justagoodolboy

I replaced my thermostat with a cummins brand thermostat and had the radiator cleaned out by a reputable radiator shop locally. Now my temp gauge constantly moves around. On 1st startup it moves all the way to the 3rd line, hangs there for about 5 seconds, then goes back to the 2nd. After that it swings from the 2nd to nearly the 3rd line. Its obviously alot worst if I am towing my trailer.

I read the thread about the jingle pins and took everything apart again yesterday evening and they are installed properly at 6 & 12. I also "burped" the system right above the thermostat housing. When I 1st bought the truck the temp guage was rock solid. Now since I have turned the pump up it overheats. Of course that could be coincidental and my definition of overheating to me is going to that 3rd line.

Also, to clarify, the 3rd line I am talking about is the 3rd skinny line, not including the thicker line that is as the start and end of the gauge.

Any ideas?

Tuckerdee

Um... some would consider this "normal behavior." Mine does it to some extent. With the pump turned up you're going to add heat to the system faster than you used to. In some cases way faster then you can get rid of it. Did you bump your timing, too? Because that will keep more heat in the engine. The thermostat takes a little time to open and you can get that bouncing back and forth affect for a while.

Are you really over heating, or is the gauge just going up until the thermostat opens?

Montana2x2

If your sure you have all the air out of the system it may be time to try a sending unit for the temp gauge or put on a good mechanical gauge and see it the temps still fluctulate.

justagoodolboy

Like i said in my original post, overheating to me is getting to that 3rd line and yes I would say it getting to that 3rd line and then dropping is the Thermostat opening and closing. However, once I hook up the trailer it sits right at that 3rd line.....

Tuckerdee

Auto or 5 speed?

I'm convinced the auto dumps all kinds of crazy heat into the cooling system in its stock form. I pull a 6k 5th wheel. With the stock torque converter I couldn't keep the temp. gauge happy NO MATTER WHAT in the summer through the mountains here in Colorado. I just tried to keep it below the 4th line! It's better now that I've added a tighter TC and an additional cooler. But it's still not where I'd like it to be. I've never heard of a water pump "wearing out" in that the vanes are worn down, but I've been tempted to pull mine out and look!

Just a thought.

BearKiller

I have three Dodge/Cummins trucks with whatever thermostats that their previous owners put in them; all three are like yours, with the gauge all over the place, up and down, up and down.


However, in my Ford/Cummins, with a seven-dollar Stant 180* thermostat from Advance, and just stuck in the hole, with no thought given to jiggle-pin placement, both the factory gauge and the mechanical gauge stay rock-solid at 180*, regardless of load or outside temperature.

Alwaysworking

mine is a new stock cummins 180* goes to the second line then opens the t-stat then runs right at the first line

Rampage1967

Mine wiggles all over . . .

justagoodolboy

Bear - I am betting you are using the 55 gallon capacity Ford Radiator that came with that truck right?

[QUOTE=Tuckerdee;2114390]Auto or 5 speed?QUOTE]

Tucker - its a 5spd. I have noticed as well that once it gets to that third line and hangs out there my AC seems to heat up as well. I wonder if that is because the radiator IS alowing fluid through and cooling the best it can, but the heat exchange is affecting my condenser.

Tuckerdee

I believe the condenser is out front. Condenser, intercooler, radiator. Seems weird that the coolant gets last priority. My A/C gets warmer too as the the temps go up. Couple of theories on that. Some engines cut the A/C out when the coolant temp goes over a certain high point. Don't know if the cummins does that. So it's possible you could hover around that point and have a not-quite-cool-enough A/C. Also, the A/C hoses have a lot of exposure to heat in the engine compartment. Once you start throwing a lot of heat out the radiator it seems possible to me that you could add heat back into the A/C system and make it not as efficient. I've been meaning to put some foam pipe insulation around the A/C hoses to test this out. Just haven't got to it yet.

bgilbert

Mechanical gauge.

dodgethis91cmns

mine sits on the first line and almost never passes it.....

dzl_damon

My 93 moves all around... the 89 stays rock solid... idk.

swany

Mine was doing the same thing, and had me a little scared. Then i noticed when my headlights were on the temp gauge went up? I call BS on stock gauges! Go with the mechanical mine always sits at 195(+/-)5*

justagoodolboy

I think a mechanical gauge is probably the best solution in case the system is functioning properly and the factory one is the problem.

BGilbert - what does your mechanical gauge read? Does it stay steady and your factory gauge bounce as I describe? A little more feedback would be appreciated.

Also, what is considered "overheating" in our truck? I realize I have a 180* thermostat, but how high can you safely sustain while towing?