In my limited experience, a rod knock will get louder with load and RPM, and
will show low oil pressure. Piston slap tends to go away with load and
higher RPM, and has no effect on oil pressure. Personal experience with one
1500 with a bad rod bearing, and 2 1275's with piston slap.
David Riker
74 Midget
63 Falcon
70 Torino
http://home.pacbell.net/davriker
----- Original Message -----
From "Ray" <rsides at delury.com>
To: <spridgets@autox.team.net>
Sent: Friday, September 28, 2001 9:05 AM
Subject: Knock, Knock
> Hello All,
>
> My 1967 1275 has developed a knock. The knock starts in around 2000 rpms
> and
> diminishes or completely goes away at around 3000 rpms.
>
> The knock occurs whether the car is under load or not - maybe a little
> less when under load. As the engine heats up the knock does seem to
> increase.
>
> Otherwise the engine runs great with plenty of power; 70 lbs. of oil
> pressure at speed, 40 at idle (idle pressure lower when hot), good even
> compression across all cylinders, does not smoke (It use to put out a
> righteous smoke screen when cold before I fixed the "PCV" valve).
>
> Using an automotive stethoscope I have not been able to clearly locate
> the origin of the knock. I thought it might be coming from the water
> pump, but last night I disconnected the fan belt and the knock was still
> there.
>
> This winter I was planning to rebuild the steering and suspension and
> pull the engine and do transmission conversion next year. But now its
> looks like I need to pull the engine right away.
>
> So what do you think?
>
> Rod bearing?
> Main bearings?
> Piston slap?
> Something else?
>
> Thanks,
>
> Ray Sides, CPA, ABV
> C. Delury & Associates
> One Capitol Mall
> Suite 240
> Sacramento, CA 95814
>
> Phone (916)441-2001
> Fax (916)441-2002
> www.delury.com
|