Re: Rapping Noise Upper End 1986 Graduate

["Kenneth Casper" <iflyfisher@xxxxxxxxxxxxx>]

Hi Ed,

I have been trying to diagnose something similiar on my 93 Spider. I had
thought the problem was with the A/C compressor and was about to check it
when my car sputtered and died a little over a week ago. It subsequently
refused to start. The problem ended up being with the main crank pulley. The
pulley had cracked and a big chunk of it had come out. I guess it finally
got so bad that pulley shifted and the crank sensor was retarding the
timing.

Just got the pulley replaced along with the motor and tranny mounts, and the
car is back on the road again. We didn't have a big enough replacement belt,
so I have a shorter one on that bypasses the A/C compressor. My noise has
gone away, but I am not sure if it was from the pulley or if it is the A/C
compressor is still the culprit. I'll have a new belt on it this week and
will find out then.

BTW, the noise on mine would change depending on if the A/C compressor was
running. If I put the blower on high, the noise would often stop for a bit
then start up again later. After the car was all warmed up, the noise would
completely go away. Will let you know how it runs with the new belt and the
A/C compressor hooked up again.

Ken


> Date: Sat, 16 Aug 2003 08:56:06 EDT
> From: Petown@domain.elided
> Subject: Rapping Noise Upper End 1986 Graduate
>
> I've got an intermittent tapping or rapping noise coming from, I think,
the
> #1 cylinder area of the engine.  It comes and goes at idle and can be
heard
> clearly from the driver's seat with the hood down.  Trying to "force" the
noise
> by blipping the throttle doesn't seem to have any effect.  I tried
switching
> the a/c on, though, and got an immediate and sustained noise as long as
the
> compressor was on (the a/c is never used).  I then turned the a/c off and
the
> noise was again intermittent, rapping for a while then quiet.  I set the
parking
> brake and fed a little clutch starting to drag the engine against the
brake and
> got the noise again.
> I've checked the valve clearances and retensioned the timing chain.  When
I
> changed the head gasket last year (car was supposedly low mileage but had
sat
> for years), I found scoring on the #1 cylinder; the others were unmarked.
The
> spark plug on #1 is always dirtier but not noticeably oil fouled.  I tried
the
> screwdriver-to-the-ear technique and listened at several areas at the head
> but, frankly, don't know what I'm doing.  I thought I could pick up a
similar
> noise, though, when listening at the #1 exhaust header.  Any ideas?
Thanks in
> advance.
>
> Ed
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