cam chain noise?
Thread Starter
6th Gear
Joined: Apr 2002
Posts: 6
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cam chain noise?
my '73 E has developed a noisy kind of rythmic "cam chain" sound on tickover. I took the covers off expecting to find loose chains, broken chain guides: I found it has Carerra hydraulic cam chain tensioners. The chains were v.tight, and the idlers very unwielding. Is this correct? How much tension should there be?The idler arms have spacers on, so are the early type which could bind up (according to Anderson).
I am going to change them for the '83+ idler arms.Anybody got any tips on how to safely remove the Carrera tensioners - like how to depress them to insert the safety pin? I have heard that if they are pulled out and allowed to snap open, this can develop into failure after they are re-fitted.
The engine has about 10k miles on a re-built engine. TIA, JG.
Rennlist Member
Joined: Oct 2001
Posts: 383
Likes: 4
From: Long Beach, California
Did you check to see whether the chains may have stretched to the point where the left side lever is hitting the chain housing? Also, when you pull the tensioners, you want to be careful that the timing chain doesn't skip a link on the intermediate shaft. The key is to get the cam to a "neutral" position, i.e, it doesn't want to spring one way or the other. The only problem I have heard about on the tensioners themselves is that you're not supposed to compress them too rapidly when you're getting them ready to reinstall.
Intermediate
Joined: Dec 2001
Posts: 32
Likes: 0
From: Milano
Hi John,
yes you should check the chain length. The pistons on the tensioners should not be more out than about 10mm. If I remember well max. travel of the tensioners is 15-18mm, so if the tensioner is that far out then the chain is stretched.
I recently replaced chains on my 72S, and I had no problems reusing the hydraulic chain tensioners. I just pulled them out by hand. To reinsert the pin I used a vice. While compressing the tensioner in the vice oil will drip out. I don't see why the tensioner should be so delicate, on the contrary I would say that after withstanding the violent chain forces for thousands of km one more single compression should not harm at all.
If the chains are indeed stretched then I suggest to redo the chain timing also while replacing.
Andreas
yes you should check the chain length. The pistons on the tensioners should not be more out than about 10mm. If I remember well max. travel of the tensioners is 15-18mm, so if the tensioner is that far out then the chain is stretched.
I recently replaced chains on my 72S, and I had no problems reusing the hydraulic chain tensioners. I just pulled them out by hand. To reinsert the pin I used a vice. While compressing the tensioner in the vice oil will drip out. I don't see why the tensioner should be so delicate, on the contrary I would say that after withstanding the violent chain forces for thousands of km one more single compression should not harm at all.
If the chains are indeed stretched then I suggest to redo the chain timing also while replacing.
Andreas
