BN4 Eberspacher Restoration and installation - 72-78

[sebgi1]

Thanks! Points were already clean. I had the light connected to the negative side... Now that works perfectly. I will reassemble everything and test it soon.
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SEB

Dogs are the most precious and valuable possession of mankind. VWs are second!

'73 Neptune blue safare camper
'71 Neptune blue tintop

[cmonSTART]

We've all done it...
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'78 Bus 2.0FI
de K1IGS

[livingskies]

I did go through many of the pages of this thread looking for the short and clear version. Can anyone help me with or point me to a relatively brief description of how the heater works, where the controls are located and how to use them, and of what to check before trying it. As you can tell, I don't know much about this.

My '74 Westfalia has a gas heater lurking on the left side of the engine compartment. As far as I can tell, it looks complete and not abused. The main advice that I recall about gas heaters in the Beetles (as in my '68 Beetle) is "don't use them and disconnect them" once they get a bit older. But I'm hoping that it is not too much trouble to resurrect the heater in the Westfalia.

[notchboy]

I have lots of vids on my channel demonstration function and what to look for.

Relax and have a browse.

https://www.youtube.com/channel/UCgCoLgTcj6CLShstmF-00gw?view_as=subscriber

Ignition on, turn the green knob on the right side of the volume - just slightly to the right. That will turn the heater on and the knob should be lit green now. If you twist the knob more to the right, you will be winding the timer clock portion. Not a big deal but you will heat it ticking.

If your heater is working, you will hear it on - the fan spinning and the pump ticking. Tic, tic, tic. If you only hear the fan spin, then the heater will not run as the points are probably fouled and the pump won't work.

If you do hear the fan and the tic, then make sure you don't see leaking gas from old fuel lines. If the heater is working, then it should fire in about a minute.

If it does not fire, then the spark/glow plug may be bad or the points to the coil are fouled.

There are several more simple scenarios - but take the time to look at the vids first. They show function and restoration/troubleshooting.

Good luck and let me know how it goes.
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[livingskies]

Thanks, notchboy. I did look at a number of your videos and can see that you have lots of experience with these heaters.

I spent a bit of time on mine. I now know that it is a BN4, which is more than I knew before. The control/knob on the dash turns, lights up, and ticks. All the fuses appear good, unless I am missing one somewhere. The fuses under the dash and the one in a twist holder near the heater are good.

I removed the plastic top cover and checked for power in there. One terminal on the front block is live when the system is turned on. I'm wondering what the small red switch inside the cover is for? It moves to the vertical I and then springs back when released.

Both leads to the spark plug were disconnected. I reconnected them. Still nothing. I did not pull and test the spark plug or glow plug functions, mainly because it looks very tight between the heater and the bodywork, and I'm not sure that a plug wrench will fit in.

One lead to the heater fuel pump/controller also was disconnected and hanging nearby. I reconnected that. Still no response from the unit. Neither terminal at the pump has power with the key and heater switch on.

Wondering what the next steps would be. Any help appreciated.

[notchboy]

There is not going to be an easy fix by putting a plug back on. These heaters get sidelined for the simplest of issues. It needs to be pulled, tested, and cleaned. That's the premise of this whole thread my man. If they sit for any duration with no use, then things get corroded - namely the points on the fan - the heart of the operations of the heater.

Pull the plug, verify its good.
Put a test light on the pump leads to see if they are getting a pulse.

Ill bet they both fail.

Oh or pull it, send it to me and Ill restore it for $300 plus parts if needed.
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[livingskies]

notchboy, I would love to send the heater to you. But considering that I am in Canada, your reasonable fee likely would be triple what it would cost if I was south of the border - after money exchange, international shipping two ways, taxes, and duties. Since this bus likely will only see summer use, some may say that having the heater in good condition may not matter much. But I like to have things working as they should. So I have not given up.

I did look at removing the unit; that looks a little daunting. So I thought it best to find detailed instructions for the best way to do that, if such instructions exist. Experience tells me that trial and error usually involves a fair bit of error. If someone can point me to instructions for removal, that would be very helpful.

In the meantime,a bit more tinkering resulted in the fan coming to life; it appears to work well. And the area around the plug became quite hot after having the heater switch on for about ten minutes. I assume that means that the glow plug works, but it does not tell me whether the spark plug portion of the plug works.

There also now is power in one of the leads to the pump. I assume that the second lead is a ground. But the pump does not pump fuel. So, I likely need a new fuel pump. I am wondering where to buy one of those? Or is a generic fuel pump OK? I expect that the flow rate matters.

And I now find that the fuel line is broken off, right at the vertical fitting where it connects to the heater. With the heater still in the van, it looks impossible to work on. I can't even see what that fitting looks like, but it looks specialized. Can anyone tell me where I can find a new fitting and line to run to the fuel pump?

Thanks again.

[vwwestyman]

Don't replace the fuel pump with a generic one!

That pump is set up to meter a specific little squirt of fuel at a specific rate. Those squirts are are timed by the points that are inside the fan housing. When the pump is working, you'll hear a distinctive tick tick tick from the pump with each squirt.

As Jason said, it is very likely those points are corroded and need cleaned up to work.

Also, sometimes the pump gets gummed up, so needs to be freed up-you can usually do that with some carb cleaner, "tapping" it with 12v, and sometimes a wrap with a block of wood.
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Dave Cook

President, Wild Westerner Club

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

[livingskies]

Thanks, I will try that tip for the pump. Just tapping an Austin Healey electric pump often gets that going, but it would be nice to have it more reliable than that for the heater. ebay has lots of Eberspacher metering pumps that the descriptions say are for D2 and D4 heaters. They don't mention BN4 heaters. Can anyone tell me whether those pumps will work, if I can't get the original to work reliably?

I now have removed the heater from the bus. It wasn't as bad a job as I feared. The spark plug has continuity, and glow plug heats. And, as mentioned earlier, the fan works.

To repair the broken small fuel fitting (the tiny piece about an 1/8" diameter and one inch long that the fuel hose fits over is broken off) I can think of two possibilities that may work. It looks as if that small fitting was silver soldered to the larger 3/8" diameter tube that projects from the heater. I might be able to solder that back together and then redrill the hole, to ensure it does not become blocked by solder. Or I could just drill a hole in the end of the 3/8" piece and clamp a piece of 3/8" fuel hose over that and run that down to the pump, using a size adapter at the pump. Can't see why that would not work, and it seems like an easy fix.

More tinkering in the morning.

[pittwagen]

Now that you have the heater out, you need to construct a test station, complete with battery, small fuel tank etc. There are few quick fixes to repairing a gas heater that has sat for years.

There are a number of repair/installation manuals in the Technical section for the 72 and on BN4 heaters. Start with this one. Download and print it off. Choose the German/English/Swedish/French one. Follow every step.

https://www.thesamba.com/vw/archives/manuals/bn4_troubleshooting_and_repair_8_1991.php

With respect to pumps, you need one with a part # 221261467A if yours is no good. Anything with a 311 prefix is for a BN2. Follow the instructions. These are pulse pumps so do not apply continuous power. Just a quick tap. If it clicks, it may be ok.

One other big issue with these heaters is the wiring. Check every connection. The female push on one's tend to crack and fail.

I have reconditioned many BN2's and 4's. About 4 years ago I did a BN4 that had sat for decades, using these instructions. It is now in my 79 bus and has not let me down once.

[notchboy]

https://www.thesamba.com/vw/classifieds/detail.php?id=2329268


Link

Link

Link

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[livingskies]

Thanks for all the help, nortchboy, pittwagen, and vwwestyman. Without this forum, I probably would not have tackled this job.

The heater is now installed back in the bus and working perfectly. This will be nice to have for cool weather camping at our favorite area lakes.

The main issues appeared to have been fuel related. The fuel metering pump was stuck, likely from sitting with old gas in it (freed up with tapping and cleaner at both ends). The fix on the broken fuel fitting at the heater seems to work well. I filed off the solder where the base of the small fitting entered the larger fitting, making for a nice, smooth round surface.. Then I drilled a small hole in the end of the larger fitting. A 3/8" hose, well clamped over the larger fitting, completed that end. At the fuel pump end, the 3/8" hose fits well over the threaded portion of the outlet end of the pump (also clamped). Not completely original, but it works well and was a relatively easy fix. New fuel hoses all the way back to the tank and to the engine fuel pump and a new fuel filter for the heater completed the work.

[notchboy]

Good to hear!
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[The Fez]

Can't seem to find the answer to this by searching so I figured this is where the gas heater brain trust is located. My 74 Campmobile has a working gas heater that I tried out only once - on a camping trip in mid-June a few years ago where I did a one-night stay at elevation enroute and it snowed. I used to have one in my 70 Beetle and love how they pump out real heat when you need it. I decided that the fuel lines ought to be replaced as they could very well be the originals. Am I correct in determining that I need 5 mm ID hose from the tank to the metering pump and 3.5 mm ID hose from the metering pump to the BN4 unit? Just want to make sure before I order stuff online.
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My projects (so far):
74 Westfalia
47 Willys CJ2A

[notchboy]

[The Fez]

[notchboy]

[orwell84]

I like the clear hose idea. When I don’t run my heater for awhile the pump loses its prime. An anti backflow valve might help that too.

[pioneer1]

Just before I send mine for scrap... i have the complete heater,wiring ,belly pan for free located in S. Ontario Canada. Pm me tonight . Jim
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"Always waiting for tomorrow ruined everything"

'85 Porsche 911 Targa

'76 Westfalia project

[busdaddy]