The Good, the Bad the Webasto ....

[Ray Davis]

Ken went out to the hangar today and removed the burner unit, and brought it to my house (I'm still working).

At a quick glance, without taking the unit apart further, there appears to be some leakage on the input banjo tube perhaps near the base where it is screwed in. In looking at this is obvious that this unit had been upgraded prior. It is a 10 bar pump.

BUT, it seems that a couple of things were done wrong:

1. The gaskets at the bottom to seal around the in/out pipes are keyed. There is a left and right gasket, and it appears that the input side is either backwards, or the wrong one. It got pretty mangled, and was letting in air. This would cause the white smoke I was seeing.


2. The banjo washers don't appear to be correct. They are much bigger then the new washers which came with my upgrade kit. The upgrade washers are very very thin, while the two washers on the banjo bolts in the unit right now, are different sizes, and much larger than what I purchased.

I'm thinking that is where the real issue is right now.


Ray

[JIM CHALOUPKA]

From what you are saying Ray you are right on top of it. Seeing everything first hand is definitely an advantage.
Some of your comments throw up red flags for you to investigate before you proceed.
That is, the incorrect gaskets and assembly of the banjo: Examine all the parts you have with a magnifying glass to be sure nothing is damaged. Cracked body, stripped threads, crossed threads nicks and like that. I'm wondering why there was the incorrect gasket and assembly? A banjo at its best is not very desirable in my book but that's what you have. If it does not assemble perfectly you will have trouble!
I'm not sure what you bought. Was it the repair kit with the bearing the banjo kit or the whole pump. Do you have a way to test it on the bench, like with a drill and bucket?
JIM

[JIM CHALOUPKA]

Ray, I read some of the previous posts and now know what parts you bought.

[blacklab]

Ray, when I took mine apart, the copper washers were thin. The new ones are thicker with some sort of "fiber" material on the inside ring. The bolts had a blue sealant on them as well. It fixed my leak. Still have white smoke on startup. I can live with that though.

[Ray Davis]

That's interesting, as my new washers are really, really thin.

I'll have to look at the service manual to see if I should be putting sealant on them.


Jim, I used the wrong word. When I said gasket, I mean "grommit". There are 4 rubber grommits surrounding the burner housing to make it air tight. There are left and right variations of these, and it won't work, espcially on the banjo tubes, if you try to use the wrong grommit.

Ray

[ChuckWall]

Ray - I am a little concerned over my comment yesterday about the upgrade pump kits and nozzles. My experience with Prevosts is limited to the Webasto units installed by Prevost - these are 24 Volt units and are higher BTU output than are used in Aquahot units. The burner units are very similar and many parts are interchangeable - but I've been buying service parts from Prevost or at a truck repair facility familiar with the Webasto Vehicle heaters as common items. I have also worked on Aquahot and bought my parts for those Webasto burners from Aquahot (Vehicle Systems). The more I read about this problem the more concerned I get about what kind of a mix of parts you may be looking at. I suspect Jim is seeing the same issues. Just be sure the parts manual and the repair manual are both for the Webasto burner you have. Bottom line - if you have an 80,000 BTU unit you need the right parts for it. It is different than the 45,000 BTU units. My coach ('94 Liberty) has a DBW2020 Webasto in it (80,000 BTU). The .35 nozzles are for a DBW2010 (45,000 BTU). The fuel pumps are different part numbers however the "banjo fuel pipes, bolts, and washers appear to be the same part numbers. Mike's drawings and parts are correct for a DBW2020. My previous comments assumed that you were working on an Aquahot unit. I am not familiar with which system may be in your Marathon. It will take more research than I have done to determine how many parts are interchangeable but the nozzles, for one, are not.

[MangoMike]

Model DBW2010 (45,000 btu's) - In the Marathon H3-45

Uses the .35 nozzle part # 5088641a for $21.

Model DBW2020 (60,000 btu's) - In the Liberty

Uses the .6 nozzle

There's also 12v and 24v Webasto units out there. But it seems, like ChuckWall said, that a lot of parts are interchangeable.

Mike

[MangoMike]

These are the grommits Ray is talking about, that surround the fuel fittings.

gromet_7206_2.jpg

gromet_7204_2.jpg


Mike

[JIM CHALOUPKA]

Model DBW2010 (45,000 btu's) - In the Marathon H3-45

Uses the .35 nozzle part # 5088641a for $21.

Model DBW2020 (60,000 btu's) - In the Liberty

Uses the .6 nozzle

There's also 12v and 24v Webasto units out there. But it seems, like ChuckWall said, that a lot of parts are interchangeable.

Mike

That's interesting to see the difference in the BTU sizing between XL Liberty and H3 Marathon.
Doesn't the H3 have more interior volume than an XL, yet it has a smaller burner??
So Mike is the XL warmer or does the H3 have more insulation and is just as warm, or can't you notice the difference.
Does it show up in the hot water supply in any way.

A couple side question I have.
When one has bus heat I assume that heat comes from engine coolant when running down the road.
If that is so, how is the Webasto linked to it? Is it in the same water circuit or is it a separate and independent system that has it's own heat exchanger "radiators" and piping?
If the Webasto heats the potable water and is linked to the engine coolant, when running down the road does one need to run the Webasto for hot potable water??
Also? (radiators = baseboard fin tube) or (radiator = radiator with fan for hot air)?? which one??

Further if the Webasto pre-heats the engine coolant if required, is that always the case every time the Webasto runs for heat and potable hot water, or must one switch it to that mode when required??

I assume the Webasto makes all the hot water on the bus, does it then heat the engine coolant if you are camped out for an extended time even in a hot environment and when engine heat is not necessary??

[Joe Cannarozzi]

It is using engine antifreeze. Some hot water heaters have a heat exchanger so engine heat keeps hot water and most installations have valves giving the operator the ability to isolate different aspects of that Webesto. Inside the coach the heat is fan forced.