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Diy Tranny Flush Procedure


Crusty1

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My 01 LS430 just turned 90k. I'm thinking about doing a "red neck" tranny flush. So much conflicting info on this topic here and on the web re. this. I bought the car with 72k on it and drained what was in the pan and replaced. It appears from faded service stickers that previous owner (who was a doctor in AZ) had regular service done at the recommended intervals from a combination of the Lexus dealership and an independent shop. I'm planning on doing my own tranny flush, often referred to on the net as a "redneck" flush and replacing the T IV with Amsoil full synthetic. By "red neck" I mean, drop the pan, replace the filter, and then use the tranny's own system to flush out the old and replace with the new. I've used this system with great success on my other 5 rigs but I'm sure this will attract some conflicting opinions...possibly.

What I'd like to know is:

1. Which line from the tranny into the radiator/cooler is the return line? Usually, there's a line on the top and one on the bottom, but looks like there's just 2: both entering at the bottom. One on drivers side; one on passenger's side. I'm guessing it's the one on the drivers side that feeds back into the tranny.

2. My factory service manual, which doesn't even provide intructions on a tranny service drain...wierd?, shows "cutting" the sealer material between the pan and tranny. Is there a gasket on the pan? Just sealer? Or both?

3. Also, it instructs me to replace the bolt designated with an "A." It's one of 19 bolts holding the pan on but it's the only one that needs to be replaced. What's up with that? Is it some kind of special thread/disposable bolt?

From my documentation I can't confirm with 100% accuracy that the previous owner had the fluid changed or tranny flushed for that matter. And I'm aware of the conflicting opinions of flushing trannies when they're over 100k without prior tranny service. (fear of clogging things up with dislodged gunk). But it's really a "catch 22" as to just leaving it alone or doing the "progressive" drain and replace through the pan at each regular oil change (ie, 3000k).

Also, I'm not a transmission professional. I only service my own trannies so I'm not giving advice for others to apply to their own situations. My depth of knowledge is mainly servicing my own stuff. Howerver, when my "professionaly built" HD towing tranny in my wife's suburban blew after just 10K, I did remove and completely tear down and rebuild the tranny from scratch on my own. So far I've got 5k miles on it and it works great. Sigh of relief! I never really appreciated what a trannsmission did until I took one apart piece by piece!!!

Thanks for your input in advance.

Dennis

PS. I've been a Toyota/Lexus owner/user for 40 years. I think Toyota ATF is a little over rated but still better than what you'll pick up at Autozone.

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For those who do the drain 2 quarts then top up with fresh and repeat a few days later.

Here is the graph of fresh transmission oil as a % of total. Since each drain you are taking away some fresh fluid it becomes a case of diminishing returns. It takes 12 quarts to get 80% clean fluid (or 20% old fluid). Similarly it takes 18 quarts to get to 90% fresh. Still better than leaving it 100% old fluid. I wonder why transmissions don't have a better scheme to drain them. With all the technology in a modern Automatic Transmission some way to let most of the fluid gravity drain (when powered off) doesn't seem that daunting.

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For those who do the drain 2 quarts then top up with fresh and repeat a few days later.

Here is the graph of fresh transmission oil as a % of total. Since each drain you are taking away some fresh fluid it becomes a case of diminishing returns. It takes 12 quarts to get 80% clean fluid (or 20% old fluid). Similarly it takes 18 quarts to get to 90% fresh. Still better than leaving it 100% old fluid. I wonder why transmissions don't have a better scheme to drain them. With all the technology in a modern Automatic Transmission some way to let most of the fluid gravity drain (when powered off) doesn't seem that daunting.

A complete fluid drain by gravity is problematic because of the fluid contained in the torque converter. Unless the engine is running the oil in the converter cannot drain as well as oil contained in servos and fluid passages. At present we're limited to oil change parlors that offer a power flush (T-Tech) to get a complete oil change.

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For those who do the drain 2 quarts then top up with fresh and repeat a few days later.

Here is the graph of fresh transmission oil as a % of total. Since each drain you are taking away some fresh fluid it becomes a case of diminishing returns. It takes 12 quarts to get 80% clean fluid (or 20% old fluid). Similarly it takes 18 quarts to get to 90% fresh. Still better than leaving it 100% old fluid. I wonder why transmissions don't have a better scheme to drain them. With all the technology in a modern Automatic Transmission some way to let most of the fluid gravity drain (when powered off) doesn't seem that daunting.

A complete fluid drain by gravity is problematic because of the fluid contained in the torque converter. Unless the engine is running the oil in the converter cannot drain as well as oil contained in servos and fluid passages. At present we're limited to oil change parlors that offer a power flush (T-Tech) to get a complete oil change.

Agreed. The "gradual" tranny flush of replacing what's in the pan is better....but not the best. On all my rigs I use the "red neck" tranny flush: same as in the tutorial here on the forums. I'm just surprized no one has detailed this out for the new 430s. It does appear a little different than the older LS line. I really like the idea of totally fresh ATF in my tranny versus a "mix" of old and new.

I'd write more but having a problem with responding here....something is wacky with the site and my keyboard.....???????

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  • 1 year later...
For those who do the drain 2 quarts then top up with fresh and repeat a few days later.

Here is the graph of fresh transmission oil as a % of total. Since each drain you are taking away some fresh fluid it becomes a case of diminishing returns. It takes 12 quarts to get 80% clean fluid (or 20% old fluid). Similarly it takes 18 quarts to get to 90% fresh. Still better than leaving it 100% old fluid. I wonder why transmissions don't have a better scheme to drain them. With all the technology in a modern Automatic Transmission some way to let most of the fluid gravity drain (when powered off) doesn't seem that daunting.

A complete fluid drain by gravity is problematic because of the fluid contained in the torque converter. Unless the engine is running the oil in the converter cannot drain as well as oil contained in servos and fluid passages. At present we're limited to oil change parlors that offer a power flush (T-Tech) to get a complete oil change.

Agreed. The "gradual" tranny flush of replacing what's in the pan is better....but not the best. On all my rigs I use the "red neck" tranny flush: same as in the tutorial here on the forums. I'm just surprized no one has detailed this out for the new 430s. It does appear a little different than the older LS line. I really like the idea of totally fresh ATF in my tranny versus a "mix" of old and new.

I'd write more but having a problem with responding here....something is wacky with the site and my keyboard.....???????

Has anyone experience of changing the fluid using a Pela Oil Extractor through the dipstick? Pela Oil Extractor Pump

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For those who do the drain 2 quarts then top up with fresh and repeat a few days later.

Here is the graph of fresh transmission oil as a % of total. Since each drain you are taking away some fresh fluid it becomes a case of diminishing returns. It takes 12 quarts to get 80% clean fluid (or 20% old fluid). Similarly it takes 18 quarts to get to 90% fresh. Still better than leaving it 100% old fluid. I wonder why transmissions don't have a better scheme to drain them. With all the technology in a modern Automatic Transmission some way to let most of the fluid gravity drain (when powered off) doesn't seem that daunting.

A complete fluid drain by gravity is problematic because of the fluid contained in the torque converter. Unless the engine is running the oil in the converter cannot drain as well as oil contained in servos and fluid passages. At present we're limited to oil change parlors that offer a power flush (T-Tech) to get a complete oil change.

It may be possible to drain the torque converter directly if the AT is designed for it. I discovered this when I changed the ATF on my mother-in-law's 1985 Mercedes 380SL. You drain the pan, and then rotate the torque converter (by turning the driveshaft, I think - it was a few years ago) until a small drain screw can be seen through an access port, looking straight up from below. Remove that plug and you drain the TC. Drained a total of about 7 or 8 quarts that way. Pretty cool, I thought.

But that's the only car I've seen that on, and certainly my '91 LS400 does not have that capability.

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Well, I ended up just driving the car up onto two large bricks, the extra 4 inches or so it raised the car was enough for me to reach the Transmission drain plug.

I drained about 2.5 litres out and remembering that last time I checked the fluid level it seemed a bit high, I replaced only 2.3 litres. I checked the level after a drive and it's OK but I guess still a little on the high side.

The condition of the fluid was not so good. I would describe it as the colour of molasses or strong black coffee.

I'll do another drain and fill in a few hundred miles and maybe continue the process a few more times. It was very easy

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