Webasto Issues, need help!

[Kevin Erion]

OK, on my 99 Marathon XL45 there are 2 switches to turn on the Webasto. 1 is for the hot water and the other is for the base board heat, they call this 12 volt water heater and 12 volt heat. When I turn on the 12 volt water heater the thing turns of in about 1 or 2 minutes. When I turn on the 12 volt heat, life is good and all floor heaters work great.
I think the flow of coolant thru the water heater is not good, the inferred gauge shows that the coolant will shot the furnace off at about 140 degrees. I have checked all vales to make sure they are open when told and I think all is good there. I used compressed air to check for blockage and come up with everything appears to be OK. I blew there the water heater with the old mouth (bad taste) but I think its OK.
Has anyone ever had this kind od Webasto problem. I think the coolant is not flowing thru the water heater at a high rate but I have no way to check it. I lost about 10 hours and 5 gallons of coolant today, not to mention 3 new ball valves just to make sure!
HELP,
Kevin

[gmcbuffalo]

Kevin
If the hot water is being heated by the 110v side of your water heater and the water is already hot the Webasto will not turn on.
Greg

[garyde]

Hi Kevin. It makes sense a high tempature sensor is shutting down the Webasto. Sorry for your hassles. Gary

[truk4u]

Kevin,

Just a long shot here, have you checked the coolant temp at the heat exchangers to see if it matches the temperature your getting at the water heater? If both are at 140, sounds like a Webasco temp problem and your plumbing and valves may be all good. If your coolant temps at the heat exchanger is higher than the 140, the water heaters may have a problem with the temp switch that tells the Webasco it's reached the proper temperature and shuts down the heater. So, I think there are two different temp switches, one at the Webasco and the other at the water heaters. All of this is assuming the 110 volt heaters are off.

By the way, the furnace function will shut down the Webasco and circulation pumps when the thermostat has reached temperature. When on the 12v water heater position, the pump will run continuously and the Webasco will cycle on and off as heat is needed for the coolant temp.

Gary had a good point about the Webasco high temp switch, but if the furnace runs OK that would seem to rule out that switch.

Are you confused yet?

[Jon Wehrenberg]

Kevin,

Just a question....on our Webasto system we have to manually open and close valves to isolate the engine from the house heating circuits.

It sounds like yours is using electric valves (probably solenoid valves) and I presume you verified they are opening. On our system the circulating pump runs continuously regardless of whether the Webasto is firing or not. Does your coolant circulate constantly or is yours set up to only circulate coolant when the thermostats call for it?

[Kevin Erion]

The 110 volt heat is off, the engine is cold. The temp at the webasto out is 140 but at the water heater it is a lot lower. The base heat works fine so I use that to rule out the pump, I think. The unit shuts off after it see's to much heat at the output, and it does not continue to run the circulation pump. It almost acts like a closed valve or a blockage in the hot water side of things but I have spent a lot of time trying to find that with no luck. I am going at it again today, new day and I hope the something will pop out and say fix this!
Thanks,
Kevin

[win42]

Kevin Jons point about valves isolating the engine from the webasto system needs to be checked. Most of us close those valves at the engine during the cooling season.
A Webasto tech couldn't get ours to run until the thermostat was calling for heat. Just a couple of shots in the dark. Good luck !!

[Kevin Erion]

OK, Webasto 101 and I though that some day it would not fire!
After checking this morning, all was OK. Last night before I called it a night I check all funtions and the hot water heater was still not working 100%, but better than when I started this little project. I needed to replace a small section of hose this morning after I check the unit and of course it had a problem.
The bottom line, I believe there was a pocket of air somewhere in the hot water heater side. By running everything last night, bleeding the air from the front foot heater and running the motor up to 190 and then having it sit and cool down overnight, I think all the air is now out of the system.
I guess I will have to wait and see if it comes back, I have no idea how the air entered the system the first time.
Thanks for all the good ideas, has anyone else ever had this problem?
Kevin

[Jon Wehrenberg]

Kevin,

Yes, and it happened when I changed my coolant. Now I used the Webasto circulating pump when refilling the system to help purge it. We have a lot of places in our Liberty system that have to be burped and I assume your system does as well.

[truk4u]

Harry,
Correct me if I'm wrong, I think you are referring to the valve we close in the summer to shut off the coolant to the heater core up front. On my Marathon, it is way down under the engine fan near the belt bellows on the driver side of the engine compartment.

Kevin,
Sounds like you sorted it out, let us know...