bluemerlin
New member
"I have a 1989 5.7L, (with
"I have a 1989 5.7L, (with closed cooling) and in chasing overheating issues, checked the thermostat. It was installed upside-down, and had a lot of deposits under it. After cleaning and replacing it (and a new pressure cap!) the cooling issue is gone, but brought up some questions.
1. The Clymer manual says to put the thermostat in the housing with the brass ring above it (which is how it came out), the mercruiser manual shows the thermostat on top of the ring, level with the top of the housing. I am guessing it does not make much difference? When I took it out, it did not have the smaller o-ring or cork gaskets installed at the thermostat either, just the lower one (with the brass rivets) and the top one (that is metallic).
2. The bypass passage around the thermostat (when it is closed) was completely blocked with deposits, but when I cleaned it out, I realized it did not matter since the top gasket covers it up anyway! This is a 140 degree thermostat, and I see in parts listings that the 160 degree kit comes with a top gasket with a cutout for the bypass, but the 140 kit does not have the cutout... Should it???
3. In the kits, there is a top gasket with no holes at all, probably for a different housing cover?
Thanks,
Chris."
"I have a 1989 5.7L, (with closed cooling) and in chasing overheating issues, checked the thermostat. It was installed upside-down, and had a lot of deposits under it. After cleaning and replacing it (and a new pressure cap!) the cooling issue is gone, but brought up some questions.
1. The Clymer manual says to put the thermostat in the housing with the brass ring above it (which is how it came out), the mercruiser manual shows the thermostat on top of the ring, level with the top of the housing. I am guessing it does not make much difference? When I took it out, it did not have the smaller o-ring or cork gaskets installed at the thermostat either, just the lower one (with the brass rivets) and the top one (that is metallic).
2. The bypass passage around the thermostat (when it is closed) was completely blocked with deposits, but when I cleaned it out, I realized it did not matter since the top gasket covers it up anyway! This is a 140 degree thermostat, and I see in parts listings that the 160 degree kit comes with a top gasket with a cutout for the bypass, but the 140 kit does not have the cutout... Should it???
3. In the kits, there is a top gasket with no holes at all, probably for a different housing cover?
Thanks,
Chris."
