webasto HL 32 D heater troubleshoot

I am trying to get the webasto HL 32 diesel heater going on a boat we recently bought. Looking through the records I can tell the heater has not worked since 2011. I was able to find a rebuild kit and installed a new burner mat, as well as replacing the flame sensor and thermostat overheat sensor. I also bought a second control panel that I found on ebay..So now the heater starts and works just like new until 8 minutes into the heat cycle when for some reason it shuts down the fuel pump and then shut's itself off.
All I have to do is turn the heater switch off then back on again and it runs fine for another 8 minutes, before shutting down again. I have checked the voltage at the heater and I have about 12.50 so I don't think it is a voltage problem.. The good people at Sure marine have been very helpful but have pretty much given up by now...any ideas?
thanks

Call sure marine in Seattle.

Is it got a water pump and is that working? If so then try bleeding the air out of the circulating system. Sounds like it is getting too hot and shutting itself down.

Does is show any fault codes
Try running for 4 minutes and then shut it down and then restart and see if it runs for 8 minutes or only 4 it may give an indication of the problem being temp or timer related
is it getting enough air flow ie is the inlet or outlet restricted try without the outlet duct fitted

man, these things can be tough. I agree with wwestman; I had one of their coolant heaters that kept shutting itself down. The problem was the circulation pump wasn't pumping enough fluid through the furnace so it would overheat. Is the HL 32 an air heater? If so, it could be the fan that's blowing air over the heat exchanger is crapping out, or obstructed somehow. How's your air flow?

You have two different air circuits in there, one where air goes in to feed the combustion then is exhausted out the boat, and the other where there is an air intake to blow over the heat exchanger and then out into the cabin. I would take a shop vac, put the hose on the blower side of the vacuum, and try forcing a larger volume of air across the heat exchanger and out into the cabin (NOT through the combustion side). If this works, than you know there's not enough air flowing over your heat exchanger and your cabin supply fan is crapping out.

check if there is an air filter installed on the return side that is plugging. Check if the return is a hose that it is not crimped or squashed partly shut. If either is the case it may restrict the air flow enough that , as already suggested, the exchanger is overheating.
Many units like this must have a VERY good flow of cabin air or the exchanger overheats and the unit shuts down.

You might also check the actual voltage at the FAN itself. If full V is not getting to the fan so it runs a bit slow the same wil occur.

A cranial cramp made me suggest this. Check the exhaust pipe and outlet for any restrictions. Collapsing pipe/hose or bug plugs, nests, are a common cause of heater trouble in RV and the units are not all that different. Again if the exhaust is restricted the combustion chamber/heat exchanger will get too hot and cause a shut down.

Webasto hl 32

Hi
I've got the same problem with my webasto hl32, cuts out after about 8 minutes The air intake pipe had been removed by previous owners, so guessing they did this to try and fix the problem
Mine is partly dismantled, on the kitchen table, waiting for me to fix it!!!!!!!!!!!!

BOATYSAND said:

Hi
I've got the same problem with my webasto hl32, cuts out after about 8 minutes The air intake pipe had been removed by previous owners, so guessing they did this to try and fix the problem
Mine is partly dismantled, on the kitchen table, waiting for me to fix it!!!!!!!!!!!!

Click to expand...

Call Sure Marine in Seattle. They can advise and ship you parts.

There is a probe that is design to turn the heater off if the fuel gets shut off
It about 2 inches long about the width of a pencil (from memory )
I bought a new one installed it and my heater still cut out
I finally sent the whole heater to sure marine they replaced the probe and it worked fine. Told me the new probe they sent me was defective
Worked for years