Webasto thermotop C No start and Flame was detected prior to combustion

[Kristina]

Trying to work out issue with webasto suddenly not heating water. Diagnostics tool showed 2 faults. NO START start (1002 the changed to code 2002) and FLAME WAS DETECTED PRIOR TO COMBUSTION 2006 

Voltage  coming in definitely fine. No blockages in exhaust. Plenty of fuel and coolant. 

What could be the issue? 

First thoughts are pump but maybe someone has a more clear idea  why flame would be detected prior to combustion and what that actually means. 

When starting kicks out a small amount of white smoke the instant it starts up. Not making the louder noise that webasto usually does on start up. 

[Jen-in-Wellies]

The manual reckons either the glow plug, or the flame sensor are defective. The heater will measure the current, or resistance of these units. A defective one may go open circuit, which could look like high temperature detected when the heater should be cold. See section 5 Troubleshooting.

https://www.butlertechnik.com/downloads/cms/7404/webasto-thermo-top-c-workshop-repair-manual.pdf

 

The glow plug is the part that ignites the fuel. The flame sensor is the one that detects if the fuel is burning. Both are needed for safe operation, so the heater will do a check that they appear to be functioning before attempting ignition and shut down if it doesn't see what it is expecting.

[MtB]

2 hours ago, Jen-in-Wellies said:

The glow plug is the part that ignites the fuel. The flame sensor is the one that detects if the fuel is burning. Both are needed for safe operation, so the heater will do a check that they appear to be functioning before attempting ignition and shut down if it doesn't see what it is expecting.

 

On older gas boilers a similar check is done but not for the reasons you describe. A flame test is carried out to check there is no pilot flame present when there should not be. If there is, this would indicate the gas valve is incorrectly passing gas even when turned OFF.

 

Is it possible for the "FLAME WAS DETECTED PRIOR TO COMBUSTION 2006" error report to be happening because it is, genuinely, detecting a flame before it starts the ignition sequence? Pretty unlikely unless fed from a day tank higher than the appliance. Perhaps the OP could clarify if the fuel tank is lower or higher than the Webasto.

[Jen-in-Wellies]

45 minutes ago, MtB said:

 

On older gas boilers a similar check is done but not for the reasons you describe. A flame test is carried out to check there is no pilot flame present when there should not be. If there is, this would indicate the gas valve is incorrectly passing gas even when turned OFF.

 

Is it possible for the "FLAME WAS DETECTED PRIOR TO COMBUSTION 2006" error report to be happening because it is, genuinely, detecting a flame before it starts the ignition sequence? Pretty unlikely unless fed from a day tank higher than the appliance. Perhaps the OP could clarify if the fuel tank is lower or higher than the Webasto.

The dosing pump supplies the diesel and is controlled from the Webasto, with each pulse from the heater delivering a small, but consistent volume of diesel. It is unlikely any diesel would get through when the pump isn't running, even with the sort of head that you might get from a day tank on a boat. 2m maximum? If it was, the chances of the flow rate being enough to sustain combustion, without swamping the heater seems unlikely to me. However, if it did happen, it would have the same effect and be detected on start up. Seeing if the heater, or exhaust was warm when this error occurs would give the clue.

[MtB]

52 minutes ago, Jen-in-Wellies said:

The dosing pump supplies the diesel and is controlled from the Webasto, with each pulse from the heater delivering a small, but consistent volume of diesel. It is unlikely any diesel would get through when the pump isn't running,

 

I appreciate that but impossible? 100% guaranteed impossible? 

 

No, hence the test. To force the user to get the dosing pump fixed if it is letting by.

 

 

 

 

 

[Tonka]

Here is the workshop mamual

Thermo-Top-E.C-Workshop-Manual.pdf

[Jen-in-Wellies]

57 minutes ago, MtB said:

 

I appreciate that but impossible? 100% guaranteed impossible? 

 

No, hence the test. To force the user to get the dosing pump fixed if it is letting by.

 

Also not 100% guaranteed impossible that there aren't ants in the combustion chamber having a summer barbecue, which would give the same symptoms.

[MtB]

1 minute ago, Jen-in-Wellies said:

Also not 100% guaranteed impossible that there aren't ants in the combustion chamber having a summer barbecue, which would give the same symptoms.

 

 

Good point. That's probably what's happening...

 

 

[Jen-in-Wellies]

1 minute ago, MtB said:

Good point. That's probably what's happening...

 

They never invited the OP along either and it's her boat.

[Kristina]

11 hours ago, MtB said:

 

On older gas boilers a similar check is done but not for the reasons you describe. A flame test is carried out to check there is no pilot flame present when there should not be. If there is, this would indicate the gas valve is incorrectly passing gas even when turned OFF.

 

Is it possible for the "FLAME WAS DETECTED PRIOR TO COMBUSTION 2006" error report to be happening because it is, genuinely, detecting a flame before it starts the ignition sequence? Pretty unlikely unless fed from a day tank higher than the appliance. Perhaps the OP could clarify if the fuel tank is lower or higher than the Webasto.

I don't think the fuel tank is higher then the webasto. The smoke is coming from the exhaust and a bit from the air intake. 

10 hours ago, Jen-in-Wellies said:

The dosing pump supplies the diesel and is controlled from the Webasto, with each pulse from the heater delivering a small, but consistent volume of diesel. It is unlikely any diesel would get through when the pump isn't running, even with the sort of head that you might get from a day tank on a boat. 2m maximum? If it was, the chances of the flow rate being enough to sustain combustion, without swamping the heater seems unlikely to me. However, if it did happen, it would have the same effect and be detected on start up. Seeing if the heater, or exhaust was warm when this error occurs would give the clue.

It gets a little "warm" since its smoking . Thoughs on pump being faulty was ie it is not pumping correct amount of diesel to start up which is an issue I have had previously with an off brand pump. It would try to start up and fail. But at this point did not have  frame was detected  prior to combustion error. 

9 hours ago, Jen-in-Wellies said:

Also not 100% guaranteed impossible that there aren't ants in the combustion chamber having a summer barbecue, which would give the same symptoms.

Haha should I genuinely check for this? We did have a lot of ants on here earlier in the season... 

[Belle]

I know you said batteries are fine but I'd still plump for low power from the batteries.

 

My voltage reads ok, but my batteries are end of life (6 years old liveaboard) and seem to lack the oomph to get started, My heater does the same as yours, but dosen't show error codes. I resart it withe the main engine running and it starts fine but billows plumes of white smoke for about 5 minutes. 

 

Is it worth trying on hook up, engine running, just in case?

 

Not an expert 🙂

 

 

[Kristina]

1 hour ago, Belle said:

I know you said batteries are fine but I'd still plump for low power from the batteries.

 

My voltage reads ok, but my batteries are end of life (6 years old liveaboard) and seem to lack the oomph to get started, My heater does the same as yours, but dosen't show error codes. I resart it withe the main engine running and it starts fine but billows plumes of white smoke for about 5 minutes. 

 

Is it worth trying on hook up, engine running, just in case?

 

Not an expert 🙂

 

 

Looking at voltage during diagnostics test the voltage is steady and high. Also our batteries are not that old. I'll try it just to cross it off since its easy to try. 

[Tony Brooks]

16 minutes ago, Kristina said:

Looking at voltage during diagnostics test the voltage is steady and high. Also our batteries are not that old. I'll try it just to cross it off since its easy to try. 

 

You need to measure the voltage at the heater - not the batteries when the glow plug is operating. Any other way will produce an invalid result and may mislead, as I fear may be the case here. You need to measure the voltage to one tenth of a volt.

[PeterF]

I had trouble with an erbespacher heater, similar to a Webasto not lighting, good battery voltage and found that the contacts on the fuse holder and fuses in the wire to the heater had corroded in the damp engine bay causing voltage drop. Replaced these and it worked.

[Jen-in-Wellies]

2 hours ago, Kristina said:

Haha should I genuinely check for this? We did have a lot of ants on here earlier in the season... 

This was meant as a joke. Ignore.

Definitely check the voltage at the Webasto during start up, as it is an easy one to do. This is a common problem. However, boats with this don't generally throw up the error code you are seeing.

You say that you've seen problems when using off brand dosing pumps. Again, this is a common problem as people want to save the money over the expensive Webasto ones and find the ebay specials don't deliver the correct volume of diesel. Is the pump now fitted a genuine Webasto, matched to the heater?

If the above two are correct, look again at the glow plug and flame sensor. This will mean some dismantling of the heater and probably removal, testing and replacement of the items concerned. If you aren't confident about this sort of thing it is probably something you'll need to pay to get done.

[MtB]

21 hours ago, Kristina said:

When starting kicks out a small amount of white smoke the instant it starts up. Not making the louder noise that webasto usually does on start up. 

 

4 hours ago, Kristina said:

I don't think the fuel tank is higher then the webasto. The smoke is coming from the exhaust and a bit from the air intake.

 

 

 

Nobody has commented on these bits so far, I don't think.

 

I've seen the smoke you describe and I think it is from excess fuel that is hot but hasn't ignited properly during the attempted start-up. The fact it is coming from both the air intake and from the exhaust tells us the main motor is not running when it should be. It also tells us the ignition sequence has got as far as delivering fuel and trying to ignite it.

 

Consequently I'm inclined to suspect main motor failure as the control board must think the motor is running or it wouldn't have heated the glow plug or started the fuel delivery. This would be consistent with your comment about the usual 'louder' noise the unit normally makes, being missing.

 

Bear in mind I'm a gas boiler specialist though, applying gas principles to a Webasto about which I know very little.

 

 

[Tony Brooks]

6 minutes ago, MtB said:

Bear in mind I'm a gas boiler specialist though, applying gas principles to a Webasto about which I know very little.

 

But a perfectly logical assessment based on the stated symptoms.

[Torblimey]

Mine started doing a similar thing last year, no fault code checked but smoking, flame out, cut out etc.

Turns out it needed a service and decoke, new filters etc although the turbine is a bit noisy too (bought a spare blower unit ready just in case) and now works fine if not better than before.

Still as shiny outside as the day it was fitted in 2003, no idea on its last service date before 2023.

I'm no expert in anyway shape or form, just a friendly imp.

[Kristina]

3 hours ago, Jen-in-Wellies said:

This was meant as a joke. Ignore.

Definitely check the voltage at the Webasto during start up, as it is an easy one to do. This is a common problem. However, boats with this don't generally throw up the error code you are seeing.

You say that you've seen problems when using off brand dosing pumps. Again, this is a common problem as people want to save the money over the expensive Webasto ones and find the ebay specials don't deliver the correct volume of diesel. Is the pump now fitted a genuine Webasto, matched to the heater?

If the above two are correct, look again at the glow plug and flame sensor. This will mean some dismantling of the heater and probably removal, testing and replacement of the items concerned. If you aren't confident about this sort of thing it is probably something you'll need to pay to get done.

It's an official webasto pump on there now 

[MtB]

23 hours ago, Kristina said:

Diagnostics tool showed 2 faults. NO START start (1002 the changed to code 2002)

 

I reckon this supports my suggestion the motor has failed. 

 

Next, I'd be locating the motor terminals and measuring the voltage on them just before the lock-out occurs.

 

If you get 12Vdc then it motor failure. If you get zero voltage then the PCB is not sending power to the motor and its probably a failed relay on the PCB, or a logic error. 

 

 

[cuthound]

15 hours ago, Jen-in-Wellies said:

Also not 100% guaranteed impossible that there aren't ants in the combustion chamber having a summer barbecue, which would give the same symptoms.

 

But surely if they were fire ants they would cause the diesel to ignite and thus the boiler would be working? 🤣😂

[Kristina]

On 07/07/2024 at 12:32, MtB said:

 

I reckon this supports my suggestion the motor has failed. 

 

Next, I'd be locating the motor terminals and measuring the voltage on them just before the lock-out occurs.

 

If you get 12Vdc then it motor failure. If you get zero voltage then the PCB is not sending power to the motor and its probably a failed relay on the PCB, or a logic error. 

 

 

In the end it was the burner unit and the fan that needed replacing. 

Burner was an obvious one once we opened it up and then smoke was still coming from the until so we then replaced the fan. Up and running again just in time for the cold. 

[MtB]

3 hours ago, Kristina said:

In the end it was the burner unit and the fan that needed replacing. 

Burner was an obvious one once we opened it up and then smoke was still coming from the until so we then replaced the fan. Up and running again just in time for the cold. 

 

Thanks for the update, not everyone bothers.

 

Much appreciated even though I'm still not clear if replacing the fan includes the motor that drives it! 

 

 

[Kristina]

On 03/10/2024 at 19:09, MtB said:

 

Thanks for the update, not everyone bothers.

 

Much appreciated even though I'm still not clear if replacing the fan includes the motor that drives it! 

 

 

That's ok , thought someone else might come across the same problem one day. 

It was the whole fan unit which also has the motor. It wasn't a big difference in price to just get the whole thing and couldn't open it up to look inside and dismantle it. It was the easiest option to just buy the whole thing assembled. 

It most likely was the motor not blowing the smoke out.