Eastound on I-84 between Pendleton and La Grande, Oregon (CABBAGE HILL; EMIGRANT HILL; DEADMAN'S PASS; MEACHAM SUMMIT), engine started to overheat. This climb with grades of 2%, 3%,4-5%, then six miles of 5-6%, then drops back to 3%, all between milepost 217 and 229 for a total of a 12-mile climb. The Mountain Directory west states "This can be a severe test on engine cooling systems in the summer."
Guess they are right. What should I do in such an event? As soon as I leveled off, the engine temp dropped back to normal; however, the transmission seemed a big sluggish.
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You don't say what engine you have, but usually the way keep the engine cool during long uphill runs is to downshift to a lower gear so the engine is turning faster and more coolant circulates. The good news is that you did make it; the preface to the Mountain Directory happens to use that climb as an example of one which frequently causes motorhomes to overheat to the point they go up in flames! At least you avoided that.
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We found Water Wetter by Redline helped our last TV stay cooler on long pulls. You might try it.
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Dick - we have already passed the rez - currently in Baker City, Oregon, will continue SE and east in a couple of days. Doesn't look like there are too many more obstacles ahead of us. That's the first time I've had a problem with this coach - Fleetwood Discovery with 330 Cat and Allison transmission.
Of course, there is still that 3-foot elevation in western Nebraska to overcome, but with a good 100-mile run at it, should be no problem.
+1 on Redline Water Wetter. Start the generator and coach A/C, then turn the dash heat on full to pull some heat out of the cooling system. Let the SO drive the toad up the grade to reduce 'main' engine & transmission load.
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If road conditions allow, before the grade, disconnect and drive the toad separately-- removing 3000 or more pounds from what the engine (and more importantly the cooling system) has to deal with is a good idea.
Turn off dash A/C, particularly if its condenser is in the air stream of the engine cooling package. Even if the condenser is not in the engine cooling package's air flow, the 4-5 HP it requires to run the A/C compressor adds to the heat load.
Run at lower speeds (partial throttle) at higher RPM's. With your engine 2000 to 2100 is good. The higher RPM circulates the coolant faster.
If you get in a bind, where temperature continues to climb, turn on the dash heater and fan to high. Yes, that dash heater is another radiator in your cooling system. Better for you to be hot for a few minutes than to burn up an engine or be stalled in a no shoulder area.
If pull off areas, pull off, transmission in neutral and engine RPM around 1500. That will cool it right down.
AND THE MOST IMPORTANT: Make not to self to clean the front of the CAC (Charge Air Cooler) at the next opportunity! The number one reason for overheating on any rear radiator DP is blockage of the air flow by debris on the front of the CAC-- the radiator is behind the CAC.
* This post was
edited 08/19/12 08:56am by wolfe10 *
Most important thing. Is make sure your radiator fins are clean. They collect road dirt and oils. Can plug up the outer edges of the core.
Actually, the radiator fins are NOT where the vast majority of the dirt will be. The CAC is in FRONT of the radiator and "filters" the dirt and debris (and clogs up) before the air gets to the radiator.
Should you clean the radiator from the back-- yes, but that is NOT where most of the dirt will be. And you can not clean from the back with enough pressure to go through the radiator, air gap, CAC and still have enough power to knock dirt off the front of the CAC. If you had that much PSI, you would bend the radiator fins.
No question, in theory, back-flushing would be preferred. BUT, it will not work in this application (sandwiched cooling system). On the few DP's with a stacked cooling system (CAC above not in front of the radiator), yes cleaning from the back works fine.