Eberspacher BN4 info and help FAQ

[Tram]

Oh yeah, and:

IIRC the fuse box layout in all the wiring diagrams is messed up. I think I was looking at it in the beginning going all "WHATHEFUCK!!" then it occurred to me to look at the 1970 diagram in the owner's manual section on here and it was a match.
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Немає виправдання для війни! Я з Україною.

[Tram]

Shit- I hope I am not too late but I just thought of a way easier way to switch your heater power from the aux. battery to the main one. Just go in the jumpseat and take the wire that feeds the heater out of the top of its fuse holder and couple it with the wire that connects the starter battery to the switchover solenoid- the terminal with the wire going down through the floor. Remove the plastic protective cover on the solenoid and add it to the terminal by just lifting the cover up- it slips off. Add an inline fuse.

Bada bing, bada boom.
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[D/A/N]

[notchboy]

Dude. I didnt know most of how it actually worked till I hooked it up.

Like the run time and cycle. I thought when it went of, it was off. Not cooling down then starting up again.

My light stays on when its on. Not with the pump like yours.

Dont get me going on the timer clock That logic threw me at first.
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[scrivyscriv]

Trying to keep the bus BN4 questions in one main thread -
does anyone know how the wires were routed in the bus engine bay? All the BN4s I have use a 6-blade female connector.. one of them came with a pigtail and the male side, but I don't recall seeing anything about how it was wired up. Other than the manuals posted to the site.. which don't get very deep on this particular topic.

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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[notchboy]

How I did all mine.

Gray - wire from the switch all the way back to the heater.
Red - straight to battery.
Brown - to the tail light grounding spade on body.
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[scrivyscriv]

I’m talking about the actual wire routing in the engine bay.
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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[notchboy]

The Red was just hung up and over the top attached to the underside of the engine bay.
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[busdaddy]

On factory M coded heaters the wires were in the same harness that goes across the shroud to the coil and oil switch, the red and grey wires continued on towards the heater in thier own small black tube.
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[scrivyscriv]

Awesome, I was going through the manuals and I found where service installations say to wire it.. it follows the engine harness too. Thanks yall.

Now another question, where do you find info on the different year dash switches?
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Robert in Memphis
Dünkelgrügen 1967 Java Green bug thread
Engine rebuild thread
If you're ever in the Memphis area, you are welcome to stop by for advice and help.

[busdaddy]

[Manfreds78bay]

This has been a great thread! I'm working on a pre 1970 BN4 now! I just got the fan to come one. For some reason the overheat switch just needed to be adjusted.

I'm planning on removing my heat exchanges and the flapper boxes. They are useless. I've never got them to work right.

I'm thinking about hooking my heater lever in the dash up to the thermostat on the BN4. Any thoughts on that?

I also need to figure a way to put the heat to front cabin. I'm not planning on camping in the winter and the defrost is way more practical. I'm wondering if I can pipe it directly from the back to the front without cutting into the rear fire wall. Thoughts? How crazy would it be to hook this thing up under the driver's pan?
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1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

[busdaddy]

[Manfreds78bay]

[orwell84]

[vwwestyman]

I'll quote myself on the heat output specs from my install thread on putting an Espar D2 heater in my Westy.

It sure seems like a lot of work to plumb a BN4 into the stock heating system, and I don't know if the BN4 fan could handle pushing the air that far. You'd probably want a booster fan to help it out. (On my Thing, I've added a flexible duct to the heat output and on occasion it'll blow the fuse as if it is overheating.)

I think Manfried is in the PNW so maybe it doesn't get all that cold, but on a late bay, the factory heater system is the single component that puts out the most heat. The other heaters are boosters/additional heat. (But good ones.)

[D/A/N]

It's a long story, but we swapped out our 181 BN4 switch for a 311 switch and realized it wasn't wired up right. As it turned out, the issue was that K on the 181 switch is keyed power but is ground on the 311 switch. I chased my tail for a good hour and a half before I found this pic that clarified what K is on the 311 switch. All is working well now but damn, why didn't VW just keep their terminal coding consistent? Between the 181 and 311 switch they move between DIN coding and their own inconsistent letter coding.

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'69 Fuel Injected Squareback. "B" D-jet. 1600 with balanced rotating assembly and lightened flywheel. Full flow and external filter.

'70 Riviera. 1904cc w/ 40mm Dellortos, 019 distributor, Steve Tims “super stock” 37x32 heads, Web Cam 218, Vintage Speed SS143 Super Speed exhaust, 1 1/2” heater boxes

[D/A/N]

So.....I guess I'm the only one who has needed help with one of these things in 2019? It's been very quiet over here since January.

In any case, I have my motor out and while waiting for parts I figured I'd look at the heater ducting. I had a suspicion that some of it had become disconnected during the winter because air output volume changed and the area over the gas tank got really warm when the heater was on. Turned out I was right. The middle duct became disconnected from the one under the back seat.

It also looks like our thermostat control cable is way too long. It's for a Stewart Warner heater and the way it's currently set up, it's hard as hell to operate the control knob under the front seat and when looking at it by the gas tank today I noticed the lever doesn't fully open when the knob is at maximum extension.

Here's the question: Rather than continue to make the wrong cable work with the right heater parts, can I just safety wire the thermostat control lever to be fully open and touching the set screw? I don't think we'll ever want anything less than full heat so I don't mind losing the adjustability of the knob.
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'69 Fuel Injected Squareback. "B" D-jet. 1600 with balanced rotating assembly and lightened flywheel. Full flow and external filter.

'70 Riviera. 1904cc w/ 40mm Dellortos, 019 distributor, Steve Tims “super stock” 37x32 heads, Web Cam 218, Vintage Speed SS143 Super Speed exhaust, 1 1/2” heater boxes

[busdaddy]

[D/A/N]