Whitey
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Hey all,
After a recent Fraser trip I noticed my ATF temps getting very high in the soft stuff, up to 120C on occasion, which is a very high temperature for the transmission oil to get to. I decided it was definitely time to upgrade the auto cooler, the OEM unit was just not cutting it.
I’d seen the great work that Tin175 has done with the Davies Craig 678, which is a 21 plate cooler;
http://www.pradopoint.com/showthread...-thermo-switch
I wanted an even bigger cooler, so I went for the 679, which is a 30 plate job.
I knew it was going to be a tight squeeze to fit in the 30 plate cooler, but with a bit of mucking around it’s not so bad. After reversing the OEM horns, and ditching some of the OEM brackets, everything fits nicely, and you can utilise three of the pre-existing threaded holes, one at the top left horn, and two at the bottom, and a pre-existing bracket hole on the right. I used some aluminium checker plate and a bit of rectangular aluminium tubing to knock together the framework.
The finished job is a nice and snug fit;
I also used the same OEM flow orientation, input at bottom, output at top, using the same circuit that flows through the side of the radiator.
After flushing my dirty brown old fluid out, and flushing through 12 litres of nice new Penrite ATF LV, I tested the new cooler out again on Fraser.
I was up at Fraser in the middle of January and it was stinking hot conditions, 42C in the shade, 60C sand temperatures in the middle of the day, and the cooler worked brilliantly. I was also testing out some new rear shocks, so I was pushing the Prado quite hard on inland tracks, and the highest ATF temperature I saw was 90C, compared to the radiator at 93C. The best reduction I saw while cruising on low tide was 33C under an 89C radiator temperature. The larger cooler in front of the radiator has not affected my engine coolant temperatures.
The Penrite ATF LV is very close in viscosity and temperature rating to the Toyota WS fluid. Penrite recommend a working temperature range of 50-80C, and recommend not to let the fluid temperature exceed 100C.
I have heard anecdotal stories that some A750F transmissions run hotter than others. Maybe I’m one of these unlucky people, or maybe the auto runs a bit hotter with the 1GR-FE in front of it. In any case I have managed to get the working temperature sorted out. I don’t believe the ATF temperature will ever exceed the radiator temperature with the new setup.
Even so, I will be changing the transmission pickup screen soon. When the ATF is burnt, it breaks down and can form tiny colloidal lumps of crap which can block the pickup screen. I have heard on FJCC of one owner having to fork out $3000 for a new torque converter because he burnt his oil badly enough to clog up the pickup screen and starve the transmission of oil.
I couldn’t see any colloids in my dark brown burnt oil, however, I will still be changing the pickup screen as a precaution.
Keep those autos cool!
Best
Mark
After a recent Fraser trip I noticed my ATF temps getting very high in the soft stuff, up to 120C on occasion, which is a very high temperature for the transmission oil to get to. I decided it was definitely time to upgrade the auto cooler, the OEM unit was just not cutting it.
I’d seen the great work that Tin175 has done with the Davies Craig 678, which is a 21 plate cooler;
http://www.pradopoint.com/showthread...-thermo-switch
I wanted an even bigger cooler, so I went for the 679, which is a 30 plate job.
I knew it was going to be a tight squeeze to fit in the 30 plate cooler, but with a bit of mucking around it’s not so bad. After reversing the OEM horns, and ditching some of the OEM brackets, everything fits nicely, and you can utilise three of the pre-existing threaded holes, one at the top left horn, and two at the bottom, and a pre-existing bracket hole on the right. I used some aluminium checker plate and a bit of rectangular aluminium tubing to knock together the framework.
The finished job is a nice and snug fit;
I also used the same OEM flow orientation, input at bottom, output at top, using the same circuit that flows through the side of the radiator.
After flushing my dirty brown old fluid out, and flushing through 12 litres of nice new Penrite ATF LV, I tested the new cooler out again on Fraser.
I was up at Fraser in the middle of January and it was stinking hot conditions, 42C in the shade, 60C sand temperatures in the middle of the day, and the cooler worked brilliantly. I was also testing out some new rear shocks, so I was pushing the Prado quite hard on inland tracks, and the highest ATF temperature I saw was 90C, compared to the radiator at 93C. The best reduction I saw while cruising on low tide was 33C under an 89C radiator temperature. The larger cooler in front of the radiator has not affected my engine coolant temperatures.
The Penrite ATF LV is very close in viscosity and temperature rating to the Toyota WS fluid. Penrite recommend a working temperature range of 50-80C, and recommend not to let the fluid temperature exceed 100C.
I have heard anecdotal stories that some A750F transmissions run hotter than others. Maybe I’m one of these unlucky people, or maybe the auto runs a bit hotter with the 1GR-FE in front of it. In any case I have managed to get the working temperature sorted out. I don’t believe the ATF temperature will ever exceed the radiator temperature with the new setup.
Even so, I will be changing the transmission pickup screen soon. When the ATF is burnt, it breaks down and can form tiny colloidal lumps of crap which can block the pickup screen. I have heard on FJCC of one owner having to fork out $3000 for a new torque converter because he burnt his oil badly enough to clog up the pickup screen and starve the transmission of oil.
I couldn’t see any colloids in my dark brown burnt oil, however, I will still be changing the pickup screen as a precaution.
Keep those autos cool!
Best
Mark
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