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Sharing my experience of transmission drain & fill on my LS460. The procedure for GX460 should be very similar.
At first I was also intimidated by the overly complicated procedure.
So I found a local mobile mechanic who has 20 years of experience working on cars.
He stopped by, dropped the AT fluid pan, replaced gasket & filter, and filled back trans fluid.
He was not very precise about the AT temperature when filling back, he mentioned that in dealership the mechanic would just let car idle for 5 min and then fill back fluid without check the temp.
After that i was able to perform the drain & fill myself, even better than the mobile mechanic by monitoring the AT fluid temperature.
tricky steps:
1. to reach the refill plugs on the driverside of the transmission, you need a proper 24mm wrench. it needs to be long and thin to fit in the small space. I bought it from ebay $30.
2. to fill back the fluid you need some kind of pump.
3. need a temp gun to measure the fluid temperature as then drop out.
Texas008 is right. The drain and fill procedure sounds complex but actually it is straightforward. It's similar to LS460 transmission fluid drain and fill. I used Techstream to read the exact transmission fluid temperature on my computer screen. A word of caution is about the torque of the transmission pan drain plug. Although Lexus service manual says it should be 15 lbf, the plug thread on the transmission fluid pan is very soft and easily stripped. Just tighten the plug to crush the washer (about 10 lbf torque) and stop. The thread of my transmission pan was stripped when I torqued the drain plug to 15 lbf and I had to order a new transmission pan, a $125 lesson learned.
I did torque to 15 ft-lbs but used my new digital torque wrench that goes down to around 8 ft-lbs with a variable setting to start vibrating as you are approaching the set torque amount. I had mine set at 25%. I will be extra careful. I plan to do another drain and fill this weekend.
I did torque to 15 ft-lbs but used my new digital torque wrench that goes down to around 8 ft-lbs with a variable setting to start vibrating as you are approaching the set torque amount. I had mine set at 25%. I will be extra careful. I plan to do another drain and fill this weekend.
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That was on my LS460. I was unfortunate to experience the dreadful "strawberry milkshake" problem - transmission fluid and coolant crossing each other - on my LS460. I had to drain and fill the transmission fluid six times and flush my cooling system 10 times, and also replace the leaking radiator, to clean the mess.
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Did you bypass the AT cooler in radiator with an air cooled external one after that? Is that even practical to do on the LS?
I think I will bypass mine when I put on my external air AT cooler next year.
I'm just curious why would you do that. Having an integrated radiator / ATF cooler not only cools but warms the ATF to its operating temperature in cold weather, at least based on my understanding.
By bypassing the original cooler you may see erratic temperatures in cold weather.
One thing to avoid potential leak in that internal unit that could mix coolant and AT fluid which from what I gather usually destroys a transmission. That being said I haven't heard of this happening on a GX 460.
That AT thermostatic switch allowing fluid to radiator only opens up when engine is hot. It is closed when cold. I've seen some temp spikes when towing that I think would be addressed with an additional cooler. Need to see what others experience is with additional coolers.
Did you bypass the AT cooler in radiator with an air cooled external one after that? Is that even practical to do on the LS?
I think I will bypass mine when I put on my external air AT cooler next year.
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I thought about using a bypassing separate transmission cooler to separate the transmission fluid but did not like adding the complexity. Instead, I will replace my radiator every 3 years from now on to avoid another "strawberry milkshake" incident. I used one of those "life-warranty" cheap radiators that RoadFrog (Chris) suggested for $75 from eBay. The quality seems OK and the vendor responds to my questions promptly. The cost is reasonable and it won't take me too much time to replace the radiator, having done it once.
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One thing to avoid potential leak in that internal unit that could mix coolant and AT fluid which from what I gather usually destroys a transmission. That being said I haven't heard of this happening on a GX 460.
That AT thermostatic switch allowing fluid to radiator only opens up when engine is hot. It is closed when cold. I've seen some temp spikes when towing that I think would be addressed with an additional cooler. Need to see what others experience is with additional coolers. https://lexusgxor.com/_media/general:a760f.pdf
Page 113 talks a little more about that thermostatic cooler.
It appears the thermostat itself actually acts as the warmer piece as coolant circulates through the thermostatic switch.
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Acrad35751 hit the point. When coolant enters transmission, if not treated at the very early stage, the transmission will be damaged beyond repair. This "strawberry milkshake" problem occurred more frequently on high-mileage 4Runners (Google "strawberry milkshake 4Runner" and you will see the reports). As a result, quite a few owners of high-mileage 4Runner installed a separate bypass cooling device as Acrad35751 suggested for prevention of the problem. Others simply replace radiators before 100K miles as prevention. In any case, develop a habit of regularly checking your coolant reservoir tank for clarity. If you coolant reservoir tank becomes blurry with pink milk-like stuff, it is an indication that transmission fluid has entered the cooling system and most likely coolant has also entered into the transmission system.
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Drained out 3 quarts & 13 ounces / refilled with 4 quarts and then drained out 14 ounces at 115 degrees. Probably 1-2 ounces in all the vinyl tubing and a tad in bottles. Pretty close to what I expected since my factory fill seems to have been about 1/2 quart low. The small quantity pics are the 14 ounces drained out so effectively the current color.
Still work to do getting better color but improving.
Side note... put an old rag over that heat shield area opposite of the fill plug just in case... had a just in case and cut my knuckle. Cheap insurance. Heat shield has an extremely sharp edge to it. Some of these pics probably won't show up correctly on a phone.
I think AT is running cooler after this last change. I notice a lot of 170-180 range driving down the freeway. I also see why 4S runs cooler. This basically forces it into lockup right away.
