Coolant housing thread size/pitch?

[mystery3]

I'm in the process of eliminating my coolant reservoir and swapping an aftermarket radiator and am interested in moving the fan switch from the radiator to the coolant housing on the front of the head utilizing one of the blocked ports or one of the different housings I have laying around. I need to know the different thread sizes/pitches used so I can order a different switch. Any input is appreciated!

[8v-of-fury]

i don't know if this will work for you.. If the temp sender that tells the fan to turn on is in the head, where the coolant is always hotter.. won't the fan stay on at operating temps? or atleast be on alot more than it needs too? Guess you could use a different sender, that would account for the ~10 degrees or so higher temp? I dunno, maybe im just talking outta my butt here lol

[R.O.R-2.0]

just use a mk1 TD water neck. the front one that bolts to the head between cyls 2 & 3.. the fan switch is located right in the water neck. no trying to find a funky fan switch or anything like that.

[8v-of-fury]

the coolant neck houses the cluster temp gauge sender, not the fan temp switch. atleast that's how every mk1 i've ever seen is. Both my gasser 1.7's and 1.6D have fan switch in rad

[mystery3]

Near as I can tell from scouring the interwebz in english and german the radiator fan switch is m22x1.5 and the idiot light coolant temp sensor is m10x1.0. Does that sound right? What about the sensor for the gp's? It's coolant temp as well correct?

[Vincent Waldon]

I think you're right on all three counts.

Note the main differences: the rad fan is controlled by a switch (and a big one at that), whereas the coolant temp gauge and glow plugs are controlled by analog sensors.

OP, this means you will have to do some fancy plumbing to re-plumb a spot for the rad switch, or build up some control circuitry to drive the rad fan off a coolant sensor.

[mystery3]

Good thinking! I can run the sensor in a pipe between the lower rad outlet and the thermostat housing-I need to extend/modify that hose anyway as I moved the radiator to the drivers side fender as far as possible so I can run a little IC on the passengers side. Now where to find a 22mm weld bung?

[R.O.R-2.0]

just use a mk1 TD water neck. the front one that bolts to the head between cyls 2 & 3.. the fan switch is located right in the water neck. no trying to find a funky fan switch or anything like that.

do i need to take a picture to show that i own a mk1 TD water neck with the temp switch in the side?

no need to make some pipe with a sensor in it that way..

its exactly what you are looking for , but you dont have to ghetto fab anything..

[R.O.R-2.0]

if you run the fan switch in the flow of water, it will turn on and function more with the temps of the water, because the fan switch wont be in a place with such poor flow..

[Wayland]

just use a mk1 TD water neck. the front one that bolts to the head between cyls 2 & 3.. the fan switch is located right in the water neck. no trying to find a funky fan switch or anything like that.

do i need to take a picture to show that i own a mk1 TD water neck with the temp switch in the side?

no need to make some pipe with a sensor in it that way..

its exactly what you are looking for , but you dont have to ghetto fab anything..

My 84 TD Rabbit has one of these, but it's not hooked up to anything. I think it had something to do with the fan after-run circuit?

[R.O.R-2.0]

it may be, as i only have the engine, but my 81 rabbit, has the same sensor, but mounted in the radiator..

idk why you couldnt take the TD water neck, and install whatever fan switch in it that you wanted..

[mystery3]

I'll post a wtb thread and try to track down a m22x1.5 weld bung and see what I can come up with sooner rather than later!

[CRSMP5]

the one in neck is for AC cars.. turns the comp off if overheating.. ive seen people use them to turn the fuel pump off too if overheating..

how it works.. if it gets too hot it opens the circuit up.. like a switch will interupt anything when it over heats..

so via a relay could use fo roverheat.. aka will need to use a relay that uses the 87a output to run a fan.. aka when no ground signal turns relay off and on comes the fan.. sad part.. made to interupt when "overheating" so hotter then supposed to be.

[fatmobile]

If ice cold coolant was coming from the radiator, it would cool what comes from the engine.
 If it's coming in ice cold and leaving hot enough to trip the switch, it's getting worked pretty hard.

 It might need set at a higher than normal trip point,
 it could start cooling before the rad gets too hot, when heading up a hill the rad fan might kick on before the gauge starts climbing to the right of normal.

 I think it would be a good experiment,.. to find out it's benefits and weaknesses.

 Yeah, that switch on the front waterneck is an AC shutoff when the engine is too hot,.. threads are bigger than the gauge/glowplug senders,.. but I don't think they are big enough for a stock rad fan switch.

 

[mystery3]

Here's the plan, I'm going to take the coolant housing with the properly threaded port and saw it of where the head flange meets the neck and dummy plug or weld the other ports, then I'm going to have it welded onto the thermostat housing. Sound like a decent idea?