A question for RV owners

Guys

My main "bag" are commercial Sprinter fleet owners (service and repair)

Every so often we will see a commercially modified van into an RV like Winnebago. So read a heavy beast all kitted out!

I am currently running down a possible overheat condition.
When running on the flat and mild climbing the engine runs at about 185/190dgf--confirmed within a degree or two by dynamic info on the scanner hooked to the truck.
In short a stabilized block temp.

Now punch it up 1/70 flat scat from Golden to Genesee (a grade which sorts the men from the boys in any vehicle) I can see the temp rise and hit the red before the summit on that section of road. Reading 252 dgf.

We got it back to the shop, cleaned the radiator/condenser, flushed it changed the thermostat.
Ran it up (blanketed up) to raise the temp to 200dgf. A rev count on the viscous coupling with an infrared revolution counter gun confirmed couple and the exterior fan came in so the system is functioning.

A further climb test dropped the top pipe temp to 242 dgf, but in my book it should be about 10 dgf lower judging by the cargo vans we normally deal with.

So a question for all the RV Sprinter 2006 TIN can owners what temps do you see when climbing?
The last test had the needle a tad below the red in the white sector at 242dgf.
Ambient wasn't too hot at about 80dgf.

I might have to go ripping stuff out on Monday!!!
Cheers Dennis

Dennis,

I've got an 06 chassis Winnebago View running at GVWR (10,200) and have never seen above 228 on the scan gauge. But I don't jam it up a grade like that, I'll run about 1/2 throttle in 3rd at 3500 RPM and watch the temp vary with the cycling of the viscous cluch fan. When the grade is really steep like 9 or 10%, then its second gear and trying to stay under 90% load.

On very long grades at 90+ ambient I've had a noticable reduction of power a couple of times at these temps as have others with the same motorhome, and the guess is that its a self protection for high trans oil temperatures.

Gary

Since all indications are that the I5 Sprinter engine is easily destroyed by overheat, I do all I can to keep the coolant temperature away from the red. Shifting down on a long climb is a very good way to do that. Increased rpm increases flow of coolant through the system and air through the radiator - both good for cooling. Plus, reducing road speed reduces the power necessary to lift the mass over the mountain.

Dennis,
Got to agree with the others here.
Climbing a long grade, in 5th gear OVERDRIVE (you knew that didn't you) 0.083:1 @ < 2800 RPMs
will run the temps right into the red.
Downshift to 4th gear (1:1 ratio) and increasing the RPMs by 500 will help alot.
Should be able to run 70 mph but the actual RPMs depends on the rear end ratio 3:92 or 4.182)
(70 mph is 2800RPM in 5th gear overdrive with the 4.182.....2625 RPms with the 3.92....
+500 RPms = 3300 w 4.182...3125 w 3.92)....right in the max. power range (2800-3250 RPMs) for a 5 cyl 2.7
OM-612/OM-647.
So, downshift to 4th gear and get the engine up into the RPM range where it makes
some horsepower, and it might do OK.
Does not sound like your viscous fan is really pulling the temp down as well as it should.
The T1N I had...towing a 4500# 7 foot wide x 10 foot high cargo trailer, never got over
220 pulling grades in very hot midwest conditions. I downshifted at anything over 205 deg.
The big engine driven fan would pull the temp right back down into the 180-190 range very quickly.
Roger

Guys
Thanks for the input.
First I have no idea how the customer is driving the van/RV, so the input from you all is very much appreciated. I will now be able to ask him some pertinent questions on grade climbing driving habits.

Roger I tested the viscous coupling as my first opening post suggested, of course that's not to say that there isn't some slip going on when it gets working hard, at least not without some more fixed equipment to test the coupling speed and continued monitoring.

Tomorrow I am going to monitor transmission cooler temps to see what input temperature might have on overall coolant readings.
Again thanks for the input
Dennis

Hi Dennis,
I caught your testing of the viscous coupling.
I don't have the T1N anymore to go out and test it,
but you might be able to do a "road test".
Cover the radiator, get the temps up, while driving, and
when the viscous clutch engages you will HEAR the big fan
and the temp will drop immediately.
Roger

Roger
Ah hah the fan Boeing effect!
Yes we have that, having at first blanking it up in the yard , & then testing it up the mounting.

At 240 DGF its a whirring like we are about to take off!

Dennis

"Cover the radiator, get the temps up, while driving, and
when the viscous clutch engages you will HEAR the big fan
and the temp will drop immediately."
Roger

Roger,

With the radiator covered the temperature controlled fan may not be able to drop the engine temperature much, if at all. As you know it needs to draw a huge amount of air through the radiator.

Gary