Tuesday, January 22, 2008 - 10:38 am, by: Richard Crockett(Crock)
This may interest you Damien....
1JZ Engine Coolant Flow - Top
Using the radiator as a starting point, engine coolant is drawn into the water pump located at the front of the engine through lower radiator hose. Once inside the pump, coolant is discharged under pressure through the two water pipes on either side of the pump. Coolant then flows through the water pipes and enters the engine through either the cylinder heads or directly into the engine block, depending on the engine model. Once coolant circulates through the engine block and cylinder heads, it flows through the intake manifold. From the intake manifold it enters the thermostat housing.
If the coolant is hot enough so the thermostat is open, coolant flows through the thermostat, the upper coolant outlet, the upper radiator hose and back into the radiator. If the thermostat is closed, coolant flows directly from the thermostat housing back to the water pump through the bypass hose. When the thermostat is partially open, coolant flow is split between the two systems.
Coolant flow for the heater core is provided typically from either a port on the intake manifold, or from a port directly on the thermostat housing, depending on the vehicle and engine combination. Coolant flows from the supply port, through a length of heater hose, through the heater control valve, through the heater core and back though another length of heater hose to a fitting on the side of the water pump.
In terms of differing pressure areas, the higher-pressure areas inside the coolant system are the intake manifold and thermostat housing. Low-pressure areas would be the lower radiator hose and the heater core return port on the side of the water pump.
Tuesday, January 22, 2008 - 11:07 am, by: Damien Murray(Stealth)
Hum You see I replaced the radiator as mine cracked the top tank. IV parked the car on a hill, with the rad cap off twice and let run for 15-20 min to bleed the system. But still the bottom pipe remains cold. Even after a hard drive]
I changed the thermostat this time last year and know it is at the top of the bottom rad pipe, so when u say "water/coolant is drawn into the water pump located at the front of the engine through the lower radiator hose" dose this not mean it would first have to pass thro the thermostat? and not on to the pump ?
The top pipe is very hot but the bottom one is cold. The dash temp gauge hasn’t moved passed half way at any point [been afraid in case I blow the HG]
it was suggested that with the 2-7 degrees C above we have been having here and the new rad with Toyota red in it that the pipe just isn’t getting anyway hot, I dismast this as the plastic pipe should at least get warm after having hot water run though it but mine stays Cold.
Sunday, January 27, 2008 - 06:28 am, by: Brian Timms(Turbo_brian)
Damien,
The cold water is drawn at the bottom, the hot water is returned at the top (this is why the top tank is prone to failer, because it's constantly blasted with hot pressured water).
Asfor the pipe staying cold, mine does as well when it's cold.
Last winter I had a few things that needed doing and testing, then re-checking, and my lower pipe stayed very cold compared to what I thought it would be, using one of those new fangdangled infra red temperature readers, I was getting temps of 65 - 70 on the top pipe, and 15 - 23 ont he lower pipe, so it was about outer body temp for the bottom pipe, which means only 1 thing, the radiator removed A LOT of heat from the water on it's way through, which can only be a very good thing.
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