BN4 Restore Help

[Lleach9]

I am restoring a 73 Thing and have recently begun working on the BN4 heater. It appears to have all the parts, but I could never get it to spin up. In disassembling, my first problem was removing the Flame Switch, which did not want to pull out. After a couple of days of work I finally got it out, but I bent the tube and broke the rod in the process, so that was the first clue.

When I opened the case and pulled out the combustion chamber there was some material rattling around inside. I shook out a pile of rust and what looked like asbestos crumbs, the second clue.

I tested the motor and it ran fine, but no spark to either the gas pump lead or the glow plug lead, so I proceeded to access the points to clean up and gap. The fresh air side cleaned up fine, but the hot side was covered in soot and the impeller was a bear to get off. When I did get it off, the points cleaned up but when I tested the capacitor, it appeared to be bad. I then checked the capacitor on other side and it also appeared to be bad.

I'm thinking now that there was some catastrophic heat event that cooked the capacitors, baked the metal-on-metal parts to the point they were fused, and burned off the asbestos layer in the combustion chamber. I attached a picture of the interior of the chamber where, I think, the asbestos should be, and you can see a small remnant left.

Is this a reasonable conclusion? Is there a way to re-insert a replacement asbestos layer, or should I look for a replacement combustion chamber, and new capacitors?

Thanks for all suggestions.

[volkybus]

Well welcome to the world of gas heaters...I`ve been into them for at least 50+ years..and my experiences when they go downyou're in trouble they're all basically the same and the one in my thing lasted till about nov,2017 when it caught fire...they work very well till that happens then I just don`t know....you r a brave man to take it all apart but putting it back to run right....food luck [email protected]. mine lasted for 14 years for me...A guy from Germany who lives in NJ rebuilds them and he goes to the shows.in the Northeast..but they ar e pricy over ,$300+.but they sure work great in Nov in Vt.

[perello]

[Lleach9]

A heater on fire, that means it’s working, right?

I found a non-working donor bn4 locally and it’s combustion chamber is in better shape. That should get me enough working pieces to get it working.

I also found a source for the capacitors in Russia, they will be here in 2 weeks, if they get through the mail system. Should be interesting.

[vwwestyman]

Interested to see how this goes for you.

I got my heater working back in 2014 by cleaning out the mud dobber nests and checking the points and all that, but it has gotten very loud recently and not working as reliably. I suspect a bearing or bearings in the motor assembly have gotten dried out and bad.
_________________
Dave Cook

President, Wild Westerner Club

1978 Champagne Edition Westy, repowered to '97 Jetta TDI
1973 Wild Westerner
My Thing

[[email protected]]

Hello
theres a lot of gas heater parts listed on here or call me

https://www.thingparts.com/gas-heater-and-parts-1973-thing/
_________________
Michael Basso
http://www.thingparts.com
New and Used VW Thing Parts Free advice
CALL 518 630 0173

[[email protected]]

the guy in New Jersey is no longer around
I would recommend Shawn Baker in New Mexico
Pretty good guy
_________________
Michael Basso
http://www.thingparts.com
New and Used VW Thing Parts Free advice
CALL 518 630 0173

[Lleach9]

I had to take a break due to some paying work, finally got back to the BN4 restore.

The Russian capacitors arrived and worked well, but they were a little too big to fit inside the covers for both sets of points. I was able to scavenge the 0.1 uF cap from the donor unit I acquired and the 0.15 uF cap seemed OK, giving me a good fan with properly energized points.

I finished cleaning things up and gave the case a few coats of paint and put it all back together. I mounted the unit and pump on a couple 2x4s to test.

I fired it up, and once the pump was primed, I hear the sweet sound of combustion in the chamber and heat coming out the proper end!

There is a little black smoke, so I will play with the fuel pressure adjustment, and I'm not sure the flame switch is adjusted correctly, it did not shut off the fan after the 2 min cool down. A little more testing before I put it back in.

Another discovery was the fuel supply line, I'm glad I didn't try to fire it up before pulling it.