I would like some advice, I think I know my answer but want the input from the forum.

I have an 88 4Runner 4wd 3.0 automatic that "Overheats" when the AC is on.

I have replaced the following:

1. New Valvecover gaskets,
2. New Timing Belt,
3. New Waterpump,
4. New Fan Bracket,
5. New (OEM-Toyota Brand) Thermostat,
6. Replaced the lower and upper radiator hoses,
7. New Radiator cap,
7. Radiator Flush.

Still has the 22 yr old Original Radiator.

It has overheated and leaked coolant twice but I could not figure out the location. I just refilled the coolant and filled up the resivor and parked it to get cool. I notice that it begins to get hot when the AC is on. So I just turn it off and keep on driving. This is a Daily Driver.

Considering all the replacement parts, I am leaning towards buying a new Radiator and hoping the problem gets solved.

Do you guys feel that if I replace the Radiator, it would stop heating up.

 

The radiator's a good bet!

 

Thanks for the input. I'm putting a new one in this weekend.

 

Its either the Rad or the fan clutch. Oh and blow and or clean out bugs and dirt in condensor fins.

 

do not forget to go over ALL the coolant hoses thuroughly...
i had the same problem... still overheated... turns out that there was a little (4") black tube that makes a 90* turn right under the plenum near the throttle body... it had a miniscule pinhole in it, but i replaced it and it was good...

heres something else to think about... if its overheating still, then good chance that your t-stat is already shot... they dont handle the constant overheating too well...