My truck ('49 w/ 235) has started to experience overheating problems. It
would get up to almost 212 (pegged out to the right) as it warmed up, then
would fall to around 190...but sometimes, I would have to turn it off and
coast till the air flow reduced the coolant enough. At idle, it will not
overheat, but still runs a bit higher than normal (around 190).
I figured that maybe the radiator had stopped flowing properly, or that
maybe the thermostat had stopped working properly, so last night, I took a
radiator I had that had been tested by a rad. shop as being good, and put in
a new 180 deg. thermostat (they didn't have any 160 or 170s as that would
have been my preference). I also have a new 7psi rad. cap on the system.
But even after doing all that, I am still having the same heating troubles.
I thought that maybe I have a cracked head or blown head gasket, but I
changed the oil...no water in the oil and no white smoke. I'll do a full
compression test and vacuum tests this weekend, but doesn't seem that either
of those are happening.
The only things that I can think of that might still be at fault: 1) is it
possible for a water pump to stop spinning without there being some external
evidence of that? I would think there would be some noise, or wobble, or
leaking, but water pump seems fine externally (after changing the
thermostat, I put my finger in the cold rad. into the water as it warmed up,
and as it hit 180, the water turned hot, but I did not notice anything that
I would call a "flow" or appreciable movement of the water, so I'm assuming
the thermostat is doing its job, but should I not be able to see a "flow"?
I don't recall ever checking this when everything was working right, so
don't really have anything to compare to (ie. normal vs. abnormal). 2) the
only other thing I saw that could I suppose be affecting this...as I was
warming the engine up, and with me under the hood, I revved the engine, but
did not see the dist. rotate at all (vacuum advance). Should it not rotate
such that I would see this externally (or does all the movement occur
internally without the outside rotating)? Tonight I will pull the cap and
hook a vacuum source up the the line and pull a vacuum and see what is
happening. If it turns out the vacuum advance is not working, couldn't that
cause an overhot situation at cruising speed, that might not show up at
idle?
TIA,
Rob
My Zen Moment for the Day: Do not walk behind me, for I may not lead. Do
not walk ahead of
me, for I may not follow. Do not walk beside me, either. Leave me the hell
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