Eberspacher BN-4 Install in a 1979 Westfalia *PIC HEAVY*

[Ian]

Alright, early this year I had a customer ask me to install a gas heater for a reasonable price. Since new Espars and Propex heaters are pretty expensive, we opted to source and install an original Eberspacher BN-4. I bought a used BN-4 unit from VDubTech in New York, and I did some extensive searching and found the heater ducts on here from a fella in Virginia. Sweet! I had an early heater so I cleaned up the fan grill and used it to avoid having to install the fresh air circulating ducts. I soaked the fuel pump that came with the heater in marvel mystery oil over night, hit it with 12volts, and it loosened up and started working! I got the heater running on my workbench before doing any final install. This was one of the more involved projects I've ever done and took quite some time, ofcourse I wanted it all to be perfect. Anyway, I wish I had one in my Bus!

Here is the heater on my extremely special top secret test stand

This Bus had an auxiliary battery setup on the drivers side where the heater was going, so I had to relocate that. I fit a battery box under the back seat and put the battery in there. When I was removing the wiring, it turned out that this auxiliary battery wasn't even hooked up to begin with!! So the customer told me not to worry about running cables for it, but it is under the back seat now if he does ever want to hook it up.

Fits like a glove with less than an inch to spare to the front door and an inch to spare on the top between the seat.

I used a picture I found in the gallery to determine the rough size of an original heater duct hole.

I carefully cut the hole with my air grinder.

This is how the outlet duct will fit.

This Bus also had the refrigerator option, which the cooling element interferes with the heater duct. The fridge wasn't working anyway, so we turned it into an ice box and removed the cooling element.

I installed a piece of space shuttle insulation then a piece of 1/8" baltic birch.

So, basically with this cabinet installed, the heater will vent out of the bottom of it and out of the top of the rear most compartment. Now the metal grates on that cabinet make sense!

I made this template for the firewall hole that has to be cut.

Gas tank side

What I do for the heater control is wire it all the way hot. I mean, if your heater is on you want it hot right. So I used an old piece of choke cable and wired it open.

Scored some foam tape from my local ACE.

Tape all the ducts where they enter and exit.

I clamped the fuel vapor lines to prevent fuel vapor from entering the heater ductwork.

I test fit everything a bunch.

_________________
All your Buses are belong to us.
Love and good roads!
IN LOVING MEMORY OF ROB CRESS 1968-2012

[Ian]

Here is the heater just sitting there, not bolted in.

I couldn't come up with the exhaust pieces and the one local guy who sells gas heaters didn't want to sell me any of them, so I made my own from stuff I found at Advanced Auto.

Oddly enough I had just the right size hole saws laying around my shop, so I cut a couple holes.

Exhaust

Intake snorkel. Funny thing is I had a 1971 Bus come in months later that had a factory Eberspacher that had been removed a long time. I looked underneath and the snorkel was in exactly the same spot I put this one in.

I used a piece of Super Beetle defrost tube to go from the heater to the snorkel. It fit perfectly on the heater, but had to be slit to be a little bigger to fit over the snorkel. So I used some aluminum duct tape to seal off the minor slit, after hose clamping it on the snorkel.

Install a brass t-fitting in the fuel line. I did put hose clamps on everything after this pic was taken.

Drilled a hole in the engine bay and put a rubber grommet on it for the 5/16" fuel line to go through. Also had to relocate the FI relays a little bit to the right. Use short screws so they don't go into the gas tank.

Here it all is without the heater.

I used all original VW electrical connectors.

For the switch I used an old defrost switch because I couldn't find a knob for my NOS timer switch. I ran the wire from the heater through a factory grommet that used to be for the fridge, and then through another factory grommet on the base of the driver's seat, and then put the switch on the base of the drivers seat as well.

After that the heater was basically installed.

We put the interior back in which was fairly involved since it had to all come out.

A few months later I replaced the engine bay seal.

That's basically it. It did take me a long time to do this, but I think it was well worth it. Obviously you can't sleep with one of these heaters running, but it really does heat the Bus up good when you're on the road.

Any questions feel free to ask. I have a lot more pictures in my gallery, but this is the condensed version.

Hope you are all staying warm!!

Later
_________________
All your Buses are belong to us.
Love and good roads!
IN LOVING MEMORY OF ROB CRESS 1968-2012

[busdaddy]

Nice work, for the ease of future installers the hole dimensions are in my gallery here: http://www.thesamba.com/vw/forum/album_search.php?...t_dir=DESC
_________________
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[germansupplyscott]

great job. the BN4 is a very good heater. in many ways it's better than the BA6, mostly because it makes almost as much heat and it is far simpler. the late BN4 that you used is the best one. if the heater doesn't have a metering pump, pass it up and find one that does.

if you were to get the outlet ducting (the orange part) from a camper - yours is from a passenger bus - you could duct the hot air through the bench into the back cabin. right now it looks like it dumps into the bench. you need the metal outlet piece, the flexible duct and the little metal duct end that screws to the bench. and you'd have to drill a 70mm hole in the bench, that would not be a deal-killer for me since it's still a 'factory' install and the warmth is worth it!
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SL

[obnoxiousblue]

Great work, I wish I had this as a resource a few weeks ago when I did my BN4! I'm curious why after all that work, why you didn't opt to install the thermostat cable though? I'm not trying to slight the work involved, looks like you really did a very nice install, it just crossed my mind.

I've been trying to figure how to rig my exhaust too... I can't find any accordion style exhaust tubing that is the same diameter as the exhaust outlet, or any adapter for that matter either. Also, what did you do for a seal there? It looks like you have a rubber O ring... I'd be curious what you did.
I also see that you have a exhaust pipe under the bus, did you make that?

Lastly, is it necessary to have a duct to the fresh air inlet? We're you used the super beetle vent tube, I have nothing... Should I?
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Mike
1964 Beetle
2001 Eurovan Camper

[germansupplyscott]

ok, i totally missed this part of how the heater is now using the 'duct' for the refer. that's great. and the early stuff i was talking about wouldn't work with the late bench/fridge cabinets. so part of my post above was a red herring.
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SL

[Ian]

[Ian]

[obnoxiousblue]

I guess you're right about the cable.

Curious about what diameter accordion style exhaust tubing you used. I couldn't find anything that was a good fit in the exhaust outlet of my BN4.

Did you thinkit was nessecary to have some sort of a seal between the accordion exhaust pipe, and the outlet on the heater itself?
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Mike
1964 Beetle
2001 Eurovan Camper

[Ian]

I bought the smallest size I could find. Then I made this adapter piece.

https://www.thesamba.com/vw/gallery/pix/1004046.jpg

I used one of those clamps to hold the adapter on the heater, then I used another of them to hold the accordian tube to the adapter.
_________________
All your Buses are belong to us.
Love and good roads!
IN LOVING MEMORY OF ROB CRESS 1968-2012

[obnoxiousblue]

That's what I had to do also. I half thought you might've found a more "elegant" solution. I'm not sure if you were able to get a good fit from that small adapter piece to the heater, but I made 4 relief cuts (think at 12 o'clock, 3, 6 and 9) that way the clamp was ale to "crush" the pipe down and get more grab.

Do you know what diameter you used?

Sorry to be a pain!

-Mike
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Mike
1964 Beetle
2001 Eurovan Camper

[Ian]

I WANT to help other people doing the BN-4 conversion.

I also made a couple relief cuts and flared the end so it would look half decent. Don't remember the sizes we just kinda bought a bunch and made something work.

Here is that pic from German E-Bay. You can see how they amputated the outlet and had some other thing going on.

One of the images on here I used for reference.

I prefer era correct installs, so yeah this style of heater was original for pancake Type 4 engines and is commonly called the fuel metering version because of the piston action pump.
_________________
All your Buses are belong to us.
Love and good roads!
IN LOVING MEMORY OF ROB CRESS 1968-2012

[obnoxiousblue]

Great stuff. Good to hear you had similar methods. Reassures me a bit.

My 77 has a BN4, I deciphered the M code plate and its evidently a factory install which was cool. I recently rehabbed my system, and just a week or to ago got it fired up. Everyone here, and posts like yours were a bg help.

Heres my rebuild

Thanks!
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Mike
1964 Beetle
2001 Eurovan Camper

[jmstu76]

Awesome write up. I would love to do this. I have a full BA-6 but I don't want the hastle of tryin to make it work correctly.
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James

'76 Deluxe Sage Green Westy
2258 cc GD case 78mm CW crank, 2.0 H-beam rods 5,325” 22mm pin, JE forged pistons with 15cc dish, JE rings, type 11 clearanced oil pump, CB Eagle 2205 Type-2 “Torque Special” hydraulic cam with matched lifters fed by CB Dual Weber 40 IDF MX with 6” foam air filters, currently 55 idle, 130 main, 200 air correction, 32 mm venturis. 27in General Grabber AT2 All Terrains, Berg Shifter, stock '76 exhaust HPC Ceramic Coated. 11/18/2020

[VDubTech]

Great job, very nice install. I'm glad the heater worked out for you and your customer!!
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First Trip in the RustyBus:
http://www.thesamba.com/vw/forum/viewtopic.php?t=279077&highlight=

[zaakystyles]

Days like today, are the days I wish I would of bought that heater before your friend did.

I then remember my set up with Dual Carbs gets in the way and a funky install would occur instead. I rather stay away from that.

Might as well keep my warmer clothes on anyways.

[thewalrus]

Great thread!!!!

I have a BN-4 and want to eventually put it in my '75. This is what I started with. Got it for free from a friend!

After I cleaned up the motor I ended up with this:

My question is, in your original install it doesn't look like you have the white plastic vent tube installed and just used a metal cover. Do you have to have the plastic tube in order for this to work?
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'73 Transporter 1.7L Dual Carb

[busdaddy]

[thewalrus]

[Lencki]

Wow that is awesome in so many ways. I'm looking to install the same heater in my 78 westy deluxe. I have the luxury of having fully functional components on the inside so am not looking to lose anything to get heat. Which brings me to my questions. 1. Does the aux battery absolutely have to be relocated? 2. Is it possible to run ducting out of fridge and under seat without moving fridge parts? It that what the picture from German ebay is of. It looks like it goes from rectangle to round.