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Kelbs

Struggling to get the Webasto Top C to start up.

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my two penneth,

 

I've had many old and outmoded webasto's donated to me over the years, one of the advantages of having a friend that works there. They are pretty solid little things and can stand a fair bit of abuse.

 

If there is fuel squirting out of the pump, and if there is water going around the circuit then it's down to volts.

 

Echoing what many others have said, check the voltage at the unit while it's trying to start, the volt drop when the glow plug kicks in is likely to be your issue, it usually is!

 

As has been mooted around, the marine version has a lower permissible minimum voltage during running, but the permissible voltage allowance of the unit is modified during the start up cycle. The difference is significant at this part of the programming, presumably to take into account that most cars only have a single battery and it needs to be able to start the car!

 

The units normal programming would allow it to make three start up attempts before going into shutdown, which then requires removal of the "heat" trigger signal to reset.

 

If there is an airlock leading to no circulation of the water, thermal shutdown will happen in not more than a few seconds of flame. and it will take a good while for the overtemp  to clear unless the water circulation is sorted quickly whilst the water pump is still running. 

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1 minute ago, Tash and Bex said:

my two penneth,

 

I've had many old and outmoded webasto's donated to me over the years, one of the advantages of having a friend that works there. They are pretty solid little things and can stand a fair bit of abuse.

 

If there is fuel squirting out of the pump, and if there is water going around the circuit then it's down to volts.

 

Echoing what many others have said, check the voltage at the unit while it's trying to start, the volt drop when the glow plug kicks in is likely to be your issue, it usually is!

 

As has been mooted around, the marine version has a lower permissible minimum voltage during running, but the permissible voltage allowance of the unit is modified during the start up cycle. The difference is significant at this part of the programming, presumably to take into account that most cars only have a single battery and it needs to be able to start the car!

 

The units normal programming would allow it to make three start up attempts before going into shutdown, which then requires removal of the "heat" trigger signal to reset.

 

If there is an airlock leading to no circulation of the water, thermal shutdown will happen in not more than a few seconds of flame. and it will take a good while for the overtemp  to clear unless the water circulation is sorted quickly whilst the water pump is still running. 

This is all pointing towards an airlock situation.

 

Before anyone tells me off any more, no I haven't checked the glow plug yet. 

 

The webasto candour has suggested that I check the circulation pump is working by taking the screws out the bottom and manually turning it. 

 

The webasto header tank is self bleeding I believe and I have bled all the Rads prior to starting. How do I get airlock out of the Webasto unit itself? 

 

Could it possibly be short cycling?

 

 

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1 minute ago, Kelbs said:

This is all pointing towards an airlock situation.

 

Before anyone tells me off any more, no I haven't checked the glow plug yet. 

 

The webasto candour has suggested that I check the circulation pump is working by taking the screws out the bottom and manually turning it. 

 

The webasto header tank is self bleeding I believe and I have bled all the Rads prior to starting. How do I get airlock out of the Webasto unit itself? 

 

Could it possibly be short cycling? 

 

 

jury rig a couple of short pipes to the heater, stick em in a bucket of water, if she starts give her a while until you have a bucket of steaming hot water! 

 

if you have trv's on your rads replace one with a conventional rad valve (usually the towel rail) and then there is always going to be a flow. if you have a single pipe circuit for your heating then i am afraid your rads can't have trv's and must all be "on" at all times

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As above this is how I tested mine before fitting to boat I just put a funnel via a pipe to inlet pipe and the outlet pipe into a bucket and the just kept filling the funnel with water till I was happy with the running on the unit,As I have said before if it does not see water then it will go through a test cycle and stop secret is a good high header tank and we’ll bleed system 

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If you search Ebay for "webasto diagnostic" you will be able to find a diagnostic lead and the appropriate software.  I have the lead permanently wired in on our boat, and run the software on an ancient windows XP netbook.  It is worth the time and money IMO, as you can see exactly what is going on inside your ebay bargain heater!

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5 hours ago, Cheshire cat said:

I think Tony may have something there. I changed my radiators and ended up with an airlock in the webasto. It fired up and heated up water in the immediate vicinity but couldn't pump it around the system. I can't remember the symptoms in terms of whether it shut itself down or not but the solution was to pull one of the water hoses off the webasto allowing it to back fill from the header tank. 

 

Once I did that everything worked as expected. Be careful not to get scalded. The water "trapped" in the Webasto was very hot.

This is exactly what's happening, water in the first 50cm of pipe is heating then nothing.

 

So it's sounding like there is an airlock at the circulation pump. If I remove the pipes connecting to the webasto a large portion of my water will drain. In heinsite I should have put isolators on the pipes just before they exit the boat into the engine bay.

 

Has anyone got a helpful tip of how to plug the black flexiable engine hose pipe while I unblock the Webasto?

 

Cheers

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56 minutes ago, Kelbs said:

This is exactly what's happening, water in the first 50cm of pipe is heating then nothing.

 

So it's sounding like there is an airlock at the circulation pump. If I remove the pipes connecting to the webasto a large portion of my water will drain. In heinsite I should have put isolators on the pipes just before they exit the boat into the engine bay.

 

Has anyone got a helpful tip of how to plug the black flexiable engine hose pipe while I unblock the Webasto?

 

Cheers

 

Not tried it on Webasto.hoses, but when working on cars I have temporarily clamped hoses with mole grips.

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The diagnostic software enables you to run individual components, like the water pump and the fuel pump.  So you set the water pump running and give your flexi hoses a  quick squeeze to shift the airlock.

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1 minute ago, Boredrider said:

The diagnostic software enables you to run individual components, like the water pump and the fuel pump.  So you set the water pump running and give your flexi hoses a  quick squeeze to shift the airlock.

Good idea, but as it’s a centrifugal pump so if there is a big air bubble in the pump it will never clear as a centrifugal pump can't shift air.

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5 hours ago, Tash and Bex said:

jury rig a couple of short pipes to the heater, stick em in a bucket of water, if she starts give her a while until you have a bucket of steaming hot water! 

 

if you have trv's on your rads replace one with a conventional rad valve (usually the towel rail) and then there is always going to be a flow. if you have a single pipe circuit for your heating then i am afraid your rads can't have trv's and must all be "on" at all times

There is only one TRV on one rad. The other three rads have standard valves and all of the radiators are teed off the flow and return pipes.

 

19 minutes ago, cuthound said:

 

Not tried it on Webasto.hoses, but when working on cars I have temporarily clamped hoses with mole grips.

I was considering clamping the pipes shut but can't picture a situation where air wouldn't find its way into the unit again. The header tank is about 30cm from the ceiling in the boat and I would have thought this would have bleed any air out naturally.

 

If I bleed all water from the webasto, while the flow and return pipes are clamped shut, then reconnect the pipes but don't turn the unit on, will any air caught in between the pipes (where they were clamped) and the Webasto make its way naturally to the header tank? Is there a way to bleed the circulation pump? Possibly by releasing the screws on it?

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1 minute ago, Kelbs said:

There is only one TRV on one rad. The other three rads have standard valves and all of the radiators are teed off the flow and return pipes.

 

I was considering clamping the pipes shut but can't picture a situation where air wouldn't find its way into the unit again. The header tank is about 30cm from the ceiling in the boat and I would have thought this would have bleed any air out naturally.

 

If I bleed all water from the webasto, while the flow and return pipes are clamped shut, then reconnect the pipes but don't turn the unit on, will any air caught in between the pipes (where they were clamped) and the Webasto make its way naturally to the header tank? Is there a way to bleed the circulation pump? Possibly by releasing the screws on it?

In case you missed my post whilst you were typing it was - it’s a centrifugal pump so if there is a big air bubble in the pump it will never clear as a centrifugal pump can't shift air.

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4 minutes ago, Chewbacka said:

In case you missed my post whilst you were typing it was - it’s a centrifugal pump so if there is a big air bubble in the pump it will never clear as a centrifugal pump can't shift air.

Thanks Chewbacka, very helpful. Have you any idea how I would be able to remove the bastarding bubble from the system without creating more airlocks?

 

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8 minutes ago, Kelbs said:

Thanks Chewbacka, very helpful. Have you any idea how I would be able to remove the bastarding bubble from the system without creating more airlocks?

 

You need to let the air out, so loosen the highest joins and that is where the air should be. I would also then clamp a pipe going to the pump then loosen the joint on other side of the pump and let a bit of liquid out hopefully bringing any air with it, tighten the joint, then repeat for the pipe on the other side of the pump.

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14 minutes ago, Chewbacka said:

You need to let the air out, so loosen the highest joins and that is where the air should be. I would also then clamp a pipe going to the pump then loosen the joint on other side of the pump and let a bit of liquid out hopefully bringing any air with it, tighten the joint, then repeat for the pipe on the other side of the pump.

Thanks Chewie, will give it a go when the sun comes back. I think I will try that but without the clamps, as if bleeding a rad. Feeling optimistic.

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13 minutes ago, Kelbs said:

Thanks Chewie, will give it a go when the sun comes back. I think I will try that but without the clamps, as if bleeding a rad. Feeling optimistic.

I don’t know how your pipes lie, but if the pump is a low spot you need to have flow from both sides and without clamping you might not. 

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I checked the header tank was full and pulled the pipe off the Webasto and put it back on again within a matter of five seconds. I would guess I lost around half a pint of water but the air was purged and the Webasto then operated as expected much to my reief.

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12 minutes ago, Cheshire cat said:

I checked the header tank was full and pulled the pipe off the Webasto and put it back on again within a matter of five seconds. I would guess I lost around half a pint of water but the air was purged and the Webasto then operated as expected much to my reief.

All done then.  You have earned a beer.

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Cool. I'll start by loosening the jubelie clip then wriggle the pipe. If nothing happens then I'll take it off. Update tomorrow 

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Unbelievable, well not actually, about par for the course.

 

I asked for a decent diagram showing the pipe runs and angles so we could advise on the best way to approach the suspected air lock that could be nearly ANYWHERE in

the system.

 

What is this black engine  hose that needs blocking while the Webasto circuit is dealt with? Central heating circuits and engine cooling circuits should be totally separate systems - that is unless the OP has for some reason put his Webasto in series with the engine cooling circuit. The automotive fitting instructions may well have showed the Webasto heating coolant but not on a boat.

 

In my view it is probably best to now drain down the system saving the liquid and then fit bleed points at any point where air could collect. If the OP is using blue antifreeze he is likely to go through all this in two year's time.

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Tony, I appreciate that you've taken an interest in this post and are trying to help however you are being patronising and unnecessarily rude. There is no need for it.

 

Yes the Webasto circuit is separate to the engine coolant system, I have used the black flexiable engine hose to run from the webasto unit to the bulkhead where they join onto the 22mm speedfit pipe.

 

I'm not ready to drain over 50L of fluid from the system just yet. I would prefer to eliminate the other possibilities first and save the worst until all other options have been eliminated.

 

Hence following advice from others first. Especially when the advice is from people who have experienced what seems to be the same issue.

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21 minutes ago, Kelbs said:

Tony, I appreciate that you've taken an interest in this post and are trying to help however you are being patronising and unnecessarily rude. There is no need for it.

 

Yes the Webasto circuit is separate to the engine coolant system, I have used the black flexiable engine hose to run from the webasto unit to the bulkhead where they join onto the 22mm speedfit pipe.

 

I'm not ready to drain over 50L of fluid from the system just yet. I would prefer to eliminate the other possibilities first and save the worst until all other options have been eliminated.

 

Hence following advice from others first. Especially when the advice is from people who have experienced what seems to be the same issue.

And you think that I have not come across it on other peoples boats?

 

You were asked for certain voltage readings by more than one person and for whatever reason failed to give them. As far as can see you have yet to confirm those voltage readings you did give were taken while the system was trying to start. long experience  by myself and others indicates that the symptoms you gave at the start were completely consistent with a lack of voltage at the glow plug. Once you established a voltage that seemed to be sufficient the next logical thing was that the glow plug was for some reason not warming the fuel enough so logic dictated the glow plug may be faulty.

 

You did not come back to explicitly state that you had not fitted  dip tube into the tank, that was left as part of a longer answer.

 

Only then did you give the vital symptom that the heater was getting hot itself and the cutting out. That clearly indicated that the most likely problem was an airlock and I explained where it was most likely to be and so this could be confirmed asked for a diagram that you seem to have ignored. You do not seem to appreciate that every boat is different and what works for one individual may or may not work for others so further information is needed to provide a solution that is most likely to succeed. So far you have deemed it unnecessary to provide that information.

 

Then, while apparently blundering about trying random cures that worked on other boats or while contemplating doing so, you start talking about "the black flexiable engine hose pipe". This phrase without any further clarification or qualification suggest that you had piped the heater in series with the engine as is normal for arctic spec automotive installations. As far as I can tell your approach does not seem very competent.

 

If, in the absence of any diagram, the airlock is in the heater unit (I think the circulation pump is part of the unit) and if it has been installed in the manner I indicated is typical then you do not need to drain down 50 litres of liquid. All you need to do is to plug the header tank outlet and drain sufficient to drop the lever in the system below the heater. I expect the radiators will stay full of liquid even though their tops may be above heater level. In fact the only liquid likely to escape is that in the hose/pipes close to the heater (assuming the pump is in the heater).

 

I also do not understand the need to block of clamp a hose. The hose you take off is normally easy to block with your thumb while you need the other waterway/pipe open and connected so the head provided by the header tank can force any air out of the pump. You will lose some liquid but as long as you are competent it will only be a pint or so.

 

I have tried to make allowances for someone who is not technically competent but who is trying to do the job but when requests necessary for a reliable diagnosis seem to be ignored, symptoms are withheld for some reason, and there is a careless use of language that leads to confusion I wonder about the motives of the person asking the question. If you want help you have to help yourself as well, do not expect forum members to be mind readers. I think that your first sentence shows the up-most bad manners and is intended to divert any blame (that is probably too strong a word) from your own conduct.

 

I have spent best part of 45 years trying to get apprentice mechanics to follow a logical diagnostic procedure and not simply say "last time the problem was xxx so I will change that".  They need to collate ALL the symptoms (not just some of them) then work out a list of possible causes starting with the most likely/easiest to test and finishing with the most unlikely/most difficult to test, then work out suitable tests and finally do those tests and consider the results. These are the steps I have tried to follow with your problem except your method of working frustrates this and eventually frustrates me as well. Look back over all sorts of topics and you will see that all too often we ask for more information and the request gets ignored, not just from my requests for more information but from many others who know their stuff. This sort of conduct does the OPs no good at all. We can not help people who will not help themselves, we can only try.

 

 

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If you're only getting a little bit of smoke and the unit isn't starting up, it's far more likely to be a lack of fuel than a lack of volts.

If you've got fuel but not enough volts there will be clouds of white smoke.

If the unit runs for about three minutes and stops it's usually because of a failure to ignite caused by one of the above.

If it fires up but cuts out after about 10-15 minutes it's overheating because the coolant isn't circulating.

 

Have an empty jar or receptacle handy before this bit.

Check you've got fuel by disconnecting the fuel pipe from the fuel pump inlet and suck on it. If you get a decent mouthful of diesel, there's no air leaks on the supply side.

Once you get that far, reattach the fuel pump inlet pipe disconnect the fuel inlet at the webasto and start the webasto while sucking on the pipe from pump to webasto.

It should spit fuel with each click of the pump, again of you get a decent spit of fuel, there's no air leak on the fuel supply so reattach it to the Webasto.

Now with the pipes firmly reattached, restart the webasto. On my Eberspacher it takes about 4 attempts from this stage to get enough fuel up to fire. You should find the fuel vapour clouds increase each attempt until it eventually runs.

If you get to this stage and it still doesn't run, there's an electrical issue or, because of previous attempts, the unit might have locked out and need resetting (you'll get an error on the display in that case). On my Eberspacher, this is done on the controller, I don't know about Webasto.

 

I hope this helps.

 

Rob

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Thanks for that Rob.

 

I finished work late today and am knackered so didn't give bleeding the unit a go, however I gave it a token start up while it was going through the start up and I could hear the water pump going I gave the hot water flow pipe a wiggle around, in between the Webasto and the bulkhead, trying to move anything along. There were several big clunks which happened. I'm not really sure how best to describe it but the pipe moved when the clunk happened and it sounded like something was having trouble passing through the pipe.

 

Is this possibly air inside the Webasto trying to get out/restricting the water flow? It felt as though it was on the flow pipe (hot water leaving the unit).

 

Beau

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In terms of wiggling or even taking a pipe off you will find it much easier to do when the pipe is hot. It's much more pliable. The air lock theory could be a complete red herring because your system has never worked whereas mine did prior to replacing the radiators. Anyway, worth a try and then its back to the electrickery.

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11 hours ago, Kelbs said:

Thanks for that Rob.

 

I finished work late today and am knackered so didn't give bleeding the unit a go, however I gave it a token start up while it was going through the start up and I could hear the water pump going I gave the hot water flow pipe a wiggle around, in between the Webasto and the bulkhead, trying to move anything along. There were several big clunks which happened. I'm not really sure how best to describe it but the pipe moved when the clunk happened and it sounded like something was having trouble passing through the pipe.

 

Is this possibly air inside the Webasto trying to get out/restricting the water flow? It felt as though it was on the flow pipe (hot water leaving the unit).

 

Beau

Hi,

Sorry no idea, could be but it's unlikely to affect the running at this stage. Assuming there's a decent amount of coolant in the system, I'd get it running first then worry about the water flow side.

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