E34 radiator leak

[Tut]

Had our first really cold morning yesterday (2 degrees F). When I left the office at the end of the day there was a small stain (6" x 12") of BMW coolant on the ground. S#$^! Drove the car home with no problems. Crawled under the car. The bottom of the coolant level sensor was wet. Wiped everything off, but that was the only wet spot that I found. Tightened plastic nut at bottom of coolant level sensor just a tad. When I went out to the garage this a.m. there was no wet spot. Naturally, the coolant level was down a bit. Did not drive the car to work.

Any thoughts on what is going on? Could I be lucky and it just be the o-ring? Is it more likely that something is cracked (radiator tank or coolant level sensor assembly)?

Thanks.

Tut

[DanH]

I'm not sure if it has the same plastic neck on the upper radiator hose as the 535, but that is the most common failure point for the radiator. It will crack and leak, especially if the hose clamp is overtightened.

If thats broken, it time for a new radiator...

[Tut]

I'm not sure if it has the same plastic neck on the upper radiator hose as the 535, but that is the most common failure point for the radiator. It will crack and leak, especially if the hose clamp is overtightened.

If thats broken, it time for a new radiator...

[bimmerd00d]

It does indeed have the plastic upper hose neck. However, i believe your leak is at teh gasket between the radiator and the expansion tank. This is where mine started leaking a while back, and all of a sudden it just stopped.

[Tut]

Dan,

The leak is at the bottom of the tank on the driver's side, where the coolant level sensor goes up in to the tank, secured with a plastic nut.

Tut

[andyman32]

Tut, you could try a new copper O-ring there, but there's a chance that the plastic has a split in it. Radiators are finnicky; if they get a little crack or split anywhere, that's that. New radiator.

On the positive side, they aren't too expensive (as I wrote in another thread, my radiator cracked last Thursday and I got a brand-new OEM radiator delivered to my door within 18 hours from radiators.com for $225... the plastic clips are a bitch to get off, though, and old brittle ones will break, so be prepared to order new ones from BMA), and it's easy as hell to put in. I didn't even have to drain my system because it had already leaked out all over the place, but it sounds like you probably will. Not the block, but the radiator. Should take you no more than 2 hours end to end. If I ever had to do it again, it would take me less than 1 hour (now that I know what I'm doing... sorta). :)

-Andy