Audi s2 Aby running hot 95 degrees or so

[Chris5044]

I’m not sure what this means. You’ve removed the Aux Rad?
What’s the mod and bypass??

The word “bypass” suggests you’ve joined the Aux rad pipes together. This would allow an easy route for the water to avoid the main rad, or indeed for the water to circulate down through the rad and up through the bypass, avoiding the engine.

The jury is out on this but definitely ..
When you remove the Aux Rad you must plug the two pipes.

Also if you’ve fitted a new MFTS (or it’s starting to go bad) it may read high, lots of them do, best way to check coolant temp is to do it in Vagcom Measuring Groups as the ECU takes it’s temperature feed from the white sensor on the back of the head.

Thank you dude, I dont have vagcom.. -- im guessing its something you plug into the s2?
What I meant is I have done the aux rad mod .... (its plugged yes). does one know where to source an new MFTS sensor from?

[Chris5044]

Mine started running hot last summer, the main rad was partially blocked.

ah good point!! Im not sure, actually its been sat awhile..

[Scarecrow]

Thank you dude, I dont have vagcom.. -- im guessing its something you plug into the s2?
What I meant is I have done the aux rad mod .... (its plugged yes). does one know where to source an new MFTS sensor from?

I recently purchased one from Quattro Corner so you could try them. They sell the genuine Behr sensors as well as aftermarket but I believe some aftermarket sensors can read high on the gauge but I could be wrong.

[Chris5044]

I recently purchased one from Quattro Corner so you could try them. They sell the genuine Behr sensors as well as aftermarket but I believe some aftermarket sensors can read high on the gauge. However, I could be wrong.

Huge thank you scarecrow!!

[newsh]

Thank you dude, I dont have vagcom.. -- im guessing its something you plug into the s2?
What I meant is I have done the aux rad mod .... (its plugged yes). does one know where to source an new MFTS sensor from?

Vagcom won’t work with the Emerald but the Emerald software will do similar stuff.

Plugged is good!

Genuine Behr MFTS as per Scarecrow above

[le mans]

I know the fan works, but I have heard about the 2 stage fan?? Can someone perhaps tell me more on how this works? Ive only noticed the fan come on or off..

From here: http://www.s2central.com/cooling02.html
“F18 turns ON at ~95C, OFF at ~84C and provides the switch to control the fan on speed 'Hi-1' whilst F54 turns ON at ~ 102C, OFF at ~91C to control the fan on speed 'Hi-2'.”

As far 95C being an issue I wouldn’t have thought so. The owners manual says ‘middle of the gauge’ is normal operating temperature. The warning light comes on and the ECU cuts boost if the temp hits 120C.

[Chris5044]

From here: http://www.s2central.com/cooling02.html
“F18 turns ON at ~95C, OFF at ~84C and provides the switch to control the fan on speed 'Hi-1' whilst F54 turns ON at ~ 102C, OFF at ~91C to control the fan on speed 'Hi-2'.”

As far 95C being an issue I wouldn’t have thought so. The owners manual says ‘middle of the gauge’ is normal operating temperature. The warning light comes on and the ECU cuts boost if the temp hits 120C.

<3 <3 <3 <3 <3 Thank you, will take this on board also. I had a friend who removed the aux rad and said that cylinder 1 (end cylinder) ran very hot

[Error404]

As John said if your tuner said it’s running hot he’s reading the ECU data from the ECT sensor, so either it is running hot or it’s a calibration error (unlikely)
MFTS is pretty much just a rough indication of if the engine is cold, at operating temp or overheating - it’s useless for accurate measurement.
Most likely your rad is under efficiency - maybe partially blocked as said above, or your thermostat is not opening fully meaning your not getting adequate coolant flow at operating temp. Other possibilities of course, air in the system, pump impeller damaged etc etc..

[Chris5044]

As John said if your tuner said it’s running hot he’s reading the ECU data from the ECT sensor, so either it is running hot or it’s a calibration error (unlikely)
MFTS is pretty much just a rough indication of if the engine is cold, at operating temp or overheating - it’s useless for accurate measurement.
Most likely your rad is under efficiency - maybe partially blocked as said above, or your thermostat is not opening fully meaning your not getting adequate coolant flow at operating temp. Other possibilities of course, air in the system, pump impeller damaged etc etc..

Hey the temp on the guage is 95 degrees. Does this help?

I will see if I can bleed the rad. Is there a way to unblock or make sure the rad is unblocked?
- or would this occur from removing the aux radiator? if not then its deffo not my mod.

[newsh]

No1. As above. You cannot trust the gauge, it’s really not that accurate . (And 95 is not that hot anyway)

No2. Does the fan come in and cycle on and off when the car is idling? Or in traffic?

No3. Bleed the heater matrix at the firewall with the screw on the rubber pipe, whilst topping up the header tank. (careful you don’t break it, it’s plastic)

No4. Bleed the screw on top of the rad while topping up. Nip up the screw and squeeze the top hose to get rid of bubbles.

No5. My car, along with many others, has run without the Aux rad for over 10 years. My car was running 450hp on a stock rad.

No6. If you haven’t done it for a while, think about replacing your thermostat and while the coolant is out flushing the rad.

[Chris5044]

No1. As above. You cannot trust the gauge, it’s really not that accurate . (And 95 is not that hot anyway)

No2. Does the fan come in and cycle on and off when the car is idling? Or in traffic?

No3. Bleed the heater matrix at the firewall with the screw on the rubber pipe, whilst topping up the header tank. (careful you don’t break it, it’s plastic)

No4. Bleed the screw on top of the rad while topping up. Nip up the screw and squeeze the top hose to get rid of bubbles.

No5. My car, along with many others, has run without the Aux rad for over 10 years. My car was running 450hp on a stock rad.

No6. If you haven’t done it for a while, think about replacing your thermostat and while the coolant is out flushing the rad.

Smashing advice bud!! thank you so much!... just gotta wait for the return of the car now.. its been away for ahile at a friends workshop who lives far away, once the parts and work get done on her to pass the MOT I can get her back and will start on this. Massive thank you. (I have fitted thermostat recently - I hope you cant accidentally fit it backwards.. Im sure there was one way. Righto ! Ill check these. Super thx and cant wait to maybe meeting some of you dudes again. You've been a massive help!!

[Chris5044]

This is great guys!! I got the s2 back yesterday! its running amazingly!! with the tune. Its very smooth delivery at 273bhp (mapped).
The degrees are ok now, it seems to have gone down to 90 degrees again and even below slightly on a drive at night yesterday!! So hopefully this issue has been resolved! The car has been sat for a while. I hope to change this and keep it going!

Big thank you to this forum and all its members!! Will be looking forward to being more active and meeting you guys again!

[steve briance]

So which bit of advice did you do that leads you to think the issue is resolved?

[Chris5044]

False alarm guys!! went out today and its reading very hot, around 100 degrees!! grr!! I've only just got the car back after it being somewhere far away at a workshop. Ill tr bleeding the radiator and go through all the advice here and give you guys an answer.

Hey sorry Steve - it just seemed it was cold last night.. bizarre, if it comes to a flush, Ive never done this before, would I blast fluid through it? or just drain it? if theres a block, will have to figure this out. Also considering an upgraded alloy radiator that is larger

[newsh]

Is the fan coming on?