Coolant level sensor replacement…OEM or aftermarket

[Tom4444]

Hey guys my coolant light is on but temp on gauge cluster is working, so I assume I need to replace my coolant level sensor?

I can do Febi for $12 or BMW OEM for $60.

From Fcp euros website it’s saying the Febi is made in China. I tend to stay away from made in China parts but lmk if you guys recommend the Febi (or another company) or just going BMW for the sensor.

[Chimi-Changa]

I've been through heck recently with these. What's the condition of the plastic threads on your tank?

I was never able to get a new tank or OEM sensor to seal properly. If it's an older tank that the sensor cap has never popped up off-they they are likely good. I ended up with a pretty good used tank and used sensor- works great now.

[Tom4444]

Cars got 206k miles but looks to be in good shape. Previous owner said it’s prob the sensor.

Thinking of replacing and seeing if light goes away. Could just spend the $12 for Febi and see if it resolves the issue. Maybe worth the Process of elimination.

Then I can just buy the BMW if it fails again.

How’s your experience with Febi for the sensor?

[Mike W.]

Just one more reminder to keep the nut on the old sensor, often the new ones have plastic nuts that only give about half a thread and won't tighten up. Try the new one, but keep the old nut at least.

[Federico]

After having an oe sensor fail after 2-3 years, I'm now running an aftermarket one and it has lasted about as much so far.
I did have issues with the nut skipping on the threads of the newish OE BMW tank, so I added some silicone tape to build up the threads and get it to work.
Also, I noticed that the threads on the tank have kind of a conical taper to them (like a pipe thread). This makes the nut slip, it makes no sense and is probably a manufacturing or design error.
There's plenty of thread on the tank, so maybe if one could mill a bit of material off the top then the sensor would thread in more tight.

[4DSC]

Bringing back this thread from the dead....

Does anyone know the exact nut size/thread pitch for the coolant level sensor? Mine will just not stay sealed on a (almost new) tank, culminating in blowing sky high off the tank during a pressure test yesterday. I went down to the local Ace to see if I could find a metal pipe cap to adapt into a nut, but there wasn't anything compatible. Closest was a 3/4" but the threads were much larger. I figure there might be something online that I could adapt with the exact dimensions. Thanks in advance.

[stuartinmn]

I assume it's a metric thread.  You could maybe try putting a few wraps of Teflon tape on it to tighten up the threads.  Another option is to put a wanted ad in the for sale section, there's probably someone here who has a spare.

In regards to the original topic of this thread...the coolant level sensor on my e30 has been intermittent for quite a while, but I've been putting off doing anything about it since I know the reservoir is full.  It would be a simple matter to check if the problem is the sensor or something else,  since it's just a switch.  Disconnect the electrical plug on the sensor and see what happens on the check light panel when it's disconnected and then with a jumper wire across the contacts.

[Mike W.]

Bringing back this thread from the dead....

Does anyone know the exact nut size/thread pitch for the coolant level sensor? Mine will just not stay sealed on a (almost new) tank, culminating in blowing sky high off the tank during a pressure test yesterday. I went down to the local Ace to see if I could find a metal pipe cap to adapt into a nut, but there wasn't anything compatible. Closest was a 3/4" but the threads were much larger. I figure there might be something online that I could adapt with the exact dimensions. Thanks in advance.

Old problem. The trick is to use the nut off the old sensor. Hopefully you still have it.

[4DSC]

Yea, unfortunately the old nut is long gone. I have tried the teflon tape, but I think that actually is what caused it to pop off during the pressure test because maybe the threads aren't seating as well. I will try the tape again in thick and thin layers. I do have a second nut off a parts car, which doesn't seat any better. Might try to hack together a "double nut" from the 2 of them with some epoxy to get some grip on the lower threads of the tank.

[Federico]

My solution was to build up the threads with F4 (silicone) tape. Has more meat than Teflon and grabs good. 
The problem seems to be that the new stock molds/plastic have no provision for material shrinkage, so the threads eventually taper to a point, so even old stock nuts have a hard time grabbing (if they do, it's because they shrunk with age). It would be nice to have a 3d printed nut with the matching taper.

[4DSC]

Thanks Federico. Will try that. I actually have some F4 tape lying around for some reason already.

[Freight]

I replaced mine recently - had to get the uro parts one. I tend to avoid uro anything like the plague, but it works fine and the nut even threads on perfectly. I saved the old nut just incase, but so far so good

[4DSC]

For posterity, F4 tape worked beautifully. 2 layers, hold the tape as you thread it on, nut grabbed great, pressure has been holding steady for 5 hours now. Thanks for the Uro tip as well, I have learned to avoid the brand as well but might order one just in case.