overcooling

[blumule]

just put in a new heater core, and now the engine temp wont even get up to operating temp. the heat coming out is warm but my gauge wont crack 120-130 degrees.pulled the stat but checked out fine.replaced it anyway ,still low temperature.its not the gauge as you can touch engine and tell its not very hot after a driving. its always maintained a good 180 degree-190 degree reading.whats-up?

[fordman]

what size radiator do you have. how many cores are in it when you look down inside it? when you refilled the rad with coolant did engine get all of the air out of it? is the heater valve open for sure? did you cross the lines?

[Joshpow]

I got the same problem, but I haven't made any change to my cooling system to cause it. It has been like that ever since I bought it. Mine is a 72 with a 302 auto. The radiator looks to be a factory radiator for a 302, but I'm not sure. I just figured it might be normal. I never have heat in the winter. I have lukewarm air at the hottest.

[fordman]

i almost forgot. do you guys have shrouds? if yours is broken. then the heater wont work properly either.

[Dragon]

The large surface area of our radiators causes excess cooling. Mine works but my gauge does not come up so for winter I put a piece of cardboard over the bottom half of my radiator and the temp comes right back to summer normal. The heater can blow you away. I have a 180 thermostat and when I had a 198 I had to pull it every summer. So now I just board up the radiator.

[BobbyFord]

A 180 degree thermostat opens a 180 degrees. Are you saying that your t-stat is not opening? Are you getting coolant circulation? If I were you I would get a digital temp probe or temp gun and see what temp the coolant actually is. Any engine with a stuck-closed t-stat will overheat. Yours is obviously opening, probably at what ever temp it is rated. Sounds like a bad gauge or sender to me. Low heater temps are an indication of no or faulty t-stat or a clogged heater core.

[Joshpow]

No shroud. Just an electric fan on a relay. Never even turns on unless I have to set still for several minutes. Then, it cuts off as soon as the truck begins to move.

[willowbilly3]

You need to burp it too. You have to run it until the thermostat opens with the cap off, then top it off. If you aren't running a recovery tank it will spit a little antifreeze out on the first couple warm up cycles.

[70shortwide]

sounds like the thermostat is stuck open. i ran my truck for years without a shroud. just put one on and i hardly saw a difference. each truck is a little different but i dont think it would make that much difference

[Dragon]

My thermostat is not frozen open or closed and acts the same way. Not generating enough heat to warm the engine all the way.

[BobbyFord]

My thermostat is not frozen open or closed and acts the same way. Not generating enough heat to warm the engine all the way.

Then run a higher temp t-stat.

[Joshpow]

Mine acts that way with a new t-stat. I know it doesn't have air bubble problems. It had the same thing going on before the change. I don't have any idea what is going on. Oh well, I guess a good jacket is the cure.

[Dragon]

Then run a higher temp t-stat.

Then I have to change it in the Summer months again to 180 . You are thinking short term, I am thinking staying out from under the hood as much as possible and having a truck that allows me to do so.

[cdherman]

Then run a higher temp t-stat.

Then I have to change it in the Summer months again to 180 . You are thinking short term, I am thinking staying out from under the hood as much as possible and having a truck that allows me to do so.

Why do you have to change it back out to the 180 in the summer? Does it boil over (in which case, I wonder if you have a good radiator and/or have put correct mix of coolant in there)? Or does your guage read high and get you nervous?

Guages are NOTORIOUSLY inaccurate. I admit, the orignal poster has reason to beleive that his changes to the system could not have broken the guage, BUT its possible. Having no fluid in the system, and then some temp fluctuations as the fluid started to run may have been enough to finish off an old temp sender. Short the wire on the temp sender to ground. Temp guage in dash should go to HOT all the way. If it doesn't, then the guage in dash is bad.

If the guage in dash does go over, then I'd try burping the system, as I've read that need to occur. However, it not just a matter of topping off the radiator. I've read that on some notorious engines, you have to drill a pin hole in the thermostat. Have heard parking up hill works too.

But failing that, assuming the thermostat is working, then I guarantee that the engine is getting up to temp, unless its way below zero outside. Try changing the sending unit.

Engines don't produce less heat with a lower temp thermostat. And they don't produce less heat with NO thermostat or a stuck open one. So engines that are overheating (boiling over) with a 195 will probably overheat with a 180. Boiling over is a sign of a blocked passage or plugged up radiator core. (or stuck shut thermostat or bad waterpump or improper coolant mix, to round out the list).

Putting cardboard over the radiator DOES help get better temp from an engine, but not because it keeps air from cooling the radiator. In very cold weather there should be little or no flow through the radiator, especially at highway speeds. What the cardboard DOES do is slow the flow of air into the engine compartment. That allows the engine to warm up higher. Think of it this way -- heat radiates from an engine too. And in very cold weather, heat radiates away from an engine so fast (especially when moveing fast down the road) that the radiator is not even necessary.

Now, if you have no thermostat, or the thermostat is stuck open, the cardboard will help too -- but you really ought to fix the problem correctly. Engines running too cool develope more condensates, leading to faster corrosion in the engine, plus they are less economical to run (burn more gas).

[BobbyFord]

Then run a higher temp t-stat.

Then I have to change it in the Summer months again to 180 . You are thinking short term, I am thinking staying out from under the hood as much as possible and having a truck that allows me to do so.

If your engine gets hot enough to overheat in the summer time then chances are you have a partially plugged radiator. Both of my trucks operate in the normal range no matter what temp it is outside.