My 1JZ start overheating while in boost the other day so I did a coolant flush. It drives fine below 4k rpm, but as soon I give it a bit of gas it overheats. Temp gauge goes to H and coolant boils over with steam spewing out.

Water pump and thermostat is fine, no leaks on the rad or the hoses.
Sounds like a clogged radiator?

 

I would imagine if the radiator was clogged it would overheat all the time. When's the last time to thermostat was replaced?

How many miles or kilometers on this car? Might want to have a dealer perform a leak down test on it.

how do you know the water pump and thermostat are fine?

 

Sounds like it could be the headgasket...

 

+1
did your radiator hose blow out yet?

 

The shop did the flush today and now it seems worst now. Overheats under light driving when the car is warmed up. The shop said the thermostat and pump is fine. No signs of blown gasket either ( milky oil, smoke, loss of power etc).
The coolant flushed out was really rusty and full of debris.
Going back tomorrow, most likely a clogged rad.
91 Soarer with 89k KMs

 

Let us know what you find out!

 

Remove your radiator, soak some vinegar in there for a couple days, then stick a garden hose on the inlet under high pressure and let it run for 10 minutes.

Reinstall the radiator and see if anything changes. Since your in BC I would say stick with the 50/50 mixture but you may want to consider red line water wetter...it will reduce temps by about 10* or so.

If that doesn't help, get a new radiator, new thermostat, and new water pump. It will defiantly cost you a lot less than having to change a head gasket and milling a warped head due to overheating which is whats going to happen if you keep running it like that (if it already hasnt happened).

Overheating is my worst fear....ive messed up a couple motors like that in the past and its no fun.

 

would a Supra radiator fit?

 

Yes I'm running one. Check to see if its from a manual or auto. They have trans cooler in the rad for autos.

 

Changed the rad, thermostat, timing belt, and water pump. Now its all good.
The old rad was so clogged it weighted 4-5 times as much as the new one.
I cut it open and it was clogged with gooey oxidized coolant and PEBBLES of rust deposit.

 

^Glad you got it sorted man...

 

Awesome...my old 2jzge radiator core was literally falling to pieces but the car never overheated.

Glad you got it fixed!