Skip to main content ↑ ↓
Topic: When/How to use Engine heat switches (Read 880 times) previous topic - next topic

When/How to use Engine heat switches

There's an engine heat switch in the kitchen near the aquahot electric and diesel switches;  there's another "red" engine block heat switch at the foot of the bed.  I've never used either one.  The coach is kept in a covered outside storage facility with electric.  Recently had trouble starting the coach in this intense cold a lot of us are "enjoying".  The engine cranks strong, turns over momentarilly then immediately stops;  the generator runs fine.  Any ideas how the use of either or both of the engine heat switches might help getting it started?
Fiddler
1959 Parris Island grad
40' 2001 U320 Build 5875
1999 Suburban K1500 toad
1986 Corvette Pacecar
ssoftail@comcast.net

Re: When/How to use Engine heat switches

Reply #1 –
If the A/H is running, (diesel switch is on)  the engine heat switch (that is located with your A/H switches) when activated (green light is on) turns on a pump in the A/H unit that circulates antifreeze through the A/H back to the engine. This will heat the engine in a couple of hours. If you just run the electric A/H element you will have marginal results. (especially if you are trying to use just the electric side for inside heat also)

The switch at the foot of the bed is what activates a 120 volt A/C heating element that is located in the engine block. (if it is plugged in under the bed) This operates completely separate of the A/H system.

Both will heat the engine. I have found the A/H is much quicker.  Either can be left on overnight for a quick start in the morning. One you will pay for with diesel the other with electric.

Pamela & Mike
Pamela & Mike 97 U 320

"It's not what happens to you, but how you react to it that matters."

Re: When/How to use Engine heat switches

Reply #2 –
If it is around 40 degrees or less we probably have the AH on anyway.  On a morning that we are departing I will turn on the engine preheat AH switch when we get up and give it two or three hours to heat the engine.  That will raise the engine temp about 60 - 70 degrees bove ambient.  Coach starts right up.  Probably a lot easier on everything.  AH on electric is OK for this inside the building.  It just takes longer.

At home in MN when we leave for warmer in Jan or Feb. it is usually cold.  The AH is on heating the coach for a couple days before we leave and the engine overnight.  The Original owner (CA) either removed the block heater or it never had one so I don't use it. 
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: When/How to use Engine heat switches

Reply #3 –
It"s good to regularly check both systems periodically-maybe once a year.  Easy to check with an IR gun.  I recently found my block heater had burned out.  I use the block heater when someone else is paying for the electric, and A-H the rest of the time.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: When/How to use Engine heat switches

Reply #4 –
Sincere thanks to all for the prompt replies;  I'll run the engine heater for a few hours today and hope it does the trick to start the engine.
BTW, what is an IR gun and how do you use it to check the systems?
Fiddler
1959 Parris Island grad
40' 2001 U320 Build 5875
1999 Suburban K1500 toad
1986 Corvette Pacecar
ssoftail@comcast.net

Re: When/How to use Engine heat switches

Reply #5 –

Infared heat sensor gun. Not very expensive and pretty handy.great for checking brake rotor temps.

Amazon.com: Etekcity Lasergrip 774 Non-contact Digital Laser Infrared...

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
Roger Engdahl and Susan Green
2001 U320 3610 #5879 (Home2) - 2014 Jeep Cherokee or 2018 F150
Hastings, MN

Re: When/How to use Engine heat switches

Reply #6 –
In your post you say the engine cranks over momentarily then stops. That is a different issue than needing heat. It should keep cranking until you release the starter switch.
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

Re: When/How to use Engine heat switches

Reply #7 –
Our diesel engines use compression ignition in contrast to spark ignition to run and need the combustion air to be hot to start. On a cold day, cranking the engine does not generate the heat necessary to start the engine. The block heater plus any other "helpers" will raise the compressed air temperature enough to cause the diesel to explode when it's injected.

Easy to check the block heater to see if it's working in several different ways. With it on, the AC voltage in the coach will drop at least a couple of volts or more. The engine will be noticeably warmer to the touch after a few hours plus you can use a IR gun to check the  engine temperature.

With a block heater working properly and installed in the correct location, your diesel should start like it does in warm weather with just the engine batteries. Extended cranking will only reduce the lifespan of the starting components and may cause a failure just when you can least afford it.

A used propane block heater arrived yesterday and I will be documenting the installation and it's effectiveness on our Detroit. Since we do mostly dry camping and mostly at high altitude, I wanted a block heater that would be independent of any electrical connection.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: When/How to use Engine heat switches

Reply #8 –
Success!  Aquahot engine heater worked like a charm; after ~4 Hrs heating, cranked and it started as normal.    It "needed the combustion air to be hot to start"; thx Pierce and Gaylie who nailed it; as well as the other Forum buddies who took the time to contribute their suggestions.  This forum is and has always been "Priceless".
Fiddler
1959 Parris Island grad
40' 2001 U320 Build 5875
1999 Suburban K1500 toad
1986 Corvette Pacecar
ssoftail@comcast.net

Re: When/How to use Engine heat switches

Reply #9 –
We have been below freezing since two weeks before Christmas and today it suddenly went to 43F so I went to the coach to check on its wellbeing.  I started the Kubota and let it run for 20min and then with boost selected I tried the main engine.  Four turns and it was away. No block heat used nor did I use the AH warm water function.  This is some good coach.
Before I get jumped on, I let it run for an hour to get the temperatures up and although I would have liked to drive it the 2ft of snow around it put a stop to those ideas, plus the slick streets.

Speedbird 1.
2001 U320 Build #5865
Daihatsu Rocky Toad
VW Touareg
'82 F100 Stepside
Beech' Debonair