Rs2 overheating???

[jade]

Change the radiator

[Tommy200rs]

I had some bad Audi RS200 days with the cooling system, boost control and multifunction sensor. Here how headace solved so far.

Hints from here: http://www.sjmautotechnik.com/troubl...g/cooling.html

My ECU wiring is like in the beginning of rs200 upgrade and one pin brings too high temperature signal from the "multifuxing" sensor. The behr sensor was sending too high to ecu and then no boost. Also the engine temp was too high.

That wiring is nasty because no ECU error rises from that multifunken sensor sending too high , just the AC Klima ECU senses the too high and no AC turn ON.
Now with new multifunken sensor installed and that works and AC switches ON.

Next problem was too high cooling water temp. Findings: 1st speed fan turns on when AC is switched ON. Bentley manual A200 show that resistor pack signal entry "low 1st speed" go through BOTH resistor pack R1 and R2. In case low speed does not work the R1/R2 is broken or relay "214" in fuse box is broken . In case fan speed one works the R1/R2 package is ok and relay 214 (443951253K 899512) also is OK.

It seems that fan speed 2 is missing for high water heat. The "easy" check is to remove the 3 connector wiring from the radiator valeo/behr thermoswitch 191959481C and just connect one abico jump wire between the most right and most left connectors. (blue/red to green/violet) After that when ignition on and In case 3rd stage "217" 443951253S (899556) relay is ok the turbo 3rd speed fan will work. It did. Then connnect the jump wire from blue/red to red/green in the midle and fan speed 2 should activate in case fan relay 2nd speed 214 relay is Ok. That also worked.

Conclusion is that the ancient behr thermoswitch has died, BUT.

An another option for overheating is that water thermostat is stuck and the thermoswitch just does not activate speed 2 because not enough water is flowing through the radiator. The fan activated speed 2 when motronic ECU measuring channel was showing close to 102C and therefore I quess that actually the thermostat must be replaced. FAN Super speed 3 did not activate at all.

No easy solution and changing the thermoswitch might not be the final solution and cooling water from radiator will come out in both change cases. I will juse the fan speed 2 jum wire and see where the water temperature ends.

continues .....