Early BN4 Eberspächer Restoration Bay Window Bus 68-72

[notchboy]

Well. I think now is as good of time as any to crack into an early BN4 rebuild. The main reason Im even attempting to do this is for a good friends resto - Ratherbebuggins Dormy Bay.

This may not work, may work awesome? We will see. I also have the good fortune of having some NOS pieces others of you may not have - like the metering solenoid/diaphragm and the fuel pump. Two of the main reasons you may be looking for a source to repair these heaters.

As compared to the later BN4's - these early ones are heavier, have more components and are problematic in regards to parts for the fuel delivery system. I hope to address these issues.

Follow along and watch me fumble my way through a restoration of the Early BN4 Eberspacher Gas HEater. Please feel free to correct me and or add your own info to the pile.


Pics of a complete nit less the dash switch, thermostat cable and two piece exhaust pipes.

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[Steve22]

I may be the only one, but I'll watch this one...
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'65 Karmann Ghia 'vert
'73 Super Beetle
'59 Beetle ragtop
'73 Sunroof Transporter

[dugfresh]

Meh... me too. Tho i can't stand this forum on the phone screen!
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78 Riviera
http://flic.kr/s/aHsjDRJPa1

[ccowx]

I will be watching this as well! I have used early BN4's in several buses and once the bugs are worked out of them, they work pretty good. I will be freshening up one in the next few months for my upcoming Bay window project. Let's hope I get it right, since I live in the Yukon!

Good luck!

Chris

[Xevin]

[notchboy]

Well Im glad DugEfresh is here too since I bought the one he has at a show then sold it to him at the same show for what I paid. So Ive wanted to help a brother out if I could

There is a success story on YouTube. He doesn't really show any fixin but it does run.




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[notchboy]

In my next post Ill be showing the differences between the early and late BN4. A question often asked.

Here is a wiring diagram for the early BN4

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[Xevin]

What's the difference between the early and late Bn4
Was the early Bn4 ever fitted on a split?
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Keep on Busin'

[notchboy]

1) Im working on it. This is a show weekend so Im gona go hang with some bruthas.

2) Yes this type of heater is found on SO 42's and earlier.

There is a cross over point when we see the what Im finding being called B2 "large" eberspacher being used. B2 for me is a smaller unit used in bugs and early T3's. But as you see below - this type is called a B2 as well.

These early types were used in Bus and Ghia applications.

Eraly install in a Ghia

And then an install that Im not sure Id accuse of being stock of an early BN4.

In a 67 Bus

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[Angleofattack]

Dear Jason,
I am glad we will be worki g together in these units. I just started messi g with mine, identical to the ones in your pictures, installed in my Pinzgauer. It used to run fine abojt a year ago, but then I left the truck in storage and now it wont run.
I found a cable disconnected, I need to find its destination. It comes from one of the three relays installed behind the heater in my truck. ( I noticed you only have one).
The issue seems.to.be the metering pump. The solenoid clicks well when directly powered with 24v, but during the start cycle, it never seems to inkect fuel, I dont hear it clicking.
It is my understanding that the pulses come from the fan motor? Is that correct?
I connected a digital voltmeter to the output connector of the thermostat and it reads and osscilating voltage between 8 and 30v, I guess due to the pulse frequency.
I'll get pictures of mine to share in the forum. Will be interesting to see differences.
Best,
Jeronimo

[busdaddy]

[notchboy]

Ok. I put a vid together explaining some of the major differences from an early to a late BN4 Gas Heater. I also try to briefly explain some of the engineering challenges from one to the next.

The points I hit seem to be the most asked questions I seem to get on these heaters.

Seen here is the early mechanical fuel pump, metering diaphragm regulator, split spark and glow plugs. Below shows the combined later versions of the metering pump and glow/spark plug.

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[notchboy]

What?

https://www.thesamba.com/vw/forum/viewtopic.php?p=8454784#8454784
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[notchboy]

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[notchboy]

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[notchboy]

The man of the hour sent on his care package with eberspacher goodies inside. It has some neat stuff like a NOS pressure regulator. I still need to take it apart to see if the diaphragm is truly usable.

Also sent on was two Eberspacher T2 & T3 (nos) timer switches. As you can see the used one got water damaged. Pretty bad. Ill see if I can fix it up. Does not look promising. That NOS T3 one as well uses a much slimmer shaft for the pull rod as seen in the pics, something I didn't know.

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[notchboy]

Today I got into the actual tear down. Wow, this things engineering is very fiddly. I had to take lots of reference pics just to have for build back. I for the late BN4 stuff as well but hardly ever used it. This is twice as complicated. Two or three times through Im sure Ill get it

Everything came off without a hitch except the thermo switch. Lots of carbon built up on the rod, but the nut broke loose! Soaking that in some earl.

Then Ill get the can apart and start some of the fun detail cleaning stuff.

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[notchboy]

I was able to pull the flame switch out finally - this is one thing that if severely gummed up can break. Taking your time to get it out is crucial. Ive broke plenty over the years.

After that I was able to pull the can off the combustion chamber. I then took the fan off the combustion chamber and cleaned it and the points for the spark plug.

After this Ill get the pump going - its looking very clean so far.


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So here is part of the problem on these old heaters - when gas turns to varnish. It sets and is like honey or gooey polyurethane. Stops these dead in their tracks. I bet if I just clean this it will work Stay tuned.

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[notchboy]

Luckily this heater is in relatively good shape. No signs of real problems of rot, water damage or rust. Cleaned and sanded the can and other bits. Ill be able to start assembling the base tomorrow.

Interesting side note. I got some rust remover today at Home Depot. All the screws and bits are being soaked in that now. I put a the crusty spark plug in there with the glow plug - the spark plug looks almost new already - Ill show that tomorrow.

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[notchboy]

Assembly time. Got most the big hard bits all cleaned and painted. Put the basic shell back together.

Im also experimenting with liquid rust remover. All the nuts and screws were soaked in the stuff for 24 hrs. All came out nice. That pic of the clow plug and spark plug? They were covered in rust. The spak looks almost new and the glow is good with lots of og paint still intact - void where the rust was.

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