regnar11b

I have had my 1990 3vz 4 runner (2 door) for almost 13yrs and its still running great. However about a month ago I replaced the radiator because it was leaking. About 4 yrs ago my battery shifted into the power steering pulley and sprayed acid all over under the hood. I poured baking powder on everything and washed it off pretty well. The only residual evidence of the acid was the paint on the radiator peeled off. Well it finally killed the radiator so I replaced it... yesterday my heater started to blow out cool air. I also noticed my temp gauge going up to 2/3 hot when it normally sits just under 50%. At idle is stayed at 50% heat then putting it in gear it would climb 2/3 towards the red but once I gained speed over 30mph it dropped down to cool again like normal. I was able to drive it home 3miles fine with no issues. After it cooled I checked my water level and it was substantially low. I'm driving my other car right now however I want to flush the heater core first before replacing it. My question is since the 2 door 90 4 runner model is so tight under the hood with the 3vz engine... whats the best way to get at the heater core lines to flush it? For access I'll probably yank the hood, but at the same time I figured I will pick up that little black heater housing valve I saw one guy posting about on another heater core question. My other big concern is where the heck did the coolant go? When I filled my new radiator I pulled it out into my driveway at about a 5% slope and burped it to so I had enough coolant originally, also I have no leaks of any kind. My oil level seems fine but I just changed my oil last month so I hope there is no water in my oil. Any advice would be greatly appreciated.

nv4runner

I'd say that your lack of heat from the heater was due to an air bubble in the heater core. That is always the first symptom of low coolant. Not sure you actually need to do the flush, but there isn't anything special about doing it. Just have to disconnect the two hoses at the firewall and use a garden hose. Just don't turn the hose on all the way. I've heard of full house pressure causing leaks in heater core.

regnar11b

update: So I added half a gallon to the radiator and it ran fine. Driving to work everything was ok but turning on the heat it was luke warm again. I could smell a little bit of coolant in the cab. Once I was at work it dripped like a sieve for a few minutes. While it was dripping I was looking under my truck and the hood and couldn't see any leaks from those spots. I was also looking at the area where the hoses go through the firewall to the heater core. The coolant was running from somewhere onto the top of my transmission and dripping off the bottom side of it. I will have to check it out further this weekend but did find a similar thread...
https://www.yotatech.com/forums/f116...3-0efi-163154/
Once I find the leaky hose or pipe I'll probably take of the plenum to get at everything easier. I'll keep this post updated with info but if anyone has more insight I would greatly appreciate it.