OK,

My vette used to have the chronic overheating problems. I have replaced the radiator (stock) all hoses and thermostat. I also replaced the destroyed clutch fan with a flex fan and aluminum spacer.

The car ran fine, sat right ast 180 like it is supposed to... Then I had sprung a heater hose leak a few weeks ago. Not a big deal- the clamp came loose allowing the heater hose to hit the exhaust manifold and it melted through. Replaced the hose, but it melted in bumper to bumper traffic- engine overheated a little (220) before I gave up and drove on the shoulder to get off expressway.

Ever since I replaced that hose and refilled my radiator (and gave it a good flush of the system as long as I was in there)- it will not warm up unless sitting in bumper to bumper traffic or if it is a hot day.

Slightly cool days it sits at about 150-160, then on hot days or in traffic it will warm up to 180. Even drag racing on a hot day only got it to 200!

Figured it toasted the thermostat? I went ahead and replaced it this weekend, still not warming up. Is it because of the flex fan? Perhaps when I did it last time I had air in the system or something (I did not flush it since I put the new radiator in 2 summers ago). I replaced the flex fan last year.
Any ideas why my car stays so (too) cool?


Thanks!
~Kevin

 

Maybe the temperature sending unit needs replaced.

Is the system building pressure (does the upper hose feel firm after driving for a while)? If the coolant never got above 180 it probably won't build pressure as it is still below the boiling point.

 

The Corvettes came with a clutch controlled fan for an engineering reason. Surely a flex fan is cheaper to manufacture and install so there must be a good reason the GM did it that way. Since you have replaced the suspect components I think I would go back the way the General did it. DId you test the thermostat in a pop of water and then heat it up to see what temperature it opens up at? More than one new thermostat has been faulty.
Gary

 

It sounds like you put in a 160 thermostat. Factory for 1979 is 195.

 

GaryS-

I did test the "new" thermostat, but I did not test the old one. I figured it was just as easy to replace as to test the old one- $2.99 + gasket. It opened at 180 or so- tested on the stove with a candy thermometer.

Yeah a clutch fan is probably the way to go, but I had a flex fan (nice and chrome) in the garage and the clutch was dead... Went with what I had- may have to change it though. It was doing just fine last summer though. This year as well until a few weeks ago. Maybe the sending unit has gone out? How do I test that? The guage is still moving, just not very far unless hot out.

~Kevin

 

I put in a 180 unit. I tested it before putting it in. Should I go with a 195? I have no idea what the old one was- I think it was a 180, but I put it in a few years ago when I was still having overheating problems. It used to overheat on anything but a cool day or unless you were at a nice cruising speed.

I suppose now that it is out I can test the old one, unless I threw it away.

 

Mine is like that as well but I never considered it a problem. I have a clutch fan, electric auxillary fan that always runs, radiator blocking condenser was removed, high volume water pump...

I realize an engine that never heats up can be as power robbing and damaging as an engine that overheats but in this case I don't think 160 is a problem.

BUT in your case some things that may be causing this-
Did you replace the 180 degree thermostat with a 160 degree one?
Did you replace the temp sending unit (if not - the old one may be defective, if so - the new one may not always match and be giving you a wrong reading).
Did you relocate the temp sending unit?
Maybe the flex fan is the problem. I've heard nothing but bad things about flex fans, get a replacement clutch fan.

Another thing to look for - watch the temp guage closely the first few minutes of operation. Mine will slowly get up to 180, then edge up to almost 200 before the thermostat will kick in and start recirculating the cool water, then you see the temp drop down quickly to 170 or so. After that I have to put in some hard runs on a hot day before I see 190.

 

Well I think I will try and locate a new clutch fan. Or should I not worry about it until the spring when the new engine will be in. The 383 will probably run hotter than the stock L82... Or is the general consensus the flex fan is a cheap band-aid?

Like I said, I put it on because it was there in my dads shop and it was free and shiney chrome! ;-)

 

I'd borrow somebody's IR temp sensor to check the accuracy of your gauge. That would seem like the easiest way to tell whether your engine was actually heating up like it is supposed to even though your gauge says