Joe77911S

From my '77 911S. Growing rattling noise caused me to pull the tensioners and discover the left side tensioner had been ground a bit by the chain. The plunger was easy to press in for a few millimeters and makes a squishy noise. Also, the right side tensioner's bolt was loose! Oh boy.

For those in the know - did any damage happen to my motor, besides the failed tensioner? It has the safety collar (as pictured). The motor ran fine, except for the growing chain noise, before I investigated. If you know anything about this, let me know. I hope the valves are okay (it had a upper end rebuild 10K ago.) Is there any way to test the health of the motor, in regards to this discovery? Is it a matter of does it run or not?

Moreover, what remedies would be appropriate? Carrera tensioners, chain, ramps, etc.? I'm not wealthy... would simply a tensioner rebuild be totally offensive? There is a Porsche kit for this. By the way, if you know a shop that rebuilds tensioners, please email me. I figure a tensioner rebuild might last another 50K miles and only cost a hundred or so bucks, compared to the full monty at about $700.
( h a l l j o s e p h @ g m a i l . c o m )

Peter Zimmermann

Joe: There are far more ways for you to make a very costly mistake than to get it back together so that it works properly. (1) Do you have P-car manuals for your car, (2) Are your tools sufficient to re-time the camshafts should that be necessary, (3) Do you have the knowledge to correctly adjust your valves (crucial for cam timing)? I think that we better start with photos of the chain box areas. Before you removed the above tensioner I hope that you put your engine on Z1/Cyl #1 and fabricated something that holds the chain tight. Never try to turn the engine with a tensioner removed or a timing chain loose, and never remove both tensioners at the same time!

Joe77911S

Thank-you for the helpful reply.

- I rotated it to Z-1/Cyl #1 pre-removal.
- Before removing the tensioners I tie-rapped the chains tight, and tie-rapped the chains together, and tie-rapped the tensioner wheels at a 'high tension' position (the chains are almost at the same tension as pre-removal). See pictures.
- However, I did remove both tensioners at the same time - they are both out right now. Could you please briefly explain why that can be a problem?
- As far as retiming the cams - I'm not equipped. I can adjust the valves.
- I assumed (probably incorrectly) I could simply change like for like with my tensioners, as long as the chains do not skip sprockets on the wheels and it is at Z1 / Cyl #1.
- The battery is disconnected... so no chance of turning the crankshaft!

Is the only reason one must keep tension on the chain is so it doesn't skip a sprocket?

Thanks for your help.
-Joe

theiceman

wow looks like you have lots of tension anyway ....

good luck changing that ramp ..... LOL ,,,,

Peter Zimmermann

Joe: Good job with the tie downs! OK, I can see by the position of the left (cyls #1,2 & 3) side idler arm that your chains are stretched sufficiently to require replacement. The distance between the idler arm and housing, at the point where the tensioner plunger contacts it, should be considerably more than it is. That condition is probably why the chain was able to contact the tensioner, when the engine was hot and the chain reached maximum length (chains stretch about 2mm as the engine heats up). Your left tensioner is probably failing because it is probably out of its working "zone," and has to really struggle to reach the idler. Your right tensioner will have the same problem, based on the distance between the chain and the upper chain guide (it's a little hard to tell because of the camera angle, but I'm sure that's what is going on).

My comment regarding removing both tensioners at once was that I've always taught to do one side, start to finish, before working on the other side. Just a technique that I feel eliminates a lot of chance for error, accidental piston to valve contact, etc.

g-50cab

Looks like you are addressing the symptom instead of the cause. I'd change the chains timing chains, new sprockets, and get either new tensioners or rebuild them - looks like you have alot of play in that chain!

Joe77911S

Thanks Pete for the information. I see now that the chain is the main problem that will need to be eventually addressed - which will of course mean cam timing. Do you happen to know how far down the collar should be from the top of the tensioner rod, where it contacts the idler arm? Mine was about 6mm.

theiceman

PS Joe those are fantastic shots. Gives me a real good idea of what I have to deal with too.

Edgy01

Are you saying that you don't have the latest Carrera chain tensioners in there (with the oil feed)? You should. They're relatively cheap insurance for the future. (I assume you don't because I can see the tensioner guards still in place).

Houpty GT

Vertex has the carrera pressure fed tensioner kit for $579. Much less than anybody else I found had it for. 1-866-668-0660 Their chain ramps are also cheaper than Pelicans by $1.25 each but the website said they were aftermarket. Does anyone have experience with aftermarket chain ramps? If they are made in China then it is a definite no go.

jester911

Why even bother with aftermarket for a $1.25

fredb

Question??
Does anyone know how much more work it is to remove the housings for the chains, I've got leaking problems behind.
My friend has the tool to do the timing.
Don't you also need a special tool to remove the cam nut at end of shaft?
Leak does happen at normal RPM, but at 210 degrees oil and 6k on tack for 30 minutes, she leaks and leaves a nice "L pattern on ground.
I was going to do both sides, I think there are 3 seals under each side.
Thanks for the advice!!

theiceman

Fred I have That EXACT issue , chain box to cam tower leak,. There is an o ring and a gasket.

Thereare some special tools required and they are different depending on the year of the car. Pete will know exactly byt mine is a 78 and i need a big *** crows foot for the nut and a special tool to hold the cam .
This of course involves removing the engine ( for me anyway as I thingk it would be easier. )

removing the chain box covers, tensioners , cam sproket and then you can get at it . You do not have to remove the chain box itself. There is a small flange that seals it all .