Running Hot Or Is It Normal ?

Discussion in 'Classic Mustang Specific Tech' started by Dougsters, Aug 1, 2013.


  1. Dougsters

    Dougsters Member

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    Just installed mechanical temp. gauge last week on my 66 C-code/Auto with factory A/C. Car has shroud and 5 bladed fan. Radiator is 3 yrs. old car has coolant recovery and 50/50 coolant mix. Thermostat is 180 deg. So after driving a(A/C off) few miles once warmed up it ran from 200- 205 deg then at signal 210-215 degrees. Stopped and checked temps with my infrared temp. gun,results: At thermo. housing at idle= 200-205 top of radiator= 205 Upper hose( middle)= 180 and lower hose= 150 degrees. I touched each hose(engine off) and lower one was cooler,hot top real hot. Is the temp. differantial normal from lower to upper? It seems to me once thermostat opens they would be closer in temps. BTW - Thermostat bypass temp.= 190 degrees. I guess if thermostat was not opening bypass would not have volume to cool motor and it would be running hotter then 200-210 aver.? Also motor is bored 60 thou. over and could be a contributor? Thanks all for your help,sorry for the novel. I never gave it muck thought till I bought Temp. gauge.LOL
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  2. Boogie's AutoRama

    Boogie's AutoRama New Member

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    Sounds like it's doing fine. ...IF it doesn't get any hotter.

    It's more important that it maintains a steady temp. The 10ยบ difference between driving and standing still seems a little wide though.
    When you run the A/C things will probably heat up.
    Have you considered using an electric fan?

    The lower hose is should/supposed to be be much cooler than the upper.
    I don't think the .060 bore is a factor.

    One last thought, if it ain't boiling over, your go to go.
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  3. Dougsters

    Dougsters Member

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    Thanks Boogies AutoRama-I here ya on the A/C but I removed Smog Pump so no pulley to drive it. I now remembered the water pump is pulling from the radiator so natuarlly the lower hose would be cooler.As far as electric fan might have to once A/C gets hooked up again. Liked your last thought about boiling over what 250 deg. for 50/50 mix to boil. I'm for sure over thinking it.
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  4. rbohm

    rbohm Founding Member

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    sounds normal to me. in fact the engine can run as hot as 225 degrees before i would start to worry.
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