Squealing Camshaft Bearing (long)

[JShadzi at aol.com]

The fact that you say it only does it at idle leads me to believe that it may be a vacuum leak past the front cam seal, not a mechanical noise caused by the bearing.  Have you looked into that as a possibility?

Javad

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>I have a squeal in the front camshaft bearing in one of my 5TQs.  To make
>sure of the problem I removed all of the belts for alternator, air and
>hydraulic pump, removed timing belt cover and checked for the source of the
>squeal with a stethoscope.
>
>The squeal (at idle) seems to come from the front cam bearing.  I recently
>repaired the head after a broken timing belt bent some valves.
>
>I think the timing belt had been previously tightened way too much (not by
>me!) as the crank sprocket and water pump teeth were badly worn and the
>timing belt broke after far less than 50,000 km.
>
>When I had the head dis-assembled I noted that the lower half of the front
>cam bearing (the surface on the head itself) is scored.  The cap is not
>scored.  This leads me to believe the timing belt was done up so tight it
>caused the scoring, the tooth damage and the belt failure.
>
>Now the question:  what to do?
>
>Is there a possibility that the belt was so tight it was pulling the
>camshaft down so hard that oil was not getting to the bearing surface?  I
>have checked the oil passage in the head under the front bearing and the oil
>return passage behind the camshaft front oil seal.
>
>The advice I have from my local (very good) machinist is to use some fine
>emery cloth (or whatever the really fine stuff is called) and dress the
>bearing surface to remove the scoring.
>
>I want to do something to cure the squeal.  It is both annoying and a
>concern that I might suffer a catastrophic cam failure.
>
>Any advise would be greatly appreciated.
>************************************************
>Dr. Ian McArthur, Consulting by Acronym, Cochrane, Alberta
>sutul at telusplanet.net
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