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Discussion Starter #1
My truck has had a tendency to overheat, but only on occasion. I replaced my thermostat recently, thinking maybe it was just "sticky" part of the time. This didn't solve the problem. It will get hot even when I just drive 6 miles, and will steam when I shut it down. Yesterday was the first time I've driven it since I replaced the thermo, and it got hot both coming and going. Before it would only do it sporadicly. The old thermo didn't really appear to be messed up, but I went ahead and changed it since I had it apart. Could I have gotten a bad thermo or one that releases at too high a temp? What else could possibly be the culprit here?
 

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Do you think your headgasket could be bad? Run it with your cap off and see if you have bubbling or pressure.
 

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Discussion Starter #3
Would I need to check for bubbling when it's warm or just whenever I start it, and what would that indicate? And how exactly could a bad head gasket be causing it? It hasn't lost any power...
 

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If the head gasket blows to a water passage it would blow hot pressure into the leak but also you would probably have some coolant loss. I would take cap off when it's cool and just start it and watch. Also have you checked the water pump, take belt off and wiggle pulley see if there is any play.
 

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Another sign of a head leak is the radiator hoses getting pressurized before they get warm.

I have been told that even a very small head leak can not only blow hot gas into the cooling system...the extra pressure somehow makes the coolant not flow as designed.
In any case, the two other posters are right...a likely cause is the head gasket. The definitive test is something some call a "block test"...you should be able to find a garage which will do a test (about 25 bucks is what it should cost) which detects even small amounts of combustion gas in the cooling system.

What does the radiator look like? Gunked up?

If you drain the coolant, you could pop the water pump and take a look the the impeller and then do a drain-down test of the radiator at the same time.

Roy
 

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I know the shop I work at has a kit for testing for exhaust gases in the coolant which would be present in the case of a bad headgasket. Its very useful for cases like yours when its an intermittent overheating problem.
 
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Discussion Starter #7
Okay, coming back home it got hot again, so I had to pull over and let it cool down. It seems to be leaking a little around the top hoses, as if the thermostat is releasing, but it can't get through the radiator. So I'll probably try to see if the radiator is stopped up. What's the best way to tell if it is and how to free it up? I also had just a little heat coming through the vent, but not as much as I would have thought for the high temperature.
 

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Choochly,

Man, I would stop driving that thing until you get it fixed. I know it is a massive chunk of cast iron, but bad things happen to good motors when they are hot.

Here is my radiator guy's quick test. Drain the coolant; remove both radiator hoses from the radiator; plug the resulting holes up with rags or whatever;fill radiator with water; when it is full pull bottom pug out; the water should GUSH out of that hole...very quickly draining the radiator. And, I mean GUSH.

If it doesn't gush, pull the radiator and take it to a radiator shop for a rod job. They take it apart and run rods up and down in each radiator tube.

Another approach is when the motor/radiator is hot, use one of those infrared thermometers (you your hand) to detect hot/warm/cool areas of the radiator...the radiator should all be one temperature without any cool areas.

If you do the first method, you should consider testing your thermostat and removing the water pump for inspection.

Put thermostat in a pot of water on the stove and heat it to 190*F (or whatever the temp is for these things) and watch it open.

Look for a loose-feeling bearing or more likely a loose or corroded impeller.

R.
 

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Discussion Starter #9
So, after examining what I did to it earlier, I finally found the problem. :D Thanks for all the help, guys, it is very much appreciated. There was an "operator error" made, which will never be made again. :doh:
 

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Discussion Starter #11
I... put the thermostat in backwards. :doh::banghead::spank:
 
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happens. Learn from it.
 
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Sorry, forget the message board automatically blocks out french lol. "Mistakes" happen, learn from it.
 

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Discussion Starter #14
Thanks. I certainly intend to.
 
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