BN4 Gas heater question: carbon deposit on plug prevent fire

bsjohnst

Hello,

I have a 73 thing that is equiped with the BN4 gas heat system. I recently got the puppy to fire up after about a year of not working (safety reset switch and a gas leak in the fuel pump). The heater works most of the time, but it often will not fire up after i've turned it on and off a lot. I found the problem to be a small bit of carbon that joins the electrode on the plug to the metal plug casing- thus preventing a spark and ignition. After cleaning this off, the heater always works normally. My question is: how can I prevent this deposit from forming? I only get about an hour and a half of run time before it happens and my heater stops working. It's getting colder here in NC and it would be nice to be able to rely on my heat without having to pull the plug and clean it after every use! Just so you know, I repaced the fuel filter that is before the fuel pump for the heater, so it is brand new and this did not fix the problem. Any suggestions?

Thanks,
Brendan

bsjohnst · Posted: Sat Nov 29, 2008 2:14 pm Post subject: Plug Gap

One more thing I meant to ask: Does anyone know what the gap on the plug for the BN4 is intended to be set to?

bmwloco · Posted: Sat Nov 29, 2008 2:44 pm Post subject:

According to the documentation I have, plug gap is 2.5 mm (0.1 inch).

Hope that helps!
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'85 Vanagon Westfalia

bsjohnst · Posted: Sat Nov 29, 2008 4:48 pm Post subject:

well... seems as if it is gapped correctly. Still building deposits though Confused

Thanks for the input! Any other suggestions?

yellow73kubel · Posted: Sat Nov 29, 2008 7:13 pm Post subject:

I would venture to guess that a carbon deposit would be too much fuel in there and it isn't burning off. Does it smoke at all? Or smell like unburnt fuel when turned on? If so, I'd check the pressure regulator and see if you can't lean it out some.

Do you have the Eberspacher manual? There was a website that had the files, but it seems to have disappeared. I have the manual on my computer if you need it.

Ian Epperson · Posted: Sun Nov 30, 2008 10:07 pm Post subject:

I'm helping Daddie O with his heater right now, and I think something is wrong with the points - suddenly, I need the manual Wink

.

Do you think you could upload it to Veewiki to the BN4 page?
http://veewiki2.webfactional.com/HeaterBN4?action=AttachFile
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yellow73kubel · Posted: Mon Dec 01, 2008 11:46 am Post subject:

It is a large (24mb) .zip file, so I don't think the wiki software will like it. I am trying anyway, if not I will put it somewhere else with a link.

I only have part 1 from the original site. There were 3 parts, but all looked the same, so I deleted the others. The one I have is the VW workshop manual for the BN2/BN4, Kubelmann's CD has the Eberspacher factory manual.

[edit] The VeeWiki site took it fine. Let me know if that archive file doesn't work though (it is a .zip packaged on Linux).

Ian Epperson · Posted: Tue Dec 02, 2008 8:25 am Post subject:

Thanks! (and thanks to Sam for e-mailing me a copy). We got his heater working late Sunday night.

I'll poke around with these copies and see about getting a good (small Wink

) version up on Veewiki.
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Daddie O · Posted: Tue Dec 02, 2008 5:45 pm Post subject:

Ian was a huge help getting my heater fixed. If I recall correctly the manual said the gap should be .4mm but mine was closer than that and wasn't making contact because the little nub on the points was warn. Now the heater works fine as long as I give an occasional whack to the fuel pump.

crofty · Posted: Tue Dec 02, 2008 7:45 pm Post subject:


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