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1973 412 WAGON
Samba Member
Joined: February 12, 2015
Posts: 68
Location: N.Dinwiddie VA
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 Posted: Sat Jan 21, 2017 9:35 am Post subject: Cold start Valve and Idle soleniod |
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| Any body got a picture and location of the Cold start Valve and Idle solenoid, on a 73 412? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Sat Jan 21, 2017 6:44 pm Post subject: Re: Cold start Valve and Idle soleniod |
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| 1973 412 WAGON wrote: |
| Any body got a picture and location of the Cold start Valve and Idle solenoid, on a 73 412? |
There is no idle "solenoid". There is the cold start valve.....and there is rotary valve with an electrically heated bi-metallic strip called the auxiliary air regulator.
It admits air for warm up.....just like a solenoid.....but it starts out open when cold.....and closes completely over about 5-8 minutes. There is no "logic" or multiple positions involved like a modern solenoid system.
I will see if I have pictures with me but I am out of town until Tuesday. Ray |
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1973 412 WAGON
Samba Member
Joined: February 12, 2015
Posts: 68
Location: N.Dinwiddie VA
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| Posted: Sat Jan 21, 2017 6:57 pm Post subject: Re: Cold start Valve and Idle soleniod |
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| Thanks Ray |
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Lars S
Samba Member
Joined: October 04, 2007
Posts: 783
Location: Sweden
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| Posted: Sun Jan 22, 2017 12:25 am Post subject: Re: Cold start Valve and Idle soleniod |
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Cold start valve
it sits at the back of the plenum:
Lars S
_________________
Porsche 914 -72, Bahia Red daily driver 
VW411 2-d -70, White, sold 
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold |
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1973 412 WAGON
Samba Member
Joined: February 12, 2015
Posts: 68
Location: N.Dinwiddie VA
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| Posted: Sun Jan 22, 2017 5:54 am Post subject: Re: Cold start Valve and Idle soleniod |
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| Lars, I thought that was the Thermal Time Switch? |
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Lars S
Samba Member
Joined: October 04, 2007
Posts: 783
Location: Sweden
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| Posted: Sun Jan 22, 2017 6:05 am Post subject: Re: Cold start Valve and Idle soleniod |
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| 1973 412 WAGON wrote: |
| Lars, I thought that was the Thermal Time Switch? |
No...the valve with a thermo time function is the aux air regulator (AAR) it gradually closes the extra air fed to a cold engine in about 4 minutes.
Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold |
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Lars S
Samba Member
Joined: October 04, 2007
Posts: 783
Location: Sweden
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| Posted: Sun Jan 22, 2017 9:10 am Post subject: Re: Cold start Valve and Idle soleniod |
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| 1973 412 WAGON wrote: |
| Lars, I thought that was the Thermal Time Switch? |
...well there is a cold start switch often called thermo time switch on top of the block close to the cold start valve, wich activates the valve during cranking if temp is about at freezing or lower.(switch temp differs).
Some say it is also a time function built in some of these but Ive never seen that
Edit: this is how it looks
Lars S
_________________
Porsche 914 -72, Bahia Red daily driver
VW411 2-d -70, White, sold
VW412 4-d, -73, Gold Metallic, daily driver
Suzuki T500, -69, Candy Gold, sold
Suzuki K50, -77, Black, daily driver
BMW R69S -69, White, sold
Husqvarna 118cc, -47, Black, Sold |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21513
Location: Oklahoma City
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| Posted: Mon Jan 23, 2017 8:17 am Post subject: Re: Cold start Valve and Idle soleniod |
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| Lars S wrote: |
| 1973 412 WAGON wrote: |
| Lars, I thought that was the Thermal Time Switch? |
...well there is a cold start switch often called thermo time switch on top of the block close to the cold start valve, wich activates the valve during cranking if temp is about at freezing or lower.(switch temp differs).
Some say it is also a time function built in some of these but Ive never seen that
Edit: this is how it looks
Lars S |
This is correct. The single contact thermo-time switch (TTS)......has no "timer" function.....other than the speed of engine warm up.
The cold start valve or injector....at least on D-jet.....only functions for a set number of seconds while initially starting the engine. The TTS is really just a bi-metallic switch that allows a "window" of time for when the cold start injector is allowed to run. It signals....cold engine.
I note that it gives a window of time....because if the engine case has not reached a high enough temperature to turn the TTS off.....the cold start injector can be activated again if the engine is turned off or stalls and a new starting cycle is initiated.
As the engine case reaches temperature.....everything has heated up to the point that there is no need for the cold start injector to be initated again even if you stall or turn the engine off or restart again.
The function of this switch as a possible timing circuit....gets confused.....because there are some early water cooled VWs and other makes of car.....that used a two wire TTS. The two wire TTS....had a heater strip inside. When you initiate start.....the cold start injector fires and the strip begins heating to turn the TTS off in a very stable amount of time without regard to outside or engine temp.....similar to an auxiliary air regulator. Ray |
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