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Discussion Starter #1
I've got a '93 Chevy 2wd (5 speed manual, no cooler) w/ an 88 x 26 inch plow on the nose. It has a mild cam (not sure the specs anymore, but with 3.73 rear gears it has to hit almost 1500 rpm to "pull" hard. After I put the cam in, and after two thermostats (190*), the temp gauge would sit at 210 all the time. Timing is set dead on according my timing light. After a recent 200 mile round trip, it dropped to about 190 -195 before I put the plow on.

Now all of a sudden with the plow on it will run between 160 to 150 and it hit almost 260 once. I know the plow directs snow above radiator, but it does this sitting idle, plowing, or heading down the road at 45 to 55 mph. Also, when the temp gauge hits about 215 the heater starts blowing cool air (no, the a/c is not on, I checked) until it gets to about 225. If I run a lower gear and higher rpm, the temp drops down to almost normal. The whole cycle (cool to hot and back) takes about 5 to 10 minutes.

I'm leaning towards a bad head gasket, but I'm hoping I'm wrong. Any thoughts on what's happening? Thanks in advance.
 

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Race it, Don't rice it!
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Low coolant level, Low coolant pressure, Low coolant flow, Air pockets, cavitation, Leaking radiator cap. Might be a head gasket too. Is it losing water? Give it a leakdown test and report back.
 

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Discussion Starter #3
Coolant level was good, still tests to -20*. Is there a quick (and warm) way to test the pressure? Kinda strange now that you mention it that it hasn't boiled over. I also put a new waterpump on when the new cam went in 2+years ago. Just more info, and thanks again.

Later,
Chet
 

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Discussion Starter #4
The source of the problem seems to be the thermostat. I changed that and it now stays nice and cool (190* to 210*) and that's plenty good for me now .

Thanks again,
Chet
 
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