Don,
Sadly, the heater capacity on the GMC doesn't seem to be quite
enough. The shop manual calls for a 195 degree thermostat, so you're
all right there. Since you said that you had your heater rebuilt at
Cinnabar, I don't think you'll have problems with it leaking hot air
this summer.
The GMC as delivered has an integrated engine and transmission oil
cooler system. It's contained in the radiator and would be referred to
as a "liquid-liquid" cooler. The engine oil and transmission fluid heat
is rejected to the engine coolant which adds heat. Aftermarket oil and
transmission coolers are available to boost cooling efficiency.
The greatest source of heat has nothing to do with the cooling
system. It's the heat riser that runs from the center exhaust ports in
both heads through a passage in the bottom of the intake manifold.
That's where an fix lies. It entails intake manifold removal to perform
the fix. The plugs are available from Mondello. The plugs are then
drilled out to 1/4" on each side to maintain the correct amount of heat.
- -Scoot Woodworth
Sadly, the heater capacity on the GMC doesn't seem to be quite
enough. The shop manual calls for a 195 degree thermostat, so you're
all right there. Since you said that you had your heater rebuilt at
Cinnabar, I don't think you'll have problems with it leaking hot air
this summer.
The GMC as delivered has an integrated engine and transmission oil
cooler system. It's contained in the radiator and would be referred to
as a "liquid-liquid" cooler. The engine oil and transmission fluid heat
is rejected to the engine coolant which adds heat. Aftermarket oil and
transmission coolers are available to boost cooling efficiency.
The greatest source of heat has nothing to do with the cooling
system. It's the heat riser that runs from the center exhaust ports in
both heads through a passage in the bottom of the intake manifold.
That's where an fix lies. It entails intake manifold removal to perform
the fix. The plugs are available from Mondello. The plugs are then
drilled out to 1/4" on each side to maintain the correct amount of heat.
- -Scoot Woodworth
