[V8] Valve or Timing Belt Rattle?

dsaad at icehouse.net dsaad at icehouse.net
Mon May 9 11:08:41 EDT 2005

I had a similar sound - and after much debugging, it ended up being the oil pump
drive bearing. That un-fortunately requires a very complete teardown - the
t-belt has to be removed. Depending on what tools you have, the front cover also
has to come off.

If it were me - I would first remove the accessory belt to see if the noise goes
away. Any problem here will be pretty easy to ID and fix. If the noise is still
there, you are probably looking at the one piece that was not replaced when you
did the t-belt - the oil pump bearing. If this does turn out to be the
diagnosis, I would recomend removing the front cover so you can replace all the
gaskets and o-rings in there. This in turn also requires dropping the lower oil
pan. It adds considerably to parts and labor cost, but you get a nice dry motor
out of the deal. One advantage is that no special tools are needed. If you
choose to replace the bearing only then you could easily end up with a oil leak.
Changing the bearing seal in place requires special tools.

I would also give a lot of thought to replacing the cam chains while you are in
there. I neglected to do that and wish I would have. I don't know how far these
chains should last, but they are not that expensive.



Quoting Dave Head <v8q at bellsouth.net>:

> 1. V8s have hydraulic lifters - no adjustment.
> 2. Did you or your mechanic follow the timing belt adjustment procedure
> for setting the belt tension? It's specific!
> 3. Could be an undertorqued cam pulley, a bad oil pump drive bearing,
> roller/tensioner bearing, timing belt tight/loose out of spec.
> 4. The belt can be inspected by removing the driver's side cover (after
> removing the electric fan).
> daves745t at optonline.net wrote:
> >First off - thanks Kneale for the Hood release tip - what a PITA!
> >
> >The reason I was trying to pop the hood was to further diagnose a rattle I'm
> hearing on the right side only - 99% sure it's originating from the valve
> cover.  I just had the timing belt and all the stuff listed on
> AudiConnection's site changed a couple of months/several hundred miles ago
> belts, bearings, pumps - the works. A couple of weeks ago I noticed a very
> slight 'ticking' that could only be heard with the hood up and listening
> closely.  I thought it was a slight valve slap - and honestly wasn't sure
> whether it was there even before the timing belt was replaced.  In any event,
> it has now progressed to where it's definitely more noticeable and sounds
> like more than one.
> >
> >I was thinking that it needed a valve adjustment and Googled it, and somehow
> stumbled on the Timing Belt Rattle issue. Does the V8 ever need its valves
> manually adjusted (I couldn't find anything about it)? Someone mentioned a
> 'tension adjuster screw', 'plastic friction block' (are they the same?)
> and/or various bearings. Is there a way to determine or eliminate any
> possible culprits?
> >
> >Finally - how concerned should I be about driving her?  Last thing I'd need
> is to have a some major internal snafu after just sinking a couple of grand
> into her for the sole purpose of that not happening!
> >
> >Thanks!
> >DaveM
> >
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