racer

often when rebuilding a pre '84 911 motor, folks would retrofit an "oil fed" chain tensioner. It was deemed more reliable than the previous version. If you share a topside pic of the motor, we may be able to point out if your motor has been upgraded or not. Then again, maybe someone here could post a pic and you could compare it to your motor.

theiceman

if the back of the engine looks like this , you have oil fed tensioners ( The line that goes down to the chain box )

GermanEnthus

Well, I finally had a chance to dive in and open her up. I learned that I do in fact still have the old spring loaded tensioners, not the newer carrera oil pressure fed one's. Luckily, I have the sleeve collars for protection, which, if the tensioners are gone, or on their way, this may have saved me.

The good news is that I didn't see any broken parts, metal shavings, or anything that would lead me to believe there's been any major damage within that area. What I did notice was that on the left side the top of the sleeve collar had some decent scoring/wear (see the first attached image). I can't see how this would be caused by a failed tensioner, but I could be wrong. I was told that the older tensioners with sleece collars shouldn't be as tight as mine though. By this I mean that the collar has no upward or downwards play, as there is next to no space between the idler arm and the bottom part of the tensioner shaft. The collar will move slightly left to right, but not up and down. Is this normal? This is the same on both the left and right tensioner. The scoring on the collar is only on the left.

My goal for tomorrow is to pull the tensioner and idler arm (while being careful to not let the cam gear move) in hopes of identifying if the chain guides have any scoring from the chain potentially moving around under load. I also plan to look at the idler arm to see if I have the older style, as I've been told the newer one is a good upgrade.

At this point, I'm going to agree with racer and probably get the carerra tensioner upgrade kit. I've read the tech article on Pelican Parts site, which seems fairly straight forward.

Any thoughts as to whether the idler arm is necessary? Anything else I should consider replacing while I'm at it? I'm under a budget, so I'd rather not replace all the components if I don't have to.

Thanks for your help everyone!

Amber Gramps

Welcome to Rennlist.

I am most likely of no help to you. That said I'd button up where you are at and look for a simpler problem. Next step may be valve covers, but I'm guessing something basic like a blown airbox, fowl plug or bad CIS parts.

If you had the ability to take off chain covers, you are well on your way to solving this. Good job so far.

Daniel Dudley

Steve and Pete are the go to guys for this type of advice, but I agree with Doug that taking the valve covers off would be a good next step, while you are waiting for one of the expert to chime in.

If you follow Steve's advice, he will no doubt continue to help you. This is a good thing.

theiceman

We all have differing opinions on things, that is what makes the internet such fun . Given this car is an unknown I would definitely either upgrade to carrera tensioners, or replace the spring ones if you can still get them ( cheaper but less preferable solution ) . While in there you should definitely replace the chain ramps.
Having said that I do respect you are on a budget.
This is certainly NOT a blown air box or any other CIS issue or part so you can relax on that front.

I do agree with while pondering what to do you should whip off the valve covers and have a look. If a head stud falls out then you can make your descison. if your going to have that fixed you have to pull the cam and cylinder heads and cylinder and then would be the time to address any tensioner issues.

Good luck and great pics btw. That first one you showed allmost looks like damage from a set of pliers from someone trying to compress the tensioner if i didn't know better.

GermanEnthus

That's what I was thinking with the scoring iceman. Probably something from installation. I'll pull the valve covers today and see if I can find anything else. I was planning on adjusting the valves anyways... Can you fill me in on this whole stud falling out thing? If a head stud did fall out, what would be the cause? Other than the time to pull all the parts to fix this, are the parts costly? I'd assume it would mean a whole new set of head studs and obviously new gaskets. Is this something I can install myself, or does it need to go to a machine shop?

Thanks again guys. The power of the internet and of course the amazing wealth of information of the Rennlist community is a great thing.

Happy Easter to all! If I find any easter eggs in the motor, I'll take pics.

Steve Weiner-Rennsport Systems

You should have about 4mm between the tensioner guard collar and the tensioner body. If its less than that, I would see if the tensioners can be depressed by hand.

If thats possible, they need to be replaced as they have collapsed. Remember, these are not spring loaded and when they lose their charge of oil, they are done.

Regarding head studs, just check each one (very gently!) with an accurate torque wrench to make sure its holding at the specified torque. If you find a loose one, thats the signature of a broken head stud and that requires disassembly of the top end of the engine, depending on where its broken.

GermanEnthus

Thanks, Steve. You're the man!

GermanEnthus

Update - left side tensioner is out. I cannot push the tensioner shaft with my fingers, even with a fair amount of pressure. The guard collar is set at the top of the shaft, and the spacing between the bottom of the collar and the top of the tensioner body is about 4mm. Chain ramps look good too - no scoring or damage.

Going to pull the right side tensioner and see how the pressure is.

GermanEnthus

Right side tensioner is the same - tons of pressure and the correct gap. (see image #1)

I was able to inspect the chain ramps further and cannot see any scoring or damage.

I've also taken off the left side upper and lower valve covers and couldn't see anything abnormal. There was no evidence of any broken pieces, metal shavings, just a clean looking motor with clean oil coating the interior.

I didn't check torque on the head studs because I wasn't positive where they are. The documentation I could find stated them as 10mm nuts, with a torque rating of 33nm. What appeared to be a head stud to me, had a 13mm nut. Can someone chime in and educate this poor fool...

Next step is to run a scope in the cylinders to check the pistons for valve impact. If all cylinders look okay, then I'm going to move forward with upgrading to the Carerra tensioners, get new valve cover, oil sump plate, exhaust, and chain tensioner cover gaskets, and replace the spark plugs/wires for peace of mind. If the chain ramps are in good shape, and probably only have 12k on them, I think I'll hold off on replacing these. I'll also do a valve adjustment, to make sure all the valves are set appropriately.

Anything else I should take into consideration with a motor that hasn't run in 3-4 years?

The page had difficulty uploading multiple attachments, so I'll provide a link to my gallery, with additional shots of the left and right sides with the tensioners out, the valve covers off, and inside the oil sump area.

http://www.flickr.com/photos/2936795...7616563664003/

Edgy01

Thanks for including excellent photos of the chain areas. You have the older style chain tensioners with the mechanical stops on them. Something you should consider is dealing with them. In 1984 Porsche finally got around to designing a solution to their constant problems and fed oil to them. Keeping oil on the bearings around the chain tensioners literally solved the 20 year old problem they presented to the 911. A kit should run about $250 and include the new oil lines and new style tensioners. It may also include the newer ramps. Can't say for sure since it's been awhile for me. Best of luck. it's great to see owners dealing with their cars themselves!

theiceman

Actually sounds like you have a great handle on the situation . Ithink the head studs are the 13mm ones. Sounds like you may have a gear rattle issue if everything checks out. You should have a total of 24 head studs ( 4 per cylinder ) by a dental mirror or some other small mirror and verify everything is there and in good shape. I agree in doing the valves now that the covers are off. With this done and the tensioners done I think you should be in pretty good shape.

GermanEnthus

Hmm... I'll see if I can find a good diagram of the head stud locations. The 13mm nuts I found only had three per side, for a total of 12. I checked Pelican for the head stud sets, and they sell them with 24? I have the original Porsche factory mechanic books with full diagrams, that should have what I need, if I can find 'em...

GermanEnthus

So I was finally able to look inside the motor at the pistons and walls. Luckily, I wasn't able to see anything out of the ordinary - no visible scoring, valve impact, or chunks of metal. I did not rotate the motor, due to the tensioners being out, so a couple of the pistons were higher than the others making it impossible to see the lower part of the piston wall. The tops of the pistons had a fair amount of carbon build up, and oddly enough, one of the pistons had a couple small areas where the carbon wasn't present, with no visible damage or indication that there was impact causing it to scrape off. Is this normal?

I still need to find the head studs and check tightness to verify whether I have any broken. If these are okay, I'm considering pushing forward, doing a valve adjustment, and tightening her back up. Here's my shopping list at the moment:

Complete Carerra Tensioner upgrade kit (oil fed)
Valve adjustment tool
Valve Cover gaskets
Ignition Wire set
Spark plugs
Muffler gaskets
Oil sump plate gaskets
Oil (filter was changed just before starting the motor, and should be good)

Anything I'm missing, or suggestions on things to take into consideration when getting a motor ready that's been sitting for 3-4 years without starting?