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webasto question
I should know this but I don’t…..Is the Webasto system tied directly with the coach cooling ststem in an H3. And if it is does the Webasto system fill itself from the Prevost coolng system. The reason why I’m asking is, I ran my system this week and the forward heat exchager in the stepwell made alot of noise like water running through it. It heated well but it wasn’t quiet. It sounded like fluid had to be added. If the answer is that it is conneccted how does someone top off the system ?
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5 Replies
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Rick, yes if you have a Webasto it uses engine coolant and the engine cooling system so the loops are complex and require some effort to top off.
Jeff might jump in here because he has been through this a lot, but I have found several ways to purge the system of air. The first is a method I think Jeff uses which is a small device that allows you to pull a vacuum on the entire system, and then you can introduce coolant through the device that almost totally eliminates trapped air.
Another approach is to use the Webasto or Prevost OTR circulating pump. It is not as elegant as using the vacuum tool above but with patience it will eventually purge the air trapped.
The final method is to use the engine to do the work. Again it is not the easiest way and helps a lot to have it up to temp so the thermostat is open but in time it will also purge the air.
On my coaches there has been a relief valve at or near the heat exchangers and if the valve is opened until coolant emerges it facilitated the bleeding of air trapped in the system.
There is no real easy way to get air out of a cooling system after a coolant change, so for me to be sure I have done so I measure the amount of coolant removed and make sure I get the same amount back into the system. Easier said than done.
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Rick,
While driving the bus, turn on the front Exchanger (furnace heat.) On my vintage I have to have the 12v heat button turned on at the panel and then I double tap the SMX control for heat. If your engine is up to full temp, the Webasto circulation pump will run, but the diesel won’t fire, it’s circulating 200 degree coolant through the heat loop. That may purge your air, if that is your problem.
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no problems at this time except that I can hear the coolant flow through the front heat exchanger when we have the webasto heat on, why I asked the question is……and tell me if my assumption is correct….if the Webasto system is a little low on coolant can it draw from the Prevost system and potentially trigger a low coolant code and or limp mode shutdown.
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It should all be your coolant system. I am not familiar with Marathon but when you run the Webasto I suspect it has a dedicated circulation pump as opposed to the engine coolant pump so it might not be air but a sound of more or less coolant flowing through a valve in the system.
When I have a hose filling my coach water tank, if I change the rate of flow using the campground faucet the noise of the water entering the coach changes based on the flow.
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The Webasto can’t be low on coolant assuming your coolant tank in the engine compartment has a full sight glass. Driving the bus with the heat on will move the coolant through the whole loop via the Webasto circulation pump.
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