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MontrealAircooledNut
Samba Member
Joined: May 10, 2017
Posts: 41
Location: Montreal,Canada
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 Posted: Tue May 30, 2017 7:16 am Post subject: Making the gas heater come out of a 43 yrs hibernation |
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So here's the situation. Bought not long ago a 1974 412 wagon. It had only one owner in its life and said owner assured me he NEVER used the heater. Not even once. I am tempted to try to start that thing but at the same time, afraid it will blow up and the car will burn down to the ground. What would be a safe procedure to revive that heater, aside from having a fire extinguisher at hand? What steps should I take, things I should check before touching that green knob in the dash?
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Notchback 1965
Fastback 1970
Beetle 1971
Squareback 1973
412 wagon 1974 |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Tue May 30, 2017 7:38 am Post subject: Re: Making the gas heater come out of a 43 yrs hibernation |
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| MontrealAircooledNut wrote: |
| So here's the situation. Bought not long ago a 1974 412 wagon. It had only one owner in its life and said owner assured me he NEVER used the heater. Not even once. I am tempted to try to start that thing but at the same time, afraid it will blow up and the car will burn down to the ground. What would be a safe procedure to revive that heater, aside from having a fire extinguisher at hand? What steps should I take, things I should check before touching that green knob in the dash? |
Ok.....its a busy day so I can't do this all at once. First......it can NOT explode  .....but when I was in high school...before I realized that.....driving down the road with it on.....my face must have looked like Edvard Munch's painting "the scream"!
But......even though its never been used....and because its never been used.....it will need to be gone completely through for several items.
1. The fuel line MUST be replaced. In areas of wide ranging,climate.....rainy spring with cold medium wet winters and sweltering dry summer.....the fuel line on mine (Texas, Oklahoma and Georgia) became damaged/cracked at the infeed point almost every 1 plus years.
This was the stock braided line.
I finally fixed this by buying about 8-10 feet of 3/16" steel line and bending it to fit into the loops in the body that carry the line down to the pump. I used a brass compression fitting that had the ferrule and nut on the inlet side hand reamed to fit onto the inlet of the heater.
Once I tightened it down......the compressed ferulle and nut now stays on the heater inlet semi-permanently so I can remove the steel line when I need to....and its leak free and safe. I connected to the pump with a short length of rubber line and two clamps.
2. The heat probe in the chamber, the thermostat in the duct work must be removed, cleaned and have the terminals cleaned. Long disuse creates poor connections.
3. The glow plug and coil connections must be cleaned very well.
4. There is an o-ring seal between the main combustion blower unit and flame chamber that must be renewed. Its common that it leaks with age and uncombusted fuel leaks here.
5. Since you need to have the blower out to replace that o-ring.....while you are there.....pull off the inner end cover and clean the points and wire connections.....always a source of not running.....and set the gap. At the other end of the blower under the other cap is another set of points. Clean, gap and lube.
6. You must check all wires in the system.....for proper connection, clean connection....and most importantly connection to the right location. This is the biggest worry.
Even if the system itself has never been used.....or tampered with.....it has several power connections that connect to other points. I found out the hard way......that if one of these is attached to the wrong location as someone was doing engine work etc......the heater can be caused to run constant and never turn off. Almost lit my car on fire from a previous owners work.
7. The heater lever up front has a switch that controls the auxiliary fan. It tends to get dirty and not function due to its location. If the auxiliary fan does not run....the system will not run.
8. The fuel pump will usually be frozen. Remove it...fill with diesel......let soak....tap on it,a bit....hook to 12 volts. Every time connect 12 volts to it it,will click once. Each click is a pump cycle.....so hook and unhook while tapping to get it run clear.
9. Check the exhaust tube connection joint
10. Check your heater boxes and cables.
Ray |
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MontrealAircooledNut
Samba Member
Joined: May 10, 2017
Posts: 41
Location: Montreal,Canada
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| Posted: Tue May 30, 2017 8:28 am Post subject: Re: Making the gas heater come out of a 43 yrs hibernation |
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Thank you again Ray for your science! This shall be a nice little project. So basically, I'll have to pull that sucker out and clean thoroughly everything that can be cleaned, bench test pump n fan. Make sure all connections are cleaned n at the right place, change fuel hose. Is it a pain to remove the heater from the car?
I know exactly what you are talking about with The Scream painting. Exactly the face I do not want to have. Smelling UNCOMBUSTED FUEL ( point # 4) and imagining it trickling down on the engine and heater boxes gives me nightmares already and thinking of it running NON STOP ( point # 6) is not something I ever want to think of.
_________________
Notchback 1965
Fastback 1970
Beetle 1971
Squareback 1973
412 wagon 1974 |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21519
Location: Oklahoma City
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| Posted: Tue May 30, 2017 10:05 am Post subject: Re: Making the gas heater come out of a 43 yrs hibernation |
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| MontrealAircooledNut wrote: |
Thank you again Ray for your science! This shall be a nice little project. So basically, I'll have to pull that sucker out and clean thoroughly everything that can be cleaned, bench test pump n fan. Make sure all connections are cleaned n at the right place, change fuel hose. Is it a pain to remove the heater from the car?
I know exactly what you are talking about with The Scream painting. Exactly the face I do not want to have. Smelling UNCOMBUSTED FUEL ( point # 4) and imagining it trickling down on the engine and heater boxes gives me nightmares already and thinking of it running NON STOP ( point # 6) is not something I ever want to think of. |
I will post a link to the manual today. I think its in the archives. Also look up ClassicCampers heater work thread. He went through a LOT of the basic issues with his.
In the wagon.....if memory serves....I "think" the wagon does not have the two access ports behind the rear seat to access glow plug and coils.
Getting it out ...is a little bit of a pain.
Of course battery disconnected....car jacked up....and disconnect and label all the plugs from the unit. It has an exhaust pipe held on by a 6mm wingnut by the fender and a 10mm clamp at the unit.
Then there are 4 rubber vibration standoffs one on each corner with 10mm nut. When you take those loose the unit drops down. Its above the transmission/bell housing area.
When you lower it partly...you can now disconnect the fuel line, the coil wires and the glow plug wire...and...there is a cable tie down on a bolt that needs to be taken loose.
There are 4-5 wires that connect to the thermo probe...that need to be marked carefully and removed....a 4-5 pin plug at the blower motor...be careful with the plug....and the little rubber plug in the top of the unit is a two wire high temp switch that pops out of the heater body.
Ray |
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