changing coolant temp sensor without spilling coolant?

[92EcoDiesel Jetta]

I have to take out a coolant temp sensor and change to another (calibrated) sensor. Any tricks in not losing any coolant? It's expensive *** and I hate spilling it!

[ORCoaster]

Loosen it up most of the way, put a cloth under the flange, have the second one ready to go in you dominate hand.  Then pull, swap and screw.  I don't generally loose more than a splash doing it that way.  Gotta have fast and accurate hands.  But raising twin boys trained me well for that.

[regcheeseman]

Put a tray on the ground and drop the lot out the bottom hose - you get an idea of how much rubbish is in your system then - without loosing any.

[8v-of-fury]

Which sensor? There's two on the front neck, one on the side neck, and one in the rad.

The two on the top neck are easy and with the rad cap left on shouldn't spill too much if any coolant when removing.. Unless your cap doesn't hold pressure/vacuum.

The one in the rad I have never done.. But I assume as soon as you crank it out she's gonna gush..

I would have a pan ready either way, and just reuse the coolant if it isn't too dirty.

[NintendoKD]

park on an incline, not too steep, and remember the parking brake
open up the rad or res cap.
put a catch pan under the coolant drain on the bottom of the rad. "I used an old coolant bottle with the top cutoff"
drain about 3/4 of the bottle, almost 1 gallon US
simply disconnect and remove the sender without the worry of losing coolant, air has now intruded the system, so be sure to refill and bleed out the air when finished.

[CRSMP5]

yours are in plastic necks right??

way i do it and loose maybe a oz or so..

pull cap off cold engine.. to make sure no pressure.. put cap back on..

grease up o-ring on new sensor..

pull clip..

with pliers twist old sensor to break ti free and lift up..

drop old sensor and pliers.. stick new one in hole..

put clip back in..

pick up sensor/pliers..

done...

yes the fan switch in rad works same way.. if quick maybe 2oz of fluid loss.. the cap holds the fluid in place/slows its leak down pretty good..

[R.O.R-2.0]

park on an incline, not too steep, and remember the parking brake
open up the rad or res cap.
put a catch pan under the coolant drain on the bottom of the rad. "I used an old coolant bottle with the top cutoff"
drain about 3/4 of the bottle, almost 1 gallon US
simply disconnect and remove the sender without the worry of losing coolant, air has now intruded the system, so be sure to refill and bleed out the air when finished.

VWs dont have coolant drains as standard equipment..

[92EcoDiesel Jetta]

park on an incline, not too steep, and remember the parking brake
open up the rad or res cap.
put a catch pan under the coolant drain on the bottom of the rad. "I used an old coolant bottle with the top cutoff"
drain about 3/4 of the bottle, almost 1 gallon US
simply disconnect and remove the sender without the worry of losing coolant, air has now intruded the system, so be sure to refill and bleed out the air when finished.

VWs dont have coolant drains as standard equipment..

Is that a cost cutting measure?

[vanagonturbo]

Old VWs dont have coolant drains as standard equipment..

Fixed!

[vanagonturbo]

yours are in plastic necks right??

way i do it and loose maybe a oz or so..

pull cap off cold engine.. to make sure no pressure.. put cap back on..

grease up o-ring on new sensor..

pull clip..

with pliers twist old sensor to break ti free and lift up..

drop old sensor and pliers.. stick new one in hole..

put clip back in..

pick up sensor/pliers..

done...

yes the fan switch in rad works same way.. if quick maybe 2oz of fluid loss.. the cap holds the fluid in place/slows its leak down pretty good..

I always pull the cap off and put it back on before swapping sensors. It bleed off pressure and allows the cooling system to function as a simple vacuum holding the coolant in while you swap it. This way will insure less than two tablespoons of loss if you are quick about it

[R.O.R-2.0]

Old VWs dont have coolant drains as standard equipment..

Fixed!

yes, all my cars are FIXED.. they all have aluminum lower water necks, and they are all drilled for a 1/8th" pipe plug. when i go to drain it, i thread in a 1" chunk of 1/8" pipe, and then all the coolant runs out the tube, and straight to the catch pan, doesnt drip, or make a big mess or anything. but i always loosen my expansion tank cap first, then tighten it back up, just to make sure theres no pressure in the system. then once you take the plug out, it just trickles. and then thread in the extension pipe, then crack the expansion tank cap and let er rip out the bottom..

this should be one of the first mods ANYONE does to a mk1/2 vw...

[92EcoDiesel Jetta]

Where exactly did you tap in this drain? Is it on the thermostat neck? This means the stat has to be hot and open to drain the block. Or is it before the stat on the block side?

[8v-of-fury]

Tapping the lower coolant neck is only a half fix. Most people don't wanna drain 180* coolant, so its only gonna drain the rad and the top of the system.. And then you still have to make a mess popping the t-stat out. I don't know if there is room between wp and block to put a fiitting...?