1990 4Runner coolant mystery (1 Viewer)

[Devils Paw 80]

If I top off radiator a leak develops somewhere in the vicinity of water pump area. It’s not dependent upon pressure in the system either, can occur when engine is cold/not running. Once coolant level drops to top of fins the leak stops. I finally replaced 30 year old radiator recently and it made no difference. Ditto with water pump and timing belt. Any idea what’s going on?
I can apparently live with it since temp never climbs past middle of gauge, no overheating. Just weird.

 

[Devils Paw 80]

I did figure this one out, eventually. It was a pinhole leak in the coolant bypass hose at top of engine, kinda hidden under accelerator cables. Trickled down near water pump area before dripping out. Fortunately Toyota still has them in stock. This is not a piece that you'd want to replace with a generic piece of hose cut to length due to the almost 90 degree turn at the front of it.

 

[aztoyman]

Thanks for posting up the solution. Dead end threads suck.

 

[creature]

Nice work. If you ever need odd coolant hoses like that 22re Performance has them. OEM hoses and gaskets.