Tell me if I understand this switch on my 1996 U320.
This switch uses the Aquahot to warm the engine prior to starting on a cold day. Say I am at a campground and it is cold out. Turning this on cycles the warm fluid from the Aquahot around the engine to pre-heat it. I would use it ~15-30 minutes prior to starting the engine.
Correct?
Sorry for the blurry picture! :)
Fred,
With the AH heater up to temp and the diesel burner on, turn on engine preheat one hour, two hours is better before starting. In frigid conditions, three or four hours is best. In below zero conditions, leave on all night.
With the engine preheat switch on, a pump in the heater takes engine coolant from the engine, circulates it through a hot coil in the heater where it picks up heat and then back to the engine. No AH heater coolant is circulated to the engine, only engine coolant which is the way the engine heats the AH coolant while you drive down the road.
Hope this helps. All the best.
Yes, but it is recommended to turn it off before starting the engine.
That sound right. Your switch is different from the one in our 2001 but the idea is the same. 15-30 minutes will probably not make too much difference. If it is below freezing I usually leave it on overnight. If we are staying over night and temps get into the 30s I turn it on when we get up, it helps. Yup, I turn it off before starting too.
Of course your AH needs heat to make the M11 happy. At these temps electric is not enough.
I second the recommendation to turn engine preheat off before starting. No critical action but no need for two pumps doing the same thing.
Good catch Lynn.
One follow-up question.
I also have an engine pre-heat switch on the side of the bedframe behind the skirt. What is the difference?
That one is a electric element, powered by shore power or generator run.
By shore power, would that be the 50A cord or another cord? I think I have a power cord somewhere near the engine compartment. I'll have to look next time I am at the coach. I would run that to the campground's power pole and use the 20A outlet?
So at a campground, I'd have two options to warm the engine? The Aquahot (via the Eng. Heat switch pictured) or the Engine Pre-heat switch (on the bed frame)?
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Yea. When you are plugged into shore power (50a, 30a or 20a) all the 120 volt AC plugs are energized. One of those plugs is in your engine compartment. The engine block heater is connected to that plug. When you switch on the block heater switch at the foot of the bed the outlet in the engine compartment is engergized and the block heater begins heating the engine coolant. The block heater is just a little element that pokes into your engine.
jor
To me, the big difference is the AH circulates the eng coolant and warms up the whole eng and related piping while the block heater element is static heat, warming up the area where the element is.
Don't know if there is any functional difference, the block heater on mine enables instant starting. What more could you want?
My U295 started as quickly as an injected gasoline engine. The 450 is a different animal. They crank a while in comparison so the more thoroughly the engine heats the less wear on the starter. I've never used the electric on a 450 and it may be fine, but with the Aquahot running all night it fired up in zero weather as if I had just driven it.
Although probably much less effective than the AH method of circulating engine coolant, the conventional block heater will, given enough time, warm the engine up pretty well. Block heaters depend on thermal convection currents to distribute the heated liquid around the the engine. This is more or less effective, depending on where the block heater is installed in the water jacket, the wattage of the heater, total volume of coolant contained in the engine, and how cold the engine is when you turn the heater on.
You can get a good idea of how efficient your block heater is by using a non-contact IR thermometer (temp gun). Some really cold morning when you don't have anything better to do, run a test. Measure the temp of the engine block at several points on both sides of the block. Then plug the heater in, and take additional temp readings at regular intervals...say, every 15 minutes. You will find the temps will increase for a period of time, then they will level off. At that point, the block heater has done all it can, and leaving it plugged in longer will be of no added benefit. Most factory installed "passive" (without a coolant circulating pump) block heaters will supposedly reach temperature equilibrium in about 2-4 hours.
It is a recommended good practice to turn the block heater off before you start your engine. There is a very small chance that the initial movement of the coolant (as you crank the engine) could "uncover" the heating element. If the element is exposed to a air bubble, it could burn out.
The aqua-hot on diesel, will heat up the engine without shore power or running the generator. Nice if you don't want to run the generator all night when dry camping in cold weather. But, make sure you have a good charge on your batteries, aqua-hot pulls a few amps.
According to the Aqua hot people at their school it takes about 2 hours for the Aqua hot system to bring the engine up to temperature. I'm sure the colder it gets it would take longer but 2 hr was their answer.
Chris
It probably depends on outside temp to determine how long it takes. If it is 5 degrees or so and you are heating the coach as well then overnight is good. Amazing to start the engine and have the coolant temp be 110 degrees right away. Be nice to your motor.
I always wondered why the 450 was so slow to start in comparison. Just the nature of the beast? Seems odd to need supplemental heat unless it's really cold. Or are they supposed to rely on those ether canisters installed?
I called Foretravel about the canister, as it seemed mine wasn't working. Was told there is a temp sensor that has to be cold enough to let the switch from the front activate. Have forgotten the number but it was colder than I usually see except in the Sierra's.