TheSamba.com :: View topic - Bn-4 heater step by step

Mon Apr 13, 2009 2:06 pm

Ok, I finally have heat!!!I can't believe how well it works. So thanks for all that helped me alomg the way,I would'nt have been able to do it without you guys.So I figured I'd put all I learned on a post that might help others get a understanding start.Hope it helps

A- Fuse w/ screw for adjustment of THERMAL SAFETY CUT-OFF under plate is bi-metal spring with a gap that is adjusted by tightening or loosening screw.Fuse should blow if temp. reaches 420*
B- TEMP. SWITCH- controls how long fan continues to spin after fuel pump shuts down.Cool down feature/ to increase the length of time blower continues to spin, turn adjusting screw ( top rear of switch) counter clockwise.
C- RESET SWITCH- small lever on rear of switch slides left and right.If heater does not ignite after a set period of time, the switch clicks off power to heater unit.To reset just slide red lever towards passenger side and it will click and stay.
D-COIL for glow plug
E-4 wires from inside heater tube

WHITE -goes to points for ignition,should interupt ground 1 for every revolution of fan.The fan spins to fast to check if points open and close w/ meter or test light unless you spin fan by hand.
BROWN-ground to body of fan.
BLACK-power supply fo fan motor
GREEN-goes to rear points for fuel pump should disrupt ground 1 for 33 revolution of fan,and stay grounded for 6 revolutions of fan

F-fuel inlet from pump under gas tank
G-GLOW PLUG w/white wire from points under fan.
Here are some other specs- FUEL PUMP should pump between 13-15 cc per 200 clicks(strokes) of pump,I used medical seringe to measure .
POINTS- both sets of points are supposed to be set at 4mm.or .0157 in.
TO CHECK POINTS- get a voltmeter that can test continuity(or test light)
open fresh air side of heater far right(driv. side)to expose fan,attach 1 wire to a 12 volt source then attach other wire to WHITE wire pic in label E and spin fan by hand the test light or tester should go off w/each revolution of fan,that tests ignition.do the same w/ geen wire to check fuel pump set of points.If they dont work I suggest just slightly cleaning face of points with very fine sand paper.

I'm not very good at explaining things in posts.But I really do have good understanding of how these things work.If anyone has any questions just ask I'll try to help -Dave

Mon Apr 13, 2009 2:49 pm

Sticky: Heating FAQs - BN4 Gas heaters & heating related topics

merge with the faq?

Mon Apr 13, 2009 3:21 pm

Awesome post, man130. Glad you have your heater running.

Mon Apr 13, 2009 4:17 pm

After all the VW's we have froze in, its nice to have bona-fide heat!

Mon Apr 13, 2009 5:00 pm

crofty wrote: Sticky: Heating FAQs - BN4 Gas heaters & heating related topics

merge with the faq?

Done.

Tue Apr 14, 2009 8:53 pm

Wow, that's alot of info right there. I remember when you first started down this road of fixing your heater you had so many questions and now you appear to be an expert on the subject.

Sat Apr 18, 2009 9:08 am

I am still trying to figure out my heater. It appears to be complete and in great shape. I need to get your email address from you to pick your brain.. Mine is [email protected], could you drop me a line?
Great post with the pics.

Thu Oct 29, 2009 12:55 pm

So after tapping just about all the components, the two issues I have are the fuel pump not pulsating and the fan takes a long time to shut off after I turn the timer off. I adjusted the temp screw a bit and since it went off I suppose it's fixed. However, I dont understand how to test the points for the pump. I did get the orange fan off and see the points but not sure what to do from here. Do I have to dig deeper? Yeh I read the "To Check Points" but I'm still dumb founded. More explaination please.?

Thu Oct 29, 2009 1:02 pm

So two sets of points? How do I get to the second set?

Thu Oct 29, 2009 3:14 pm

Basballfreak-If you look at photos above (the one with pic of orange fan on right )is pic of points for ignition.Guess you found them. The next set is the other pic one down ,it is on the opposite end of that same fan housing unit ,if I remember correctly only a small cap covers them ,I remember their were only two screws and they were filled with red paint ,under there are the points for fuel pump .Did you check your pump with direct 12 volt current.Just get a positive and negative, unplug wires to pump and connect neg. then only tap the positive wire to other post (only for a second at a time )you should here the tic tic tic with each tap of power,if not tap pump with wrench or somthing just to free up inside Good luck P.S the fan is suspose to stay on for a little while ,to cool down the unit ,remember when it works it will be very hot. Bye the way read "please one more BN4 question" under the fix your BN4 heater sticky it will help alot

Thu Oct 29, 2009 3:28 pm

So the second set of points is not under the first set, huh? I gotta take the entire caseing apart? Cause I did get to the first set and took that ring out but was afraid of going any further since it seemed to be tight. I just double checked the pump and I rigged to from the plug up top and primed the line. It does work and I got the heater to work for a minute til the few drop oif fuel that I just shot in there ran out. SO I'm kind of thinking that the pump isnt "pumping", even though it has power which is why I need to get to the other set of points.

Thu Oct 29, 2009 4:00 pm

The pump often seizes if it isn't used regularly. If it seizes, some percussive maintenance will help it out. Often that means that you hit it, it works for a few tics than stops, hit it again, it works longer then stops, hit it again and it's good.

I've helped people troubleshoot these heaters several times. On almost every heater that the owner was trying to get running, the pump had seized. Only once did I see a heater where the points weren't triggering the pump. I'd investigate the pump and be sure you're not getting 12v pulses down at the pump before tearing into anything else. Un-seizing the pump is a whole lot easier than adjusting those points.

Thu Oct 29, 2009 4:28 pm

Excellent sharing. Are you willing to send me your data on this to add to our RoMTOC Thing Data CD. This would make a great addition to our already large files on the gas heater.

Thu Oct 29, 2009 4:31 pm

But when I put ground to the brown and white wire and 12v to the green side then tap it, it does pump one squirt each time. Do it again, same thing. Still you think the pump? Its as if the current is just steady and not pulsating.

Thu Oct 29, 2009 4:32 pm

Also you can check to see if the points are working without taking apart. go to the step by step post .All the points due is interupt the ground.So if your brown wire coming out of heateris going to a good body ground ,then get voltmeter and hook to some positive then find in post which wire go's to pump points I think green if I remember,then turn fan by hand remember you only should get reading once every 33 turns (actually it lasts for about 6 turns if I rememer.That way if you get ground ,no need to open.But listen to Ian beat that pump !!

Thu Oct 29, 2009 4:39 pm

Im pretty sure I did that. I thnk I got a steady light from the green as soon as I turned the temp switch on. I did notice that the coil won't start sparking until I short it out. Then it works fine until I shut everything down. Then I gotta short it out again to get it to work

Thu Oct 29, 2009 4:54 pm

NO NO NO do not use heater switches,this is only to test points,Get an alternitive 12 volt source seperate wire from anywhere (directly from battery?) and use green wire only for ground like I said It will interupt the ground WHEN YOU SPIN FAN BY HAND, DONT TURN IT ON it spins to fast usually for a reading.IF your using a test light it should prob, be off till you spin fan ,and count like 40 times to be sure you got the right spot on cam,then light will light for about 6 spins of fan then go out and repeat,make sure you have good ground from brown wire on fan housing and good ground to body.Do you understand when you say it works when you short it out your bypassing the points ,that what your checking so dont short anything ok

Thu Oct 29, 2009 5:01 pm

OOOOOOOOOOOOOOOOOOOO. Ok. I understand!. I will try that and let you know. Thanks.

Thu Oct 29, 2009 6:01 pm

So I definitely have the white wire (first set of points) light up for each rotation. However, I got nothing with the green (second set). I guess I gotta take it all apart now to see what I got..?? Does this sound right. It's making sense now.

Thu Oct 29, 2009 6:18 pm

baseballfreak20 wrote: So I definitely have the white wire (first set of points) light up for each rotation. However, I got nothing with the green (second set). I guess I gotta take it all apart now to see what I got..?? Does this sound right. It's making sense now.
You may have ended your test prematurely. The first set of points closes once per revolution of the fan. The second set of points only closes once every 33 revolutions. See that gear? That's why. To test the second set of points you need to spin the fan as many as 33 revolutions.