I went on a trip towing the 5th wheel and climbing the last hill I noticed the temp climbing. When I left the next day the temp went almost to 240 and I pulled over and let it cool. I removed the thermostat and no change. Now it runs at normal temps on level ground but as soon as I start climbing it gets hot. Is it possible I have a blown head gasket? If so would I lose coolant or have water in the oil? What else can it be?<br>Coolant level is fine after 600 miles and everything seems normal until I get to a hill<br>

 

Sounds like your thermostat is giving you fits. You would have either water in the oil or vice versa if it were a headgasket.

A word of caution do not run without the t-stat, an engine with the thermostat removed will operate in the radiator bypass mode, causing an overheat condition.

Here are the part numbers for the t-stats. One is a 180 and the other a 190. One is a Cummins update to cure the overheat problem, but I cant remember which one. Just be sure to get them from Cummins.

Cummins Part Numbers
3954194 (180° )
3937171 (190°

 

This may sound stupid, but are you sure the rad is full of water? Just because the overflow bottle is full does not always mean that the rad is full. Other than that, as has been said I would install a new thermostat.

 

and yes you can have a blown head gasket with no fluid cross contamination. use and emission tester over the open rad cap and check for exhaust. also check and make sure the rad cap is good.

 

Since you have the t-stat already out, remove the radiator cap. Fill the radiator with water, start the engine, and carefully look in the top of the radiator for signs of water flowing. Don't get your face too close, and dont' run it too long. If you run it too long, the water may start to 'boil' out of the radiator, causing burns if you are too close. You may have a bad water pump, leading to a possible blown head gasket.

 

A little easier way to check for a head gasket leak to the cooling system, at least on the 24 valve, remove the thermostat, remove the belt, start for a minute with the water level full to the thermostat housing. Do not run for long, no cooling. Any leak will show up as bubbles in the water. This works with any engine that has the thermostat high and horozontal.

 

mine would do the same thing when towing up hills ( only on hills towing) was my fan clutch not engaging... now it never gets above 190 towing in 90*- 100* temps ;D

 

We pulled the head today and found the head gasket leaking in the area around the thermostat housing. It appears that the cause of overheating was a bad fan clutch and I would guess that is related to the head gasket.<br><br> I’m sure that is also why I will be installing my third lift pump while I am into it (hahaha). The second one is down to 6psi @WOT<br>

 

<br><br>That's not bad! Zero is bad!

 

I’m having the same problems of overheating especially pulling trailer up hills. I replaced the fan clutch a year ago but I rarely drive the truck except for plowing snow or hauling something and was wondering is there any way to test or make the fan clutch engage manually to see if it is working? I don’t hear the roar everyone is talking about when it kicks in and is are wondering if it is even working. I replaced with new one only because I had everything apart while replacing a new fuel pump and figured I’d do it while I was there. TIA

 

If it's on a 2nd gen you can use a candle lighter to heat up the bi-metal spring on the fan clutch and then start the engine.
A lot of 2nd gens coated the rad with oil from the crank vent and dust stuck to the radiator.

 

Since its electronic Is there a way to jump at a connector or something to make it kick in manually instead of warming up the spring ?or can you use a scan tool and turn it on or off it’s in a 2006.

 

2006 is too young for me, sorry.

But you can search and post in the subforum for your year.

 

a couple of years ago I bought a enclose v nose trailer haul a couple of my money pit bikes and gear to Colorado and it was hot going there . No problems until I started pulling some grades and sustained boost . The temps came up so I had to slow down and take it easy as I did not want to cause a head gasket problem . It really got under my skin so when I got home I waited till black Friday sale and bought a new Mishimoto radiator . Replaced all of the hoses , flushed the system and seemed to make a decent change in the heat rejection . I went to New Mexico this year and pulled a few decent grades , enough to test the cooing system. Seems to help . Some how the automatic stayed together one last time , I looked down at the boost an I was pulling 24 lb in overdrive on s stock 47rh . I backed off to 20 or so . I bought a low mileage g 56 to replace it and not look back . .