OVER HEAT OR JUST RUNNING HOT

On A recent trip home from Yellowstone the van started running hot while climbing hills. At least twice I had to pull over and let the van idle and cool down. When I say hot I mean the gauge was in the low side of the red. Normally the gauge is right in the middle of the range.
We made it home and now I need to figure out what was the problem. Any suggestions of what to check?

1. Fluid level. Leaks?
2. Fluid change (doesn't cost much).
3. Debris around radiator.

Then run it up a steep hill with a load. As a reference, my needle has hovered just below, and never above, the 215 mark, which is the tick mark between 180 and 250.

belt tensioner, belt condition, and fan clutch are also culprits.

I've experienced similar temps rising whenever climbing +6% grades in my T1N 2006 140 wb 2500 High Roof; 90k miles. Especially in summer weather over 95 degrees F.

Best easy remedy is to simply do a manual shift from "D" to 4th gear when climbing inclines. Do this by bumping the shift lever once to the left. This puts you in 4th gear (instead of "Drive"), and keeps the engine's RPMs up over 2000 level. Engine runs more efficiently, temps stabilize at 2200-2300 RPMs. In "D", I've experienced that the lugging strain in "D" uphill promotes temps rise.

I also suggest turn off AC, for less engine burden. At top of hill, bump shift lever once to the right to return to "D".

Driving a heavy cargo van requires techniques different than a passenger car or truck when climbing hills. Hope this helps. I've yet found the need to pull over and cool down.

You should not be seeing temps near 250F except in extreme circumstances. Not normal.

my 04 was running a little hotter than normal on hills, little worse on every trip. I had recently replaced belt and a few pulleys so I knew they were doing their job. Following a suggestion from an old post search, I replaced the viscous fan (the mechanically driven fan between the radiator and the motor). The fan clutch is filled with viscous fluid that when not working properly will not turn the fan as fast when you need more air movement through your radiator.

Since replacing the fan clutch and fan (sold as a single part from Mercedes) my temps have never gone over 215. As a test, I drove east up the Ortega in So. Cal fully loaded in Drive (again trying to see if repair was successful).

It worked for me, and wasn't a difficult repair at all. If I remember it took less than 30 minutes assuming you have all the right tools.

Thanks for al the suggestions. I believe it may be the fan clutch. I heard when you try to turn the fan by hand it should have a good amount of resistance.
My fan has minimal resistance when I turn it by hand.
The AC wasn't working during the trip I have a hole in the ac hose that still needs to be repaired as well.
I will check the belts and tensioners as well.
any one have any problems with the thermostat or water pump being an issue causing the van to over heat?

Wood.n.you said:

my 04 was running a little hotter than normal on hills, little worse on every trip. I had recently replaced belt and a few pulleys so I knew they were doing their job. Following a suggestion from an old post search, I replaced the viscous fan (the mechanically driven fan between the radiator and the motor). The fan clutch is filled with viscous fluid that when not working properly will not turn the fan as fast when you need more air movement through your radiator.

Since replacing the fan clutch and fan (sold as a single part from Mercedes) my temps have never gone over 215. As a test, I drove east up the Ortega in So. Cal fully loaded in Drive (again trying to see if repair was successful).

It worked for me, and wasn't a difficult repair at all. If I remember it took less than 30 minutes assuming you have all the right tools.

Click to expand...

Same experience here. The clutch is a wear part, and europarts SD sells the clutch separate.

the fan clutch was the cause of my 2006 T1N overheating. It was going on for a year with me trying to figure out why. It was fine on level ground, but any hill and temps climbed. Once the fan clutch was replaced, temps dropped 20-25F.

Took me a lot longer than 30min though, somewhere between 60-90min.

Most are surprised by the amount of debris between the rads blocking air movement, like feathers, grass, leaves, seeds, plastics, styrofoam pcs and mice

Don't forget grass hopper guts!

Dennis