Hi Forum,
I recently found coolant slowly dripping from bottom of the reservoir. In removing the reservoir, the level sensor came out on its own. I assume this is what was responsible for the leak as the tank looks fine and the hoses were good. I pushed the sensor back in place and it held, but I am skeptical that it will withstand the pressure in the reservoir. I haven't reinstalled the tank yet as I wanted to confirm that the sensor is just pressure-fitted and depends on its o-ring to stay in place. Is that the case or is it somehow sealed otherwise?

Thanks in advance.

The sensor clips in, so you may have a broken tab. But the sensor is not exposed to coolant, it reads a magnet in a float within the tank. That cannot be the source of the leak.

Ah, thank you. I didn't know that. Of course, now I'm back to finding the leak.

Probably its either the seams of the tank when its hot as it expands, or the hose connections to the tank. The former is a very common problem. The solution is to replace the tank.

Well, it turns out that there's a crack in the tank body that wasn't visible when the plastic was damp. Now that it's dry, the crack is obvious. I'm going to give JB Weld a shot and if that doesn't hold, I'll spring for a new one. The tank is surprisingly inexpensive. On Parts Geek, it's less than $60. R&Ring the tank is easy enough that having to redo it won't be a great hardship.

Don't try and fix it. As you said, a new one is surprisingly inexpensive - a blown head gasket is not! Repair is a total false economy.

+1 to replacing it.

I had the same issue. It was a minor leak and only occurred with a hot engine. The coolant dripped onto the exhaust and immediately vapourised so it took a while to locate. This was in July. I put off changing the Expansion Tank until ..............





..... it finally split the following January. YES - that is snow around the wiper and grille. Bad choice to delay!

Graham

As others have advised, replace it and save yourself a ton of very costly issues down the road if you attempt to repair it instead. I keep a new spare coolant reservoir on hand because I know I will eventually have to replace the one I installed back in September 2017 again. These things never were very robust and if you get 5 or 6 years out of one, that is about all you can expect. They sit there and bake in the engine bay and unfortunately this particular grade of plastic will not hold up over a long period of time....

Advice taken. New tank on order. I am going to reinstall the old one just to see if the repair held. In the meantime I won't be traveling any great distances that could result in serious overheating. Thanks for the replies.

Get the new tank, worth every penny, My sensor light would not go off, but I could not detect any leak. Replaced it and problem solved. Your JAG is worth taking care of. Minor cost, knowing it's done right is the only way to go.