Transmission Fluid Exchange Writeup

[MikePL]

OH, and another thing... I've read the FSM and it says that the tranny needs 12.4 quarts to be filled up from dry condition. So I bought 14 quarts. Why do people need 18 or 18 quarts to change the fluid? Is it a safety margin to make sure old fluid is well diluted or is the FSM a bit off?

 

[prossett]

Can I ask a really dumb question? What's wrong with dropping the AT pan and draining out the fluid that way, and replacing the filter at the same time?

I'm ready to swap out my ATF, but I thought I'd do the filter as well, since I don't know when or if it was ever changed. But now I'm thinking maybe I should just follow the FAQ.

Is the hose method just a way to avoid skraping off and resealing with gasket sealant without getting ATF all over the driveway or is it because dropping the pan has other disadvantages?

Oh, and another thing - Elsie has an aux tranny cooler set onto the front of the condenser. Any warnings on how that would affect an ATF change?

 

[LX_TREME]

Can I ask a really dumb question? What's wrong with dropping the AT pan and draining out the fluid that way, and replacing the filter at the same time?

Nothing wrong with it, I dropped the whole tranny, use small sharp blade and skrap off the old gasket <- remember you must have passion doing these

Pic 1 - All clean with new filter in.
Pic 2 - Nice and clean no residue, no old gasket.
Pic 3- Close and seal with new Toyota gasket.

 

[corsair23]

Can I ask a really dumb question? What's wrong with dropping the AT pan and draining out the fluid that way, and replacing the filter at the same time?

My understanding is that simply 'draining' the AT only removes about 4 qts of ATF. I would assume this would be the same whether you drained the fluid out via the drain plug or by plug and dropping the pan. What was explained to me is that remaining fluid stays up in the torque converter. This is why the drain/fill process doesn't net you "new" fluid until after numerous drain/fill cycles (there is a spreadsheet on this...maybe earlier in this thread?).

My understanding also is that you really don't need to replace the filter which therefore further negates the need to drop the pan.

 

[prossett]

OK, makes sense. Thanks.

Here's another one: instead of refilling fresh ATF through the dipstick while it drains out the hose, what if you also disconnect the other hose (going to the tranny) and sink it in a clean bucket of fresh ATF?

That way it'll eliminate the risk of running the tranny dry, and you don't need to stop to fill, and not bother with the funnel...

I'm sure you guys have thought of this before, so is it something like not enough pull to suck up the ATF out of the bucket?

 

[MikePL]

Prossett,

I have also thought of using the other hose to suck in new fluid but it simply didn't suck any fluid at all. I tried to put a funnel on the hose and use gravity to fill but the fluid didn't want to come down fast. So in my case using the dipstick tube was the only possible method.

There is very little risk of running the tranny dry if you are careful. My method was to:
- drain the pan
- check how much has drained and fill the same amount
- use a transparent bottle where I made a mark every liter (or quart, whatever).
- I turn the engine on and wait till one liter drains (around 30 seconds).
- fill one liter through the dipstick
- drain another liter to the bottle
- fill another liter and so on.

With such a small amount of 'drainage' you won't make the pump run dry. It only takes around 8-10 drain/fill cycles so there is not much running around the truck and turning it on/off.

 

[corsair23]

OK, makes sense. Thanks.

Here's another one: instead of refilling fresh ATF through the dipstick while it drains out the hose, what if you also disconnect the other hose (going to the tranny) and sink it in a clean bucket of fresh ATF?

That way it'll eliminate the risk of running the tranny dry, and you don't need to stop to fill, and not bother with the funnel...

As I understand it, the tranny pumps fluid from the tranny to the cooler and back to the tranny (mentioned in earlier posts and by Christo re: what they use).

Since it is a closed system, the pump pushes the fluid through as opposed to "sucking" the fluid through. Once you break the loop (i.e. pulling the line at the cooler) the pump can't push the fluid through the loop anymore, only out into the bucket. And since there isn't any suction you can't "pull" fluid into the tranny from a separate bucket full of clean ATF - Thus the reason a professional flush/exhange done by a shop like Slee really does involve a pump, just a low pressure pump that matches the AT's pump pressure.

I still haven't seen this question answered though:

"Don't both the DIY exhange method and the drain and fill method both mix the ATF fluid in the end?"

My assumption is the answer is yes, but that the DIY exchange doesn't mix the old and new ATF as much as the drain and fill method would. I assume with a professional shop doing the exchange using a low pressure pump that the mixing would be even less. But in either case, to get 100% new fluid I would say you are going to go through more ATF than what the tranny will hold normally.

 

[SUMMIT CRUISERS]

I did 3 vehicles in the last 3 weeks by the method MikePL states. The only difference I did was I verified how much fluid came out of the tranny pan on the drain--refilled the same and only allowed the amount less 2 qts to be pumped out. Each vehicle I did had different drain amounts. My 92 FJ80 drained approx. 5 qts so I only pumped 3 qts out and then I refilled with 3. My 99 LX 470 drained approx. 4 qts so I only pumped out 2 qts then refilled 2. Of course I repeated this with about 3 to 4 gallons each vehicle.

By keeping 2 quarts in the pan it keeps you from running the pump dry. Results were incredible. All vehicles shift much smoother. Each vehicle took about 18 to 20 qts to flush out the old to make it look new. All vehicles were drained with the front end raised by being on car ramps.

Great fluid exhange write-up takes about 40 minutes per vehicle.

 

[cruiser-poor]

I found an awesome aftermarket kit with a new filter and hard rubber gasket. It’s made by WORLDPAC and has an exact copy of the filter and the gasket is so much easier than messing with gasket maker. When you drop the pan with this gasket you won’t have to deal with the trouble of removing the liquid gasket seal which I found to be a PITA! I bought the kit from Napa for about $60.00 and it worked out great with no leaks at all.

George

You can also get just the rubber gasket from NAPA if you don't need the filter. P/N is 1-8076 for the gasket (for the later 343F tranny). So far it's working fine and yeah, it was definitely easier than using the RTV. I'll bet it comes off easier too.

 

[cooldry]

Great writeup. I don't know the history of my LC. If the tranny fluid hasn't been changed regularly, will something get screwed up if I start to use syn oil?

 

[Beowulf]

Great writeup. I don't know the history of my LC. If the tranny fluid hasn't been changed regularly, will something get screwed up if I start to use syn oil?

Probably not but it holds around 20 qts if I remember correctly so that could cost a bundle to do a full fluid replacement with synthetic ATF. IMHO, syn is more important in the engine, transfer, and diffs than in the auto tranny. I would recommend taking it to a trusted mechanic that uses the machine that does the fluid exchange. Don't put in any "cleaners" or other additives and if it is a good shop then they should have a premium ATF available.

-B-

 

[C6H12O6]

Great write-up. I just did this yesterday. It took me about 20 quarts to get the fluid coming out to be looking new enough to stop. Got her all topped off and the shifting is NOTICEABLY smoother. I can't believe I've had two cases of ATF sitting in the garage since last winter waiting to do this. Pretty easy job.

Between this and new tcase oil, it's like driving a different truck.

 

[zcruiser]

This procedure is what's known as a Rodney Flush by the 60/62 guys...

https://forum.ih8mud.com/showpost.php?p=1155843&postcount=10

 

[treerootCO]

I went to the store to buy some Mobil1 Synthetic and at 8.00 a quart, I went for the cheap stuff until payday. My transmission developed a real bad stumble/surge off the line and I wanted to know if fluid would help before buying the good stuff. Picked up 3 gallons of DextronIII and flushed it. Even if I was going to flush with Mobil1, I still might run the cheap stuff through to remove all the old fluid. Amazingly, the stumble/surge went away and the shift points are smoother. Fluid levels were correct before and after too.

 

[elhombre]

Don't be ashamed with the brand of fluid you put in the cruiser. I am like you in that I have the cruiser "sickness" but don't have the wallet size to back it up with synthetic ATF. I did the flush with Walmart (super tech) fluid for the last 3 springs and have been happy with the results. When I first got my cruiser, the fluid exchange was the same color that you have in your picture. Just last week I did it for the third time and the fluid came out clear and only slightly darker than new. I used 1.5 gallons at $8.50/ gallon. The fluid also smelled the same as the new stuff. At this price, I put this job as an annual event. Mmmmmm......clean fluid......

 

[Fly Rod]

I just completed the flush via the trany cooler yesterday. My observations are thus:

Use a hose long enough to let you watch the flow from the drivers seat if solo. I was suprised at how fast it flowed. I ran it into one gallon jugs and shut it down before it got over half full. Refilled at least that much and do it again. By the time I ran through the gears once I had a half gallon drained. Keep plenty of blue shop towels around as I spilled alot.

All told I ran 3 1/4 gallons of new through the system. This is a job at most.

 

[bpassmore]

I will be doing this possibly on Sunday. Thanks for the great write up! I have 80k miles right now - The fluid looks very clean, but I dont know if it has ever been changed. I dont expect to do the pan drop part at this time. Your thoughts?

 

[kiwidog]

Fluid Change.

IMHO

Fluid change unnecessary expense.

The torque makes 90% of the heat in and automatic. If the fluid is run too hot it will oxidize and change color. That what it is designed to do. If the heat doesn't rise much above 180 then the fluid won't change color. Some automatic shed metal and clutch material more than others. Over the life of the transmission this will also color up the fluid a little.
The transmission usually fails not because of bad fluid but because of a bad seals inside one of the clutch packs and the clutch slips and sheds material which contaminates the fluid which causes more damage to other parts of the transmission. You have a negative feed-back loop, a little damage begets more damage. They can also fail because of hard part failure, such as a sprag clutch, pump, bushing, or thrust washer failure.
I think you are wasting you money with a fluid change unless you run a lot of horsepower and inadequate cooling then then you will have problems that won't be fixed by changing the fluid.
Sure synthetic fluid takes more heat, but for the most part unnecessary if you have adequate cooling, and strong clutch pack seals.

Just another opinion, Flame me if you like, but I think fluid changes are a waste of time for the most part if the fluid has good color and smell, and is not contaminated with water.

Thanks jb

 

[jdsti]

Probably a stupid question but how do you shift through the gears? Whie its lifted off through ground?

 

[OhioCruiser]

IMHO

Fluid change unnecessary expense.

The torque makes 90% of the heat in and automatic. If the fluid is run too hot it will oxidize and change color. That what it is designed to do. If the heat doesn't rise much above 180 then the fluid won't change color. Some automatic shed metal and clutch material more than others. Over the life of the transmission this will also color up the fluid a little.
The transmission usually fails not because of bad fluid but because of a bad seals inside one of the clutch packs and the clutch slips and sheds material which contaminates the fluid which causes more damage to other parts of the transmission. You have a negative feed-back loop, a little damage begets more damage. They can also fail because of hard part failure, such as a sprag clutch, pump, bushing, or thrust washer failure.
I think you are wasting you money with a fluid change unless you run a lot of horsepower and inadequate cooling then then you will have problems that won't be fixed by changing the fluid.
Sure synthetic fluid takes more heat, but for the most part unnecessary if you have adequate cooling, and strong clutch pack seals.

Just another opinion, Flame me if you like, but I think fluid changes are a waste of time for the most part if the fluid has good color and smell, and is not contaminated with water.

Thanks jb

+1. I'm in the same boat