Jump to content

Webasto 90st with a 60 a day habit


davids3511

Featured Posts

6 hours ago, Mike the Boilerman said:

Assuming this device works in a similar way to a conventional boat webasto I can't imagine the fault being anything to do with the glow plug. The glow plug is only operated during the ignition sequence. 

The problem. We have here is combustion continues correctly for an hour or more then fails. The task is to find out why. The only reason I can imagine is fuel starvation after an hour out so leading to the flame extinguishing, rapidly followed by resumption of the fuel supply injected into a hot combustion chamber hence the clouds of vapour from the exhaust. The flaw in this line of reasoning is there would normally be a flame detection function to cut off the fuel in the event of combustion failure. 

Consequently I conclude there must be two consecutive failures occurring (combustion, then flame detection), OR, I'm barking up the wrong tree entirely. 

 

 

 

That's the problem, without known good components it's very difficult to test. I will say the internals look almost new. I don't know how much use it had before I purchased it but when cleaning the flame detection pin it just popped out, wasn't siezed in at all. Minimum of coking too. 

Link to comment
Share on other sites

The most likely thing to cause the established continuous combustion to cease is removal/failure of the steady flow of fuel. I'd be suspecting fuel pump failure or possibly even water in the fuel. Can you jury-rig up a different and temporary fuel supply with say, a bit flexible tube into a jar of new clean diesel to the fuel pump inlet? 

Diesel heating appliance failures are as often fuel supply faults as appliance faults in my limited experience. 

Did it ever work reliably or has it always done this in your ownership?

Link to comment
Share on other sites

14 minutes ago, Mike the Boilerman said:

The most likely thing to cause the established continuous combustion to cease is removal/failure of the steady flow of fuel. I'd be suspecting fuel pump failure or possibly even water in the fuel. Can you jury-rig up a different and temporary fuel supply with say, a bit flexible tube into a jar of new clean diesel to the fuel pump inlet? 

Diesel heating appliance failures are as often fuel supply faults as appliance faults in my limited experience. 

Did it ever work reliably or has it always done this in your ownership?

It has worked reliably for a month after I bought it. First time there was a problem I had let the batteries run down (or it ran them down itself). I have already drained the fuel and replaced it from another source so no fuel contamination. 

Link to comment
Share on other sites

13 hours ago, Mike the Boilerman said:

Assuming this device works in a similar way to a conventional boat webasto I can't imagine the fault being anything to do with the glow plug. The glow plug is only operated during the ignition sequence. 

The problem. We have here is combustion continues correctly for an hour or more then fails. The task is to find out why. The only reason I can imagine is fuel starvation after an hour out so leading to the flame extinguishing, rapidly followed by resumption of the fuel supply injected into a hot combustion chamber hence the clouds of vapour from the exhaust. The flaw in this line of reasoning is there would normally be a flame detection function to cut off the fuel in the event of combustion failure. 

Consequently I conclude there must be two consecutive failures occurring (combustion, then flame detection), OR, I'm barking up the wrong tree entirely. 

 

 

 

Fuel tank vent blocked?

Air intake getting blocked?

 

Bod

Link to comment
Share on other sites

Webasto's like working hard , once the small tank of water is hot they go into a go slow mode, this causes coking up and is not good for them, my 5 kw webasto heats my hot water tank in about 20 minutes after that the webasto goes slow for about 10-15 minutes and then shuts down completely. restarting it it can get a bit hissy and sometimes just run the fans and pump and sometimes emits white smoke. I have been told that repeatedly doing this can be fatal for the unit.  As the OP's is bigger things may be different but unless it is roaring constantly all the time it probably is not happy.

Link to comment
Share on other sites

2 hours ago, Boredrider said:

Have you seen the manual: https://www.manualslib.com/manual/941151/Webasto-Thermo-90-St-D.html

It refers to flashing light fault codes on the switch - do you have a switch that flashes?

Hi No flashing lights, it's solid on. 

1 hour ago, Detling said:

Webasto's like working hard , once the small tank of water is hot they go into a go slow mode, this causes coking up and is not good for them, my 5 kw webasto heats my hot water tank in about 20 minutes after that the webasto goes slow for about 10-15 minutes and then shuts down completely. restarting it it can get a bit hissy and sometimes just run the fans and pump and sometimes emits white smoke. I have been told that repeatedly doing this can be fatal for the unit.  As the OP's is bigger things may be different but unless it is roaring constantly all the time it probably is not happy.

Not coked up, looks almost new in the burner. 

2 hours ago, Bod said:

Fuel tank vent blocked?

Air intake getting blocked?

 

Bod

Thought of both of these, disconnected air intake and sucked through it, no problem. Left lid off the fuel tank in case it was creating a vacuum but no go. 

Link to comment
Share on other sites

Today, it worked for about an hour then smoke everywhere. Wasn't terrible to start but by end of day it was awful. Have it in tomorrow for diagnostic at Advance Auto Electrics in Trafford park. I think I've reached the end of what I can reasonably try by myself. Cheers to everyone for the suggestions. 

Edited by davids3511
Link to comment
Share on other sites

45 minutes ago, davids3511 said:

Hi No flashing lights, it's solid on. 

 

That in itself is useful information. It tells us the pcb is failing to detect the fault. So (assuming we are correct and the 'smoke' is fuel vapour due to failed combustion) the flame supervision function has failed. Either the flame detection sensor or the pcb has failed, probably. 

Link to comment
Share on other sites

41 minutes ago, Mike the Boilerman said:

 

That in itself is useful information. It tells us the pcb is failing to detect the fault. So (assuming we are correct and the 'smoke' is fuel vapour due to failed combustion) the flame supervision function has failed. Either the flame detection sensor or the pcb has failed, probably. 

Knowing my luck it'll be the most expensive part to replace. How do I replace the PCB or it is s full new ecu at £400?

Link to comment
Share on other sites

That battery voltage sounds a bit low to me. Have you tried a new heavy duty say 150 Ah battery. You need to check voltage at the input to the Webasto.  I have recently seen a new example of this unit all wired with 2.5mm domestic cable through the cheap red type isolator. This resulted in a large voltage drop and frequently cause ignition failure then lock out.Boat service people locally could not reset unit so owner had to pay a premium with manufacturer twice . One more thought, have you got some sort of seal fault on your fuel tank that results in the pressure inside rising when hot and pushing the fuel into the burner above the designed flow rate

Link to comment
Share on other sites

Guys, I think it was resolved today. Battery's aren't up to running the webasto, even wired in parallel. Has it tested and fault codes read and it was showing low voltage (9.4), flame failure and fuel pump error. The tester reckoned low voltage caused fuel pump problem which caused flame failure. 

 

I bought a new battery fully charged (tested it in shop with my multimeter) and the problem immediately cleared up. 

Cheers to everyone for all the help and suggestions. 

 

 

Link to comment
Share on other sites

1 hour ago, davids3511 said:

Guys, I think it was resolved today. Battery's aren't up to running the webasto, even wired in parallel. Has it tested and fault codes read and it was showing low voltage (9.4), flame failure and fuel pump error. The tester reckoned low voltage caused fuel pump problem which caused flame failure. 

 

I bought a new battery fully charged (tested it in shop with my multimeter) and the problem immediately cleared up. 

Cheers to everyone for all the help and suggestions. 

Good to know it's now sorted. This now leaves you with the challenge to charge that new battery up FULLY every day. 

Link to comment
Share on other sites

20 hours ago, davids3511 said:

Guys, I think it was resolved today. Battery's aren't up to running the webasto, even wired in parallel. Has it tested and fault codes read and it was showing low voltage (9.4), flame failure and fuel pump error. The tester reckoned low voltage caused fuel pump problem which caused flame failure. 

 

I bought a new battery fully charged (tested it in shop with my multimeter) and the problem immediately cleared up. 

Cheers to everyone for all the help and suggestions. 

 

 

Glad to see you got it sorted David poor batteries are certainly the killer of any forced air heating system and your feedback is a good reminder battery voltage alone cant always be relied upon to indicate battery capacity or condition.

Rick

Link to comment
Share on other sites

4 hours ago, dccruiser said:

Glad to see you got it sorted David poor batteries are certainly the killer of any forced air heating system and your feedback is a good reminder battery voltage alone cant always be relied upon to indicate battery capacity or condition.

Rick

Had a big panic today when I came back and it was smoking. I though I'd spent £55 on diags and £200 on batteries for nothing. Figured out a gust of wind had blown up the exhaust (will have to fit it better over the weekend) and blown out the flame. Once it was reset all was ok all day for the first time in weeks.

The problem for me was not understanding battery life. In the cleaning world, the equipment we use is fairly light on batteries, a 120ah battery will last 3 days between charges. Our equipment has a shutoff at 11.5v so when I saw the batteries reading 12.05v under load I though they were fine, they are for window cleaning. I think the webasto requires much more umph and I didn't understand that. For me things were pointing at a battery issue but when a spare battery that I though as good didn't make a difference I allowed myself to discount the batteries.

Again, a big thanks to everyone for the help.

Link to comment
Share on other sites

Just  remember that any battery only has a limited number of discharge charge cycles made worse by heavy use and persistent under charging.  A figure of around 200 full cycles is not unusual . If you can operate with 2 batteries used on alternate days you have a better chance of recharging them

Link to comment
Share on other sites

4 hours ago, cuthound said:

Can't you rig it up so the Webasto batteries can be charged by the van alternator when driving between jobs?

Thst should significantly reduce the draìn on the Webasto batteries and help prolong them.

Or just leave the van running like the do on icecream vans.

Neil

Link to comment
Share on other sites

5 hours ago, cuthound said:

Can't you rig it up so the Webasto batteries can be charged by the van alternator when driving between jobs?

Thst should significantly reduce the draìn on the Webasto batteries and help prolong them.

Work is usually tightly packed, I probably only travel 5/6 miles a day. 

1 hour ago, Neil Smith said:

Or just leave the van running like the do on icecream vans.

Neil

Yeah but the ice cream van has someone in it. I might be round the back of a house for a hour with a van running out front with an 9k cleaning system in it. Vans do get stolen for the systems, they are usually found a few days later with no system. 

Link to comment
Share on other sites

1 hour ago, davids3511 said:

Work is usually tightly packed, I probably only travel 5/6 miles a day. 

Yeah but the ice cream van has someone in it. I might be round the back of a house for a hour with a van running out front with an 9k cleaning system in it. Vans do get stolen for the systems, they are usually found a few days later with no system. 

What about asking the customer whether you could plug in a mains battery charger to keep the batteries charged whilst you are doing the cleaning?

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.