Turbo Cooling Pump

[martinjs]

im trying to figure out how to actually get it working (dont think it ever has in last year at least) put a new sensor in water manifold whilst doing my engine work last month but still havent had it going
pulled both wires off and joined them together and comes on (along with fan) as it should, is there anything else to check, whats the larger sensor in the water manifold for?

martin

[Mihnea]

Martin, if it does come on if you put both wires against each other it should be okay, for me it means that you're not heating your engine enough

the large sensor is the multi(mal)-function sensor, it gives the coolant temp information to the dash temp display and also has a function that totally cuts the boost control if the coolant gets over 120°C.


hth,


Mihnea

[Martynf]

Martin, here's a quick way to test it that I've noticed to prove it works:

Take the car for a run to get it nice and hot. Switch off the engine and slowly!!!! release the expansion tank cap just a little to let out a little pressure and leave the cap a little bit loose. Wait for the fan to come on (which also turns the pump on) and you should notice that the coolant level in the expansion tank rises as coolant from the rad comes back into the header tank via the small bore overflow pipe. This is the electric after run pump circulating water around and back up to the tank.

By releasing the pressure in the water system, when the electric pump runs, water will always take the easiest route out. So with the tank cap loose, the electric pump pumps water up to the header tank, rather than round the engine, as this is the least resistance route. That proves the pump is working if you see water come back into the header tank.

HTH
Martyn

[Josh-stateside]

Nice tip! i need to remember that once the motor is in.

It's an on going learning process

thanks
Martyn

[Martynf]

cheers Josh ;-)

We all learn something new everyday! Hope you get that bearing sorted and engine in ok.

Martyn

[S2central.net]

Wanna know an even easier way to test the TCP without starting the engine...

When you turn the key to ignition position you will hear the TCP run for about 4-5 seconds. Its a subtle normal hum of a pump. If someone else turns the key on, you can feel the pump running with your fingers.

This test does not verify the sanity of the thermotemp switch in the water rail that activates the after-run sequence - Martyns trick is best for that...


Cheers,

Paul

[martinjs]

i did this test first paul and was ok, then put the wire across the connectors and definataly came on along with fan, thermo stat was changed recently and temp guage was just above 90 when turned engine off so is definately hot enough.
but heres another one for you....
i have an annoying coolant leak also, when leave car after a run its fine then after 30 mins or so starts leaking
but miraculously stops after a 10 mins
drips from next to the sump plug.:mad:
so everytime i return theres a nice 12" wet patch.
level in expansion tank drops a inch every couple of days.
some heavy investigating is needed in the morning i think


martin

[martinjs]

ill be damned if i can get the pump/fan to come on when engine is turned off.:mad:

when engine hot and idling, if you turn engine off whilst fan is on should it stop with the engine or carry on till it turns off itself?

on previous audis ive had the fan will keep going if you turn the engine off whilst its running.

ps. my mysterious water leak didnt show itself today

rrrggghhh:mad: :mad:

martin

[Martynf]

Mart,

I've noticed one mine that if the fan is running when you switch the engine off, the fan stops, which I thought was a little odd... but then it will come on again mabe in a little while in after run mode.

mart

[martinjs]

martin (proper spelling lol:nana

it couldnt be a dodgy sensor could it?

martin

[Martynf]

Always possible Martin I think I'm right in saying the sensor that turns these on is the small 2 pin one next to the 3/4 pin one in the water manifold. You could try to test it for open circuit as I don't think it should ever be open circuit!! then maybe swap it over with a known working one (like the one I have here you can borrow - my old one which is known to work) although it's not nice to change!

This could also be the source of the water leak maybe???? maybe the sender has cracked or something and no longer works, letting some water through it under the right conditions... possible....

Martyn

[martinjs]

okay ill check it out

cheers m8

martin

[paradyne]

Hi MartinJS,

I've got a leaking TCP, that gives exactly the same symptoms as you. I dont seem to loose much coolant whilst driving, but when stopped I do.
The TCP coming on briefly when the ignition switched on explains why it leaks just as I start up!!

My replacement part arrives tomorrow (£68.47 +vat from Audi main dealer)

MartynF - thanks for the info before - needed it pronto. Fog and indicators installed now, thanks for your hlp with those.

Cheers,
Nick R

[Martynf]

No problemo :-))) so now it all makes sense... why the leak at start-up and after run....

[martinjs]

@paradyne, well that would make sense, id thought about this but ive never had the pump working to justify this, maybe it waits till ive gone then comes on, ive waited like 15mins for it

martin