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Fabian Bordon
TryHard
VIC
TT

Posts: 352
Reg: 02-2007

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Tuesday, October 23, 2018 - 01:34 pm, by:  Fabian Bordon (Aether) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Hey guys,

Had an issue with my old fan clutch which wasn't engaging, opened it up to find out that it had no silicone oil left in it. Bought a new dayco fan clutch, replaced the old one and the fan clutch starts of engaged, disengages about 30 secs later, but then re-engages whilst driving after about 20-30mins and won't disengage. Checking the engine temp via odb port and ecu, it is sitting around 80-90 degrees Celsius. Thinking it might have been a faulty fan clutch, I bought another after market Japanese brand, same issue. I have since changed the radiator, both ect sensors, replaced the thermostat twice, now running a TRD thermostat, bled the system and pressure checked, no leaks. Confirmed that the aux fan kicks in by testing sensor in hot water. Water pump is 10 years old with only 5000km done since replaced. It seems that the engine is not running hot, but the engine bay is heat soaked. Car is running a greddy front mount intercooler. Touching the radiator top hose and bottom hose there is a difference in heat, but the bottom hose is getting warmer indicating water flow.

Any help guys would be appreciated, as the fan is robbing engine power, wasting fuel and sounds like a jet taking off at the lights. Not willing to drive it the way it is at present.

Also regardless of outside temp the thermo fan engages after 20-30mins of driving.

Cheers,
Fabian.
Tai Johnsen
Goo Roo
QLD
JZZ30 Pov Manual LSD & black! + 89 Z20 Aerocabin

Posts: 1796
Reg: 04-2006

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Wednesday, October 24, 2018 - 02:55 pm, by:  Tai Johnsen (Privatejohnsen) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

I have chased this issue for years..

Firstly, it sounds like the clutch fans are doing what they are supposed to.

Freespin when cold, and lock up when hot. When its cold a valve closes not allowing the silicone out of the center, but it takes a few secs for it to capture it. hence why it stops after 30 sec. When its hot, the valve opens allowing the silicone out and locking the hub to drive the fan. The point at which this happens is controlled by the bimetallic strip with an adjustment screw to set the desired opening temp.

I eventually changed to thermo fans being PWM controlled by my ECU and found that even with the fans on 100% the coolant temp will heat soak up to 96 degrees C because the temp sensor is on the outlet of the block at the top, and the thermostat is on the inlet of the block.

So the bottom rad hose is say 80 degrees, the thermostat is closed only allowing a small amount of coolant through the small hole, and the outlet is piping hot.

I turned the fans off completely and let the engine come up to 105 degrees and the bottom rad hose was now hot. I then turned the fans on and in about 10 seconds the temp was down to 80 deg, and then rose back up to the 90's once the thermo closed again.

I have since set my fans to 20% until 96 degrees, and then they ramp up to 100% at 100 degrees.

So far they stay at 20%.

I think the reported temp and the thermostat position make it seem like it is running hot.

For some reason toyota made it that way..
Fabian Bordon
TryHard
VIC
TT

Posts: 353
Reg: 02-2007

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Wednesday, October 24, 2018 - 03:43 pm, by:  Fabian Bordon (Aether) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

Thanks Tai, seems as though the coolant temp in my car is not getting anywhere near the temp required to open the thermostat nor kick in the aux fan which I read triggers at 88 degrees celcius. As mentioned am running a TRD 72 degree thermostat at the moment and still the fan clutch engages. Does the airflow through the radiator dictate when the bimetallic spring opens the thermo reservoir or is it just engine bay temps?
Tai Johnsen
Goo Roo
QLD
JZZ30 Pov Manual LSD & black! + 89 Z20 Aerocabin

Posts: 1797
Reg: 04-2006

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Thursday, October 25, 2018 - 09:49 am, by:  Tai Johnsen (Privatejohnsen) Quote hilighted text Edit Post Delete Post Print Post   View Post/Check IP (Moderator/Admin Only) Move Post (Moderator/Admin Only)

The clutch fan just heat soaks through the block.

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