'73 Thing Heater - Power Not Interrupted to Pump

[CarlSpackler]

I looked through a bunch of the heater posts and didn't find this question. Sorry if it's been asked and I just missed it. The issue I'm having with my heater is that the pump has power to it constantly. If I tap the wire on the post of the pump along with the speed of the fan it fires up and runs great. If I just leave it connected I get one tick when the thing starts, then nothing. Putting an indicator light on the lines to the pump has the light on constantly. I've taken the heater apart and cleaned the points. I didn't adjust the gap, but I can see the points open and close when spinning the assembly by hand. The heater worked fine two years ago when I was using it. Last winter I was rebuilding the beam so I didn't use it. When I got the beam done and everything back together the heater wouldn't work. I'm not sure where to go next. I guess I'll take everything back apart and gap the points, but since I can see them moving and I know everything is clean, I'm not sure that will help.

Any other thoughts before I take this thing apart again?
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'67 Micro Bus
'73 Thing
'91 Westy

[mondshine]

As I understand it, there should be constant power to the pump whenever the heater is switched on.

However the ground wire for the pump is a "switched ground", as designated by the white trace on the brown wire.
The ground wire is switched once per 33 revolutions of the fan motor by one of the sets of trigger points integral with the fan motor..
That is the tick-tick-tick you hear when the pump is operating normally.

I would look for a fault with the trigger points, their wiring, or with a stuck pump.

You can check both sets of trigger poinds without disassembling the heater.
Here's a points check video; the video is in slow motion…

Link


https://www.thesamba.com/vw/archives/info/wiring/Thing_Eberspacher_BN4_Heater_Wiring.pdf

Good luck.