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Wed Sep 10, 2008 10:37 pm

So I was putting in the rear seat/bed back into the bus to measure for the new flooring I was about to instal, when I thought...hmmmm, maybe I should take that big black pipe out and have a look.

Yep, I think I opened a can of worms there. There was this fine grey dust with specks of black moldy looking stuff, and even some bright blue stuff within! Well, I cleaned it up the best I could, but still couldn't clean up all the stuff inside.

Ah...the famous Eberspacher control lever thing. So this is what moves when I pull the knob on the seat pedestal. I confirmed it moves, by putting my finger between the screws and feeling the difference between when the knob was pulled out (screws closer) and when it was pushed all the way down (screws farther)

Of course I couldn't resist the temptation to fire it up and see... and of course, it didn't work :( Sure the fan blew and everything, but no heat, and no whoosh sound of the thing catching.

I was just wondering, should I take it out from this end (or at least this switch part) to see if maybe all it needs is a contact cleaning? Or should I take it all out from the engine compartment side of it. How hard would that be? I know I can't see any of this stuff from the engine side of it. In fact, looking at this pix, its the first time I've seen this fuel-vapour hose too...right on TOP of the switch!! :shock:

Said hose still looks good and didn't feel hard and crackly, so I guess it should hold. I know that once the seat is completely in (only the top part is in now) its going to be real hard to take it all out again :?

What do you fellas think? If I were to take it out frm this end, how would I do it? Can't seem to see any easy way out... :roll:

Thu Sep 11, 2008 6:07 am

I had always wondered how heated air from an engine-comparment mounted, Eberspacher BN4, petrol-fired auxiliary space heater, was ducted into the rear passenger cabin!?! 8)

Is there another duct to provide heated air to the windshield demisting system?

Thu Sep 11, 2008 8:30 am

Don't take it out unless you never drive or camp when it's a little cool or have big plans for the space.
Try pushing the red button sticking out of the left side of the top cover near the front, with the underseat knob pulled out all the way you should hear tick-tick-tick-tick as it runs. No ticking?, put a test light between the 2 wires going to the fuel pump, the light should blink every second or 2, if it blinks the fuel pump needs work, if it doesn't try jumping between the 2 wires that connect to the switch you just found and see if it blinks now.

NASkeet wrote: I had always wondered how heated air from an engine-comparment mounted, Eberspacher BN4, petrol-fired auxiliary space heater, was ducted into the rear passenger cabin!?! 8)

Is there another duct to provide heated air to the windshield demisting system?
No, it just blows out forwards under the rear seat.

Thu Sep 11, 2008 8:39 am

busdaddy wrote: Don't take it out unless you never drive or camp when it's a little cool or have big plans for the space.
Try pushing the red button sticking out of the left side of the top cover near the front, with the underseat knob pulled out all the way you should hear tick-tick-tick-tick as it runs. No ticking?, put a test light between the 2 wires going to the fuel pump, the light should blink every second or 2, if it blinks the fuel pump needs work, if it doesn't try jumping between the 2 wires that connect to the switch you just found and see if it blinks now.

Oh no...I meant taking that little square piece where the cable connects to...you know, to see if the switch works or not. I really like the idea of the Eberspacher in there, I'm sure it does a bang-up job of heating the bus no cold days. I was just wondering if it would be any easier to work on that since I got the seats and all out or not.

OK, I'll try all your suggestions when I get home tonight. Thanks for the tips!

Thu Sep 11, 2008 8:48 am

I'm not too sure you can get the switch out from that end, the duct it's on is attached to the heater. It's not very often that switch fails, the bimetal spring does expand with age sometimes so you may have to pull the knob out further to reach cut in temp. A continuity test between the terminals is all you need.

Fri Sep 12, 2008 10:57 pm

busdaddy wrote: Don't take it out unless you never drive or camp when it's a little cool or have big plans for the space.
Try pushing the red button sticking out of the left side of the top cover near the front, with the underseat knob pulled out all the way you should hear tick-tick-tick-tick as it runs. No ticking?, put a test light between the 2 wires going to the fuel pump, the light should blink every second or 2, if it blinks the fuel pump needs work, if it doesn't try jumping between the 2 wires that connect to the switch you just found and see if it blinks now.

I traced the wire from that switch to the inside and found I could access it from the top hatch over the engine. Without pulling the wires out, I stuck my multimeter in there (it has an audible continuity tester) and the thing beeped even with the knob pushed all the way back in. So I guess it must be permanently on?

Tried doing the test light on what I thought is the fuel pump. There was a brown wire and a green wire. I switched on the timer and the fan came on and the test light was just one continuous light. No blinking, no ticking.

Halfway through, with nothing happening, I tried pushing the red button at the top and the whole unit stopped and started again.

Now I'm not even sure I was doing the test light on the actual fuel pump even. My setup looks different from the one in the manual. In the schematic, the fuel pump is below and the solenoid fuel valve is inside the cover. In my case, the two are one after the other, below the actual heater. So now, in retrospect, I must've been testing the connection between the solenoid instead. :oops:

However, I remember that I could not get at the wires on (what I think is) the fuel pump. They're shielded by a black plastic cap... :?

Sat Sep 13, 2008 8:04 am

busdaddy wrote: NASkeet wrote: I had always wondered how heated air from an engine-comparment mounted, Eberspacher BN4, petrol-fired auxiliary space heater, was ducted into the rear passenger cabin!?! 8)

Is there another duct to provide heated air to the windshield demisting system?

No, it just blows out forwards under the rear seat.

So apart from providing heating for rear-seat passengers, is there any useful purpose in having one!?!

Sat Sep 13, 2008 8:06 am

NASkeet wrote: So apart from providing heating for rear-seat passengers, is there any useful purpose in having one!?!

like having heat isn't useful?

Sat Sep 13, 2008 8:15 am

germansupplyscott wrote: NASkeet wrote: So apart from providing heating for rear-seat passengers, is there any useful purpose in having one!?!

wtf is that supposed to mean? like having heat isn't useful?

Ignoring for the moment your abbreviation of a foul-mouthed expletive, it means, does an Eberspacher BN4 heater, provide any significant heating effect to the driver & front-seat passenger and/or contribute to the demisting & defrosting of the windscreen & cab side windows!?!

Sat Sep 13, 2008 8:32 am

You'll have to disconnect the wires to test the switch properly, although you have accidentally determined the coil in the relay that switch controls is good.

Your heater doesn't have a fuel solenoid (pre 72 only), the device below the heater with the fuel line on each end is the metering pump, same deal for testing it, both wires off.
The metering pump gets 12 volts through the green wire whenever the heater is energised, all the safety switches are closed and the thermostat switch is closed. The brown/white wire comes from the points in the combustion blower and provides a pulsed ground to run the pump, you can test it by disconnecting both wires (spade terminals, pull off straight) and connecting a test light between them.

If you are lucky and you get a blinking light at the fuel pump wires the fuel pump is stuck from lack of use, removing it and bumping it against something wooden or hitting it with a dead blow hammer on the ends a few time usually gets it loose.

If you get no - pulse from the brown/white wire the points in the combustion blower are not making contact and things just got complicated. Let's hope it's a stuck pump.

Sat Sep 13, 2008 8:40 am

NASkeet wrote: Ignoring for the moment your abbreviation of a foul-mouthed expletive

my apologies, nigel, i did edit that out of the post but it was too late...

Sat Sep 13, 2008 8:41 am

NASkeet wrote: germansupplyscott wrote: NASkeet wrote: So apart from providing heating for rear-seat passengers, is there any useful purpose in having one!?!

wtf is that supposed to mean? like having heat isn't useful?

Ignoring for the moment your abbreviation of a foul-mouthed expletive, it means, does an Eberspacher BN4 heater, provide any significant heating effect to the driver & front-seat passenger and/or contribute to the demisting & defrosting of the windscreen & cab side windows!?!

Even coming out in the back they heat up the whole bus so well you can all take off your coats, a 5-10 minute preheat while you have your morning coffee in the house melts the frost off all the windows. The engine supplies enough heat to keep the windshield clear unless your bus is full of holes and gets really wet inside or you just picked up a soggy soccer team. The BA-6 is better, but I like heat, no matter where it's coming from.

Sun Sep 14, 2008 4:58 am

busdaddy wrote: NASkeet wrote: germansupplyscott wrote: NASkeet wrote: So apart from providing heating for rear-seat passengers, is there any useful purpose in having one!?!

wtf is that supposed to mean? like having heat isn't useful?

Ignoring for the moment your abbreviation of a foul-mouthed expletive, it means, does an Eberspacher BN4 heater, provide any significant heating effect to the driver & front-seat passenger and/or contribute to the demisting & defrosting of the windscreen & cab side windows!?!

Even coming out in the back they heat up the whole bus so well you can all take off your coats, a 5-10 minute preheat while you have your morning coffee in the house melts the frost off all the windows. The engine supplies enough heat to keep the windshield clear unless your bus is full of holes and gets really wet inside or you just picked up a soggy soccer team. The BA-6 is better, but I like heat, no matter where it's coming from.

Unfortunately, the location for an Eberspacher BA6, is taken up by my braking system's, twin remote-acting, vacuum servos! :cry:

Sun Sep 14, 2008 9:06 pm

busdaddy wrote: You'll have to disconnect the wires to test the switch properly, although you have accidentally determined the coil in the relay that switch controls is good.

Good to know that I can accidentally determine something :lol: So I really shoved the probes deep into the sockets, this time, disconnecting the two blue wire. Same result, my meter beeped whether the knob was all the way in or out. :?

busdaddy wrote: Your heater doesn't have a fuel solenoid (pre 72 only), the device below the heater with the fuel line on each end is the metering pump, same deal for testing it, both wires off.
The metering pump gets 12 volts through the green wire whenever the heater is energised, all the safety switches are closed and the thermostat switch is closed. The brown/white wire comes from the points in the combustion blower and provides a pulsed ground to run the pump, you can test it by disconnecting both wires (spade terminals, pull off straight) and connecting a test light between them..

I did this with both sets of wires. Once with the actual fuel pump, and the other with the other real pump.

busdaddy wrote: If you are lucky and you get a blinking light at the fuel pump wires the fuel pump is stuck from lack of use, removing it and bumping it against something wooden or hitting it with a dead blow hammer on the ends a few time usually gets it loose..

And...I was lucky!! Yes, on both occasions, the test light pulsed, indicating the fuel pump is just stuck maybe? What does the pulsing actually tell you? Anyway, I gave it a good whack with a rubber mallet, and well, lets say it was a good thing i was monitoring it so closely, cos, the area on the outlet side of the fuel metering pump started to get wet. Fuel was leaking out of it! So shut off the engine, and wiped it all dry. Started it up again, and well, it kinda just weeps out. I took the hose off completely, and it just weeps out every time I hit the pump with the mallet. I just tried it again, and the outlet at the metering pump is bone dry. :(

busdaddy wrote: If you get no - pulse from the brown/white wire the points in the combustion blower are not making contact and things just got complicated. Let's hope it's a stuck pump.

So it appears that I have a stuck pump. What do I do now? I think perhaps the first order of the day is replace all the fuel lines in the heater -eh :oops:
What size is that small hose going from the metering pump to the heater itself?

So in the midst of all this, I put in the floors, wife put in the curtains, cleaned up the bus, and well, I think she's ready to go for the inspection now! I'll be posting pixes of the bus in readiness soon. :D

Mon Sep 15, 2008 8:18 am

Nice job on the curtains, floor, etc., looking good.

Good news that it has a pulse, the combustion blower is the first thing that goes in when the heaters built and is a big job to fix.

The fuel line from the tee to the pump is regular 6mm fuel line, the line from the pump to the nozzle is 4.5-5mm, 6mm will work with clamps, that line isn't under pressure it only drips out of the open nozzle.
Since it's leaking the pump should come apart. You'll have to remove the pump and measure the amount of threads exposed on the outlet end for reassembly. Loosen the thin 17mm jam nut and unscrew the cylinder/valve assembly from the end of the pump, be careful with the O ring near the end of the piston, it's often petrified but may still work. Try blowing compressed air through the cylinder towards the outlet to confirm the check valve is free, try blowing through the inlet to free the inlets check valve and purge the pump of anything nasty. Put a little grease or oil on the piston and reassemble the pump, use permatex #2 or teflon on the threads and try to get it back close to the original measurement. Check the end fitting for tightness (10mm) and check the inlet fitting (17mm) as well (there's a screen under that one you may want to look at too).
If it doesn't start pumping little drips after a few minutes (takes a while to pick up fuel if there's air in the lines) try sucking on the outlet with a big syringe (pharmacy) and a bit of fuel line, leave it running and watch the syringe to confirm the fuel level is rising ever so slightly.

While your'e waiting for fuel to come out reach around and feel the spark/glow plug (middle of heater @ 11:00 viewed from rear), it should be very warm. Once you have fuel coming from the pump hook up the line and give it another minute to pump fuel up to the nozzle. After a minute or two you should hear a faint jet engine roar and smell something, after 30+ seconds the motor should speed up slightly (glow plug turns off), yours should be a recirculating heater so you don't have to listen for the vent damper to open.

Don't wait more than 2 cycles of the safety switch for it to fire up, if it's not burning by then remove the spark plug and make sure it's not wet, look for dripping fuel from the exhaust now and then too, keep a fire extinguisher nearby and read this http://www.thesamba.com/vw/archives/manuals/bn4troubleshooting.php

As for the thermostat switch not shutting off don't worry about it yet, it may still work when the heater warms up a bit. Wait till the heater's running to see if it cycles.

Mon Sep 15, 2008 10:58 am

busdaddy wrote: Nice job on the curtains, floor, etc., looking good.

Thanks! Hope to be doing the VW show next year. No budget for a new poptop fabric, but we'll make do. What the heck, looks like a champ when the top is down :lol:

busdaddy wrote: The fuel line from the tee to the pump is regular 6mm fuel line, the line from the pump to the nozzle is 4.5-5mm, 6mm will work with clamps, that line isn't under pressure it only drips out of the open nozzle.

I'll try this out. I have extra from the time I did the regular fuel pump. The regular fuel line does look kinda big though. It might not fit in the slot of the grey cover with the Espar logo on it.

busdaddy wrote: Since it's leaking the pump should come apart. You'll have to remove the pump and measure the amount of threads exposed on the outlet end for reassembly. Loosen the thin 17mm jam nut and unscrew the cylinder/valve assembly from the end of the pump, be careful with the O ring near the end of the piston, it's often petrified but may still work. Try blowing compressed air through the cylinder towards the outlet to confirm the check valve is free, try blowing through the inlet to free the inlets check valve and purge the pump of anything nasty. Put a little grease or oil on the piston and reassemble the pump, use permatex #2 or teflon on the threads and try to get it back close to the original measurement. Check the end fitting for tightness (10mm) and check the inlet fitting (17mm) as well (there's a screen under that one you may want to look at too).
If it doesn't start pumping little drips after a few minutes (takes a while to pick up fuel if there's air in the lines) try sucking on the outlet with a big syringe (pharmacy) and a bit of fuel line, leave it running and watch the syringe to confirm the fuel level is rising ever so slightly.

OK here's the thing: The pump itself doesn't leak. When I said weeping, i meant it was weeping out of the outlet nozzle (the one with the fuel line) when I took off the hose. I believe it was weeping as the hose was dry and cracked. After shutting everything down, and starting again, it stops weeping. I'm thinking I might as well take it apart anyway and shoot some compressed air into the thing, maybe its just stuck? The big nozzle thing is a good idea, I might try that on the outlet first, give it a good suck and see if anything comes out.

busdaddy wrote: While your'e waiting for fuel to come out reach around and feel the spark/glow plug (middle of heater @ 11:00 viewed from rear), it should be very warm. Once you have fuel coming from the pump hook up the line and give it another minute to pump fuel up to the nozzle. After a minute or two you should hear a faint jet engine roar and smell something, after 30+ seconds the motor should speed up slightly (glow plug turns off), yours should be a recirculating heater so you don't have to listen for the vent damper to open.

I think I felt that part accidentally. I was feeling around for anymore leaks when I touched something REALLY hot!! :shock: Lets say it was hot enough for me to pull my hand out really fast and stand up at the same time. Yep, found out that the engine hatch is really hard metal. :oops:

I have never heard that roar yet, but yes, mine is a recirculating one. I removed the plastic thing and will put it back once I'm certain the whole thing works.

busdaddy wrote: Don't wait more than 2 cycles of the safety switch for it to fire up, if it's not burning by then remove the spark plug and make sure it's not wet, look for dripping fuel from the exhaust now and then too, keep a fire extinguisher nearby and read this http://www.thesamba.com/vw/archives/manuals/bn4troubleshooting.php

As for the thermostat switch not shutting off don't worry about it yet, it may still work when the heater warms up a bit. Wait till the heater's running to see if it cycles.

All good advice, thanks! I'll probably be doing this sometime this week, so stay tuned!

Mon Sep 15, 2008 12:45 pm

Good to hear, even better if you don't need to take it apart. Don't expect any roaring until you've got clicking.

Take the pump out and give it a few good whacks against the end of your workbench, don't hit it on the hose fittings or the terminals but right beside them. The compressed air sometimes helps too. It will click when you apply 12 volts across the terminals when it's freed up (one single click per contact).

Mon Sep 15, 2008 2:42 pm

busdaddy wrote: NASkeet wrote: germansupplyscott wrote: NASkeet wrote: So apart from providing heating for rear-seat passengers, is there any useful purpose in having one!?!

wtf is that supposed to mean? like having heat isn't useful?

Ignoring for the moment your abbreviation of a foul-mouthed expletive, it means, does an Eberspacher BN4 heater, provide any significant heating effect to the driver & front-seat passenger and/or contribute to the demisting & defrosting of the windscreen & cab side windows!?!

Even coming out in the back they heat up the whole bus so well you can all take off your coats, a 5-10 minute preheat while you have your morning coffee in the house melts the frost off all the windows. The engine supplies enough heat to keep the windshield clear unless your bus is full of holes and gets really wet inside or you just picked up a soggy soccer team. The BA-6 is better, but I like heat, no matter where it's coming from.

The BN4 makes alot of heat. I put one in about 10 years ago in my 78 after reading about it on Type2.com. It gets the whole bus nice and toasty. Not so much with the top popped or while driving as the camper is not relatively air tight. But parked you are golden if you have that thing running. The AM warmup gets all of the frost and base snow melted for easy cleaning. Good for driving is a motorcycle heated vest plugged into the DIN socket or 12v outlet.

The pipe that goes through the gas tank chamber is round on the back end. If you wanted to take the whole section out, you would need to pull the body of the heater first and then that section out through the engine compartment. What you can consider would be to eliminate the Bowden cable going into the switch you are showing. There is really no need for it. The heater control via the timer or dash mounted switch is enough, since the Eberspacher will not really "overheat' your interior, there is no need to reduce the amount of heat coming from your heater. I have that switch fixed in the full position.

BTW, FYI, WTF is probably acceptable, IMO
JKLOL :lol:

Tue Sep 16, 2008 5:05 pm

Have you checked that the injection nozzel in to the combustion chamber, is this blocked.

And I wouldn't hit part of you heater with a mallet, fuel pumps in working condition cost a packet.

If you search the web there are a few technical documents around showing how to service and set up one of these.

I think there are scan's of the service manuals on the samba under "technical/manuals" the look to list at bottom one called heating and air conditioning.

Good luck with getting this BN4 working, I have one in my bus and when camping it makes the interior realy hot after about 5 mins.

Ian