[alanbmoore]

I changed my coolant as part of Level 2. I pulled the water temp sensor out of the lower rad hose to drain, as well as using the engine block drain. I cleaned the O-ring and the sensor body and carefully re-installed it. Now I have a leak there, and it's driving me nuts! After I park the car, I'll get maybe a half-ounce, or 2-inch diameter puddle, under the rad hose. No idea how much it leaks when I'm driving; I don't see streaks on the bottom of the car, but who knows.

How do I fix this? New O-ring? New sensor? Can I do it without draining and replacing all the new coolant?

[m3grl]

Always use New O-ring or seals . Drain and reuse your new coolant.

[deilenberger]

A new O ring will likely fix it.

To change it without draining the whole system - put a CLEAN pan under the hose. With the engine DEAD COLD - leave the coolant cap on, you want a vacuum above the coolant (think of lifting water in a straw with your thumb over the top.)

Have someone with you who you'd trust to change the O ring.

Remove the sensor, stick your thumb in the hole (or over it - depending on the size of your thumb) and hand the sensor to the other person to replace the O ring. Then reverse the process.

Or if you buy a new sensor, you could probably do it by yourself.

DO NOT INGEST any of the antifreeze - it's poisonous. You might consider wearing latex gloves.

When done - any antifreeze/coolant that ended up in your clean pan - dump back into the reservoir tank.

[alanbmoore]

I was thinking of the thumb procedure already. Thanks, I'll give it a go. It was a fancy green O-ring, and I didn't see it spec'd on realoem.com. Will the dealer have it, or should I just use a standard O-ring?