Webasto issue...please help!!!
 

Hello everyone, wish you all good and stay healthy. I am new to this group, i hope someone can help me a little. So the car is e53 2004 3.0d 218hp, it has webasto aux. heater with remote, and it was working perfectly. But now from few weeks i realize that it doesn't heat up the cabin like before. It blows almost cold air. The car runs fine ,heated up quickly, when driving the aux. heater works and heats up the coolant fast.I read it through bmw scanner and there are no errors about aux.heater. :/

INPA would give more detail with live data how the Webasto behaves. If it works normally while engine is running but not on pre-heating the most likely culprit is aux water pump. It may not yet show as direct fault code but Webasto internal temp would rise very quickly on pre-heating if there is no circulation.

+1. I've had bad aux pump no code. It's easy to find and put your hand on the pump to feel for vibration, you might even. Get it to jump start with a little "percussive maintenance"

The pump works, i have tested it -car off-with ignition key On and gas pedal to the floor for 10-15 seconds and the pump starts.And when turn off the car the pump continue to work about 1 min.By the way when i got the car the aux.heater didn't work and after i read with bmw scanner there was a error "circulation pump" i replaced it and the heater start to work perfectly. If the pump doesn't work it will not start the heater. But the heater makes the all 30 min cycle when turned on- but now blows cold air.

The circulation from Webasto goes via heater core anyways so there is a discrepancy. It can't be burning properly if it only blows cold.

Time to clean the burner unit? If the burner is clogged with carbon, it will be much less effective at heating the coolant....

On a boat but similar unit... https://www.canalworld.net/forums/in...vicing-photos/

Yes i know something is wrong, that's what i said. It goes through the all cycle of 30 min, the unit itself is hot, but it blows cold inside. Very strange. Today i checked all the hoses, and some of them are cold some are hot.The hoses on the pump are ,let say cold(warm). When driving the same hoses are very hot.The hose that is on the top of the webasto is hot, the one on the bottom is cold (warm).There are 3 hoses that goes inside the cabin, the left one is cold (warm) the other two are hot.

Is it possible the flow rate of the circulation pump too be lowered?

New update.
After driving about an hour, all hoses were hot (pump hoses,hoses that goes in cabin,upper hose on the webasto) exept one hose on the changeover valve (above the pump)and the hose on the bottom of the webasto unit- it was cold as winter :)
What does this changeover valve do?I find out that when remote start webasto this valve gets really hot, but the hose is cold(that hose on the bottom of the webasto unit)

On rest state the change over valve directs return flow from heater core to engine return line. (Webasto supply is from engine upper hose.) (Webasto - heater core - engine - Webasto in series) When change over valve is activated (pre-heating) the return flow from heater core is directed back to Webasto. (Circuit bypasses engine coolant flow.) (Webasto - heater core - Webasto in series)

https://www.realoem.com/bmw/enUS/sho...diagId=64_1411