wykp

Hi, first time poster here – got a question regarding my '95 SR5 Pickup 4WD (3VZE). I got the truck last November with 196K miles and now it's 9 miles away from rolling over into 200K! It's been running great so far, only "major" repair was replacing the clutch master and slave cylinders. The first thing I did when I received the truck was an oil change and a radiator flush (with the help of this forum, thank you very much) since I noticed it was full of the green stuff. Got some of the concentrated Toyota red coolant from the dealership and flushed away. It's been great for the past 3K miles, however I noticed something recently that wasn't happening before:

I can't seem to open the radiator cap without having the coolant spill out directly from the top of the radiator. Immediately, I screw the cap back on to avoid having coolant spill all over the engine bay and my floor. I also noticed is that even when I top off my reservoir to the max line, a few hundred miles later and it drops down, requiring me to top it off. Shouldn't it be transferred over to the overflow reservoir thus preventing the aforementioned overflowing issue? I checked the hoses going from the radiator to the reservoir and there does not seem to be any blockages. Temperature gauge remains a hair below the center, at normal operating temperatures whether I'm driving 10 miles to work or 300 miles out to the desert. Overheating has never been an issue. No milkshake on the dipstick either. No smoke from my exhaust. What can it possibly be?

I'm not mechanically inclined whatsoever, but this forum has been an invaluable source of knowledge that has allowed me to start doing my own work and I can't tell you how thankful I am for you all and how great it feels to be (somewhat) self-reliant. At the age of 27, it's about time, I suppose!

Any insight would be much appreciated.

RAD4Runner

You mean there's absolutely no coolant overflowing into the reservoir? Then, you could be losing coolant through a fine crack in the radiator or a leak somewhere in the cooling system.
Have it pressure checked?