Bought the 87 4runner 4cyl, auto, 4.88 gears, 33 inch tire with 230000 Miles on it with zero background on the cars past. I did a full tube up and started driving. I took it to the hills and it ran great. One day probably on my 6th trip to the hills 120 miles round-trip noticed the temp riding on a pretty steep grade. I changed the radiator hoses and t stat and cap. It ran well and didn't over heat. Till I took it on a long trip and it overheated on a hill again. Well this last trip it over heated on every hill it could. I had to stop and cool down and go again. I don't know where to start. No violent contamination, no milky oil. I did a compression check and the numbers are as follows. Dry 1 = 150 2 = 130 3 = 135 4 = 140 Wet 1= 177/180 2= 165 3= 150 4= 165 Thanks for any help.

 

Original radiator?

 

It doesn't look original. When I flushed it it did have gunk come out. The t stat I put in has a 3/16 hole in the bottom as well.

 

That radiator looks like a 3 row?

My rad has space in front of the frame cross member.

Granted - thats like the 3rd radiator (370K on the odo)

gap between the rad and the cross member
I usually stuff a 2" block of foam in here (i.e. AC weather strip) - It had that weather strip when new

 

Off the cuff I suspect HG
A leak down test will help find that..

 

It's always the damn head gasket. Lol. I'm in real deep if that's the case. Do some people opt for a rebuilt motor over the cost of the head gasket replacement? I hooked some compressed air to each cylinder and looked for bubbles in the radiator but there were none.

 

Did leak down test and head gasket looks good. Now what? I looked into the radiator and noticed the top fins were all clogged up. Also when I first spun the fan clutch it spun almost a full turn cold. When I turned it again it locked up. I also did the magazine test on it and it didn't shred it.

 

new radiator time.

 

Might be time for a new thermostat as well.

 

Stock radiator or v6 radiator? Which is better for the 22re. I've been looking and it confusing. I'll throw a t stat in as well. Toyota stat or 3/16 drilled?