Timing chain tensioners Part II

[davidbir]

I was asked to post photos when I took the timing covers off (Gunter?) Here they are:

L/h Side:


R/h side:


I am pleased with how clean the inside of the engine is considering it has 122,000 miles.
Anybody spot any problems there?
I was hearing a rattling on the over-run.

[sc_rufctr]

Hate to state the obvious but they're not the pressure fed chain tensioners.

This could more than explain the rattling on the overrun...

Also can't tell from the photos but the chain ramps (brownish plastic) may be worn.
But the chain tensioners would be the first thing I would look at.

The problems with the chain tensioners are well documented. Most people upgrade to the pressure fed type when rebuilding an engine if it hasn't already been done.

"Carrera Chain Tensioner Update Kit, 911 (1969-83)" = $740.25

Not a cheap upgrade but what options do you have?

Hope it works out OK.

[ossiblue]

Certainly not an expert, but I think I see something that looks like worn teeth on one of the cog wheels (see photo).


Experts can comment on how serious this may be.
And +1 on Peter's comments about stock tensioner problems.

[TimT]

I missed the earlier post.. what year engine is it? The cams look like they have been changed.. bolt instead of large nut holding the cam gears on..

At a minimum the tensioners should have the safety collars installed

[davidbir]

Sorry, in my mind EVERYBODY remembers my last post in which I was changing to hydraulic tensioners ! it would have made more sense to continue that thread I now realise....

I experienced rattling from the engine on the over run. It was noticeable to bystanders but not the driver. I am now in the process of fitting hydraulic tensioners but was asked to post photos in my last thread,

[Gunter]

David,
Looks like the correct center-bolt-cam for an '82 SC and the tensioners look properly extended.
On the left side, how much clearance is there between the top of the idler-arm and the case?

You can test the mechanical tensioners by squeezing them and see if they expand back.
Pry carefully with a large screwdriver on the left one against the case and the plunger and use very large channel-lock pliers for the right side.
If they have a strong extension, your noise-problem may be something else.

If you have all the parts to convert to hydraulic tensioners, go ahead if you want to but make sure that you keep the cam timing. TDC compression stroke for #1 Cyl is the best position.

Check the cam sprockets and the idler sprockets for missing, or badly worn teeth.
If they look good, the only thing I would do is possibly replace the ramps if they're really worn.
I would NOT use a new chain.

Be careful with the oil line replacement on the right side because of the adapter for the oil pressure.

[davidbir]

Many thanks, I will do as you suggest.

ps how many 911s are running around without all those f*%$#@ little screws in the rear shelf?

[Gunter]

If you're referring to the M6 screws for the tin ware, you want every one of them in place.
Use lock washers so they wont come loose and make the tin rattle.
Canadian Tire sells metric screws, buy a few extras. M6 about 10 mm and 15 mm long.

If the shelf is rusty, clean up and paint with black Tremclad or Rustoleum.

What is the clearance between case and top of the idler on the left?

[davidbir]

OK, the clearance between the top of the idler and the case on the left is about 1/4 inch which looks ok to me. However, I think I have found the source of the rattling noise on the over run-it is the small aluminum bracket behind the a/c compressor that is attached to the top of the r/h cylinder head:

This bracket was very loose and could well have been the source of the rattle!!

In any event, I now have Carrera tensioners fitted! I used the following method to hold the chain-somebody suggested it but, I'm sorry, I forget who:


I found that using the hollow end of a 3/8 drive extension as a ram to push the shaft into the tensioner while it was submerged in oil worked very well.

Thanks Trog, Gunter and others who helped.

[930 slant nose]

if any one knows at what height do you put the lock collars do you spin the motor till the highest point of the tensioner then put lock almost in the middle or whats your thoughts
thx