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bsjohnst Samba Member
Joined: July 21, 2007 Posts: 60 Location: Winston-Salem, NC
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Posted: Sat Nov 29, 2008 1:54 pm Post subject: BN4 Gas heater question: carbon deposit on plug prevent fire |
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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 |
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bsjohnst Samba Member
Joined: July 21, 2007 Posts: 60 Location: Winston-Salem, NC
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Posted: Sat Nov 29, 2008 2:14 pm Post subject: Plug Gap |
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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? |
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bmwloco Samba Member

Joined: March 19, 2006 Posts: 1093 Location: Asheville NC
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Posted: Sat Nov 29, 2008 2:44 pm Post subject: |
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According to the documentation I have, plug gap is 2.5 mm (0.1 inch).
Hope that helps! _________________ '85 Vanagon Westfalia |
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bsjohnst Samba Member
Joined: July 21, 2007 Posts: 60 Location: Winston-Salem, NC
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Posted: Sat Nov 29, 2008 4:48 pm Post subject: |
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well... seems as if it is gapped correctly. Still building deposits though
Thanks for the input! Any other suggestions? |
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yellow73kubel Samba Member

Joined: August 17, 2008 Posts: 789 Location: Columbia, SC
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Posted: Sat Nov 29, 2008 7:13 pm Post subject: |
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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. |
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Ian Epperson Samba Member

Joined: January 12, 2005 Posts: 2262 Location: Alameda, CA
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yellow73kubel Samba Member

Joined: August 17, 2008 Posts: 789 Location: Columbia, SC
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Posted: Mon Dec 01, 2008 11:46 am Post subject: |
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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). |
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Ian Epperson Samba Member

Joined: January 12, 2005 Posts: 2262 Location: Alameda, CA
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Posted: Tue Dec 02, 2008 8:25 am Post subject: |
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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 ) version up on Veewiki. _________________ VW-181 shirts and stickers.
http://ian.epperson.com/vw |
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Daddie O Samba Member
Joined: November 16, 2008 Posts: 79 Location: Sacramento, CA
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Posted: Tue Dec 02, 2008 5:45 pm Post subject: |
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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. |
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crofty Judas of the North

Joined: August 09, 2000 Posts: 19760 Location: Land of Whine and Phonies
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Posted: Tue Dec 02, 2008 7:45 pm Post subject: |
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Daddie O wrote: |
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. |
That must be a PITA! _________________ Your Vanagon sucks, Stop waving at me.
HamburgerBrad wrote: |
I slept on crofty's tent once. I passed out drunk from two bottles of Everett's brother's wine. |
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