<VV> Re: Engine Knock only at low RPMS

[Mike Kost]

Brian Goldin wrote:

>
> Again I appreciate everyone's help.
>
> Last night I did another visual inspection of the crank case and didn't
> notice anything cracked or unusual with the crank. I also rocked the crank
> back and fourth carefully and I didn't feel anything but a nice smooth
> movement.
>
> When I took the drive train out, last week, I replaced the torque 
> converter,
> diff and transmission.  The flex plate seemed in good shape but I didn't
> re-torque the bolts or anything.  Last night I also checked out the old
> torque converter and I didn't see any signs of abrasion.
>
> Bob Slusher made a good recommendation to check the lower bolts 
> holding the
> bell housing to the engine to see if they have washers (i.e. sticking out
> where they might hit the flex plate).  When I take it out on Saturday (I'm
> sure I'll have to) I'll be sure to check this out.
>
> I'll also carefully inspect the pulley but based on where the sound is
> coming from, and the behavior, my gut feeling says that this isn't it.
>
> Steve Goodman has had a similar problem and suggests the cam gear
> (http://autos.groups.yahoo.com/group/fastvair/message/32441). 
> <http://autos.groups.yahoo.com/group/fastvair/message/32441%29.> 
> Before I take
> the engine out I'll definitely drop the oil pan to check the gear out.
>
> As evident through the posts many are putting their money on a broken 
> crank
> or bearing problem.  This does make sense but it still bothers me that it
> doesn't always make this sound; being that it is only at low rpm and only
> when a cylinder has compression (spark plug installed).
>
> I'll dig into it on Saturday, and definitely post the final diagnosis.
>
> If anyone wants to have a couple beers and wrench on it with me, I'm in
> SoCal.
>
> Brian
>
>
> -----Original Message-----
> From: WadeHalsey [mailto:hihal@adelphia.net]
> Sent: Thursday, May 06, 2004 11:48 AM
> To: virtualvairs@corvair.org
> Subject: Re: <VV> Engine Knock only at low RPMS
>
> Remember in Brian's original description of the problem that he had
> replaced the torque converter.
> He also told me that the noise seemed to be coming from the bell housing
> area.
> I suggested to him that the flex-plate to TC bolts might not be tight.
> Haven't heard back
> from him on that idea.  Mike Kost's suggestion to check the bolts to the
> crankshaft applies
> to flex-plates as well as flywheels though.
>
> Wade Halsey

When I had my flywheel problem it did seem to show up more when the 
plugs were in. I believe this was because of the forces as each cylinder 
goes past TDC. There is a slight downward push as each piston passes TDC 
on the compression stroke. This causes a clunk as the bolts move from 
one side of the hole to the other.

-- 
Mike Kost
Show-Me Corvair Club