Please forgive me if I am stating the obvious, but did you replace the
thermostat? I saw an ad late last night that said a new type is available
that fails open, causing the engine to run cooler than desired in the event
of failure but doesn't lead to overheating.
I forgot to mention that the guage will indicate no temp at all untill it
will all of the sudden snap up as high as it can go. Its not a graduall
increase in temp. Dont know if this makes a difference.
Probably a bad sending unit. Since you indicate you did get the motor
to meltdown temps, you should have your radiator cleaned out by a
radiator shop. With Small Block Chevy engines there is always casting
sand left in the coolant galleys. When you get one over 260, you get
casting sand in the radiator.
You should also check the tempiture your fans come on at.
Well I'm not so sure the engine is really running at super high temps,
because it doenst smoke or anything when the guage indcates that high of a
temp, and I can put my hand on the intake and other parts of the engine
w/out being burned. The fan does come on the second the guage snaps up. The
fan is running on a hypertech cold fan switch on at 177* off at 166*. Could
it be possible that I have an air lock in the system?
Nope dumb as this sounds I've never blead the air from anything other than
an LT1 that had screws right on the water pump. One of my friend told me
that with the TPI engine as long as I dont drain the block than I wouldnt
need to worry about air in the system. There is a massive plug on the water
pump I dont know if I should use that it just seems too big... The T-stat is
going to be changed this weekend. And as for the sending unit I have no I
dea it was working fine untill the water pump started leaking ang thats when
the gouge started giving false high temps...
The big plug on your water pump should not be disturbed. Some cars have
a heater hose (or bypass) that goes there. A lot of the after market
pumps come with that hole in them, even though the applications 80% are
sold for do not use it.
To bleed air from a GM V-engine, fill the radiator slowly. wait until
it stops purging air. Start the engine with the cap off, let the
thermostat open keep the coolant level down only an inch from the
I don't have a book at home that covers the testing of your coolant
temp sending unit for the gage. Finding out the test procedure on line
should not be too hard.
Or you can do what I do, drill a 1/16" hole through the thermostat.
this will let air past it and prevent air lock. I read on some boards
where guys drill a hole as big as 3/16, this will just let way too
much water though and slow down engine warm up.
Remove 333 from email address to reply.
To confirm the sending unit is defective, check the resistance of the
unit when the engine is cold [100* or lower]. Resistance should be high
at around 1365 ohms. Next, run the engine until it is fully warmed up
and check resistance again as it should now be low, around [I think] 150
I fill it at the Tstat w/rad cap off. I button up the engine, run it for
about five minutes and shut down. After I grab a beer, the Tstat's open and
warm with no pressure. Crank 'er up and ensure circulation.
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