Webasto combustion fails to accur

[Jen-in-Wellies]

12 minutes ago, MtB said:

 

Puzzling isn't it?

 

There is clearly a difference in the installation of this Webby on the test bench (where it works) and in the boat (where it doesn't). The task is to find and pin down what the difference is, but the OP simply bats away and dismisses every suggestion about areas to investigate.

 

This Webby is not going to work ever, with this approach.

 

From personal experience, whenever I've had an intractable technical problem that has taken ages to fix, the root cause, nine times out of ten, has turned out to be something I'd dismissed early on as "it can't possibly be that, because...". The last tenth ones are truly hard to find. The other nine, I could have found early on with the clues I had right there, if only my thinking hadn't been blinkered by what I thought I knew.

Never dismiss a possible cause. Work through each one systematically, regardless. One thing fault finding does is teach you humility!

[MtB]

14 minutes ago, Jen-in-Wellies said:

From personal experience, whenever I've had an intractable technical problem that has taken ages to fix, the root cause, nine times out of ten, has turned out to be something I'd dismissed early on as "it can't possibly be that, because...". The last tenth ones are truly hard to find. The other nine, I could have found early on with the clues I had right there, if only my thinking hadn't been blinkered by what I thought I knew.

Never dismiss a possible cause. Work through each one systematically, regardless. One thing fault finding does is teach you humility!

 

 

Yep. This is exactly my own experience and I fault-trace stuff every day, I do it for a living! 

[Kristina]

10 minutes ago, Jen-in-Wellies said:

From personal experience, whenever I've had an intractable technical problem that has taken ages to fix, the root cause, nine times out of ten, has turned out to be something I'd dismissed early on as "it can't possibly be that, because...". The last tenth ones are truly hard to find. The other nine, I could have found early on with the clues I had right there, if only my thinking hadn't been blinkered by what I thought I knew.

Never dismiss a possible cause. Work through each one systematically, regardless. One thing fault finding does is teach you humility!

Understanding that it’s ether of three problems. Power, fuel or air. Have in no way been dismissive but testing for these issues now several times. Currently waiting on new webasto brand fuel pump as one we have was a cheap one, will check and with multimeter next time also but after running diagnostics several times which shows voltage as it starts up it doesn’t drop low from what we can see. The seller  had it working at 12.29V from video he sent me.

Surely it’s a process of identifying possible issue then testing for this issue don’t know why this thread is getting all dramatic 

[MtB]

6 minutes ago, MtB said:

From personal experience, whenever I've had an intractable technical problem that has taken ages to fix, the root cause, nine times out of ten, has turned out to be something I'd dismissed early on as "it can't possibly be that, because...".

 

My experience rhymes in that after finally cracking a particularly difficult fix, I realise with the benefit of hindsight all the evidence was there in plain sight, waiting to be seen or found.

[Tracy D'arth]

The most obvious cause is always the first one to be dismissed as not possible in my experience.

 

Because we all have experienced new faulty goods over the years, when something fails to work out of the box we tend to assume that it is faulty. So we dismiss the fact that its our fault for not fitting it or using it correctly.  We are all perfect until proven not to be.

[Kristina]

13 hours ago, MtB said:

 

An even quicker and more helpful test is to measure the terminal voltage during the start-up sequence where the supply cable connects into the Webby. This will rule in or rule out everything to do with the power supply wiring, new loom or not. I expect it needs to be 12.0V or higher but the manual will probably give a minimum value in the fault-tracing section. 

Ok will test with voltmeter next, waiting on webasto brand fuel pump also since we have a cheap one 

[Kristina]

12 hours ago, MtB said:

 

 

 

 

 

Good point, given the OP says it is a reconditioned one. My money is still on inadequate power supply. The symptoms are consistent with shagged out (technical term) batteries if this is a truck unit. The startup current drags them down but it still lights, but as the heater plug stays ON for quite a while after ignition it continues to cane a knackered battery and soon the voltage drops to cut-out voltage, and the unit shuts down.

 

 

 

Turns out it’s a car webasto , batteries might be the issue, will check voltage again next time. What should it not drop below to  cut out? 

[Tony Brooks]

Even an automotive Webasto should not play up if started and run with the engine running and revving a bit to charge the batteries. That should provide between about 13 and 14.X volts depending upon the state of battery charge at the time. Even 13V is way about the automotive low voltage cut out figure.

[Kristina]

10 minutes ago, Tony Brooks said:

Even an automotive Webasto should not play up if started and run with the engine running and revving a bit to charge the batteries. That should provide between about 13 and 14.X volts depending upon the state of battery charge at the time. Even 13V is way about the automotive low voltage cut out figure.

That’s what we did last time we tested again using this logic also and had new fuel in a can as another engineer suggested this 

[Tony Brooks]

2 minutes ago, Kristina said:

That’s what we did last time we tested again using this logic also and had new fuel in a can as another engineer suggested this 

 

I am just trying to give you some pointers in reply to your question about the marine cut out voltage.

 

 

If the Webasto cut out with the engine revving then as long as the alternator was charging I do not see it can be a BATTERY voltage or cut out voltage setting problem. However, that does not mean it is not a voltage problem, but the only way you can get a handle on that is to measure the voltage at the glow plug and the main positive terminal on the Webasto when starting and while running with the engine revving and charging.

 

If those are within about 0.3V maximum of the battery voltage the wiring is probably OK, if they are lower than you need to look for volt drop between battery and Webasto.

 

You locate volt drop by putting a decent voltmeter between battery positive and the glow plug or main positive connection on the Webasto and operating it. If you find more than about 0.3V start stepping the battery end of the meter to the next point in the circuit so probably master switch in, master switch out, possible main fuse in, main fuse out, domestic distribution board/fuse and so on. When the volt drop lowers you will have just stepped over a problem section. Ignore ANY readings without the unit running.

 

Then you do the same on the negative side of the circuit.

 

If there is zero or less than about 0.3V of volt drop it will be a fair assumption it is not a voltage issue AS LONG AS THE ENGINE WAS RUNNING AND CHARGING FOR ALL TESTS.

 

If it is not a voltage issue that only leaves fuel or overheat.

 

How far around the central heating circuit does the output pipe warm before it cuts out? If the pipe is gradually warming and the warm area extending then as long as the output fitting or close to it is not uncomfortably hot I would suggest (no more than that) that it's not a circulation problem. If, on the other hand, the heat does not travel along the pipe and the output connections gets hot very fast it indicates a probable circulation problem.

 

I wonder if you have connected your extra pump pipe connections up backwards, so it is actually fighting the Webasto circulation pump and stopping the flow.

 

If that checks out then it leaves fuel and as you say it is not a Webasto fuel pump and as I understand the flame is controlled by altering the pulse rate of the pump I would be very wary of non-standard fuel pumps.  You seem to have tried running with a small fuel tank connected directly to the fuel pump so in my view that makes air or dirt in the fuel less likely unless dirty fuel has messed up the pump valves.

 

I repeat that I am not familiar with the intricacies of Webastos because of my experience of the 1960s/70s models that worked differently, so would never have anything to do with that type of heater, but the above is, in my view, a generic logical fault-finding sequence.

 

 

 

 

 

 

[bizzard]

Final solution. Apply to 221b Baker Street.

[Kristina]

30 minutes ago, Tony Brooks said:

 

I am just trying to give you some pointers in reply to your question about the marine cut out voltage.

 

 

If the Webasto cut out with the engine revving then as long as the alternator was charging I do not see it can be a BATTERY voltage or cut out voltage setting problem. However, that does not mean it is not a voltage problem, but the only way you can get a handle on that is to measure the voltage at the glow plug and the main positive terminal on the Webasto when starting and while running with the engine revving and charging.

 

If those are within about 0.3V maximum of the battery voltage the wiring is probably OK, if they are lower than you need to look for volt drop between battery and Webasto.

 

You locate volt drop by putting a decent voltmeter between battery positive and the glow plug or main positive connection on the Webasto and operating it. If you find more than about 0.3V start stepping the battery end of the meter to the next point in the circuit so probably master switch in, master switch out, possible main fuse in, main fuse out, domestic distribution board/fuse and so on. When the volt drop lowers you will have just stepped over a problem section. Ignore ANY readings without the unit running.

 

Then you do the same on the negative side of the circuit.

 

If there is zero or less than about 0.3V of volt drop it will be a fair assumption it is not a voltage issue AS LONG AS THE ENGINE WAS RUNNING AND CHARGING FOR ALL TESTS.

 

If it is not a voltage issue that only leaves fuel or overheat.

 

How far around the central heating circuit does the output pipe warm before it cuts out? If the pipe is gradually warming and the warm area extending then as long as the output fitting or close to it is not uncomfortably hot I would suggest (no more than that) that it's not a circulation problem. If, on the other hand, the heat does not travel along the pipe and the output connections gets hot very fast it indicates a probable circulation problem.

 

I wonder if you have connected your extra pump pipe connections up backwards, so it is actually fighting the Webasto circulation pump and stopping the flow.

 

If that checks out then it leaves fuel and as you say it is not a Webasto fuel pump and as I understand the flame is controlled by altering the pulse rate of the pump I would be very wary of non-standard fuel pumps.  You seem to have tried running with a small fuel tank connected directly to the fuel pump so in my view that makes air or dirt in the fuel less likely unless dirty fuel has messed up the pump valves.

 

I repeat that I am not familiar with the intricacies of Webastos because of my experience of the 1960s/70s models that worked differently, so would never have anything to do with that type of heater, but the above is, in my view, a generic logical fault-finding sequence.

 

 

 

 

 

 

Thank you will try tests the voltage the way you said and fit the new pump next time.

 

We did consider the second pump is backwards so double checked, but can see in header tank coolant is moving in the same direction as running the webasto or just connecting the second pump on its own to a battery. 



 

[MtB]

44 minutes ago, Tony Brooks said:

If that checks out then it leaves fuel and as you say it is not a Webasto fuel pump and as I understand the flame is controlled by altering the pulse rate of the pump I would be very wary of non-standard fuel pumps. 

 

A very good point, the volume of fuel sent on each pulse needs to be exactly right and a non-branded pump could easily be sending the wrong volume on each click.

 

And developing the point, when this heater is working in the bench according to the supplier, was he/she using your dosing pump or their own? 

 

 

[Kristina]

5 minutes ago, MtB said:

 

A very good point, the volume of fuel sent on each pulse needs to be exactly right and a non-branded pump could easily be sending the wrong volume on each click.

 

And developing the point, when this heater is working in the bench according to the supplier, was he/she using your dosing pump or their own? 

 

 

They used their own. So we bought a proper one should arrive next week. 

[Tracy D'arth]

1 hour ago, Kristina said:

Thank you will try tests the voltage the way you said and fit the new pump next time.

 

We did consider the second pump is backwards so double checked, but can see in header tank coolant is moving in the same direction as running the webasto or just connecting the second pump on its own to a battery. 



 

I am somewhat horrified that you can see circulation in the header tank.

You have a feed and expansion pipes into the tank?  Why? You only need a feed pipe to the highest point. It should never be over pumping.

If you have circulation in the tank then you are constantly introducing air into the water. This will cause severe corrosion in the radiators and the heater and will cause air locks to form in the high points of the plumbing.

[matty40s]

1 hour ago, Tracy D'arth said:

I am somewhat horrified that you can see circulation in the header tank.

You have a feed and expansion pipes into the tank?  Why? You only need a feed pipe to the highest point. It should never be over pumping.

If you have circulation in the tank then you are constantly introducing air into the water. This will cause severe corrosion in the radiators and the heater and will cause air locks to form in the high points of the plumbing.

The Webasto header tank is designed to do this with an In and an Out feed, ideally, when all bubbles are out of the system, there should also be a bypass pipe below that you can open up.

 

[nb Innisfree]

FWIW TRY white diesel or paraffin, you migh have introduced high sulphur diesel into your tank? 

We tried everything with our Mikuni, sent it be checked & cleaned, all OK, checked voltage, broke seal and played around with pump speed, even tried spare control box that Mikuni let me borrow, nothing worked, even if I got it running it would smoke. 

The one thing I didn't try was white diesel, but fate lent a hand in the form of ultra low sulphur diesel which was just being introduced, that did the trick, over a period of a few weeks as the old diesel was replaced with ULSD the prob disappeared and our Mikuni fired up every time and ran perfectly. 

Edited October 6, 2022 by nb Innisfree

[Cheshire cat]

Is high sulphur diesel still out there?

[nb Innisfree]

Just now, Cheshire cat said:

Is high sulphur diesel still out there?

Don't know but some might get through as boiler fuel? (gas oil) 

[Tony Brooks]

It might be for industrial use but it should not get into any form of transport use. However, you never know, wide boys will be wide boys. I also suspect some Third World countries are still happy with high sulphur diesel so that is another potential source.

[nb Innisfree]

15 minutes ago, Tony Brooks said:

It might be for industrial use but it should not get into any form of transport use. However, you never know, wide boys will be wide boys. I also suspect some Third World countries are still happy with high sulphur diesel so that is another potential source.

I don't think high sulphur is actually illegal for off road use, but I might be wrong. 

[Tracy D'arth]

1 hour ago, matty40s said:

The Webasto header tank is designed to do this with an In and an Out feed, ideally, when all bubbles are out of the system, there should also be a bypass pipe below that you can open up.

 

Yes, the bypass must be opened otherwise the circulation through the tank will aerate the water as I said, that would cause air locks and corrosion.  The water must not pump over in the tank.

Edited October 6, 2022 by Tracy D'arth

[Kristina]

4 hours ago, Tracy D'arth said:

Yes, the bypass must be opened otherwise the circulation through the tank will aerate the water as I said, that would cause air locks and corrosion.  The water must not pump over in the tank.

That’s a system with a calorifier tank no? We have a heat exchanger so no bypass valve 

 

 

[Tracy D'arth]

18 minutes ago, Kristina said:

That’s a system with a calorifier tank no? We have a heat exchanger so no bypass valve 

 

 

It must not pump over in the expansion/feed tank.

I am not talking about a bypass on the heating circuit but under the tank connecting the feed and expansion pipes so that it does not pump over into the tank.

[matty40s]

6 hours ago, Tracy D'arth said:

Yes, the bypass must be opened otherwise the circulation through the tank will aerate the water as I said, that would cause air locks and corrosion.  The water must not pump over in the tank.

 

Incorrect, it MUST pump over in the tank if the owner keeps taking it off to take away for repair and then replumbing it back in again. That is why Webasto have designed and reccomend what I have suggested.

Once there are no bubbles coming through, and header tank level is stable, the lower bypass pipe should be opened up.....meaning the expansion tank reverts to just that.

9 hours ago, Tracy D'arth said:

I am somewhat horrified that you can see circulation in the header tank.

You have a feed and expansion pipes into the tank?  Why? You only need a feed pipe to the highest point. It should never be over pumping.

If you have circulation in the tank then you are constantly introducing air into the water. This will cause severe corrosion in the radiators and the heater and will cause air locks to form in the high points of the plumbing.

It wont cause severe corrosion if the correct mix antifreeze is used, and the bypass pipe opened when ALL air bubbles are removed from system.