inb4 Mango :eeps:

If you haven't seen this link, check it. It goes over how to maintain the cooling system.
http://forum.e46fanatics.com/showthread.php?t=914109

EDIT: Just saw you say you'll work on the cooling system in the Spring. Well if you aren't doing complete maintenance on it now, I don't think you'll need anything else at the moment.

 

Lol'd at the Mango comment. I've been here long enough to know that he's the Cooling System guru.

Have no worries, I've already read that link and I'm no stranger to BMW cooling systems. I owned an E36 before my E46 and I'm aware of the cooling system issues that both have.

And yup, just as I said I'll take care of everything else in the Spring. I wish I could now, but I'd rather not take it to a shop to have it all done when I can do it myself when I have time to in the Spring.

Just making sure I won't need anything else to fix the issues I'm having now.

 

Ah okay just had to make sure. Well hopefully others chime in, because - and not to scare you or anything - my cooling system just failed a few days ago. :eeps:

 

:eeps:

You're not helping to ease my worries. :rofl:

I'm just hoping that the rest of the system will be able to hold up until the Spring...

 

The coolant level must have been a bit low, and once the coolant went into the heater core... it triggered the low coolant light. Fixing the small leak, drain/fill with new coolant, and bleed properly should do the trick and eliminate the problem.

 

The coolant level must have been a bit low, and once the coolant went into the heater core... it triggered the low coolant light. Fixing the small leak, drain/fill with new coolant, and bleed properly should do the trick and eliminate the problem.

Exactly what I was thinking. Makes sense logically. It's good to hear another person thinks the same!

Thanks for your input.

 

If it's just that particular slow leak you're trying to address, just buy the o-ring. Look up the part number for the IAT sensor.

 

I've read that while some have had success only replacing the o-ring, others have not. In the interest of getting my car on the road sooner, I'll just bite the bullet and replace the sensor, too. If I had a BMW dealership local to me and could drive my car to get parts at other places, I'd just try replacing the o-ring first, but I can't do that right now. I need to place my order at BMW tomorrow, have them ship me my coolant and sensor, then replace it. If I only buy the o-ring and it doesn't solve the problem, that'll likely mean another 2-3 business days of downtime.

 

I could not get the O ring, had this problem 2X on both of my E46's, my old one just out of nowhere started leaking, and the one I have now after foolishly reusing the sensor on a coolant system swap. Just annoying. Others have had success getting the O ring, suspect it depends upon your dealer.

 

IAT sensor o-ring, 8mmx3mm, 13621743299.

 

Fixed it.

Replaced the sensor and the o-ring and the leak is gone.

 

Hi,
This is exactly what I was looking for !

Will replace the o-ring first and will see if issue is fixed without changing the sensor.
Do you recommend getting an original BMW part or things like o-rings can be found at NAPA ? (for example)

Tks

 

Finding an O-ring that fits is tough to do. When I had this problem, the ONLY vendor of this size O-rings I could find would sell them only in lots of 144, which, with shipping, cost more than a new sensor.

If I ever have that problem again I will first pull out the sensor and wrap it in teflon tape and put it back in. Who knows? It may work.

I tried to measure the original O-ring, and as nearly as I could tell it was:

Original O-ring Inch
ID 8.2 mm 0.323
CS 2.6-3.2mm 0.102
OD 13.4 mm 0.527
I was measuring a 5 year old O-ring, so the cross-section was flattened a little, and cross section may have shrunk a bit, ID may have stretched when I removed it.

 

https://www.fcpeuro.com/products/bmw-temperature-sensor-o-ring-091158010

I replaced mine because it was only $1 to tack onto the order and it seems to go bad for so many people. The o-ring I received wasn't green, but black. And contrary to what FCP has written on that page, green o-rings* are generally a kind of nitrile, not silicone.

I put dielectric silicone grease on the ring when I replaced it.

*https://www.globaloring.com/oring-colors

 

O'Reilly's carries the coolant temp sensor in stock. Looked identical to the OEM part and works fine if you are looking to locate one quickly.

 

Success !!!

o-ring changed, leak gone .

little cracks were visible on old o-ring

Great forum.