I wanted to post this in case someone ran across this issue but couldn't figure it out on their own. I replaced my heater control valve recently and got around to driving the truck a fair amount this weekend. 87 4runner 22re 5sp. I went to grab something from the passenger floor board and noticed a considerable amount of coolant under the floor mat. my first impression was that the heater core was leaking. but instead of pulling the dash and starting that PITA job I retraced my work on the heater control valve and found that a band clamp on one of the heater hoses wasn't tight. since the hose from the valve runs over top of the heater core line the coolant was pissing out back into the cab and running down the heater box/fan area and dripping into the carpet. I snugged up the band clamp, peeled up my new carpet top dry everything out and topped off my overflow bottle. it took a little driving around to get all the residual out of the dash. dumb mistake on my part but I would have been a lot madder if I had pulled the dash to replace a perfectly fine heater core.

 

I have a tiny gurgle going on up in there... Time to rip it open I guess.

 

Heater core ain't a fun job!

 

I think id rather pull my transmission again than do that.