The Ultimate Stewart Warner Gas Heater Thread

[foamermetal]

So I went from fuel coming out the drain that was on fire to completely working for a day. Now the heater turns on but no combustion. I have no spark to the plug. Plug wire ohm checked good plus replaced it with a new one. Still no spark. Coil checked good primary side and secondary. Even swapped it to a new one I had. Still no spark. Point gap is at .018" and filed a bit to make sure its clean. No spark. I have looked over and over at the service manual for the heater and I'm coming up with nothing. My questions are is there a test for spark at the points? Should there be a spark at the points? Is there a check of the condenser? Seems the rotation of the air motor and fuel pump would need to be disabled to flick the points like in the distributor. I've reviewed the wiring diagram but cant see if there is anything that triggers the points to fire except the thermostat. Is there a test for that? Possibly continuity? I do hear it click if manually pressed and the knob is working it as well. The fuel pump is sending fuel to the solenoid and its not pumping into the combustion chamber. That's a lot I know. Would appreciate any help. Getting chilly out there. Thanks.

[busdaddy]

You've seen the service and shop manuals for those located here, right?
www.thesamba.com/vw/archives/manuals/heater_ac.php
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[foamermetal]

Well things have escalated. As I posted earlier on the checks I've done I checked the thermostat. Not sure what the manual means by the cold side of the micro switch. Put the light on it and it stays on just as the manual says. Took the thing off the heater and checked continuity and the switch breaks as it should. thermostat moves as it should when heat is applied. Put it all back together and turn it on and it now blows the 20 amp fuse. If i disconnect the double wire at that supposed "cold side of the micro switch, the one on the front not the bottom the thing will run. Still no spark but it runs. Blower motor and the motor that turns the pump. I don't understand how the switch tests good but put power to it and fuses blow. Swapped it with another that tested good and the same thing. Still have no spark at the plug. Any thoughts? The bottom wire from what i can make of the diagram goes to the negative on the coil. disconnected that and it still blows the 20 amp fuse.

[foamermetal]

How does a thermostat short out when there are no wires connected? When heat is applied it moves as it should. Is there a precise amount it moves? Should it cool back down enough to switch the micro switch? It doesn't. Only moving the knob in does it activate the switch.

[busdaddy]

The overheat switch in the burner assy shorts out the whole system, I don't know if it's self resetting, or has to be done manually. The idea is it kills the unit until you can have it serviced at a shop.
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Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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[foamermetal]

Well I figured out the plastic cam on the temp selector wasn’t contacting the micro switch. Fixed that and no more blowing fuses. The heater runs but no spark still. I removed the points off of the fuel pump and found someone had glued the terminal back to the body that holds the points. I’ve got about 5 sets of used points but can only find one. Is there a test of the capacitor. The reason I ask it I get continuity across each end of my cobbled up setup on the right in the picture. Even thought it’s all sloppy. When I check the other one on the left I get nothing. Should it have it or not? I’m a fabricator and know enough of electronics to get smoke out of them.

[foamermetal]

The overheat switch ohms out like the manual test says so that's not an issue. If i can get my head around these points being bad or good we can move on to more reasons for no spark at the plug. Traced and checked all the wires in the harness and found no issues.

[foamermetal]

UPDATE: Of the five spare heaters I took another set of points and condenser and installed after unsoldering the points and setting the gap and soldering it back together. The ole heater fired right up and is working as it should. I guess the botched wire terminal that' s riveted to the points housing was occasionally shorting out. Thanks for all that gave suggestions for the help.

[foamermetal]

Well that was short lived. Got in this morning and she didn’t fire up. Did notice some fuel drip out of the drain. May be a solenoid issue. When switched off the dribble bubbled. Back to investigating.

[foamermetal]

Took the burner loose from the heat exchanger. Noticed it was wet with fuel. Overheat temp sensor checks good. Solenoid on the front clicks when energized. I guess I need to get in to the valve and nozzle. I found a better breakdown of the burner on the 61 heater shop manual. It’s 100 pages long and has the burner repair kit parts. Anyone have a photo of theses parts to repair the burner.

[1vwjedi]

I live in Arizona. So you rarely ever see one here. But I’m skinny and I hate the cold. And love vw’s. We know stock heaters suck. Over the years I collected parts and pieces. And have 3 working units. And yes if you mention the two words together.( gasoline and heater). People trip. But I’m hear to tell you they rock. Big time instant heat regulated by a thermostat. And good thing or it would blast you out of that car with heat. Not many understand them thoroughly. Do to the Fred flinstone techknowledgy. In the way that it isn’t a fuel pump on them. It’s a metering pump. Every 27 revolutions of the fan and it stokes the fire with a spritz of fuel. There are multiple safety features on them making them very safe as long as you inspect fuel lines and such. Pretty ingenious units. One shaft on electric motor. Also runs a set of points to ignite fuel. Also runs mentoring pump. Just a great design considering how old they are. If you can find a complete unit. Many times from sitting half the year being unused or maintained. It’s like a weed eater sitting around to long. It just wants attention. A little cleaning. As long as all the components function. They work better then any heater I ever seen in a vehicle.

[1vwjedi]

Keep in mind those heaters have a set of points in them. And just like an old vw. You gotta check em out. Make sure they open and close. Reset them. Sand connectors for a good connection. Just like your old bug . If it don’t spark. First place to check is points.

[busdaddy]