Apparently the coolant temp sensor must be replaced (about 30 bones) whenever you replace the lower radiator hose. I didn't realize this until I had a leak following a complete cooling system overhaul. For some reason, the o-ring must shrink, as it is a very loose fit in the new lower hose fitting.
By luck, I had a package of cheap o-rings in the garage which were slightly oversize compared to the old one. I changed the o-ring out and end of leak. I can't say if this o-ring will last forever, but if it does fail, it's a pretty simple fix down the road.
Anyway, if you want to save the 30 bones, here's the details:
"Brasscraft" brand o-ring twin pack from Home Depot or Lowes (not sure)
Package number 0567
Dimensions: 5/16" I.D. (9/16" O.D.) x 1/8" Wall
This o-ring is a snug fit, so it takes a good push to get the sensor seated in the hose fitting.
Yeah, good tip. I replaced everything except for the damn sensor, so I also found this out the hard way (and I didn't have spare o-rings sitting about)...
I did the same thing - used one from a pack of assorted O-rings that I had in the garage. Ideally, you should use a brown or green O-ring, as those will withstand the harsh environment better. but, I used a black one almost 50k miles ago, and haven't had a leak since.
Green = old hardened O-ring = leaks in new hose.
Black = new soft rubbery O-ring = no leaks.
you can also try flipping the oring around backwards....it gets a flat spot on it from how it is installed and turning in around puts a
'fresh" part of the oring up against the seal area. Worked on my car.
good stuff guys...i just found the leak from my sensor this afternoon and logged on to see if anyone else had the same issue...bingo! thanks! :thumbsup:
I just replaced the hoses, thermostat, and expansion tank hoping not to need a new temp sensor. It leaked pretty good at the sensor. Tried different o-rings till it stopped leaking. So far so good. Saved a few bucks but drove myself crazy trying to stop the leak.
I am trying to replace the coolant temperature sensor in my 2000 328i which is located in the lower radiator hose. As many other posts have stated, mine is leaking. However, when I went to do the "easy" swap, the old sensor won't come out. I pinched the 2 little levers on the side to release it and pulled but it won't budge. Any ideas how to get it loose? Also, does this sensor have any control over the electric fan cooling the ac?
It does indeed just pull straight out. Use gloves so the "ears" don't cut into your fingers and you can tug harder. Rock it back and forth (it will only move a little each way) while pulling it out. Keep at it and the plasticized o-ring will eventually give.
The fan is activated based on the ECM calculation
(sensing ratio) of:
***8226; Coolant outlet temperature
***8226; Calculated (by the ECM) catalyst temperature
***8226; Vehicle speed
***8226; Battery voltage
***8226; Air Conditioning pressure (calculated by IHKA
and sent via the K-Bus to the ECM)
The fan is activated based on the ECM calculation
(sensing ratio) of:
• Coolant outlet temperature
• Calculated (by the ECM) catalyst temperature
• Vehicle speed
• Battery voltage
• Air Conditioning pressure (calculated by IHKA
and sent via the K-Bus to the ECM)
I know this is an old thread but I just wanted to add that the equivalent o-ring from Danco is #31 ring. 10 pack is #96745 for about $3 at lowes. I had to squint at tiny numbers to read them so maybe I can save someone the trouble.
Do you know which section of the store... Is it plumbing?
I have a very small leak on the driveway and hoping it is this. Can I get at this from above or is this requiring jacking up and dropping the plastic shield etc. Hopefully not
I spotted a leak in my wifes E46, found the sensor to be the culprit and looked here for advice finding this thread. I had an O-ring that would fit already in my hardware supplies, and I really appreciate the OP posting this, as I was planning a trip to the dealer to replace the entire sensor. Thanks.
Especially the guy who posted the O-ring dimensions! I was stuck like a truck and through a google search your reply got my 2006 E60 back on the road and for $0.81 at Lowes!!!!
I came and registered just to say thanks. Always share your findings, DIYs, and mistakes - you never know who it will help and where!
No worries! Glad you were able to get it repaired. :thumbup:
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