C3 Thermostat housing

[Bruce Haegley]

Tech/Info/Manual states that the 1974 L48/L82 thermostat housing part number should be 336790. It also states that there is no port in that part. In realty, that part includes a pipe fitting for an EGR Valve port. The L82 thermostat pictured on in the Assembly Manual page 6Y 6 does not show a port.
Mine looks like the one in the assembly manual and is part number 3377660.
Thanks for ending this confusion.
Bruce

[Joe L.]

Re: C3 Thermostat housing

Bruce-----

For 1974, all L-48s and LS-4 used thermostat housing GM #336790. This housing has ONE NPT fitting for the EGR switch. I believe that L-82 with manual trans used a different set-up, though. For this application, the EGR switch may not have been located on the thermostat housing and, if so, the thermostat housing was without NPT fitting. In that case, thermostat housing GM #3877660 was used (I think you're misreading the numbers).

It's also possible that some, or even all, L-82s were configured just like the other engines with the EGR switch on the thermostat housing. In that case, the GM #336790 outlet would have been used.

[Harmon C.]

Re: C3 Thermostat housing

There is some things that will be changed in the 73-74 manual on thermostat housings as i talked with the team leader in Orlando. Part #3972128 may be added for 1973 and more research on the 74's may be needed .