not an easy task but well documented on Pelican. Bleeding is the key with new kits.

The re-timing of your camshafts is your greatest mechanical challenge. It is a very nuanced process for each generation of engine type.

Order hydraulic tensioners. Be done with it. They are easy to prime (not with Wayne's method just by dunking in oil!) but with a cheap oil can. They can then be squeezed down in a vice. Easy. Just check the ball valves in the top.

The tensioner thing has been discussed - it's like an oil thread. But they are easy to put in - they cannot be rebuilt, but good ones rarely fail. But bad ones - and I have had bad ones out of the box - stink. But you will know if they stink from the get-go.

HOWEVER - they are not the only weak link in the chain (no pun intended). You must replace the idler arms with the new upgraded wide-bearing arms. It's an easy thing to do - but the prices on the set are ridiculous. They really are. Porsche or whomever aught to be wearing masks - but they must be done - because I think it's these that are the actual weak link in the chain - not the tensioners. You can run the engine on one failed tensioner - but one of those idler arms bind? You're screwed. I bit the big one and found a set - but the price is nuts - and no one has them used.

I'd politely ask John Walker what he thinks, because he has seen and done everything.

Thank you everyone for th4 advice. Good tip about asking John Walker.

Great thread! I need education in this area, also. Thanks to all!

Robert

To me it looks like those teeth on the idler and cam sprockets are showing signs of wear.

About 15 years ago, I bought a set of tensioner upgrade kit for $500. I thought that was money well spent. Now, it's $2,000, not so well spent. Rebuild your tensioners, put the collars on.

You mentioned this "You must replace the idler arms with the new upgraded wide-bearing arms"

Do you have a part number for what you are talking about because I can't figure out what you mean?


Scott

Might give you some insight here:

http://forums.pelicanparts.com/911-engine-rebuilding-forum/876205-new-chain-tensioners.html

This is it here at Pelican (almost $700 now - crazy, really):

PEL-REBKT-17N

http://forums.pelicanparts.com/uploa...1552181891.jpg

Thanks. I guess I need to take mine apart and get a part number to see what I actually have in there. Not sure what else they did when they upgraded to the collars.


Anyone have a picture of how you secure the chain to keep it from moving? I am having a hard time visualizing that as I have never messed with one of these before.

I looked at my part number on the tensioners and it is 901.105.519.OR
I could not find much info on these.

Correct me if I am wrong, but those idler arms won't work with the original style tensioners the OP has?

Is there an option for a brass insert for the OE idler arms? Or can the OE tensioners be modified? I know Henry has an option for upgrading the old idlers to work with the Carrera tensioners. See post 10 here http://forums.pelicanparts.com/911-engine-rebuilding-forum/876205-new-chain-tensioners.html