Webasto fault-free but doesn't run

Robin_Cox

Member
I suspect that this is going to be one of many Webasto threads over the next couple of months judging by history..

The Webasto has run fine in previous years. I've used the reader on channel 18 aux heating and there are no fault codes. Coolant temperature in the Webasto data reads correct (ie this morning it was cold when I tested it, and gradually increases as the engine warms up correlating within a degree or so of both normal coolant temperature sensor output feeds.) - so it doesn't appear to be the failed Webasto temp sensor issue reading 110 degrees centigrade at startup that others have encountered.

Running the actuator tests I don't see or hear anything with the glow plug run (but I didn't previously either when the pump was working), the fuel supply pump clicks rapidly as normal, and the fan spins up normally.

However, the last few mornings when it has been frosty, simply put the Webasto hasn't run when it would in previous years. The various acceptance criteria I know of for it to work (external temp, coolant temp, alternator voltage, engine running, internal heating system on HI, Econ not activated) were all as I expect them to be.

One thought that comes to mind : a few weeks back I had to fit a replacement diesel heat exchanger on the floor of the car in front of the rear drivers' side wheel. While it was up on the stands, the mechanic noted that what I now know is the fuel pump for the Webasto was hanging loose on its pipes / connection to the loom, so that was cable-tied back into place in the alcove behind the fuel cooler.

Doing a bit of reading about Webasto fuel pumps, I've read something to the effect that their orientation is critically important both for avoiding trapped bubbles, namely that the outlet end (which also has the connection to the loom) needs to be above the inlet end (from the fuel tank). The way that my pump has been secured, the outlet is a good inch lower than the inlet.

see the section marked "pump mounting" on the following page : https://www.letonkinoisvarnish.co.uk/eberspacher_fuel_2.html

from where I have borrowed the following diagram (in case the above page is lost at some point).

wp99524a1d_05_06.jpg



Mine is essentially the reverse of the left-hand image, the outlet with loom connector socket is canted around 15 degrees downwards. The pipe to the heater then doubles back on itself towards the centre of the car and then runs to some clips that take the fuel out / return pipes under the car to the engine bay.

Could this be a reason for the Webasto not running - possibly fuel starvation? Is the A2 webasto fuel pump also supposed to be fixed into a specific position?

One further note - I replaced the coolant temp sensor a couple of weeks back and lost the usual amount of coolant. Bled the radiator, but not the Webasto, but then again it wasn't necessary when the thermostat was changed last year so I hoped I'd got away with that. Will go check that now.

I know that running this diesel pump dry can burn it out quickly, so I would rather fix this sooner than later. Any thoughts gratefully appreciated.
 

audifan

A2OC Donor
All you can do is locate the Webasto pump as directed and then see if thing improve. Hopefully all good.
 

audifan

A2OC Donor

Robin_Cox

Member
I'd forgotten about the ability to get the burner itself to run using Basic Settings - I was just using the actuator checks that make various components tick and whirr. If Basic Settings doesn't elicit a running heater if I get a chance in the morning then I am minded to go back to my mechanic - the bracket is corroded to hell and even the body of the pump isn't in great nick - there were links on here the other day to replacement fuel pumps so it shouldn't be too hard to get a non-OEM 12V heater and get this swapped in. From cross-referencing part numbers (it is a 4B0 A6 C5 part used on a wide range of vehicles as well as on the A2) it appears to be the Webasto DP30 pump rather than the larger DP42.
 

steveb

Member
you could check for an airlock by seeing if the inlet and outlet hoses are hot when the engine is running and up to temp
 

Robin_Cox

Member
The Webasto internal coolant temp sensor follows the car's coolant temp sensor readings closely when it is running and obviously pump giving circulation, so I am reasonably hopeful that there isn't an airlock.

After the school run this morning I decided to have a crack at switching the heater on manually as suggested above using instructions from another Webasto thread. Basic settings - channel 022 - run .. resulted in the status changing to "heater test" instead of "off" ; fan noise, then pump noises, then immense amounts of acrid white smoke coming from under the bonnet to the point where I began to think I'd set the car on fire. It smelt strongly like a fire in the chip fryer when I was working in McDonalds 30 years ago.. whereupon I remembered my trials using 30% vegetable oil in the summer, so I wonder if some of that was in the pipework and burning off as it has had 2 complete fills of diesel since then but no Webasto runs.

Was monitoring the temperature and it got up to 40 or so degrees before I began to get a bit worried that this was actually a bonfire rather than a Webasto test, so I switched everything off (ignition key) then tried desperately to find a combination of button presses in the reader to switch the basic settings off.

Ultimately it put itself into "heater off", "after-run" and the smoke started to dissipate so I knew it wasn't carrying on out of control.

Main thing is that it lights, the pump works, and the fan works ; just need to see if it will do it by itself on a properly cold morning now if all criteria are fulfilled. I might have another go at this at the weekend with the laptop where I should have a little more control over the basic settings.

Thanks as usual for all the suggestions!

EDIT :

reading the manual, it appears that in VCDS section 018 - Auxiliary Heater, Basic settings - the heater test channel is to run is 022, while to switch it back off again when you want/need to, apparently the basic settings channel to select and run is 033. I am yet to test this (tomorrow's job) but it is repeated enough times over a page or two that this seems to be clear.
 
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Andrew

A2OC Donor
Good Evening,

That was scary, I suppose if driving the smoke would have wafted away and gone unnoticed.

A rare post from me in a diesel thread. Have you checked the ambient temperature sensor is working correctly? I remember the climate unit triggers the Webasto - 'wake up Mr. Webasto it's cold out go ahead and do your thing'. Besides a rogue sensor giving too high a ambient temperature and inhibiting Wabasto function one member had to replace the climate unit for correct trigger function but you have probably read the thread.

Andy
 

Robin_Cox

Member
Good Evening,

That was scary, I suppose if driving the smoke would have wafted away and gone unnoticed.

A rare post from me in a diesel thread. Have you checked the ambient temperature sensor is working correctly? I remember the climate unit triggers the Webasto - 'wake up Mr. Webasto it's cold out go ahead and do your thing'. Besides a rogue sensor giving too high a ambient temperature and inhibiting Wabasto function one member had to replace the climate unit for correct trigger function but you have probably read the thread.

Andy
this was a thought that I've had for some time, although the read out on the dashboard suggests it is working. I need to also check VCDS feeds for external temperature readings in other channels just in case it is interpretation of the external temperature by one specific controller that is the problem.

Worth pointing out that normal Webasto function elicits a small puff of steam around the wheel arch base which dissipates quickly unless it is a cold and still day, however this was full on Red Arrows-grade smoke coming out of every panel gap on the front third of that side of the car so even in motion I suspect that it would have been rather evident :) ... ! My conclusion is that it was telling me it believes there is a new Pope..
 

CrispyEdd

Member
I remember when my vw touran created a scene from top of the pops one morning. I didn't even know it had a webasto. The whole car was engulfed as all the years of turd in the webasto exhaust cooked. It had spend its life in Cornwall so probably never fired. After that it was fine. Temp out side was 4 deg or just below and I just started xar and put heater on, nothing more to it than that. Believe 4 was the switch on for the smoke screen.
 

PlasticMac

Member
this was a thought that I've had for some time, although the read out on the dashboard suggests it is working. I need to also check VCDS feeds for external temperature readings in other channels just in case it is interpretation of the external temperature by one specific controller that is the problem.

Worth pointing out that normal Webasto function elicits a small puff of steam around the wheel arch base which dissipates quickly unless it is a cold and still day, however this was full on Red Arrows-grade smoke coming out of every panel gap on the front third of that side of the car so even in motion I suspect that it would have been rather evident :) ... ! My conclusion is that it was telling me it believes there is a new Pope..
Eat your heart out Mr Bond, you don't need the trick Aston!
Mac.
 

kp 115

Member
I'd forgotten about the ability to get the burner itself to run using Basic Settings - I was just using the actuator checks that make various components tick and whirr. If Basic Settings doesn't elicit a running heater if I get a chance in the morning then I am minded to go back to my mechanic - the bracket is corroded to hell and even the body of the pump isn't in great nick - there were links on here the other day to replacement fuel pumps so it shouldn't be too hard to get a non-OEM 12V heater and get this swapped in. From cross-referencing part numbers (it is a 4B0 A6 C5 part used on a wide range of vehicles as well as on the A2) it appears to be the Webasto DP30 pump rather than the larger DP42.
Hi Robin_Cox,
Have a look at this seller lots of useful bits.https://www.ebay.co.uk/itm/Fuel-Pump-Filter-Bracket-Holder-Mount-Heater-Rubber-Clamp-Shock-Absorption-/133922517400?mkcid=16&mkevt=1&_trksid=p2349624.m2548.l6249&mkrid=710-127635-2958-0

Mine runs really well on the 2stroke mix 👍
Hope that helps
 
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Robin_Cox

Member
An update .. having spent a few days reading the Workshop manuals descriptions of the Webasto Auxiliary Heater control logic and how this is linked into the climate system - as well as the climate system control logic and various measurement channels to look at, and finally having some time and daylight on my hands I decided to hook up the Laptop with VCDS-Lite rather than the VAG401 reader, which although very good for most of my uses is for some reason incapable of speaking to Climatronic systems.

First thing that I found was that the climate system had a long list of fault codes that I was unaware of (not having hooked the laptop up to this car in 18 months once I got the steering working). Many of them probably legacy from when the battery went bad a calendar year ago (actually found to be the starter earth but it caused brown-outs repeatedly until I solved the problem) - and although being the freeware version it didn't annotate all of them I have cross-referenced the codes and found these were all various flap positioning errors, probably due to the voltage fluctuations a year ago. These all went when I cleared the codes. I also watched the flap positioning channels and the temperature sensor channels (03-06, 07-09), and eventually channel 12 (rear screen heater and auxiliary heater status) ; all seemed to move between numbers and change normally when I altered air distribution as expected from the workshop manual. This was all done with the engine running, a/c temp turned up to HI and so on.

A couple of the fault codes were a bit more durable that were translated correctly even in the demo version : G89 temperature sensor (that's the air intake temperature one up underneath the dash) - sporadic fault open to earth, and G65 a/c pressure sensor open to earth (this is the one that is still broken in half and awaiting replacement with a new a/c condensor / heat exchanger, so no surprise here - it's not going away until I replace the a/c components). After another couple of rounds of clearing these the only error left was the G65.

Moments later the Webasto burst into life with another slightly less dramatic cloud of vegetable-oil smoke than last week - so this would suggest that some of the accumulated codes (probably the G89 fault) are sufficient to prevent the Webasto from firing up, maybe because of confusing temperature values (it looks at both ambient temp sensor G17 (behind the bumper), G89 air intake sensor and dashboard temperature feeds and works out what the temperature is likely to be based on what the car is doing, so any sporadically wonky values here presumably are enough to trip the system off due to ambiguous values). The car is getting another full tank of diesel this week so I'm hoping the burner pipework will clean itself out in the next couple of days.

Fingers crossed now that this is a solution - I am going to source and replace the G89 if possible but at the very least I know now what one issue may be.
 

audifan

A2OC Donor
Can you remove the fuel pipe from the Webasto end and run the fuelling check through VCDS to flush the line completely? Just catch the fuel in a suitable size container as once the test starts it must run to completion - if at all possible in Lite?
 

Robin_Cox

Member
I can do that easily using the VAG401, doing it in Lite wouldn't be possible in the basic settings 'pipe filling' mode as it would give a message about needing to upgrade to a paying version to access basic settings ; however, now I've spent some time on the manual I should be able to use the equivalent basic setting channel in VAG401. Alternatively run the actuator test on the metering pump as you say with the fuel input to the webasto directed to a pint glass for a few seconds should be enough to flush it - I guess that the dead volume of the tube won't be more than 50-100mL in total so it shouldn't take much to resolve this.
 

audifan

A2OC Donor
I would err on the larger side for fuel catchment perhaps as much capacity as 2l. The Webasto by the sound of it is only designed to run on pure diesel so any additive may cause incomplete burning and possible flame outs. So no veg oil, no two stroke and no kerosene. Would also have to think carefully if using cetane enhancers in the fuel.

If you can access the glow plug could be worth checking its condition and burnt on contaminates and the burner element from the manual

Display on VAS 5051 and output at printer
Possible causes of fault
Fault remedy
01407
Loss of flame
- Constriction or leakage in air intake or in exhaust system.
Fault in fuel supply to additional heater.
Combustion air blower -V6 defective.
Glow plug with flame detector -Q8 defective.
Metering pump -V54 defective.
Leak in additional heater.
Deposits on burner element (only when running additional heater on vegetable oil methyl ester)
- Check additional heater air intake and exhaust system.
Check fuel delivery​
 

Robin_Cox

Member
Re-reading the aux heater book it appears that the veg oil methyl ester comments above are linked to regions where implementation of Biodiesel was instigated early, so the burners do have to run with that present, they just are prone to being a bit mucky by the look of it - possibly a need for calibration of the fan speed / CO2 output for different fuel types. The school run today was enough to get the Webasto burning completely cleanly by the time I was 5 minutes up the road, although there was a certain amount of smoke present just as we started the journey. Really glad that I've been through this process over the past week or so, it has led me to have a better understanding of the car and there is a satisfaction of having found an apparent solution. The difference with the Webasto running in terms of heating the car up was huge and very well timed.

Thanks again all for the helpful comments and thoughts - it has all contributed to solving the problem.
 

audifan

A2OC Donor
👍
Really glad the Webasto is working. I am not sure the veg oil itself had either thickened or "gone off" making the initial light ups for the season harder. The fuel trapped in the line from previous cold use to first use of the next season will be very stale and could also produce a poor fuel spray as it enters the Webasto.. It is a pity that the line can not be emptied of fuel and then primed for the first winter start automatically.

I have seen nuts and seeds in the Webasto exhaust before.... Stuart Little's stash no doubt.
 
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