Feel good Friday.... just in time for the weekend... coolant repairs

[LHD_Kid]

Isn't it nice when you get through a few small niggles and everything is back working how it should?

I had some issues with Samco hoses losing integrity - either splitting or just getting very soft. This resulted in significant coolant loss a couple of times (fortunately I always carry spare water and was lucky each time)

Changed the old Samco hoses to Roose hoses... while I was at it I wanted to get the temp gauge reading more accurately and also get both speeds of the rad fan working when it should...

So... changed hoses, bled and road test. Coolant weep from bleed screw on matrix hose. Remove screw, check o-ring, no issues... wtf? Turns out the bleed fitting was apparently not glued in properly and it was weeping up the side of the fitting, not through the bleed screw.

Phone call to Roose... very helpful, new hose arrived in Belgium in 2 days... bleed fitting fitted really well in a slightly longer tail - as per my suggestion, a clamp round the fitting... belt and braces... apart from the hassle I can't fault how they resolved my issue.

Fit and test... no more leaks... yay...

New Behr MFTS, new Bosch ECU temp sender and a new Behr rad fan switch later... temps look right... fan comes on and off as it should... boost is at the correct level (also linked to an N75 issue)

Happy days...

Here's a pic of my new hose with the clamp. Much better idea IMHO...

[psiconauta911]

I LHD Kid!

I have a problem with the temperatures on my ABY as my fan just turns on when the gauge hits the 3rd dash after 90ºC, this happened after the dealer changed the sensor in the water manifold, I´ve already had the temperature sensor in the main radiator changed to no avail.

The dealer tryed to solve the problem for hole 3 days with no result, he says that the rad fan as 4 speeds, one for when the A/C is on, one for when the gauge goes over 90ºC and it´s controled by the ECU(and this is the one that isn´t working), one for when the gauge it´s around 98ºC (3rd dash after 90ºC on the gauge) and another emergency one at 110ºC, the last two are controled by the sensor on the main rad and the first of this 2 is the one that I get!

Since you talk about a similar problem and a Bosch ECU temp sender and a Behr MFTS(I think this one is the sensor on the water manifold) can you show me some pictures of this two or the part number or have any ideas on this as the car has been like this for a year now and although it never overheated it´s working hotter than it should and the dealer hasn´t been able to solve a problem that happened during one of their interventions!

regards and thank you for any help!

[LHD_Kid]

I can share a few bits of hopefully useful information...

1 - only use a Behr MFTS - pretty much all the cheap ones read high on the gauge. The MFTS feeds the water temp gauge in the instrument cluster... it is, as you say, fitted in the water manifold...

2 - I changed the ECU temp gauge to a Bosch unit as I found it on German ebay. This feeds the ECU with temp information and is in the back of the head by the firewall - this has nothing to do with the rad fan and nothing to do with the temp guage...

3 - The fan has 3 speeds. My fan worked correctly, you can also check this by taking the plug out the sensor switch (bottom of the main rad) and bridging the terminals. Bridge pins 2 and 3 for second speed and bridge 1 and 3 for the 3rd (fastest) speed.

The 1st (slowest) speed can be checked by putting the air con on - I don't know which system you have, but on mine I set the clima to "auto" and the fan started

So. Thermostat should open around 87°C. This is in the block so temp should be accurate. Fan should come on at 95°C at second speed and 3rd speed at 102°C. For me, the switch was not starting the fan for the 2nd speed at 95...

The gauge will read higher when the fan comes on. This is because the gauge takes the temp from the MFTS in the water manifold, by the head, whereas the rad switch is in the bottom of the rad - arguably the coldest place in the coolant system...

I'll find some numbers and pictures for you...

Gauge pic courtesy of URS4Boy...

The pic of the dash is where the fan 2nd speed now starts

[LHD_Kid]

Just to be clear...

The ECU does not control the fan, it is the clima (for slowest speed) and the rad fan switch in the bottom of the main rad for the other 2 speeds (actually, this is 3B information...)

My advice, Verify the rad fan actually works correctly by bridging the pins.

Once you know the fan works, check the switch (main rad) with a multimeter, boiling water and a thermometer (like testing a thermostat)

Check which brand of MFTS they fitted in the water manifold...

If it runs hot, the garage probably fitted a Meyle .... which are useless...

[LHD_Kid]

Check out this : Linky

[bertman]

where did you get the MFTS sensor from mate?.Bought so many over the years and most have over-read or under-read really badly

[LHD_Kid]

where did you get the MFTS sensor from mate?.Bought so many over the years and most have over-read or under-read really badly

German ebay... here: Linky


This one seems to read perfectly... maybe just luck, and wasn't stupid money either...

[psiconauta911]

I´ll look into clarifying those data with dealer, the Mfts and the rad temp sensor where all put in by the audi dealer, don´t know the brand though!
I had a topic here a while ago and the audi mechanic insisted that there are 4 speeds though he can´t say about the first one and why it isn´t working, but the temperatures are within limits he says, I´m betting its the MFTS they put in that was no good since the problem apeared right after that!, it must be reading wrong!