DeTomaso Mailing List: May 2001, Message #49

ART STEPHENS wrote:

> [this was a MIME-encoded message - it has been]
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>      I began the inspection of  my blown?, engine today.  The problem occurred as I was coming down the
> hill from Mount Charleston on my way back to Vegas.  I had backed out of the throttle in 5th gear and I
> was probably turning somewhere in the neighborhood of 3000 rpm.  The engine was not under much of a
> load when the noise started, like I say, I was decelerating.  I pulled the valve covers today and everything
> looked fine, no obvious problems.  My buddy Roger talked me into checking the push rods to see if they were
> all straight.  They were all straight except for one.  The push rod for the exhaust valve at the #4 cylinder is
> bent.  My question is Why?  I could understand if I had been pushing the engine hard that I might have
> floated a valve, but I wasn't pushing hard or turning many revs.  I recently did a valve job and milled .020
> off the heads, I also replaced the valves.  I probably haven't put more than 500 miles on the engine since I
> did the work.  In that 500 miles, I've driven the car harder than I did when the noise started, I would think
> if my problem had been valve float leading to piston/valve interference, the noise would have started after
> one of my hard runs.  I'm kind of thinking that it may be a spun rod bearing as others have suggested.  I
> am also thinking about installing a shorter push rod, (mine are stock length), and seeing what happens.  The
> push rods are new Manleys, installed at the time of the valve job.
>      Any advice or thoughts would be more than welcome.
> Art Stephens<br clear=all>
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I suspect the pushrod has been bent for some time and you only found it now.  In a case I had, a few pushrods got bent on initial start up of the
engine, but were never discovered until  a few years later when I once again had the valve covers off.  The engine ran fine, I had non-adjustable
rockers and simply tightened them down to spec.  However, the valve stems had not been checked for proper installed height, thus, I had
collisions that basically  bent the pushrods until things were fine.  The down side to this is that first, I bent pushrods, second, the load on
the cam eventually wiped a few lobes off, which is how I eventually found the problem.

An interesting note however, is that I too had a strange "other" noise in the engine, which I began attributing to a spun bearing or a broken
piston skirt.  I have yet to disassemble that particular engine, though it "is" on an engine stand.  I have no idea what I will find.  I had
replaced the bent pushrods, replaced the cam, etc. and ran the engine again, but the "other" noise didn't go away.

Please let us know what you find.  I bet it's not the pushrod giving you fits.

Asa Jay
<but I've been known to be very wrong in the past>



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   Asa Jay & Shelley Marie
   Laughton - Spokane, WA
     1973 Pantera L 5533
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