help needed: 1jz coolant flow question

**e30-323ti** · 07-01-2013, 07:40 PM

Those look to be 2JZ heads which have the heater outlet pointing up.

That first pic, has the water coming out of the head and back into the water pump inlet, so doesn't go through the radiator at all, just back into the block.
This would normally go through the cabin heater core (restriction/heat transfer) before re-entering the pump/block.

The 2nd pic, I presume (as you have) the inlet side is all blocked off, as well as the rear inlet to the water pump.
And presume the flow out of the head will split happily between the front and rear outlets....
This seems the more sensible solution.

I also recall seeing a 1G-G(t)E head on here with a header system running down the middle of the head, where the (3) big allen head plugs are on a 1JZ.
Was pretty extreme

**ATMO_BT1** · 07-01-2013, 08:08 PM

Yeah they are both 2JZ although I assumed the coolant flow would be the same, am I mistaken?

Does anyone have a 1JZ coolant flow diagram? Or can draw one? Would help alot!

**e30-323ti** · 07-01-2013, 08:56 PM

Closest I have found, and I am under the impression all JZ's are the same.

Other than the N/A engines having no oil cooler or for turbo(s)
EDIT: Found the 2JZ-GTE diagram

**lexsmaz** · 07-01-2013, 09:35 PM

I certaily would not be taking the thermostat out of any equation, especially these style thermostats as they have a round plate on the bottom of the thermostat which blocks a water bypass port in the block when the thermostat fully opens, the bypass is there to direct water around the block when the thermostat is closed to aid in quick warming up & so if you took the thermostat out the water could flow any way & the easiest path is probably within the block & so would / could then suffer from over heating ..

**e30-323ti** · 08-01-2013, 06:46 AM

What ^he^ said.

I recall reading recently when someone did that (may have been on an RB), as they had fitted electric water pump and the coolant just did laps of the block / head.
In the end they put the thermostat back in (on the dyno) but planned to have the bypass welded up or something....

Diagram updated above as I found the 'GTE one.
My plan is to remove all the white external pipework...