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S2 ABY Over heating at idle

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  • #31
    70C can be seen on the motorway, but it is as a function of the sensor being cooled by the air, in my experience cheap aftermarket sensors do this more than decent ones.

    There should be a boot around the sensor, if missing it will also contribute to it.

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    • #32
      Originally posted by B5NUT View Post
      Been out and check the bottom connecter on the rad, it looks in good condition and so does the plug, however this time when I plugged it back in I gave it a bit more wiggle and I heard a click noise! So it may have not been plugged in fully..

      Also scanned the car and I do have a fault code on the engine about the coolant temp sensor. I will look to replace this
      00522 - Engine Coolant Temperature Sensor (G62)
      29-10 - Short to Ground - Intermittent
      90 deg. is normal running temp but be aware that the multi function sensor on the water rail that supplied the signal to the dash gauge can be inaccurate, a lot of new ones read higher than they should which has worried a lot of people!

      G62
      This is the white sensor on the back of the head, it’s the one the ECU uses to calculate warm up enrichment and fuel air mixture. (Nothing to do with the radiator fan switch, sometimes referred to as the Otter switch because it lives under water).
      If you pull back the rubber boot on the G62 you may find the wires twisted or broken., I’ve seen this a couple of times.
      Otherwise I’d fit a new one, they’re cheap, and a new 2 pin plug (or at least replace the pins) if it looks dodgy.

      S2 Coupe 3B Project


      Ur quattro restoration

      S2 Avant

      Boost is the new rock and roll!
      sigpic

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      • #33
        Went out for a drive this evening and traffic was very light. Temp wise the car is now running at 85 which is better that the 70 I was seeing. When I got back I left the car to idle and sure enough the temp started to rise. Interesting the fan was kicking in but only for a second then went off, also as the fan kicked in the engine revs fluctuated and it also most stalled, did this twice (about a minute apart) before I just switched the engine off. The fan then kicked in as I suspect the bay temps were too high.

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        • #34
          Doesn't sound right. I would replace the switch at the bottom of the radiator and the one behind the head as Newsh pointed out. Before you do that, replace your old bottle and put a good quality radiator cleaner in and run it for a good while. Flush and re fill with plain water, run up to temp and re flush. then replace the sensors and re fill with pink anti freeze and your new bottle. Hold the bottle up as high as you can to release any trapped air whilst engine running and cap off. I've done all this on mine and everything is working perfectly. Also check the connections on the resistor plate which is up in the N/S of engine bay.
          Nothelle S2 Avant in restoration
          Wr Ur Quattro (also in restoration)

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          • #35
            So after more reading it looks like I could have a fan stage speed fault. I was reading this thread and I've never heard the fan run at low speed https://www.s2forum.com/forum/techni...an-not-working

            Also found other owners who also experience revs dropping when the fan kicks in https://www.s2forum.com/forum/techni...r-fan-comes-on

            So tomorrow I'll try and test the low speed fan, and see if it working. I've also ordered all temperature sensors/switches. Over the next few days my house is going to look like a TPS branch!

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            • #36
              The temp gauges always read higher, does VCDS give a reading?
              I'd try a really good flush and some fresh G12 ..
              What is oil temp reading etc?

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              • #37
                On mine the "stage 1" fan kicks in at idle (gently) for about 10 - 20 seconds, which is usually enough to cool it down sufficiently. This will cycle every few minutes or so. "Stage 2" which I have only heard and felt on a few occasions, kicks in like a mule and does bring the engine revs down by a couple hundred rpm for a second. Is it significantly faster and louder than stage 1. I hope this helps?

                Cheers

                Steve

                P.S. I also have a "new" MFTS which reads 100 - 105 deg on the dash gauge when the actual water temperature is 90 deg (evidenced by stage 1 fan kicking in only in exactly the same time and way when the old MFTS read 90 degress...)
                The Perfectionist
                sigpic
                Audi Class Concours winner Stoner Park 2014, ADI Concours D'Elegance Class Winner 2008, Runner up 2014. Winner, S2Forum Show'n'Shine Billing 2006 & 2008.

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                • #38
                  I have checked the the temps with an IR thermometer so the engine temp gauge on the dash was over 100 and the IR temps read over 100 on the block and the aux rad. The main rad was ever so slightly cooler but not by much. No low speed fan kicked in there was just a blip of a high speed fan (about 1 second) where the engine revs dropped for a split second. So 100% I've got a fault on the low speed side of thing.

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                  • #39
                    Okay, So I can share my experience in these troubles.
                    Had exactly similar problems and it was a lot of causes why it was like that.

                    I actually changed a water pump outside in the rain and radiator because I didnt do all the easy steps first. Still not quite sure.

                    So first thing is bleeding it properly, I thought I had done it proper but I was wrong.

                    What I found out I had to do to get water pump etc working correctly with thermostat was filling the hose from top of rad and down to the "water rail" full as well as the tank etc. First then I had it running with the coolant reservoir tank a little higher and after a very long time it was a "bloop" and the last air released.
                    You can check the hoses going in to the heater matrix in the rear if its warm.

                    Changed thermostat to an original one, I cooked it at home with a temp gauge to make sure it wasnt the problem. Fit it in the correct way (as manual says, not sure why or if its important, but hey if it says so why dont do it ).

                    Changed the sensor on the bottom of radiator.

                    In my case there was a dead relay, it was all burnt out. Changed that to a new one, went over all the hoses etc.
                    Suddently both low speed fan and high speed fan worked.

                    Took it for a drive and it stays on 89-90c while driving, 93c in traffic. (The temp gauge inside is probably wrong because of old sensors, and new ones reads often too high anyway). - This is with a new original rad + aux rad.


                    Just some tips from me as I was struggling like crazy with weird temps / "overheating".
                    Also Im coming from cars where 90c is the normal, but these cars seems to be a lot warmer or at least display shows this.




                    https://www.s2forum.com/forum/member...-3b-1991-coupe

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                    • #40
                      If you short Pin3 and Pin1 in the contact you will get full speed on the fan.
                      If you short Pin3 and Pin2 you will get half speed on the fan
                      If it doesnt work its probably a relay, its 1 relay for the half speed and 1 for the full speed if I dont remember wrong, dont remember what NR and position though :/
                      https://www.s2forum.com/forum/member...-3b-1991-coupe

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                      • #41
                        If I can get the low speed fan to come on then I think it should be problem solved. I will be changing the pump but with the timing belt.

                        If still see higher temps then I may think about trying to retrofit a fan on the Aux auxiliary radiator.

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                        • #42
                          Lots of us ditch the Aux rad, no overheating problems. You’d need it in traffic in Southern Europe maybe.

                          S2 Coupe 3B Project


                          Ur quattro restoration

                          S2 Avant

                          Boost is the new rock and roll!
                          sigpic

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                          • #43
                            I'll need it in Darlington, in rush hour traffic can take me 30 minutes to do 3 miles from the town center back home.

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                            • #44
                              Or a larger alu rad would probably work, if you don't have AC I guess the cooling would be a bit better also.
                              https://www.s2forum.com/forum/member...-3b-1991-coupe

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                              • #45
                                The car has AC. Will be looking into the low speed fan today, will short pin 2 &3 and see if it kicks in if not then I've got a relay issue or wiring issue.

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