Changing The Mfts, Do You Drain All Collant Or Not

[220bhp]

To change the mfts and the temperature sensor in the back of the head is it necessary to drain all the coolant.

[PeteRR]

Not if you're quick enough swapping them over. You'll loose a small amount of coolant but not much.

[UrS4boy]

To change the mfts and the temperature sensor in the back of the head is it necessary to drain all the coolant.

First of all you need a 29 mm deep socket. It has to be deep so the switch part fits into the socket far enough so the socket can contact the hex part of the MFTS. Doing the swap is pretty easy and does not necessarily mean draining anything.

If you are good, you can do it with out draining the rad and still only lose about 200 mL(or less) of coolant. I changed mine on my AAN in my Sunday clothes while waiting for my wife to come out of the house to go for Sunday brunch. I was just trialling it to see how I would do it when we came back home and before you know it (about 5 minutes), I had removed the old one and replaced it with the new one. There was some tricky finger work while doing the Dutch-boy dike plugging thing with one finger and handing-off the old one from my right hand to my left hand and then feeding the new one from the left hand to my right hand and then starting the threads by hand. NOTE: All this was done with the engine just warm from getting out of the garage to the street. DON'T DO IT with the engine HOT!!

HTH

[220bhp]

Chears,all done ,no prob's

[andyg plym]

...

where did you get the mfts and how much?

cheers

andy

[QuattroFever]

sorry, but what is an MFTS?? Fan Switch?

[topsparky]

sorry, but what is an MFTS?? Fan Switch?

multi function temperature switch
is how the ecu sees how hot or cold the engine is

[QuattroFever]

cheers dude

[dest]

I need to do mine soon, do you have to remove anything to get access?

[GT500]

Nothing to move, just when you release the plug connector they usualy fall apart! hot and cold 10.000 times and it all gets a bit brittle.
Get a plug from the stealers at the same as ordering mfts, GSF ones are faulty out of the box!

HTH

[s2_southwest]

Does this sensor drive the temp gauge on the dash? My temp gauge doesnt work anymore, ive replaced the 2 sensors on the water manifold and had the one on the main rad changed a while ago, i guess that leaves the mfts sensor at the back of the head

[LHD_Kid]

The small one on the back of the engine is only used by the ECU (by the bulkhead) the larger of the 2 in the water manifold is the MFTS, which is the one that drives the guage....
Chris

[UrS4boy]

The small one on the back of the engine is only used by the ECU (by the bulkhead) the larger of the 2 in the water manifold is the MFTS, which is the one that drives the guage....
Chris

That is true for the AAN, ABY and ADU but the 3B uses the MFTS for the ECU coolant temp signal. See the link below for a better explanation and reference link:


http://forums.audiworld.com/s4s6/msgs/148742.phtml

HTH

[LHD_Kid]

This is quite interesting...... why is it then, that the small one by the bulkhead is connected to the ECU? (1991 3B) surely it would be obselete if the MFTS is used by the ECU?
I know mine is connected, as I had troubles with cold starting.....
Might have to delve deeper into this one....
I suspect on the 3B it uses both, but the point was that the MTFS drives the guage, not the smaller one. (Incidentally the posters referring, both have ABY's)

Chris

[Condor]

mfts

Hi, I'm going to be replacing the mfts on my 3b as have temp gauge symptoms (reading low) I think engine maybe over fueling too and now taking slightly longer to start from cold, my question is does the sensor need a washer when being replaced? is anything required on the threads when installing a new mfts ie ptfe tape/joint paste?
Thanks....