Coolant leak from thermostat housing

[DrCharles]

At least I HOPE that's where it's coming from, since I got it hot when the serp belt jumped off the pulleys (although the temp gauge wasn't pegged, just high end of the normal band, and the overheat light didn't come on). It's too high up to be "just" the head gasket, and it's not trickling down from the upper rad hose itself.

Anyhow, before I drain most of the coolant, pull the alt and the fuel filter bracket to get in there for the two-bolt housing (thanks, IH engineers) I was wondering if there's any tips/tricks from keeping this leak from recurring, other than not overheating it

I did get a new t-stat last year and it is working properly. Is there possibly a gasket vs. antifreeze/SCA incompatibility, or maybe the shop that did the heads used RTV or something too slippery on it? Won't know if there's a pit or a crack in the housing or the mating surfaces until I get in there. Not today with freezing rain and ice falling!

 

[DrCharles]

I found this article useful: http://www.nickpisca.com/diesel/engine/6-9-7-3-idi-thermostat-replacement/

He shows several things (like chasing the bolt holes, and carefully cleaning the block and housing mating surfaces) that may or may not have been done... I shall see.