Coolant Sensor

[jsm3]

I have been getting the dreaded "Check Coolant Level" light on shutdown. The coolant level is fine and the engine temp gage indicates normally. I did add some mix just before this started about a month ago and figured the system must have needed bleeding. I used this process:
1. Warm engine and then shut off engine
2. Open Heater (thumbscrew to red, temps to 90 on both sides) with key in acc position (opening the valves)
3. Loosen bleed screw (not remove) and let about 1-2 oz's of fluid kinda spurt and gurgle out (mopping as I go with a rag)
4. Tighten screw

I repeated this process over several days and still have the light, so...I figured (Thanks to the search here) it must be a coolant level sensor. I checked my Bentley and found absoultly nothing about changing one of these things. In fact, I found no mention about it's existance at all!!

Can anyone tell me: a) where in the hell it is (Bottom of expansion tank?) and b) the steps I need to follow to change it out. (I checked Pelican DIY too). If it's in the Bentley, page please. It's a 98 e36 M3 Vert.
TIA,
JSM3 :(

[RRSperry]

pn 61 31 8 360 458 levelling switch radiator
It in the expansion tank

[ja///Mnn]

Try doing this first. It worked on mine.
The sensor is located on the bottom of the expansion tank. Pull out the wiring from the sensor and shoot some WD 40 into the wiring plug. Plug it back on and wait a few startups or so to see if Low Coolant msg comes back on. If it doesn't you probably had bad contacts or moisture problem. If it does, then the sensor is most likely bad. Good luck :)

[rennfahrer]

well, don't wanna scare you buddy, but might want to check the content of your coolant.
see if it's still "coolant" and not coolant+oil.
:)

[Bernanke]

Try doing this first. It worked on mine.
The sensor is located on the bottom of the expansion tank. Pull out the wiring from the sensor and shoot some WD 40 into the wiring plug. Plug it back on and wait a few startups or so to see if Low Coolant msg comes back on. If it doesn't you probably had bad contacts or moisture problem. If it does, then the sensor is most likely bad. Good luck :)

hmm never thought of that , would silicone lubricant work as well?

[jsm3]

Try doing this first. It worked on mine.
The sensor is located on the bottom of the expansion tank. Pull out the wiring from the sensor and shoot some WD 40 into the wiring plug. Plug it back on and wait a few startups or so to see if Low Coolant msg comes back on. If it doesn't you probably had bad contacts or moisture problem. If it does, then the sensor is most likely bad. Good luck :)
I'll give this a try this weekend. I have looked at the coolant and it does not look like there is any oil in it...keeping my fingers crossed.
jsm3

[HomeBrew1781]

I am getting this as well. Engine Temp is fine though. I am taking it to the shop sometime next week. Don't worry I am not driving it, I have a second car so that I can sit the M during the winter. Let me know what you find out though.

Thanks,

Scott

[Speedlimits?]

i get this on my 99 dealership has replaced the sensor umpteen times, so i think that i am going to pull it and check for moisture on the connectors.

[Speedlimits?]

i just swung by autozone and got some dielectric grease and got the contacts on the sensor located on the bottom of the expansion tank. I will let the car cool off completely and then see if the senor comes on. I only get the message when the car is cold or occasionally immediately after shut down. Hopefully it will just be an easy fix. Not really a big deal just a pet peeve.

[Bernanke]

i hear ya, big pet peve. let us know the results.

[MLOVE]

I replaced my coolant level sensor a few months ago and it went bad again. They just go bad. Make sure you get the right one. There are 2 and they both have different connectors. I am going to try to unplug it and clean it.

[Bernanke]

FIXED!!

hey guys. i got some silicone lubricant today and sprayed down the inside of the plug as well as the prongs and then put the sensor back one.... BINGO. problem is now fixed. it has only given warning message only once and thats probably because i didn't even clean the prongs. I will go back and clean them off and it should fix the problem completely. i'm glad i didn't have to pad $25+ for a new sensor :)

[jsm3]

FIXED!!

hey guys. i got some silicone lubricant today and sprayed down the inside of the plug as well as the prongs and then put the sensor back one.... BINGO. problem is now fixed. it has only given warning message only once and thats probably because i didn't even clean the prongs. I will go back and clean them off and it should fix the problem completely. i'm glad i didn't have to pad $25+ for a new sensor :)
How did you get the damn plug off?! Mine doesn't seem to budge at all. Is there a clip mechanism I am not seeeing? I cannot get to the bottom of the sensor w/o removing the lower rad hose as far as I can see. Did you do this first? (98 e36 m3 vert)
tia,
jsm3

[Bernanke]

hey guys, the warning returned, looks likei will have to go back and clean everything,

[indicaM3]

my car started giving that message too, at every start up and shut down. had sensor replaced, no dice.

[resisTm3]

yup, im getting that reading too now as of couple days ago... ever since i saw it i just put my Ignore face on... that works too :)


brett.

[Bernanke]

hehe ya ignore face works for some but it just irritates the hell out of me so ima fix it. I think a q-tip dipped in silicone libricant and rubbing it on inside of the plugs terminals should solve the problem, that and use soap to clean prongs or something to that extent (maybe alcohol is better). i'll let yall know

[resisTm3]

yeah definately keep us informed, sooner or later ill snap, and ill need a way to fix it w/out using a chainsaw...

btw ur car looks hot!

[Bernanke]

yeah definately keep us informed, sooner or later ill snap, and ill need a way to fix it w/out using a chainsaw...

btw ur car looks hot!


will do, thanks :D :cool

[FAPM3]

We ride motorcycles and have had similar problems. Caig Labs, http://shopping.netledger.com/caigstore make products designed to clean and protect electrical contacts. Great products - just looked at the web site and they are now avaialbe at Radio Shack.

These are much better than silicone sprays. And theyy are available in little spray cans - 20 cc.s. I've had great luck with them.

[jsm3]

How did you get the damn plug off?! Mine doesn't seem to budge at all. Is there a clip mechanism I am not seeeing? I cannot get to the bottom of the sensor w/o removing the lower rad hose as far as I can see. Did you do this first? (98 e36 m3 vert)
tia,
jsm3
Ok, I'll ask again...anyone...anyone..., Bueller? Is the setup I am describing with the sensor being blocked by the lower rad hose different from everyone else's? Can someone advise me, pleasse? If I don't hear back soon, I'll just have to tear the hose off and get to the bottom of the plug to see if that frees it up so I can remove it. Anyone?
jsm3:help

[Bernanke]

hey guys. well I was cleaning it again today for 20 min. I used windex to clean contacts with a towel and used one of my swiss army knife attachements to clean inside the plug (along with windex sprayed in there). after multiples times cleaning both prongs and plug with windex to the point where both were shiny, the warning STILL has come up. it may change over time but i've shut it off twice, and it came up again. if it does not go away after a few tries I guess it will be time for a new plug.

[RRSperry]

Have you tried a multimeter to see if the actual switch is working, or check the continuity of the wires?

[John V]

Ok, I'll ask again...anyone...anyone..., Bueller? Is the setup I am describing with the sensor being blocked by the lower rad hose different from everyone else's? Can someone advise me, pleasse? If I don't hear back soon, I'll just have to tear the hose off and get to the bottom of the plug to see if that frees it up so I can remove it. Anyone?
jsm3:help


The lower rad hose blocks the removal of the sensor. You have to remove it to remove the coolant sensor. Unfortunately, this is a pretty effective radiator-drain procedure. You can either drain the rad and re-use the coolant (no need to drain the motor) or just pull the hose and make a mess.

Be careful removing and reinstalling the sensor. It's plastic on plastic. Things can break. Take your time.

Whoever noted that there are two different sensors is correct. They are not compatible with one another. The cutoff date is 6/95. My car being a 6/95 made it tougher - my parts guy got me the wrong one initially. D'oh!

Good luck.

John

[Bernanke]

Have you tried a multimeter to see if the actual switch is working, or check the continuity of the wires?


naw, i have not. not to good with multimeters. i have a feeling the sensor portion actually exposed to teh coolant is probably covered in gunk which is part of the problem.

[o8OneLight8o]

I have this problem too, and it seems that none of the procedures work to clear...I also went to autozone to get a code read, and got a P0125: Closed Circuit blah blah blah, insufficient cooling level, so maybe if you clear the code, this control check will go away...

And since my boy is yelling at me...."disconnect the muthafukin' battery for 5-10 minutes and see if comes back, damn...do I have to do everything around here?!"

[Bernanke]

hmm interesting. i may need to disconnect the battery again (i will be doing that this week anyways b/c of the long list of mods i'm installing. i'll let you know if that works but most probably its just needs some TLC cleaning.

[jsm3]

The lower rad hose blocks the removal of the sensor. You have to remove it to remove the coolant sensor. Unfortunately, this is a pretty effective radiator-drain procedure. You can either drain the rad and re-use the coolant (no need to drain the motor) or just pull the hose and make a mess.

Be careful removing and reinstalling the sensor. It's plastic on plastic. Things can break. Take your time.

Whoever noted that there are two different sensors is correct. They are not compatible with one another. The cutoff date is 6/95. My car being a 6/95 made it tougher - my parts guy got me the wrong one initially. D'oh!

Good luck.

John

Thanks, John! But, damn, that's what I was afraid of. My car's extended BMW factory warrenty runs out in Nov. Think this would be covered? :lol
Is there a removing-fog-light-type secret about removing just the electrical plug w/o doing the rad hose? Is there some chemical I should use to help break the first turns? Silicon spray? Also, since I have a 98 are there two possible sensors for it or just one before and one after the date?

I have to move this weekend so it's going to be awhile before I have any time to tackle this.
jsm3

[John V]

Thanks, John! But, damn, that's what I was afraid of. My car's extended BMW factory warrenty runs out in Nov. Think this would be covered? :lol
Is there a removing-fog-light-type secret about removing just the electrical plug w/o doing the rad hose? Is there some chemical I should use to help break the first turns? Silicon spray? Also, since I have a 98 are there two possible sensors for it or just one before and one after the date?

I have to move this weekend so it's going to be awhile before I have any time to tackle this.
jsm3

There were not any running changes to the sensor after 6/95. Just get the post 6/95 sensor and you should be fine.

There is no way to remove that sensor without disconnecting the lower rad hose that I can see. But it's so easy to remove, why worry about it? Just put a bucket down there to catch the coolant and you can reuse it when you're done.

John V

[jsm3]

Well...i messed around with tha damn thing, bleeding, etc. to no avail. I saw then I was going to have to drain the rad and pull the lower hose, so I took it in to my dealer w/ my sensor I bought there and had then do a complete flush (It had been 3-4 years) and install the sensor. It works perfectly now...no light! Of course it cost me $165 plus $29 for the sensor, but that's not too bad.
jsm3

[Bernanke]

ya, seems like I will have to do that as well.