The Life and Death of a Gas Heater

[suntour]

After sixteen years of driving without heat, I finally broke down and decided to get my gas heater working. The previous owner had done quite a hack job on the electrical and I assumed that was why it wasn?t working. After rewiring the missing and/or damaged areas I fired it up. To my delight it turned on and started blowing air! However it would not produce any heat and sounded a bit loud. I should mention that I have never heard a gas heater run before so I have no idea what they are supposed to sound like. So I read the service manual and tested everything I had immediate access too and everything worked fine except the fuel pump. It wouldn?t run as it was suppose to.

After a careful read of ?Help me cried the gas heater? on Samba.com I checked the pump and it also works fine, also had almost 12volts (11.85volts) going to both leads on the pump. Hmm.. Must be the something wrong with the 1:33 gear setup like it talked about on Samba. I pulled the heater and removed the orange plastic fan and points cover. Oh, ?there is the problem? I though. There was almost zero gap on the points but overall the points looked pretty good. I did a quick clean of the points, reset the points gap to .018 (manual specs are .015-.02) and put it back together. No luck, still wouldn?t fire up and the pump still didn?t click.

So I removed the heater again, chased out a bunch of spiders out including a stubborn black widow in the exhaust pipe with a propane torch and pulled the blower motor out.



That motor is a pain in the A@&?s to get apart. Then I found the real problem. The shaft for the motor had somehow come loose and ground into the motor casing on the internal fan side; hence the shaft is no longer running parallel inside the casing. That also explained why there was no point gap on the other side of the shaft since the cam was out of alignment and why setting the point gap was so difficult. I also assume that the reduction gearing for the 1:33 pump electrical pulse is also no longer in contact with the shaft and therefore doesn?t work correctly.





So this leads me to a few questions. Is there anyway to fix the blower motor housing? Does someone have a spare blower motor to sell if it can?t be fixed? (Thought I should ask before I contact the heaterman for a replacement, I assume he isn?t cheap.) Is the internal fan supposed to have this notch in it or is it broken too? And does anyone have a picture of where the two wires to the pump come out of the wiring harness? Since the P.O. removed all of this, I don?t know what it is supposed to look like.

Sorry about the length of this post. I hope it makes sense instead of sounding like a long meaningless ramble.

Thanks.

[Bob Ingman]

suntour I have contacted Pierre Macua our resident gas heater expert. We should hear from him before long. Sorry I was not able to help personally but I am gas heater illiterate. Cheers. Bob Ingman

[suntour]

Bob,

Thanks for contacting the heater guru for me. I look forward to hearing Mr. Macua's input. For the life of me, I can?t figure out how the motor shaft got all out of whack? The shaft must have chewed a good 1/8? out of the housing. Go figure?

We need someone to develop a replacement heater unit that runs on those green propane canisters you can pick up at any hardware/sporting goods store. It would eliminate the need for a pump and a bunch of extra electrical wiring.

[pjmacua]

Hello

I'm sorry but I'm not a gas heater expert or guru.
I've just managed to repair mine and I like to understand how it works

Is there anyway to fix the blower motor housing? Does someone have a spare blower motor to sell if it can?t be fixed? (Thought I should ask before I contact the heaterman for a replacement, I assume he isn?t cheap.) Is the internal fan supposed to have this notch in it or is it broken too? And does anyone have a picture of where the two wires to the pump come out of the wiring harness?

The radial fan wheel is balanced so the notch was made at the factory.

You can find several good pictures of my gas heater repair here (near the bottom of the page):
http://www.181spirit.com/tech_chauffage ... ge_bn4.htm

I will be able to send more pictures if you need, in a few days (not at home for the moment).

About the play at your shaft, I'm sorry but I don't know the reason.

Regards
Pierre-J MACUA

[suntour]

Mr. Macua

Thanks for posting the link to the pictures they were a huge help.

I have a few questions for you if you don?t mind. In the picture (chauffage_bn4_04.jpg) what are the two extra components on the external housing for? One looks like a condenser from a distributor with the two green wires? If I am not mistaken the green wire from the motor sends the impulse telling when the pump is supposed to pump (every 33 revolution) and the other has the two black wires (power to the blower motor) that looks like a relay.

Also how did you get the motor housing apart? I can?t seem to find a seam in the casing where I can pull it apart. I think if I can get the housing apart I can solve the motor shaft alignment problem.

Also picture (chauffage_bn4_01.jpg) is perfect! Thanks! I now know where the two wires to the metering pump are supposed to go! And I see that your internal blower fan also has a notch in it. I thought the notches looked to uniform to be broken but I have seen stranger things happen when parts break.

Oh and why did you install the extra ground strap to the blower motor? Or is that something that the European BN4?s have.

Thanks!

[pjmacua]

You're right about the condenser (picture chauffage_bn4_04.jpg). I forgot to tell you that my car is a military Type 181 and that it has got some extra parts like this one: part number 181 035 261B - suppressor condenser. The other one is a relay.

how did you get the motor housing apart?

Did you arrive at the stage shown in the picture "chauffage_bn4_11.jpg"?
Removing the radial fan wheel is the most difficult part. Then you have to remove one clip on the other side and a "spacer".
Once the motor is out of its housing, remove the 2 cover caps (one screw on each end).

why did you install the extra ground strap to the blower motor?

This ground strap was already on the car when I bought it.

Regards
Pierre-J MACUA

[suntour]

Mr. Macua

Yes I did get to stage of "chauffage_bn4_11.jpg". I too found that getting that radial fan off was difficult. That 2.5mm allen head set screw was really frozen in there. I was absolutely convinced I was either going to strip the head out or break the allen wrench with all the torque I was using on that thin little wrench but it finally came loose. Since that fan is in the heart of the combustion area I assume the heat really set it in there, it didn?t want to budge.



I had found a screw on top of the motor housing (combustion side) that was buried under a lot of crud and removed it, hoping that would allow me access to the second set of points and the plastic gear that tells the metering pump when to give a squirt of gas. What I couldn?t find was a seam in the motor housing that told me where the top cap came off. So I cleaned the motor with denatured alcohol and finally found the seam. Gave it a little love tap with a rubber mallet and it popped right off.



After a close inspection I found two problems. One: the motor shaft has also eaten into the lower part of the housing so I assume the motor is now dumpster food. I am, however, surprised that the motor would still run when power was fed to it. But with the shaft not running parallel to the housing it is useless for making the points open and close for the coil accurately, and the spiral gear was no longer making contact with the plastic gear. With out the plastic gear turning the cam that is attached to it, it will not open and close the points for the metering pump every 33 revolutions.



The second problem I found was the plastic gear had damaged teeth, so there was a flat spot and it wouldn?t turn even if it was in contact with the spiral gear. yippy?


(picture of the damaged teeth)


(picture of what the teeth are suppose to look like, please note all the metal flakes from the shaft grinding into the housing.)

So does anyone have a spare motor they want to sell?

[Bob Ingman]

Justin somewhere we have a 181 Swap and Sell Thread. I`ll dig it out and you can make a post there. This thread is going to remain where others can refere to the photos you and Pierre have provided. Cheers. Bob

[suntour]

Does anyone know if the internal/radial fan inside the heater can be rebalanced? I was wondering if mine somehow got out of balance and resulted in the motor shaft eating away at the housing. Could something as light as this fan cause this effect on the motor? Does anyone know a home brewed way of testing this theory?

Oh and Mr. Macua, what does the extra relay on your heater do anyway? If I am not mistaken the suppression condenser next to it would cut down on electrical interference for military communication systems, does the relay work in a similar way?

As long as I am thinking about the BN4 heater, does anyone know if you can get those paper warm air ducts (part# 181-819-325 & 181-819-326)? Does anyone make an aftermarket setup (plastic, fiberglass, metal)? Mine are looking pretty sad.

Thanks you Bob for digging up the sawp and sell thread!

[Bob Ingman]

Justin for the heater parts try Mike Basso at Things Unlimited.
[email protected] Bet he has them. Bob

[Jersey Thing]

Greetings -
I have a question since we are on the subject of heaters. I have a '73 and was curious on how it works, does it pull gas from the tank or do you fill manually, how does one use it? Sorry for the stupid questions.Is there a link that i can read up on the subject?

Thanks


Jersey

[Jersey Thing]

Greetings -
I have a question since we are on the subject of heaters. I have a '73 and was curious on how it works, does it pull gas from the tank or do you fill manually, how does one use it? Sorry for the stupid questions.Is there a link that i can read up on the subject?

Thanks


Jersey

[suntour]

http://www.thesamba.com/vw/forum/viewtopic.php?t=66846

This is the link to the thread "help me" cried the gas heater! on Samba.com I found it to be a great starting point for understanding the mysterious BN4 gas heater. Just ignore the first few lines since there was a bit of confusion as to what type of BN4 they were talking about. We have the one with a metering pump if your Thing is a U.S. model built in Mexico. (Maybe other model Things, but I don?t know? I saw a freaky picture of a square gas heater in a really late model German Thing the other day.)

Jersey Thing, The fuel for the BN4 is sucked out of your gas tank. Turn your wheels to the left or right (doesn?t maker what direction) look at the area between your fenders and wheels to see the bottom of your gas tank. You will see a T in the fuel lines coming from the tank. One goes to you engine and the other should have an inline fuel filter that continues to a metering pump. (Metal cylinder looking part with gas lines coming out of both ends and two electrical wires on one side, covered in crud. you can see a picture of it at http://www.181spirit.com/tech_chauffage ... ge_bn4.htm Under the heading "3- Pompe à essence" Thanks to Mr. Macua.)

This will be bolted to your fire wall by means of an insulated metal loop. This feeds the heater gas.

As for how it works. Turn the green knob on your dash clockwise a little bit and this turns on the heater. All the way clockwise if you want to use the timer (approximately 30 min. timer, used to shut off heater if your engine is turned off but you still want heat, to prevent you draining the battery to much) The red knob to the extreme left of your dash controls the temperature. The more you pull the knob out the hotter the heater runs.

Also I heard this saying some where on this post, I think it was Bob Ingman? "The only stupid question is the one not asked." Believe me I am still trying to unravel the mystery of the BN4, After fixing the wiring on mine and tearing it completely apart I have a much better understanding of how it works now, but I still find my self scratching my head wondering about something or another on it.

Oh, and I think I have a lead on some good parts for my heater. I also received a email back from Mike Basso at Things Unlimited he sells a heater core for $75 or $40 for just the motor (has to take apart a core, personally I would get the core just for the extra parts)

[Jersey Thing]

Thank you...i will try to digest all this and attempt to take a stab at it.

[Kubelmann]

Let me say this about that. The RoMTOC Thing data CD contains all of the current data on the BN-4. For those that are working on their heaters, y'all need to fork out the $10 an get the CD. I have two 73 Things with complete BN-4s and both are cut loose from gas line feed. Both will run when the cars are running as dail rigs/ I have lots to do to get both Things where I dream they will be. I just need to get to that point in my resto goal. K-mann