No possibility of an air lock - I put the sensor in the hole directly beside the thermostat housing. Whenever I took the plug out, I had quite a bit of antifreeze seep out. Once again, my heat is good - but only after my engine has gotten to about 150 degrees.

Don't see how the AFC would matter on this, but it works correctly.

Thermostat definitely isn't in backwards, I've done that before, too .
If the ambient temp is 60 degrees or below, it won't get warm (over 150) without cardboard up front. I know the thermostat has not released, because I can feel the top hose and squeeze on it, and there is no fluid in it with the engine running.

 

The upper hose and top of the radiator should always be full of coolant regardless of temperature or weather the engine is running or not.
As for the clutch, they always have a lot of drag on them and don't "free wheel" cold. They do get tighter as they get hotter. With the temp sensor next to the thermostat, what you see on the gauge is what you got provided the gauge is accurate.
Check it with the heater turned off and check the heater coolant valve and make sure it is closed. See if that changes anything.

 

Where might I close the heater coolant valve? I am not aware of that.

OK, drove it this morning without a fan for about 10 minutes, and came home. The temp was at 150 when I pulled in the driveway, but the coolant in the radiator was already hot, and steam came out whenever I took off the cap. So it's obvious that, no matter what my thoughts are on the stat, water is getting in the radiator from somewhere. The standard temperature thermostat is supposed to open at 180, correct? I'm thinking about just going ahead and ordering a cummins thermostat kit for it just to make sure it's not opening too soon. Is it entirely possible that coolant is coming in from the bottom hose?

 

At the firewall there should be a vacuum driven valve in a heater hose. The heater core acts like a mini radiator and take heat from the engine. If you have air conditioning, it can even take more heat from the engine through the heater core. Check and see if the AC compressor is running. The water pump will pressurize the whole system without the thermostat opening. There are also some small holes in the stat that allow some passage. The thermostat will prevent coolant flow, but not stop heat transfer entirely. Try to take a temperature measurement of the upper radiator hose near the radiator after you have driven it and it is hot.

 

I do not believe I have that valve, as there is no AC in my truck. The coolant runs though all the time.

I do not think it will be beneficial to check the temperature of the radiator, because when the engine is sitting at 150, the top of the radiator is hot enough that I can't hold onto it for long without getting burned. However, I will bring my temp gauge with me tonight and stick it in the top of the radiator once I've driven it around a bit.

 

You should have that valve with out without AC.
If the radiator top is that hot, then the thermostat is working and your engine is getting up to temperature. At this point I think your gauges are wrong. Use one of those infrared thermometers so you don't have to open the system. They aren't that expensive any more and are very handy.

 

150 degrees is hot enough to be uncomfortable to the touch. I still maintain that it's not getting up to 180. Both the stock temp gauge and the aftermarket coincide with each other according to marks on each one. Just a sec and I'll go check for that line.

 

Here ya go:



I know exactly what you're talking about - my gasser has one of those. My truck doesn't have vacuum-controlled HVAC, though.

 

I hear tell there is a 195° thermostat that works on our trucks.

 

http://dodgeram.info/tsb/1991/07-01-91.htm

 

Is the radiator full when it's cold? Overflow tank hooked up and full? If you can remove the cap while it's hot and not get water boiling out, but just steam, you're needing some more coolant.


Not only does it waste power, it wastes fuel, plus my truck runs cooler with a working fan clutch. Granted I am not trying to run A/C (yet), but even at 110+ it doesn't run much hotter than when it's cooler out.

My Autozone clutch ran for two years, when the water pump went out it puked coolant all over everything and that's when I noticed it was locked up.

I am thinking if one were to have some issues with the fan not cycling properly when it's hot out and the truck has a grill guard it shouldn't be hard to rig up a small electric fan on the back of the grill guard to push some air through to the fan clutch for sitting still or in traffic where there isn't good air flow through the radiator.

 

I would try a 180 degree thermostat from a gas burner. This will all you to confirm your gauge readings. It does not have the block off. There was something in an old thread about using that thermostat in Alaska. Anyway that will confirm your gauge readings. I am not advocating running the thermostat except for test purposes. If you don't pull any kind heavy why not just go to an electric fan and not worry about the fan clutch? There are multiple threads about that also. Good luck. Just my two cents, Mike.

 

 

So, did I totally stump everybody with this, or what?

 

Unless there's a redneck path somewhere, like extra heater hosing or tank type engine heater or something, the hot water has to be getting into your radiator somehow. So let's go there.

1. It has to get past the thermostat.
a. thermostat opening prematurely.
1. faulty thermostat (not)
2. Exhaust gas in coolant, bubble, slight overheat. (usually shows as a spike on the gauge.)
I noticed that the coolant level isn't clear to the cap. If the cap was off long enough for the radiator to cool down a bit, it'd be normal. If it's like that when you remove the cap, it is not normal.
b. coolant bypassing the thermostat
1. gasket
2. housing
3. installation

That's about all there is. Dog it.