Another cooling issue....

[MyTi82]

yea guys another cooling thread. i have researched the threads and i know all about bleeding the system and i def expect the first reply to be to bleed the system.

i guess i just wanna make sure that my thinking makes sense and if i am over looking anything.
so let me bring u up to speed.

i was coming back from running erruns on a hot summer day (>90 degrees out) and i was smelling something weird but at first thought it was from outside. i get to a stoplight and i see light smoke coming from the front of the hood where the grills are. i take a quick glance at my dash, everything looks normal (no lights and temp gauge @ midpoint). i quickly pull over and cut the car off and look under the hood. it seemed as if there was smoke coming from the fan shroud area. and a weird funny smell like kids crayola hand paint. i come back the next day to check it out. i cut the car on n let it idle. after about 15min i see the smoke appear again and think ok, the auxillary fan needs replacing. i get one from bavauto and replace it. the car had to sit for about a week while i was trying to figure out what was up and getting the part. both times i also checked the coolant levels and it was at the bottom of the expansion tank. i honestly didnt think much of it at first because my coolant level is usually below the cold mark, but this time, i will admit it was low enough i could see the black part of the expasion tank.
so after i put the new fan in, it started to over heat after a while idling. i did a lil more research n though, no prob.....just add more coolant and bleed system (properly of course). so i have done that about 4-5 times and its still over heating.

now i am not saying that i am a master at bleeding these guys but i am a lil confused on what to do.
the current situation is as follows

i have noticed that the auxillary fan doesnt come on at all.....either with AC on or under long idle.
from what i read on the forum is that it may not come on if everything else in the cooling system is working properly, which i believe it is.
however, my thought is that if the fan doesnt come on, then the car will overheat.
i also did a lil test i drove it around the neighborhood a few times, watching the needle. i did this for about ten min.....and it pretty much stayed at mid point. though it seemed to kinda move from like a mm before and after midpoint, but not really passing midpoint.
i then stopped like down the street from my house and just let it idle. after about 5min, it went past midpoint. i immediately drove a good 200ft to my house and as i did that the needle went back to mid point. and of course the fan didnt come on.
basically i was trying to see if it was overheating at idle or in general.

my thinking thus far is this.
that due to coolant being low the temp sensor that tells the fan to come on is fried (info that i got from the forum). at first i thought is wasnt coming on because the sensor wasnt in contact with the coolant and thus didnt know to come on (also info i got from the forum). and the reason why it overheats at idle is because no air is moving through the radiator since the fan isnt coming on. and it doesnt over heat while driving is cuz there is air moving through the radiator.
so is this thinking correct or no?

option B is basically......keep bleeding the system and the reason why the needle went back to midpoint after driving to my house is cuz the air bubble passed.

i am more inclined to go with option A because i have bleed the system the recommended times and because the needle isnt doing a pendulum action, moving back n forth from past midpoint to midpoint which would indicate to me passing air bubbles.

so sorry for it being so long but i wanted to be detailed and also let yall know i did search. i didnt want to get fussed at by u know who u are. lol.

so option A or B? voting starts NOW!
so i am thinkin i should replace the sensor.

[spidertri]

You are losing coolant, the steam you were seeing was from a leak in the system somewhere. You need to find out where it is leaking and replace that part. If the steam was coming from the front you should check the radiator and hoses for any dried coolant.

[MyTi82]

Originally Posted by spidertri

You are losing coolant, the steam you were seeing was from a leak in the system somewhere. You need to find out where it is leaking and replace that part. If the steam was coming from the front you should check the radiator and hoses for any dried coolant.

it wasnt steam, it was definitely smoke with a funky smell and def coming from the fan which i replaced

[1996 318ti NY]

Fan temp switch on rh side of the car is probably the problem with the fan as for losing coolant??? no idea just a leak search i just had the same problem luckily i have a plethora of spare parts in my garage literally a whole TI haha. whenever i was idle the car would get hot and if i sat parked it would get way hot swa my fan wasint coming on changed the fan first like you that didnt work then i changed the switch and it worked beautifully once again.


GL with it.

[MyTi82]

Originally Posted by 1996 318ti NY

Fan temp switch on rh side of the car is probably the problem with the fan as for losing coolant??? no idea just a leak search i just had the same problem luckily i have a plethora of spare parts in my garage literally a whole TI haha. whenever i was idle the car would get hot and if i sat parked it would get way hot swa my fan wasint coming on changed the fan first like you that didnt work then i changed the switch and it worked beautifully once again.


GL with it.

thankz.....i think i will order the part n replace it. i was also think relay or fuse to. it says its under the steering wheel but like where under there? i am aware these coolant parts can have hairline fractures so i am thinkin thats where the coolant is going. i plan to change the coolant parts after this winter so that should take care of that.

any tips on changin the sensor or is it pretty much straight forward as it looks? wat size wrench u use?

[spidertri]

If you didn't have any coolant in the expansion tank that says there is a leak.

[xxxJohnBoyxxx]

Hold up. If the fan does not come on with the A/C on then it is a issue other then the temp switch on the rad. Maybe a relay. The fan should always run when the compressor is on to cool the condensor. I think you have a relay issue or at least that is where I would start looking.

John S

[MyTi82]

Originally Posted by xxxJohnBoyxxx

Hold up. If the fan does not come on with the A/C on then it is a issue other then the temp switch on the rad. Maybe a relay. The fan should always run when the compressor is on to cool the condensor. I think you have a relay issue or at least that is where I would start looking.

John S

i c. but question, u saying the fan should come on when i cut on the AC, but i thought if the sensor is fried then it wouldnt come on. i think i read that in another post......though i might have misunderstood.

either way i have looked for the relay/fuse but i am not sure where it is under the steering wheel as the fuse box under the hood says thats where it is.

[MyTi82]

hey guys, i still need a lil help with this.
so i finally found the fuse.......it was behind the bottom dash. actually very simple to get to. it was blown so i replaced it. problem solved right? nope......the fan still wont come on. so things done so far.

bleed system
replaced fan
replaced fuse.

whats missing? fan will still not come on at all.

[familytruckster]

If the fuse was blown there is a problem somewhere else.

The relay could be bad, wiring could be smoked. Did the fuse blow again?

[xxxJohnBoyxxx]

Fan relay. I think it's green. Here is how it works. The sensor only turns on the fan by connecting ground to two wires when it reaches a certain temp if the sensor goes bad the fan just doesn't come on.

The A/C fan function is separate from radiator sensor. Anytime the compressor turns on the fan has to be on and it bypasses the radiator temp sensor. It the radiator temp sensor reads very hot then the fan will kick to a high speed.

I think you have a relay issue just to get power to the fan to just turn it on. Internet guess from what you have told us. The relay will be in the fuse box.

[MyTi82]

Originally Posted by familytruckster

If the fuse was blown there is a problem somewhere else.

The relay could be bad, wiring could be smoked. Did the fuse blow again?

no, the fuse didnt blow again......

[MyTi82]

Originally Posted by xxxJohnBoyxxx

Fan relay. I think it's green. Here is how it works. The sensor only turns on the fan by connecting ground to two wires when it reaches a certain temp if the sensor goes bad the fan just doesn't come on.

The A/C fan function is separate from radiator sensor. Anytime the compressor turns on the fan has to be on and it bypasses the radiator temp sensor. It the radiator temp sensor reads very hot then the fan will kick to a high speed.

I think you have a relay issue just to get power to the fan to just turn it on. Internet guess from what you have told us. The relay will be in the fuse box.

i have seen a green relay in the fuse box......will it say fan or something so i will know for sure. also, i am assuming these are dealer only relays?

[xxxJohnBoyxxx]

Originally Posted by MyTi82

i have seen a green relay in the fuse box......will it say fan or something so i will know for sure. also, i am assuming these are dealer only relays?

Not dealer only relays. I purchased a few from my local auto parts store but you need a good parts guy to cross ref them.

Also what year and make car and I will tell you what position it should be in. I think there are 3 green relays in there.

Do you have a Bentley Manual?

[MyTi82]

Originally Posted by xxxJohnBoyxxx

Not dealer only relays. I purchased a few from my local auto parts store but you need a good parts guy to cross ref them.

Also what year and make car and I will tell you what position it should be in. I think there are 3 green relays in there.

Do you have a Bentley Manual?

unfortunately i dont. Where is the best place to get a Bently Manual?
i have a 97 318ti.