So I just replaced my coolant temp sensor, the car has been starting hard and now that its cold it only fires up on ether but runs fine once you get it going. I checked the AP one 50 degree day trying to start and i was getting a reading of 220 off the bat. Once disconnected it started fine. Anyway the new one is in, fired right up. However when I went to replace the coolant lost during the procedure the car just didn't want to take it. I cracked the bleeder valve open a bit more assuming maybe I still hadn't opened it enough and it took a bit more but I then realized that a sizable amount was leaking under the car. I watched my ect readings and it took forever to climb up to 196 (as far as i know the thermostat should have been open then ) but the coolant level still didn't drop. Oil temp at this point was around 180 and i didn't want to wait much longer cause I was scared the temp wasn't accurate cause of the missing coolant and it would be higher. I stopped for now. An hour later it starts fine and theres no oil in coolant or vice versa so i think I'm ok, I just really need to get the car up and running. Any ideas on where I should go from here? I've done this many times before but it was usually faster and easier and i didn't care as much about the cars. This is my girlfriends car so the last thing I wanna do is blow a head gasket or worse

Thanks in advance

Ps. The heat is blowing hot the whole time so I'm assuming there's a decent amount left in the system

 

R56 Coolant System - Filling and Bleeding (without Vacuum Bleeder)
- Before filling radiator:
* swtich ignition ON - do NOT start engine
* set heater temperature control to full warm
* set blower control to low
* set set heater control (if installed) to maximum

- Start engine and run at idle speed for one mintute (coolant reservoir cap open). Adjust coolant level to MAX level, and close cap.
- Run engine until it reaches operating temperature.
- After engine has cooled, recheck coolant level.
- Top up so that coolant level is at MAX.
- If trapped air cannot be bled manually, pressure-bleed system using cooling system vacuum bleeder.

You coolant temp of 196deg F is LOW; that's not running temp.
The coolant temp at normal operating temperatures is 215-220deg F.

Oil temperature can be as high as 250deg F before being concerned.
Typically highway driving will be around 180deg F.
Idling in traffic will push to 200-210deg F...
And heavy driving / track days will see 220-250deg F.
If you're pushing pass 250deg F, then it's time to be concerned.

- Erik

 

So are you saying don't bother with the bleeder valve and just let it vent through the reservoir? Thanks a ton btw. I guess these run a bit hotter on the street than I'm used to

 

Correct, the overflow reservoir is designed to be the top part of the system to allow air to surface in the tank.
No doubt you should check the level for the next couple of days, but I would complete the procedure above from the Bentley Service Manual.
Past that, you should be in the clear.

- Erik

 

The factory manual says this.

 

Thanks guys, I have bled the majority of my older cars without using the bleeder at all and just leaving the cap open. I noticed on this car that seems like the higher point of exit rather than the bleeder screw. I think I will just drive it a bit with the cap loose and be mindful of the temps. I'm not used to cars running this hot without the thermostat opening and it just freaks me out a bit

 

Just went for a 15 minute drive at 45-60mph most of the way. Coolant temp got as high as 224, oil 220. Still noticed that the hoses going to the radiator are not the slightest bit warm bit I guess temps are within range. One thing I noticed is that from switching to 5w-30 Mobil 1 to 0w-40 the average oil t has been higher by 10-15 degrees, used to be in 185-200 range and after the switch it seems to hover between 210-215

 

Ok I know something is still amiss, I've been doing a few short 15-20 min test runs and tonight for the first tike I shut off the heat. So far the hottest reading I got on access port was 224 but with the heat off I finally got up to 235 and then it droopeed and I stopped to check and had a slight boil over. At first when the temp fell i was thinking it was the thermostat opening but still not circulating through radiator. Also interestingly enough the fan isn't coming on, even when I turn AC on so I'm not site its related but seems odd.

When my cts first started showing signs of malfunction the fan would always run even if I just moved the car in the driveway and shut it off. I'm now wondering if the fuse for the fan blew and it controls the thermostat as well? One thing I find interesting is the interior heat still blowing hot. This makes me think the water pump should be fine, its just running in a closed circuit through the engine and heater core.

The car starts and runs fine even in cold so I know that the cts was at fault but now I have a car that starts easier but I just don't trust

Any ideas?

 

I can't really help but 224 is not out of the ordinary. My dealer even says 230 is okay. I've seen 230 on my gauge a couple times. I use an OBDII gauge that get's the reading from the car's sensor and not an aftermarket one.

Something's up with the fan for sure. 230 it should be on full power. Mine comes on about 225 or right when the AC is turned on.

 

I have thermostat, water pump, hoses and BMW coolant on order, so hopefully this is squared away this week. Ill start with the thermostat as I'm thinking that it has to be an electrical issue if the fan isn't turning on either and i know there are other sensors in the housing. If it ends up being a dme issue I'm at the point where I'm about to get an aftermarket temp sensor for the auxiliary fan and run it to a secondary power source and bypass dme altogether. Hopefully it doesn't come down to that though

 

Swapped out the thermostat today as I was impatient and hoping that was the problem. Filled radiator as much as possible and heater core, then used thin funnel to fill from coolant temp sensor hole. This seemed to work well. Preliminary tests of 10 mins or so idling and revving then bleed, then 5 mins drive, quick bleed, and repeat then trying to drive with the heat off look like the thermostat is opening. After I parked for a min I felt the radiator hoses and both were warm finally! Also then fan seems to be turning on with air conditioning now so I can only assume it should work when the car is hot too. On the downside there is a teeny bit of water on my oil cap, but it could be wfrom having it parked with the pcv hoses and stuff off and it being wet outside too so we will see

 

Had my girlfriend drive around for 20 mins and things seem normal. Temps with the heat off got up to 225 and fell to 218 then stayed between 220 and 224f

Oil temps were a bit high though getting to 227, though that seems to still be within normal range and I am not sure how accurate the reading on obd2 is

Also i have noticed that since switching to 0w40 from 5w30 my oil temps have been about 10-15 degrees hotter

Before while i was running the bad coolant temp sensor my water temp sensor was showing a reading of 165 Max and oil temp was around 205-212 so i guess if the water temp is now at 22ish it makes sense the oil would be hotter too

Gonna switch back to 5-30 and see where that gets me

 

Sorry to thread jack, but how do you get oil temp via obdii? I didn't think there was a sensor for it...

 

I'm not sure of the exact sensor location but accessport and scangauge among others both read it so I'm assuming that there's some OEM provision

 

Did you set up an xgauge? I'd like to know this... Afaik it's only a water temp sensor in our r56s

 

Replacing engine coolant temperature sensor on mini cooper s.....is it supposed to be so hard to screw in?

 

I have a new motor in my 08 Cooper S (from Mini dealer) which included the water pump and thermostat and Im regularly in the 224-226 F range. I was in traffic yesterday with ambient temps at 50F and I hit 233 F. This reading is via an Aerforce guage plugged to the OBDII port.. I was getting kinda nervous. Once I started moving the temp moved back down to 226.

If my memotry serves me, 240F triggers overheat condition.

I couldnt tell if the fan was on with all the ambient nose. I've bled the system multiple times. According to the Bentley manual, the fan doesnt come on until 226F. But should it be allowed to hit 233F? AC wasnt on. I did turn it on, but maybe I didnt go to max, because the temps didnt drop fast as they normally would with cooling fan turning.

I dont know how to proceed.

 

Mine usually runs at 215-225F, but out of curiosity I did plug in a log reader and watch that temp go up to 230F as I redline a couple drives. When I come to a stop at the light, I can hear the fan running and bringing it back down to 226F before the traffic light turns green again. I did encounter at bad thermostat before, but with that happening, engine after warm up I can drive for about 5 minutes, then I get the limp mode with a overheat warning.

 

I could see how a bad thermostat would do that. For sure. That's not my case. It holds steady at 224-226 F but that one time I hit 233 F in traffic yesterday I got spooked. The temps dropped but slowly over a few minutes. I was sure the cooling fan should have come on.

Is there a cooling fan relay which could be bad? The coolant temperature sensor is new, as it came with the new OEM motor.

 

I checked the cooling fan 30amp fuse and it had continuity.

I tried putting the AC on high (its 40F outside) but the fan didnt come on with enfine at 199 F. I suppose that's due to the outside temp?

I guess I could disconnect/unplug the coolant temp sensor which should force the cooling fan on, no? (and throw an error code in the process Im sure).