DeTomaso Mailing List: December 2000, Message #173

> Maybe these things fail right away if they are going to fail? I had no
> slop in the timing chain, 
> my engine had just had a complete rebuild. It just failed. 
> 
I think they fail when a piece of debris momentarily locks up the pump.
Going from memory (I might be confusing engines here), the stock oil 
pickup has a strap with a hole in it to allow oil to flow, even if the
screen 
gets clogged.  A fair size piece of debris could get sucked through, 
locking up the pump rotors.  The shear pin and pump driveshaft would see 
a large spike in loads.  On 5.0's, the driveshaft usually twists.  On
351C's, 
the shear pin snaps.

At least some of the 400's use a different pickup without the hole, just 
a fine mesh screen.  As long as you change your oil on a regular basis, 
this works fine and won't allow debris to pass.  However, if the pickup 
gets clogged, you won't be able to pass much oil.  I've torn down engines 
that were like that.  Apparently, the previous owners never changed their 
oil.

With aftermarket pans, you're stuck with whatever the manufacturer 
provides.  

Dan Jones