cbolt Posted November 19, 2014 Share Posted November 19, 2014 I installed a champion 3 row aluminum radiator after an engine rebuild along with an autometer electrical gauge which senses the temperature at the LH cylinder head. The thermostat is functioning correctly and opens using a thermometer in a pot of water on the stove at approximately 160-180 degrees. The funny thing is the gauge goes to approximately 220 degrees before the thermostat opens and I can feel the upper hose getting hot, and see the water flowing through the radiator. My question, is that normal temp for the engine when the temp sender is located on the cylinder head? I was under the impression with a 180 degree thermostat would keep the temp at approximately 180 degrees. This is my first experience with a gauge instead of an idiot light so I don't exactly know what it should read. Thanks in advance Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted November 19, 2014 Share Posted November 19, 2014 electric gauge readings can vary greatly depending on voltage to them if you have a thermometer you can put down the radiator cap opening to double check your gauge I usually put my sending units as close to the thermostat as possible, it is possible that the temp at the head is that warm did you drill a hole in your stat to help purge the air out? Quote Link to comment Share on other sites More sharing options...
dbreese Posted November 19, 2014 Share Posted November 19, 2014 Air pocket? Just throwing out an idea. David Quote Link to comment Share on other sites More sharing options...
cbolt Posted November 20, 2014 Author Share Posted November 20, 2014 I did drill a small hole in the thermostat to eliminate any potential air pockets, or at least I thought so. What would some other solutions to a possible air pocket be? Quote Link to comment Share on other sites More sharing options...
John S Posted November 20, 2014 Share Posted November 20, 2014 My 70 350 reads high also. When I point infrared temp gun at thermostat and sending unit in left head the reading is much lower than temp gauge, approx. 183 to 188. Also I temporarily installed mechanical temp gauge in rt head and that reading verified that the electrical temp gauge was not accurate. I also changed sending unit twice with no difference. John S Quote Link to comment Share on other sites More sharing options...
cbolt Posted November 20, 2014 Author Share Posted November 20, 2014 So you are saying you have had bad gauges right out of the box? Quote Link to comment Share on other sites More sharing options...
72-CLASSIC_RIDE Posted November 20, 2014 Share Posted November 20, 2014 Maybe its the Temp Sensor itself. Depending on engine year, the earlier circa 70's cars used a Temp Sensor that internally used wax to help measure temperature. Cant explain how it works but in a nutshell, newer Temp Sensors and I don't know the break off point altered the way engine temps were measured. So maybe it is the wrong Temp Sensor giving you erratic readings. Just a thought. I have seen those sensors advertised periodically stating they are for our cars. Doug Quote Link to comment Share on other sites More sharing options...
cbolt Posted November 20, 2014 Author Share Posted November 20, 2014 Solved! Must have been air in the system. I took it around the block this morning, put about 3 miles on it, and the temp held rock steady at 180. Thanks for everyones help. I was like a nervous parent.... I am sure lots of us have been there! Quote Link to comment Share on other sites More sharing options...
Sam (Bones) Posted November 20, 2014 Share Posted November 20, 2014 rather be lucky than good any day! Quote Link to comment Share on other sites More sharing options...
cny first gen 71 Posted November 20, 2014 Share Posted November 20, 2014 rather be lucky than good any day! Quote Link to comment Share on other sites More sharing options...
footballubet Posted November 22, 2014 Share Posted November 22, 2014 Glad you got that worked out. Those little air pockets can be a real PITA. Especially on the newer cars with the closed system. Quote Link to comment Share on other sites More sharing options...
cbolt Posted November 22, 2014 Author Share Posted November 22, 2014 It was funny the timing of the whole thing. Prior to starting my engine I was following Rodney's troubles, and thought I might as well drill the hole in the thermostat just in case. I have never had an issue on any previous rebuild but wanted to be safe than sorry. I initially thought the whole I drilled was too small, causing the warmer temperature reading. Bottom line is I am glad I got it worked out as well. Quote Link to comment Share on other sites More sharing options...
John S Posted November 23, 2014 Share Posted November 23, 2014 Good you got it resolved. Previous posts stated sending unit. The two units I got from parts houses. Probably generic designed to fit many applications. Found one specific to 1970 Monte. But also have electrical issues, gauge reads OK until lights are turned on, then gauge jumps to the right and reads erratic. I have known circuit board is bad now I finally have ambition to change it since weather has turned colder. John S Quote Link to comment Share on other sites More sharing options...
cbolt Posted November 23, 2014 Author Share Posted November 23, 2014 John, the circuit board is a cheap and easy project. I recall changing mine with the dash in the car, just moved forward on the lowered steering column enough to allow my arms to fit back there. I used to work on aircraft so I am used to monkeying with parts in tight spaces but you may decide to remove the whole dash prior to swapping the printed circuit. Whichever route you go, good luck! Quote Link to comment Share on other sites More sharing options...
John S Posted November 24, 2014 Share Posted November 24, 2014 You're right. It looks as though all I have to do is "roll" it forward and I should have enough room to get it out. I still have some good finger dexterity left so I shouldn't have a problem. John s Quote Link to comment Share on other sites More sharing options...
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