another cam chain noise question

[Ramblin MAn]

You may remember me, I have the e21 with the transplanted m42 in it. The previous owner had all his work done by a trusted BMW mechanic (just the type of people I don't trust). It had a custom intake on it which I replaced with a stock one and got the car running right again.

In the last year the car has ran a total of 3 to 4 hours. I finally got seats in the car and I'm finally ready to get it tagged and start driving it. However, I notice at idle and only at idle, I can hear what sounds to me like the cam chain. Take the RPM above 1000 rpm and it goes away. The the motor seems really strong, but I've only driven down the block and back. Its very quiet above 1000 rpm and I don't remember this noise last year.

any guesses out there?

Also, I have not removed the tensioner, do these motors use a ratchet style timing chain tensioner?

[b318isp]

No, they have a hydraulic tensioner. They are a known fault, cheap enough to buy and easy to fit. See my site for the details.

[Ramblin MAn]

Thanks, I'll get one ordered today.

Its funny, this is the first time I've ever ran across this kind of tensioner and I can think of several reasons to NOT have one designed like this but only one reason to have a design like this, and thats only if I knew the chain was prone to stretching and I wanted to give it some slack when the motor was not running.

Part of me says its ingeneous, another part says why didn't they source a stronger chain.

[gearheadE30]

I don't think the chain is bad. Remember, it is a '91 piece and was probably designed to be cost-effective as well...