Newer engine installed.. Fan wont turn on, temp guage doesnt move
 

I did a little searching, but im still not exactly sure ill get the correct answer without explaining things.. Anyways, you might know me from this thread (http://www.318ti.org/forum/showthread.php?t=27480) I bought a clubsport, and within 13 miles of purchasing, the head gasket blew...

well, I got a good used motor. My mechanic put it in, and the car honestly starts runs and moves as it should.. One minor thing is holding us back from officially letting it out of the garage..

The fan WILL NOT turn on. also, the temp guage on the cluster, doesnt move a smidgon! This may have been the reason my previous motor blew up. not sure!..

anyways, we tested the fan using the paperclip trick(see, I did search a bit!) and both low and high worked just fine. Checked all fuses and thoselooked good as well. Turned on the AC, and the fan still wont turn on.. SOMETHING isnt right here. everything else works just fine on the car. Im thinking its possibly one of the blue or black sensors plugged into the head of the engine.. the blue is the temp sensor, and the black(under the damn intake) is the "remote thermometer sending unit" .. am I correct so far?

Tested the radiator temp sensor? on the passenger side of the radiator. and the actual plug that goes into the radiator has no voltage, but the sensor to put into the radiator plug has good voltage. I dont know if it makes a difference or not.. But we are stuck right now.

Anyways, id like your guys input. as this seems like SOMETHING has these all related somehow..there has to be something that isnt sending a signal, or something plugged into the wrong sensor , something! ugh I just want to be able to drive my damn car !

thanks for any help guys.

Anthony

My guesses...

Bad temp or unpluged sender on head is gauge issue and will casue drivability issues when warmed up due to DME thinking engine is cold.

Relay is fan issue and most likely what caused the car to overheat many times before you purchased it and blow that head gasket.

Please explain the radiator sensor check again since I don't get it. There should be a 4-prong plug that fits the sensor. The sensor is only testable in a pot of boiling water with a ohm meter. The plug should activate the fan with a paperclip if not you have a bad relay.

With the A/C on the fan motor is run by relay and all sensors are ignored. If A/C is on and no fan you have a relay issue.


Please be aware these are all internet guesses. I don't even know if it's a M42 or M44 motor.

Good Luck, John Smith

Its a 95 clubsport, so its an M42. The radiator sensor, maybe I didnt check it right.

The fan works with a paperclip in both high and low. but does not come on if I leave the car running. Also the temperature needle doesnt display any heat readings.. When I start the car, the needle jumps the smallest bit, telling me that its getting power, but its not getting any temperature signals sent to display.

Ok sounds like you have a bad head temp sender for the gauge. Also make sure the radiator has enought coolant. If there coolant is full and the fan does not come on when it gets hot you have a bad radiator sensor too. If you can paper clip the fan on and the sensor won't turn it on the sensor has no water on it or is bad. The sensor only works by when it reaches around 210 degrees it connects the two wires for low fan. Make sure the A/C compressor clutch is plugged in and the compressor is engaging or the fan won't turn on.

Hoipe this helps.

Relay is good if you can jumper the radiator sensor. Check coolant I bet it was not burped correctly and the water level is below the sensor so it can't read water temp in the radiator which turn on the fan.

The gauge is head temp sendor related. Pull the plug off the head sensor and paper clip it and the gauge should go full over heat...That will let you know the wiing is good and only the sensor needs replaced. If there are two sensors did you reverse the plugs? I don't know M42 like M44's but I do have one coming for repairs today or tomorrow and can take a look at the sensor layout

Does the A/C compressor clutch kick in when you turn on the A/C? Big question since it should always bypass all sensors and go high fan...

replaced the sensors and the temp works!... now .. onto my next problem.. a check engine light.. and when the AC is on, the car has an odd idle(it jumps from .5~1 rpms).. I think this is related to another problem I have which is : Lets say im crusing down a long road in 5th gear at 65mph , and up ahead theres a red light, so I throw it from 5th into neutral and just coast.. Well, when I do this the car stalls out.. but this only happens when the AC is on..

Clean your idle control valve.