DIY - Temp. sensor coolant leak repair

Originally Posted by jwdilljr

Can drive maybe 3-4 miles at most going real slow and red over heat light will come on, also my heater will not get warm...here's a pic, when you pour coolant in you can look under the car and see it coming out, just don't know where it's coming from

Sounds like a cracked expansion tank or a broken hose. I'd get under the car, have somebody pour coolant and see where it's coming from.

i dont see a leak but every now and then my car will start geting hot wheni idle on a hot sunny day and have AC on/off and im stuck in traffic.

you think this is what i need to fix?

any help guys

Originally Posted by momo_oo[][]oo

i dont see a leak but every now and then my car will start geting hot wheni idle on a hot sunny day and have AC on/off and im stuck in traffic.

you think this is what i need to fix?

Not much to go on but here's a couple thoughts.

If you are not losing fluid, maybe your thermostat is malfunctioning. If it is closed, it will not allow the coolant to circulate and that could cause over-heating.

Your engine fan is not working. If you have the electric fan, it will only come on when the enginer heats up. idling in traffic means no air flow thorugh the radiator and engines get hot. If your fan is not turning on, your engine will over-heat.

Another pssibility could be air in your cooling system. Have you bled the system to ensure there is no air in it? Look on the WIKI for cooling system and it will tell you how to do it. It's really quite simple.

Good luck and I hope you figure it out. These engines have a very low tolerance to over-heating

Thanks djstrachan, Will look into this some time this weekend.

I found the sensor here for $16.87

http://www.eeuroparts.com/Main/PartD...id=13621433077

Trying to find a temp sensor for my girlfriend 2006 330i bmw - ebay sent me the wrong part. http://www.ebay.com/itm/300521176928...#ht_1296wt_952

Any other sites I can check.

Anyone??

Originally Posted by utfootball4

Anyone??

Ck the sponsors at the top of this page.

I would recommend OEMbimmerparts.

I'm doing this DIY at this very moment and I want to correct the origianl author regarding the retaining clip that holds the wire harness. He says "pull out and hold the chrome retaining clip and pull the connector straight up. If it resists, that means you are not pulling the clip out enough" LOL. Don't *pull* this clip. The clip is designed as a *push* release. Contrary to the photo -- don't pull it away from the axis -- just push it in and it releases. It is in its outermost position at rest.

Thanks though -- this post saved me a bunch of dough.

The temp sensor O-ring is a standard AS568-203 size. Found them at www.oringwarehouse.com for 5 cents a piece.

!! Awesome thread !! Thanks for all the insight and advise.
Just had the opportunity to perform the coolant sensor replacement on my 03 330i. My biggest issue was to 'gently' remove the sensor. I was unable to get enough leverage while holding down the tabs on each side. It was not moving.
Ended up tying a tie wrap around the sensor to compress the tabs and then gently wiggling and pulling the sensor out with a pair of pliers.
Worked like a charm.



Thanks again all,

Wolf

Hi Wolf

I see my coolant dripping down and almost looks like from the bottom of expansion tank. Is this Temp sensor O ring issue? Also where is Temp sensor located? Is this visible from once I open the hood or Do I need to remove anything to access this?

Thank you for your help.

Originally Posted by pillpusher

Hi Wolf

I see my coolant dripping down and almost looks like from the bottom of expansion tank. Is this Temp sensor O ring issue? Also where is Temp sensor located? Is this visible from once I open the hood or Do I need to remove anything to access this?

Thank you for your help.

No, likely cracked expansion tank, could also be leaking from one of the hoses that attaches to ET, coolant level sensor, ET cap, or radiator neck. Search the threads for leaking expansion tank on e46s.

The temp sensor is in the lower radiator hose, left side as you're facing the car. If you follow the lower radiator hose from the thermostat down and to the left, the temp sensor is right where the hose attaches to the radiator. You might have to remove your fan to see it.

Will try that this weekend and see
Thank you for the help

Originally Posted by jcourcoul

Have you noticed that the coolant level seems to slowly drop but all the hoses look clean and dry?

Oh, I meant to post this last summer, but I followed this DIY and it was super simple. I got the sensor from oembimmerparts.com for cheap and had it swapped out in about 30 seconds. I didn't even spill any coolant in the process.

Nice post Jcourcoul!

Originally Posted by Scottji

No, likely cracked expansion tank, could also be leaking from one of the hoses that attaches to ET, coolant level sensor, ET cap, or radiator neck. Search the threads for leaking expansion tank on e46s.

The temp sensor is in the lower radiator hose, left side as you're facing the car. If you follow the lower radiator hose from the thermostat down and to the left, the temp sensor is right where the hose attaches to the radiator. You might have to remove your fan to see it.

Scotti

Finally managed to put it together, Looks like it was expansion tank. Once replaced it started leaking from different area the upper radiator hose @bigger connection

Hose snapped in fine, But starts to leak as soon as I start the car.(it never leaked from there before). I added a picture ignore the marked area but right under Min/Max sign
Is any right way of snapping it? or do I need a new hose to replace? I also lost a lower radiator hose small clamp in the process

Thank you for the help

Originally Posted by wolfegar

!! Awesome thread !! Thanks for all the insight and advise.
Just had the opportunity to perform the coolant sensor replacement on my 03 330i. My biggest issue was to 'gently' remove the sensor. I was unable to get enough leverage while holding down the tabs on each side. It was not moving.
Ended up tying a tie wrap around the sensor to compress the tabs and then gently wiggling and pulling the sensor out with a pair of pliers.
Worked like a charm.



Thanks again all,

Wolf

NICE!! using this method today, as my sensor is leaking and I just got the part from RM euro today.

I have a 2005 e46. There was a weep at the sensor. Thought I could just pull the sensor and replace the o ring. Not so much. It took a lot of force and the top part of the sensor separated from the bottom of the sensor. the top has the electrical and a resistor at the end. The white electrical grease had solidified and the resister remained with the lower part. So was forced to buy whole assembly. When I put the new sensor assembly inI , it went in easily, probably because I used a little oil on the o ring. I also think it would be easy to get out by squeezing on the prongs. Long story short be cautious about lifting the whole sensor out but be prepared to replace the whole sensor and not just the o ring.

Thanks for the DIY. I WOULD NOT HAVE ATTEMPTED THE REPAIR WITHOUT IT. GREAT PICTURES AND DESCRIPTION.

Originally Posted by Microflight

I have a 2005 e46. There was a weep at the sensor. Thought I could just pull the sensor and replace the o ring. Not so much. It took a lot of force and the top part of the sensor separated from the bottom of the sensor. the top has the electrical and a resistor at the end. The white electrical grease had solidified and the resister remained with the lower part. So was forced to buy whole assembly. When I put the new sensor assembly inI , it went in easily, probably because I used a little oil on the o ring. I also think it would be easy to get out by squeezing on the prongs. Long story short be cautious about lifting the whole sensor out but be prepared to replace the whole sensor and not just the o ring.

Thanks for the DIY. I WOULD NOT HAVE ATTEMPTED THE REPAIR WITHOUT IT. GREAT PICTURES AND DESCRIPTION.

Micro, good for you. New sensor is GOOD. I replaced just the o-ring and the new one lasted just for a year, I have a couple of them , so I keep replacing them, but One day I'll just splurge and spend $16 on a new sensor :-) Replacement o-rings are great but they just do not last too long...

Originally Posted by bshade1

I am uncomfortable with the word "lube" being thrown around so much.

That is all so very interesting. Just exactly what previousl experiences in your distant background makes you so sensitive to "lube"?

Thanks for the input. i got the new sensor in but the radiator fan still does not seem to be coming on. I started car and let it sit in park with the air on for about 20 minutes and still no fan, but no overheating warning either.

A little worried to drive it don't want to get stranded.

Any other thoughts on what would be causing the radiator fan not to come on?

Let me know thanks.

Originally Posted by gnuts

Thanks for the input. i got the new sensor in but the radiator fan still does not seem to be coming on. I started car and let it sit in park with the air on for about 20 minutes and still no fan, but no overheating warning either.

A little worried to drive it don't want to get stranded.

Any other thoughts on what would be causing the radiator fan not to come on?

Let me know thanks.

That on your 750li or on an E46 3-series? Just checking. I've only experience with E46 so what I say only applies to E46...

Is your E46 automatic or manual? The fan setup is different between the two. Manual has one (or two?) electric fans, automatic has one electric forward of the radiator, one mechanical aft of the radiator. The temp sensor switch only impacts the electric fan.

The fan itself may be bad. See if you can disconnect the fan and feed it 12v directly. If it spins a nice healthy speed, it's probably not the fan. Perhaps a fuse in the fusebox or a relay.

Good luck!

Hi, I've diagnosed my coolant leak to be the coolant temp sensor as well and successfully replaced it very painlessly using this DIY so I thank you. After replacing it with a new sensor from the dealership, I find that it still wiggles after its clipped in to its slot. Did you find that to be the case as well or am I looking at a bigger problem then just what used to be the O-RING on the sensor.

Originally Posted by sparkybp

Hi, I've diagnosed my coolant leak to be the coolant temp sensor as well and successfully replaced it very painlessly using this DIY so I thank you. After replacing it with a new sensor from the dealership, I find that it still wiggles after its clipped in to its slot. Did you find that to be the case as well or am I looking at a bigger problem then just what used to be the O-RING on the sensor.

What's your mileage? It's not necessarily a bigger problem but you might need a new radiator hose if the housing the sensor goes into feels loose. If you still have a leak just replace that hose, it's not hard.