The Stovebolt Site Forums The Shop Area Engine Shop Running warm, '49 GMC 250, 228

Maybe some of you remember a few months ago I lost a fan blade while driving and it nicked the 'tator. I never had an overheating problem before. 'Cept when the old bellow style themostat stuc 1/2 open; 1/2 closed. Yanked it and went to the closest parts store and was told, "No way man". Knowing he was full o'crap, I simply put it back together without one. Didn't have time to chase one down or to school the parts guy. :rolleyes:

So lately She's running 195' plus if I get on the highway and maintain 50 mph. It is full of 50/50 coolant, fresh oil {full}, starts and runs smoothly. Basically nothing has changed. Here is what I don't understand... When it is hot, I can take off the cap without fear of overflo, but it has a bit of foam at the neck. No water in the oil! Could the head gasket be leaking? It does seem to loose a bit of coolant periodicaly. But not out the exhaust. Engine has less then 30k original miles, hence the bellowed 'stat I removed.

Anyone wanna take this? TIA

Thomas

I wonder if there is something wrong with your water pump. It could be the head or head gasket though. Let's hope it is just the water pump.

You can go to your local parts store and get any standard 180 thermostat. I haven't been following the thread, but here is what I would do: I don't know if the foam is an indicator of anything. Is the gauge accurate? Use a handheld food thermometer to directly check the coolant in the radiator. Losing coolant does point to head gasket leak. If you suspect a headgasket leak, drain enough coolant to remove the thermostat. Refill with coolant to the top of the thermostat housing. Remove belt, start engine, and check for air bubbles. If you have overheated the engine you may have a warped head/ leaking gasket. There is also an exhaust sensor that can detect exhaust gases in the coolant. Finally, some will argue that removing the thermostat caused the overheating. There has been much discussion on this board about this issue. It has been my experience that removing the thermostat only results in a cold engine.

First off you need to replace the thermostat. I had a 68 Valiant with a slant 6 in it and once I had a thermostat go bad just as you had. I removed it an put it back together and I noticed that at highway speeds it would run kinda hot. I spoke with an old guy and basically what he said is the water is going through the radiator so fast that it has no chance to cool. This made sense so I put a thermostat back in and the overheating was gone. I put a 180 degree thermostat in and it never overheated again. Once I put AC in the car I went to a 195 degree stat and it could idle in 100 degree heat with the AC on and never get over 200. Also a thermostat in the engine will help it warm up faster especially in cold weather and prevent hot and cold spots in the engine. It helps keep all of the engine at the same temp. This also helps the engine to run better. Also make sure the replacement fan has the proper pitch and that the radiator is not blocked by bugs, leaves etc. Good luck.

Not to beat a dead horse, but it has been my experience that removing a thermostat causes my 302 gmc to run cold whether using a stock radiator or a 4 core aftermarket. This is idling and running down the interstate. The anecdote that the water flows too fast to cool is not an absolute truth.

I too spoke of the too much water /not enough time to cool aspect. Everyone thought I was crazier than I actually am...

How does a water pump go bad besides the bearings? Is it possible the pump has sat in the system for 54 years and simply deteriorated? Just not pushing enough? I have a heater core in the cab that will disagree! SOB has plenty of circulation.

I ordered a reman Water Pump from napa for $32.50 and the "rad" is going in for R+R Friday. Is the "not long enough in the RAD" realistic? Makes sence to me, but no one seems to agree.

Thanks Again!

I have seen radiators get hot at highway speeds and run just fine around town. It didn't matter what the temp was. The core gets pluged up and can not transfer heat fast enough at highway speeds. A stuck thermostat or removed one will normally cause a cold engine. It takes a lot of work from the engine to heat up with out a stat.

If the water pump set with a blade or two in water for 30 years, it could be bad, or the clearance in the impeller is worn. But at higher rpm's it should pump more water than at idle and your problem would be reversed.

I'am betting the radiator is plugged and the problem showed up at the same time as the thermostat went bad or the weather changed.

Joe

Thanks everyone! The 'tator is out and going in tomorrow/today. {man it's late} Pump and stat going in too.

I sure hope it aint the Flugal valve thats bad :p