Webasto Remote Heater

Mine has not been working so ran the test on it today as it has had a new burner tube and glow plug in the past, no faults showing and it fired up, i think my problem may be that it is seeing the coolant temp incorrectly see below .. (I did start the engine) it cut out once the temp in measuring blocks went up to about 110 deg C any ideas ?
Webasto 3.jpg


webasto 1.jpg


Temp VCDS .jpg



Temp Gauge .jpg
 
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The 51Deg C is the coolant temp

The 103/9 Deg C is the temp the webasto temp sensor thinks the coolant temp is and so turns it off because it thinks it's reached the upper limit ?
 
Webasto upper temp limit for the coolant is 70 degrees C. Or 80 for cold climate zones.



Relevant Workshop Manual, Diesel Direct Injection and Glow Plug System; Repair group 01


  • ‒ The engine control unit will switch on the additional heater if the following conditions exist:
    • ‒ The operating and display unit -E87 transmits a request via the convenience data bus or the heater control electronics has switched input to earth (ECON button not pressed).

    • ‒ Engine speed is greater than 600 rpm.
    • ‒ The ambient temperature measured by the engine control unit is below 6°C (only on vehicles without air conditioner).
    • ‒ The coolant temperature is less than 70 °C (or less than 80°C at very low ambient temperatures).
    • ‒ Capacity utilisation of alternator -C is less than 60% (with electric additional heater only).
 
Hi Howie,
I’ve had similar trouble with mine since the MOT, interestingly I stopped using 2 stroke oil in case it failed the mot on emissions.
Found my bottle of oil added to a tank of shell standard diesel & it’s purring away in the cold temperatures.
Hth
Keith
Hi Keith

Many thanks, thats very interesting that 2 stroke may help, i have used 2 stroke in the fuel so will add some again for good measure!!
 
This from the manual here Webasto Thermo Top C | Webasto Thermo Top C Manual | Butler (butlertechnik.com)

Which would seem to suggest 105 deg.C as a cut off, which just about ties in with what i'm seeing ?

2.4.2 Temperature Sensor The temperature sensor senses the coolant temperature in the heat exchanger of the heater as an electrical resistance. This signal is routed to the control unit for processing.

2.4.3 Overheat Protection Overheat protection, controlled by a temperature resistor, protects the heater against undue operating temperatures. Overheat protection responds at a water temperature in excess of 105° C and switches the heater off.
 
Think the 105 is an internal safety overheat to prevent damage. But the Audi manual states coolant temp below 70 degrees or 80 if really cold to operate. So looks like the coolant is at 51.3 but the Webasto is up to 105. The engine may not have been running allowing the Webasto to over temp or there is some form of blockage in the Webasto pipes preventing flow through the unit.
 
I started the engine a couple of mins after starting the webasto, so it shouldn't be a lack of flow unless the pipes are blocked somehow, it was showing the 103 deg.C temp very quickly.

Re the flow, the heater did get warm as a result of the webasto was running so would guess the flow is ok ?

I will check those measuring blocks with the car cold, that should give a clue

I wonder if that sensor can calibrated
 
How is the water pump? I thought the engine needed to be running before the Webasto unless there was an auxiliary pump to circulate the coolant?
 
Water pump is 20k miles old, I can try it the other way round, the guide for testing suggested start the webasto with the engine off so you can hear it, as soon as i heard the fan going i started the car so i don't think it's a circulation problem.
 
All I can suggest is a cold start, with the engine first then the Webasto and watch the coolant temperature and the Webasto temperatures simultaneously. 5Kw is a lot of heat trying to go into those pipes, lack of movement or air lock in the system to me would cause the Webasto to get too hot. But to be honest I do not know at what internal temperature the Webasto normally runs. I assume hot at the start then as the coolant warms the Webasto cools a bit but must be running over 70 degrees minimum.
 
Water pump is 20k miles old, I can try it the other way round, the guide for testing suggested start the webasto with the engine off so you can hear it, as soon as i heard the fan going i started the car so i don't think it's a circulation problem.
Hi Steveb,
The system isn’t designed to run with no flow, you will cause very localised hotspots within the heat exchanger as indicated by your readings, any attempt to make it run prior to running the engine would require a auxiliary water pump to circulate the water thus preventing your current situation.
Hth
Keith
(Sorry Steveb I didn’t see the remote in the title so ignore my comments please)
 
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I checked the Temp. the webasto is seeing before i started it or the engine. So this is overnight cold

Cold .jpg
 
Did the Webasto actually start? Looks like the max internal safety over heat may be faulty. Sorry no idea if that is a replaceable part on its own or a higher assembly needs to be replaced. Is there any Webasto software that can check for faults and perform a reset on the system? Do not think VCDS can reset but may be hidden away.
What faults are you getting from VCDS?

The manual starts here.

 
i'm looking through the manual now to see if it mentions any kind of reset.

VCDS shows no faults and the unit did run until that temp showed to high and switched it off. so i would guess in VCDS thats not a fault ?
 
Have you done any work on the cooling system recently? If there was an air lock or partial blockage in the Webasto that would allow it to get too hot very quickly. Have you tried adaptation in VCDS or other menu items for more information?
 
Cooling system hasn't been touched for 20k miles

The temp check today was cold from overnight, nothing had been running, agree on the possability of an air lock but it shouldn't make it show that hot with nothing on.

ill look into adaption options
 
Possibility that is a stored overtemp reading. Could be a genuine reading or the overtemp sensor gone faulty. Have you checked the electrical connections on the Webasto, a corroded pin could give the same issue.
 
Reading through the manual suggests no way of adapting the Webasto temp. sensor

" The temperature sensor (for the coolant temperature in the heater) is permanently installed (in the heater control unit -J162) and can neither be checked nor removed".

So looks like take it apart and see if it can be replaced, guessing it's on a circuit board of some sort
 
Check the wiring first though, never know may be an external connection playing up. Doubt it though.
 
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