2010 D40 ST engine heating up on hill climbs

[5thwheelerboyz]

For the past six months I’m noticing that the temperature gauge starts to climb on steep hills when the RPM is around the 3500 mark.

It is probably obvious and expected considering the scenario as it only happens when I’m towing my 3 tonne 5th wheeler. I also have a Steinbauer performance chip installed.

I don’t push it up the hills but try and get a good run at it. It use to only happen when the RPM was up round the 4000 RPM but it happens more often now at the lower RPM. To bring the temperature down, we turn the heater and fan on to full and it brings the temp down immediately. We now do this as a matter of course when approaching a steep incline.

All fluids look normal so I’m just at a loss as to what it could be. The truck is due for its 50,000km service and I’ll mention it to the service guys.

I also spoke with the company who installed the Steinbauer and asked if the exhaust should be upgraded. They said that because of the type of exhaust that is installed in these now, it wouldn’t be advisable. Something to do with the box that burns off the carbon.

I never encountered this when I towed my previous vans albeit they were lighter. The truck handles the load very well on open road; it’s just the hills that are the worry.

I have no idea on what upgrades are available out there or what needs to be checked on the engine so any help would be appreciated.

Steve

 

[kernels]

The last time we heard almost identical symptoms it was a clogged radiator, new radiator completely solved the problem.

 

[5thwheelerboyz]

Excellent, I'll mention that when I take it in for a service.

Thanks for your help.

Steve

 

[ourd40]

Is it just me or does 3500-4000 rpm's sound like a lot or am i babying my nav to much?
I rarely rev it to 3 and couldnt imagine going that high for an extended time.
My first thought was that load up a hill at those revs would get it pretty dam hot even if it was running good !?

 

[Old.Tony]

I don't like revving mine that hard, but to get up some hills in higher gears that's what you need to push it at. My car gets warm trying to climb with 2T behind it - it's gotten gradually worse too.

I had my radiator removed and it didn't fix the problem. It's true that the transmission would be loaded up and producing heat but I'm not sure it's going to be hot enough to create extra heat in the coolant (since the gearbox should never exceed 120C or so).

I am shopping for a new radiator, but I suppose we could have a problem with the water pump. I'll see when we go towing next how it performs.

What we've been doing to alleviate it is to just use the gearbox to amplify the torque (stay in low gear, don't rev it just take your time). Works a treat.

 

[5thwheelerboyz]

I do work the gears manually but over the past few months it seems to heat up quicker. I try and not push it up the hills but I still have to get over them.

Will check the radiator out next.

 

[kernels]

Something worth checking before the radiator is the fan coupling, get the engine hot, then do the old rolled up newspaper test. With a hot engine the fan clutch should be fully engaged and you should not be able to stop the fan with the rolled up newspaper. Just watch your hands and fingers and don't put anything solid into the fan blades.

 

[Old.Tony]

Something worth checking before the radiator is the fan coupling, get the engine hot, then do the old rolled up newspaper test. With a hot engine the fan clutch should be fully engaged and you should not be able to stop the fan with the rolled up newspaper. Just watch your hands and fingers and don't put anything solid into the fan blades.

Absolutely right ... we tested my fluid coupling on Friday and it's going to be replaced on Tuesday.

We were a little different with the test: two basic observations told us that it wasn't working.

1) With the engine running at normal operating temperatures, observe the fan as the engine is turned off. If the fan continues spinning after the engine has come to a stop, the fluid couple has probably failed.

2) With the engine OFF, try to turn the fan with the hand. Mine could be flicked and it would spin over several times before stopping.

 

[5thwheelerboyz]

Thanks guys, all good advice. I've just tested the fan and it doesn't spin so I would say that is working correctly.