Quarta2six

Replaced water pump and hoses recently but was unable to replace O-Ring for temp sensor Item#3 when I replaced the lower rad. hose #2. Finally got it today saw a tiny leak from it being so old. Wondering if anyone knows how much coolant will come out when I take out the sensor. Just curious dont want a mess after Ive already cleaned everything up a few days ago. Thanks fellas.

Hyper_545i

Replaced the same sensor last year. Lost only a few drops. With that being said, the car was parked for a few days cold and I left the reservoir cap on! If your quick you should only loose a minimal amount of fluid, but of course, prerpare for the worst and make sure you have enough on hand to replenish and be prepared for a cleanup in case.

Quarta2six

I figured somebody had to change it before. My car has been parked for a couple days now so same boat hope I have the same results. My sensor is still good just need a new O-ring ECS sells just the O-ring now. Thanks for the feedback bro

Hyper_545i

Anytime bud! Good luck. Remember to keep the reservoir lid closed to keep the fluid from rushing out as it is a pressurized system. I replaced the entire sensor so it was literally pull one out and put the other one in. If you are actually replacing the O-Ring, depending on how long it takes it may spill more fluid. That is why I opted to change the entire sensor, also because I know the sensor probably will need replacing in the future anyway. Try to get something to catch the fluid handy in case. Speed is key! Good luck bud! Let me know how you made out.

KyleB

Had the same problem, and I lost a whoooooole bunch! hope you're luckier than I was. I am fortunate to have a dealer less than two miles from my house; ended up buying an entire new sensor as the ring isn't serviced separately. Yes, I could have hunted through the Autozone parts bin for a ring, but I'm not much of a gambler when it comes to that sort of stuff.

turboawd

like stated above, as long as the coolant system is NOT pressurized(hot) then you should be alright.
you could loosen the fill cap to relieve pressure, then retighten it before removing the sensor.

westsidebalto

Careful....if the system is still hot, you could scald yourself. A $20 jug of BMW coolant is a lot less costly than a hand or an eye.

As somebody else pointed out, the O-ring will take sometime to replace. Remember than when fluid is guzzling out of a hole, four seconds can feel like four minutes. I'd have something to catch the spillover fluid and also have some distilled water on hand to top up if you don't have an BMW coolant.

Also, be careful removing the sensor. I replaced all of my hoses a few months ago as preventative maintenance, but I was not able to remove that sensor without breaking it. This left me in a pinch, as I had to run over to the dealer and shell out $50 for a new one instead of waiting a few days for a $25 one from the internet. I might even have the old O-ring (which was only a year old) if anyone wants it.

turboawd

oops, edited my post above. coolant system should NOT be pressurized.

also, one other trick, when you remove the resorvoir cap, squeeze the upper radiator hose a bit, then tighten the cap while still holding the hose. this will cause a slight vacuum.

twh

Your toolbox should include a couple different sized rubber stoppers. They come in handy from time to time to stop leaks while you fiddle with things or get the right part.

Quarta2six

Definitely appreciate all the feedback from you guys. Posted the same thread on Bimmerfest only got 1 hit. Changed the O- ring took me a couple seconds As Hyper suggested I just made sure the car was cold. It sat for a couple days since I don't drive it during the week. I left the expansion take cap on and just removed the sensor. I only lost a couple drops of coolant nothing major at all. Went smooth, thanks for all the advice for sure.

Definitely a good tip. Will look around for some.