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Holiday1 · 07-28-2022, 03:52 PM

I have a 2007 HR Endeavor. 400 hp Cummings. On a long uphill, maybe 4 to 5 percent grade I have to shift to 4th gear and drive about 35 mph to keep the eng. temp below 225. I've had the radiator cleaned twice now and it still over heats. I actually thought this was normal until I just talked to a guy parked next to me. He has a 2005 Monaco with the same motor and tranny. He goes up the same long hills as I, but at 60 mph and his temp never gets near 225. What do I need to do?

Skip426 · 07-28-2022, 04:11 PM

Forth gear at 35 mph ; what RPM are you turning ?
When the rad was cleaned did you have the thermostat changed ?

I think your lugging the engine .

Here's info from Allison on mountain driving .

n2zon · 07-28-2022, 04:21 PM

Quote:

Originally Posted by Holiday1

I have a 2007 HR Endeavor. 400 hp Cummings. On a long uphill, maybe 4 to 5 percent grade I have to shift to 4th gear and drive about 35 mph to keep the eng. temp below 225. I've had the radiator cleaned twice now and it still over heats. I actually thought this was normal until I just talked to a guy parked next to me. He has a 2005 Monaco with the same motor and tranny. He goes up the same long hills as I, but at 60 mph and his temp never gets near 225. What do I need to do?

A couple of things come to mind to start with.

Check the fan clutch or fan controller. With the engine above the thermostat temperature, the fan's roar should be clearly audible to a vehicle behind or next to you, and markedly louder than it should be on level ground.

The thermostat might not be opening all the way. You can test the old one by putting it alongside a known good one in boiling water. (Note: Do *not* run this engine without a thermostat.)

Jzack · 07-28-2022, 08:58 PM

I have this exact problem with our 340HP Cummins ISB. Clean radiator yet I need to nurse the accelerator over mountain passes to keep it below 220F. I too thought this was "normal" for a DP.

I eventually found that the Horton fan clutch had leaked out some of the viscous fluid. When this happens, the fan no longer turns at full speed.

Inspect your fan clutch for any oily, dusty, dirty patches on the clutch or the fan blades.

Apparently, this is a very common problem on the ISB Cummins that turns at a much higher 3,000 RPM. Not sure about your 400 Cummins but it is worth a shot.

Holiday1 · 07-29-2022, 09:02 AM

At 35mph in 4th gear rpms are 1700
Normal operating temp runs about 190 degrees. So I don't think it's the thermostat

96 Wideglide · 07-29-2022, 10:59 AM

Quote:

Originally Posted by Holiday1

At 35mph in 4th gear rpms are 1700
Normal operating temp runs about 190 degrees. So I don't think it's the thermostat

That doesn't sound right

.

I could see that speed / rpm's in 3rd gear.

wolfe10 · 07-29-2022, 11:20 AM

Is your cooling package SANDWICHED (CAC in front of radiator)?

OR STACKED (CAC above radiator-- cooling package one layer thick)?

OR SIDE RADIATOR/CAC?

If rear radiator-- clutched fan?

At what RPM do you climb those long/steep grades (where you are likely to overheat)?

Then we can give advice specific to your coach.

dizcom · 07-29-2022, 11:43 AM

Change your thermostat. Check that the fan is coming on as it should.

Ray,IN · 07-29-2022, 06:31 PM

"Having the radiator cleaned" may not mean much. How was it performed and with what?
Most DP owners use Simple Green Extreme for aluminum to clean the radiator sandwich of oily dirt and road grime. Simply spraying with a hose only accomplishes getting it wet.

Holiday1 · 08-02-2022, 05:22 PM

The fan is hard bolted to a pulley that's turned by the belt

Holiday1 · 08-02-2022, 05:27 PM

Radiator has been cleaned twice in the last 2 years by both Freightliner and Cummings. I did a fairly steep grade today. Outside air temp. 86. In 4th gear eng temp was only 198 rpm 1700. In 3rd eng temp stayed the same rpm 2200

Jzack · 08-03-2022, 05:32 AM

Ok, so it isn't the fan clutch, looks like you have a direct drive fan. Not the radiator either.

This problem seems intermittent too since you stayed under 200F on the last grade. I'd start looking at the thermostat. Could be sticking partially open/closed.

wolfe10 · 08-03-2022, 05:43 AM

Quote:

Originally Posted by wolfe10

Is your cooling package SANDWICHED (CAC in front of radiator)?

OR STACKED (CAC above radiator-- cooling package one layer thick)?

At what RPM do you climb those long/steep grades (where you are likely to overheat)?

Then we can give advice specific to your coach.

And, if sandwiched, was it cleaned from the FRONT or BACK?

These details DO matter if you want good advice.

BrianGlenn · 08-04-2022, 08:10 AM

I also suggest thermostat and coolant flush and change if you do not know when that was done last.

Coolant heat capacity (ability to transport heat away from block and remove in radiator) decreases as coolant becomes contaminated with sludge/particulates. This is when coolant additives deplete.

In addition the 400ISL is wet sleeve and needs appropriate levels of SCA to prevent sleeve pitting. Changing out coolant will provide both benefits. I recommend Fleetgaurd OS Compleat (Blue) or Fleetgaurd OAT Compleat (Red). Last time I checked Blue was half the cost of Red. I run Blue.

New coolant and flushed system with new thermostats is cheap insurance to protect against $35k engine rebuild.