87 260 T-stat Housing-Something Doesn't Look Correct

[Ryan50]

I have been having a random idle overheat. See attached photo of t-stat housing. While researching part numbers to order t-stat and gaskets, I noticed that there is a notch in the sleeve on top of the t-stat. A pic of a new sleeve does not have this notch. It appears that someone modified this sleeve. Why would someone do this and what could it hurt?

 

[alldodge]

I have been having a random idle overheat. See attached photo of t-stat housing. While researching part numbers to order t-stat and gaskets, I noticed that there is a notch in the sleeve on top of the t-stat. A pic of a new sleeve does not have this notch. It appears that someone modified this sleeve. Why would someone do this and what could it hurt?

There are three different designs for your model year. Two of the three designs require cutouts for bypass. From your pic I believe you have the one in the link below. If this is the case then the slot appears to not be needed.

http://www.mercruiserparts.com/Show...r=210&bdesc=STANDARD+COOLING+SYSTEM(DESIGN+I)