[DeTomaso] Valve seat fail and piston damage

[Asa Jay Laughton]

I would replace it.  The groove created a thinner space between the top of the piston and the underside of the piston.  This can cause a weak spot and certainly the thermal dynamics will be different.  Also, without cleaning up the gouge and smoothing it out, it will create opportunities for hot spots which could lead to preignition.

Best is to find a like-for-like piston.  Next best is to fill that groove (weld?) then smooth out the top surface to look like new.  This sounds difficult and not something I would do, but I’m a chicken-shit like that.  ;)

Just my $7 (2-cents adjusted for inflation)
Asa  Jay

Sent via radio waves

> On Mar 26, 2024, at 20:28, John McKee <johnmckee at cox.net> wrote:
> 
>    I need a recommendation for an engine builder/machine shop in Orange
>   County, CA.
> 
>   Back story:
> 
>   After sitting for 10+ years I finally fired up my engine a few weeks
>   ago. It sounded good for 10 minutes then I had a bad clatter in the
>   valve train. At first it appeared to be a loose rocker but there was
>   weird interaction with the valves of cylinder #4. I popped the head off
>   and found that the exhaust seat had come loose! While dancing around
>   the seat also made some deep marks on the piston head.
> 
>   My gut tells me the piston is trashed and needs to be replaced. I have
>   a friend that says I should repair the head and go as is. I don't know
>   if anybody on this forum has an opinion.... But, when is a "witness
>   mark" a catastrophic failure in the waiting?
> 
> 
>   I posted photos on the picture forum at this link.
> 
>   [1]https://pantera.infopop.cc/topic/valve-seat-failure-and-piston-damag
>   e
> 
> 
> 
>   Thank you for your thoughts,
> 
>   John
> 
> References
> 
>   1. https://pantera.infopop.cc/topic/valve-seat-failure-and-piston-damage
> _______________________________________________
> 
> 
> Detomaso Email List is not managed by POCA
> Posted emails must not exceed 1.5 Megabytes
> DeTomaso mailing list
> DeTomaso at server.detomasolist.com
> http://server.detomasolist.com/mailman/listinfo/detomaso
> 
> To manage your subscription (change email address, unsubscribe, etc.) use the links above.
> 
> Members who post to this list grant license to the list to forward any message posted here to all past, current, or future members of the list. They also grant the list owner permission to maintain an archive or approve the archiving of list messages.