monoman

Hello all, i just read a post with the exact problem I have but there are no solutions yet so I thought I would start my own thread. Okay, 91 4runner 3vze. When i bought my yota about 2 years ago I noticed that it had a leak in the filler neck of the radiator and always leaked when the radiator was full. For whatever reason the rad liked to stay consistently at half full and for this time period of 2 years it has worked fine (half full). Im trying to get my rig up and ready for this years snow so I thought I would replace the radiator with a good condition used one that I flushed then did now own backyard pressure test to make sure it did not leak. Over this last weekend I installed the radiator and filled it up w/fluid and burped it by running it hot with the cap off on a slight elevation then adding as needed. The truck ran great the first day and then the next day i drove it to the store and back (2 miles) and noticed it was leaking coolant at the rear of the motor. I drove it home and pulled it into my garage and warmed it back up and tryed to spot the leak but I cannot find it. It does not seem to be coming from a hose, but its dripping down the front of the transmission. My first thought was the head gasket but I checked my oil and everything's fine, the truck still runs and drives like it always has. My second thought is a freeze plug? im not sure but i have a feeling that the previous owner had a idea about this problem and it was not disclosed to me. I would appreciate any help or advice from you all. thanks!

91muddog

go rent a cooling system pressure tester from autozone or orielly.
go home and pressurize your system to spec(check the psi on your rad cap for spec)

all you can do then is get on your coveralls, a flashlight and a mirror and get down and dirty. climb all over, under everywhere, youll find the leak!

Kroum

Did you find the leak? I think I have the same leak, only mine drips a bit overnight, and I never see it dripping while or after driving, always the next morning. This is sporadic since it has happened only 2 times for the 2 weeks I've owned the 4runner.

zero503

I had this same problem, for me it was the water bypass hose, its like a little u bend on the sensor block on the back of the motor, Its near impossible to get without taking of the upper intake manifold and that in its self is fun with all the hoses going to it. its about 3 or 4 inches below the top of the intake and about 4 inches back. The part is only about 5 bucks at napa. id bring it in tho they couldn't find it on the computer.

TNRabbit

You can pull the hood (HIGHLY RECOMMENDED) & replace that bypass hose if necessary. Once the hood is off (4 bolts, 5 minutes), you have more access & LIGHT to actually see. A long pair of needle nose pliers are essential here.

I second getting the coolant pressure testing kit. Saves a LOT of time & guesswork.

monoman

yep found the leak and wrote this on it...
https://www.yotatech.com/forums/f116.../#post51798184