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Topic: "Eng. Heat" switch? (Read 941 times) previous topic - next topic

"Eng. Heat" switch?

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 H.
1996 Foretravel U320 4000 Build #4993 (Previous motorhomes 1985 Airstream 345, 1977 Argosy 20)
Sevierville, TN
ViewRVs.com

Re: "Eng. Heat" switch?

Reply #1 –
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.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: "Eng. Heat" switch?

Reply #2 –
Yes, but it is recommended to turn it off before starting the engine.
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Lynn & Marilyn Sickel
Tollville, AR
1997  U320  40'
2021 Chevrolet Silverado pickup
Motorcader  17257

Re: "Eng. Heat" switch?

Reply #3 –
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.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: "Eng. Heat" switch?

Reply #4 –
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.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: "Eng. Heat" switch?

Reply #5 –
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?
Fred H.
1996 Foretravel U320 4000 Build #4993 (Previous motorhomes 1985 Airstream 345, 1977 Argosy 20)
Sevierville, TN
ViewRVs.com

Re: "Eng. Heat" switch?

Reply #6 –
Quote from: ViewRVs –
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.

Dan - Full timing since 2009
2003 U320 40' Tag 2 slide

Re: "Eng. Heat" switch?

Reply #7 –
Quote from: AC7880 –
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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Fred H.
1996 Foretravel U320 4000 Build #4993 (Previous motorhomes 1985 Airstream 345, 1977 Argosy 20)
Sevierville, TN
ViewRVs.com

Re: "Eng. Heat" switch?

Reply #8 –
Quote
By shore power, would that be the 50A cord or another cord? I think I have a power cord somewhere near the engine compartment.

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
93 225
95 300
97 270
99 320

Re: "Eng. Heat" switch?

Reply #9 –
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.
Richard & Betty Bark & Keiko our Golden Doodle
2003 U320T 3820 PBDS
Build # 6215
MC # 16926
2016 Chevrolet Colorado 4X4 diesel

Re: "Eng. Heat" switch?

Reply #10 –
Quote from: rbark –
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?
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS

Re: "Eng. Heat" switch?

Reply #11 –
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. 
Rick & Rhonda
2003 U320 4220  Build #6199
Was
91 36' GV 300 Caterpillar, 92 40' U280 300 Cummins, 97 36' U295 300 Cummins, 2002
U320 450 Cummins
(Guess we're hooked)

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Re: "Eng. Heat" switch?

Reply #12 –
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.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: "Eng. Heat" switch?

Reply #13 –
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.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: "Eng. Heat" switch?

Reply #14 –
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
1999 U 320 DGFE
Build Number 5523
Chris & Elka Lang
In the field, Lonoke AR

Re: "Eng. Heat" switch?

Reply #15 –
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.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: "Eng. Heat" switch?

Reply #16 –
Quote from: Johnstons –
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 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?
"Not so  long ago we were a nation of risk takers, riding five million pounds of  thrust straight into space."  Joe Gresh
Chuck Pearson
1996 U295
2018 Can Am X3 TurboRS
 

Re: "Eng. Heat" switch?

Reply #17 –
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.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean