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Pre-Heating the engine
At what temps do you have to start worrying about preheating your engine to avoid any damage?
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51 Replies
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Tim,
The only times I have used it was when the temps were mid 30’s and below. On really cold nights where it was gong to be below freezing all night, I would leave the engine block heater on, bay heater on and the webasto on.
Not saying this is the right or best, but it’s how I used the heaters before started following proper temps.
2005 XL Thompson Coach
Rarely tow anything behind us.
Sold: 1993 Liberty that we loved for 12 years. -
When the engine was cold soaked and temps were single digits I left the block heater on for several hours.
If we overnight without hookup and do not run the generator, unless the temps are single digit the engine still has not gotten so cold starting is an issue. If it is cold enough to run the webasto that takes care of the preheat because the engine is at 160.
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Tim,
When it is 40 or below, I turn on the block heater an hour before we plan to take off when we are on the road, or when we are leaving home. When the coach sits at home, I run the underfloor heat when it goes below freezing.
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That was my next question … An hour before?
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If it is sub zero an ohour is unlikely to be enough. You just have to use your judgment.
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The only reference I had before PC was two entertainer coach owners that helped me a lot. They said if it was below 40 they would swing by the bus about 8-10 hours before leaving and turn on the engine block heater. They said it would have to be almost too cold to travel if the engine cooled down too low after running hard and then a 5-7 hour stop.
Davy
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Ok, Greenhorn here again, would one of you brains please explain the operations of the Wabasto. I know how they work, and what they will do. I know they will heat the coach because I have used it. I also know it will heat my hot water, but how is it controlled? If the forced air heating thermostats are satisfied in the coach and under the bay, how does the wabasto keep my water hot? Also how does it heat the engine with all thermostats satisfied? I guess I just don’t understand how the water heater and the DD take control of the wabasto when they need heat.
Block heater was mentioned, where do you turn it on, and what are we heating. Water or Oil?
Green
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Steve,
The Webasto heat exchanger has a circulating pump to move coolant around the heating loop. There are numerous items to be heated by the loop such as fan coils for interior heating, fresh water heater and the engine for preheat. If you are sitting for a while and your coach has valves to isolate the engine, it would be more economical to close the coolant flow off to the engine until ready to preheat the engine and to travel down the road.
The Webasto heat exchanger heats engine coolant. The hot coolant coming in from the Webasto to the engine warms the oil and the block. The part of the Webasto heating loop that goes through the fresh water heater, heats the water there. A block heater, if installed, is a separate electric heating element inserted into a engine coolant passage. There would be a separate on/off switch inside for it just like for the Webasto.
With the Webasto turned on inside, and the coolant in the heat exhanger below the cut in temp of the control thermostat located on the top of the exchanger, the thermostat closes telling the control unit (brain box on the side of the burner) to start the burner. The burner runs till the control thermostat is satisfied when it opens telling the control unit to shut the burner down. Or it runs till the switch inside is turned off.
Hope this helps.
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Steve
One of your Liberty boys needs to jump in here but most block heaters are in the rear CS engine bay.
Your looking for an unplugged extension cord that usually is hanging in the rear corner, plug the cord in to 110v and it will start the heating element for the block.
Some cold weather builds also have oil heating plugs but I doubt you have that.
Later
bv -
OK … So another green horn question. On my panel to the left in the cockpit, there’s a button that says “block heater.” I though you just pressed the button to turn on the block heater. I definitely hear something turn on in the engine compartment when I hit that switch. I thought it was the engine heater. Are you saying you also have to plug in a plug in the engine compartment in the engine bay? I saw a cord back there and wondered what it was for … Rudy, is the switch to isolate the Webasto from running thru the engine in the Webasto bay or engine compartment?
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You could have 2 ways to turn it on. If your on shore power you might ignite it off your dash but if you have no power going to the bus you would have to use the plug in back.
Truks is closer to your vintage, he will know.
Your engine loop water off the webasto is a valve to the right of the radiator on a straight pipe. Looks like a water valve you have at home.
Later
bv -
Tim,
That button is the Webasto block heater switch. It fires the Webasto to heat the engine. The block heater is in the curb side engine compartment and has to be plugged in to the 120v recepticle next to the cord. The block heater is controlled with a breaker in your AC panel in the bedroom and labeled “Block Heater.”
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THIS IS FOR A LIBERTY about 1996 to 2006 STEVE. With the webasto on the circulation pump comes on it sends coolant around to the different heat exchangers , if coolant temp is cool the burner will will come on , the circulation pump runs all the time as long as the webasto is on inside , but not the burner it comes on when the coolant cools off, To heat the motor open the engine pre heat valve in the back drivers side behind the tag, if you are using the webasto to heat the water bay or hot water , the engine pre heat valve needs to be open and the two valves for water heater also ,if you are parked and no gen or shore power or you have shore or gen and the breaker is off for the electric bay heater or if you are driving down the road the motor will heat the coolant with the two valves open and the engine pre heat shut off . The water bay has two heaters electric and webasto , they share the same thermostat if the breaker is off inside , the webasto will work as long as valves are open and it’s turned on , the engine pre heat only needs to be open if you want to heat the hot water or the heat exchanger or the motor when parked . There is also two valves or three in water bay on curb side that need to be adjusted, above black tank , it all depends on the year of coach , that need to be adjusted to heat the hot water with the webasto. Do not turn those valves unless you know which one to turn so many turns or close , they should be set to heat the hot water when driving down the road as long as the two valves at the back are open one in webasto bay and one on the motor , you will not need to heat the water when parked if your hot water tank breaker is on inside. Just for info some coaches the valves are on the drivers side engine bay that’s where the webasto is.
I never use use the block heater , the breaker is inside to turn it on , the plug is at the side engine door to plug it in , if it was very cold day I might
I use the webasto to heat the motor it never gets enough work any ways
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So Peter, No issues running into freezing weather and not pre-heating your engine? Just asking since this is my first winter trying to figure this out before I can get out of KS mid January.
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If it’s cold I just turn on the webasto and engine pre heat and heat the house with the other heat exchangers , I like it that way because the bed room is nice and toasty because motor is hot also , I have never turned on the block heater unless the webasto quit , which it has not. Have run the bus in -35 below and no issues, fuel gel is the only thing I worried about when it was cold, but when it was that cold I left bus running all night on high idle and the gen running and the webasto just to be safe . I got caught in a storm in November in Canada
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