bump
I have had this problem on my 90xj as well. Early this year, when i couldnt pass emmisions I replaced the leaky cap/bottle. I believe i got them both online. again the bottle was a much weaker plastic than oem and the cap overtightened.
I used the combination for the last several months just using the cap @ its sweet spot...
Today, my wife pulls up in the jeep to drop off my daughter so she can go to work. she left the engine running and in front of the house i'd say 5 minutes max. when she went back outside there was smoke and coolant running down the side of the street.
The engine didnt overheat as per the gauge, I grabbed some pliers, popped the hood(i bet HALF of you know why i needed the pliers
)and looked around for a blown hose.
traced the leak to the cap, it was spewing out coolant, and i could tighten it a 1/4 turn.
again the kicker, i have never removed the cap since the combination were installed beginning of this year, just always made sure was tight and in the sweet spot.
a few weeks ago I got lazy and didnt shine a flashlight to the bottle to see where the level was and simply opened the bottle, topped off the coolant and put the cap back on, yes i could tell there was a difference and the sweet spot was how should i say smaller than before.
Removing the cap was and is the problem with these bottles/caps now. tomorrow im going to use t.tape, another rubber washer from the oem cap, and a hose clamp.
I'm going to mark the max and min line with a sharpie so there will never be a reason to remove the cap again unless i need to top off.