Pierburg heaters and cut-off valve wiring "Haynes style" + thermoswitches

An alchemy of sparks, copper wire and earth

Moderators: Moderators, User administrators

Post Reply
bambily
Posts: 15
Joined: 12 Oct 2016, 21:08
80-90 Mem No: 17375
Location: Sweden, Borås

Pierburg heaters and cut-off valve wiring "Haynes style" + thermoswitches

Post by bambily »

(E D I T: Sorry, wrong forum!)

1. In posts on this forum and on multiple images I've found when looking for how to wire the manifold heater, carb body heater, automatic choke heater and the idle cut-off valve the first two is said to belong to the thermoswitched +12v while the two later should be connected to the ignition +12v. However when looking in my bus (1.9 DG '83) the three heaters are connected in series, while the idle cut-off valve is connected separately. Looking at the schematic in Haynes "service and repair manual" the diagram clearly matches my bus setup in that regard. Who's right and who's wrong here?

F35: Thermoswitch for inlet manifold preheating
J81: Inlet manifold preheating relay

N51: Heater element for inlet manifold preheating
N52: Heater element for throttle channel heating/carburettor
N1: Automatic choke
N3: By-pass air cut-off valve

2. F35 "035 919 369 C", this do have two connectors, I guess that one should be connected to +12v as input while the other connector is outputing that current until the specified temp (55-65C) is reached?

3. J81, how do I verify that the relay do work?

Image
T3 '83 1.9L DG - Camper

User avatar
Mocki
Membership Admin
Posts: 15923
Joined: 29 Sep 2005, 09:27
80-90 Mem No: 428
Location: Mansfield tel/txt 07947137911
Contact:

Re: Pierburg heaters and cut-off valve wiring "Haynes style" + thermoswitches

Post by Mocki »

If you were to wire the air bypass solenoid to the thermal switch, as soon as the engine reached temperature the the air by pass would close and idling would become a issue , stalling at tick over everytime . The Haynes diagram is correct , only the heating element should be connected to the switched circuit . 

 
Steve
tel / txt O7947-137911
👀
________________

1989 2.1LpgWBX HiTop Leisuredrive Camper
1988 2.1 Caravelle TS TinTop Camper 
 

bambily
Posts: 15
Joined: 12 Oct 2016, 21:08
80-90 Mem No: 17375
Location: Sweden, Borås

Re: Pierburg heaters and cut-off valve wiring "Haynes style" + thermoswitches

Post by bambily »

Mocki wrote: 31 May 2021, 07:23 If you were to wire the air bypass solenoid to the thermal switch, as soon as the engine reached temperature the the air by pass would close and idling would become a issue , stalling at tick over everytime . The Haynes diagram is correct , only the heating element should be connected to the switched circuit . 

Ah yes, that makes sense. But the difference between Haynes and the wiring purposed at (for example) viewtopic.php?p=8155279#p8155279 is that the automatic choke heater is connected to the ignition +12v.
T3 '83 1.9L DG - Camper

User avatar
bigherb
Posts: 2477
Joined: 27 Mar 2008, 13:50
80-90 Mem No: 5789
Location: West Kent

Re: Pierburg heaters and cut-off valve wiring "Haynes style" + thermoswitches

Post by bigherb »

They are not wired in series they are just Daisy chained in parallel. There is early and late wiring, yours is the late version, early the choke element didn't go through the thermoswitch.
1982 Camper 1970 1500 Beetle Various Skoda's, Ariel Arrow

bambily
Posts: 15
Joined: 12 Oct 2016, 21:08
80-90 Mem No: 17375
Location: Sweden, Borås

Re: Pierburg heaters and cut-off valve wiring "Haynes style" + thermoswitches

Post by bambily »

bigherb wrote: 31 May 2021, 11:48 They are not wired in series they are just Daisy chained in parallel. There is early and late wiring, yours is the late version, early the choke element didn't go through the thermoswitch.
Thanks for the explanation! That mystery "solved" then. :)
 
T3 '83 1.9L DG - Camper

Post Reply