I may be chasing a non-problem, but would like some second opinions.
I changed from SW to FW cooling using the Moyer kit over the winter. System is still running without a thermostat until I get comfortable with it. This year the system has been running hot - cruise speed under power has been limited to keep the gage under 200. I finally realized the system was losing coolant through the water pump, and perhaps running with low coolant level. A rebuilt pump was installed, which still dripped. Finally I bit the bullet and installed a new MMI coolant pump. Another thing I've been doing recently is to check temperatures with a non-contact infra-red thermometer (Radio Shack 22-325).
Today I installed the new coolant pump, cleaned the temp sender unit, filled the system, and then ran it dockside in gear at 1400 RPM. The temp gauge finally stabilized at 160F. Other temps measured with the IR gizmo were: SW in 73F, SW out ??, coolant in 98F (at pump), coolant out 125F (at exh. manifold elbow), aft/port end of head 152F, stbd of #1 plug 176F, fwd end of head 196F (to port of temp sender).
I'm not sure what to make of these numbers. First thought that coolant out at 125F is wonderful - ignore the others. I expect the metal to run hotter than the water, otherwise there's no heat transfer. Also, the port fwd end of the head has basically no circulation so will run even hotter. And the temp sender is driven as much by the temp of the head as the temp of the coolant.
So, question #1. What is the real temp limit on things? Obviously you don't want to boil the coolant, but I'm far from that! What about the temp to warp the head? What about the temp to affect the head gasket? What about the temp to burn the paint off the head? What haven't I thought of??
The gauge temp I know how to fix. Pull the sender out of the head, plug the hole, and install the sender into the outlet of the exhaust manifold with a tee. That will give me an accurate read of coolant temp.
I guess question #2 becomes: Has anyone else checked head temps vs water temps?
Al Schober
I changed from SW to FW cooling using the Moyer kit over the winter. System is still running without a thermostat until I get comfortable with it. This year the system has been running hot - cruise speed under power has been limited to keep the gage under 200. I finally realized the system was losing coolant through the water pump, and perhaps running with low coolant level. A rebuilt pump was installed, which still dripped. Finally I bit the bullet and installed a new MMI coolant pump. Another thing I've been doing recently is to check temperatures with a non-contact infra-red thermometer (Radio Shack 22-325).
Today I installed the new coolant pump, cleaned the temp sender unit, filled the system, and then ran it dockside in gear at 1400 RPM. The temp gauge finally stabilized at 160F. Other temps measured with the IR gizmo were: SW in 73F, SW out ??, coolant in 98F (at pump), coolant out 125F (at exh. manifold elbow), aft/port end of head 152F, stbd of #1 plug 176F, fwd end of head 196F (to port of temp sender).
I'm not sure what to make of these numbers. First thought that coolant out at 125F is wonderful - ignore the others. I expect the metal to run hotter than the water, otherwise there's no heat transfer. Also, the port fwd end of the head has basically no circulation so will run even hotter. And the temp sender is driven as much by the temp of the head as the temp of the coolant.
So, question #1. What is the real temp limit on things? Obviously you don't want to boil the coolant, but I'm far from that! What about the temp to warp the head? What about the temp to affect the head gasket? What about the temp to burn the paint off the head? What haven't I thought of??
The gauge temp I know how to fix. Pull the sender out of the head, plug the hole, and install the sender into the outlet of the exhaust manifold with a tee. That will give me an accurate read of coolant temp.
I guess question #2 becomes: Has anyone else checked head temps vs water temps?
Al Schober
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