73-87 Chevy _ GMC Trucks > Engine/Drivetrain
Weird cooling issue
bd:
--- Quote from: Dave78 on September 28, 2021, 11:09:05 AM ---Another oddity, turning the heater core fan on results in an immediate jump of 5 degrees hotter. I have no idea how running the heater makes the coolant run hotter. This happens even after the thermostat is fully open and has stabilized at 180.
--- End quote ---
Use a voltmeter to validate the engine, cab, and blower motor grounds to B-.
Dave78:
Solved the issue.
Pulled original sending unit out of head. When I had it out I shook it and can hear something rattling inside. Weird seeing as how I thought they were solid but who knows. Anyways, put in an equus gauge and sender in the driver side head. Put the old unit that goes to the factory gauge in the intake next to thermostat.
Cranked it up, and within a minute or less the intake gauge said it was already at 160 degrees or so. Spiked up to 210 a couple times. Head gauge barely had hit 100 degrees. Got it up and to temp, drove around and with a 180 degree stat I never broke 165 degrees at the head. Driving down the road over 35-40mph the temp would fall to 160 even. Ambient temp was -2f with a piece of cardboard halfway covering radiator.
So 160 at the head seems awful low to me. Going to a 195 stat should be a good idea as well right? Also have an extra space in my gauge holder thinking an oil temp gauge wouldn't be a bad idea. Any good place to mount the sensor?
I should also note that my temp gun was being interfered with by the goofy aftermarket headers to previous owner installed. The same goofy headers preventing me from installing the gargantuan oil filters that came equipped on 366 C-60 trucks that I like to run.
JohnnyPopper:
Wow a rattling sender!
I think the ambient temp of -2f is a factor, especially since you only got it up to 30-40 mph. 55-75 mph might tell a different story.
I would do a 195 anyway, sounds like cold country requires it.
BTW Thanks for the follow up!
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