Transmission Cooler Line/Fluid Replacement

[Guitarplaya39]

I've just discovered the metal trans fluid cooler lines that come out of the radiator are very rusty and starting to leak. Replacement parts are on the way, but now my concern is dealing with the transmission fluid...

First, I must admit that she's at around 230k miles and I've never changed/flushed the transmission fluid. I know that flushing at high mileage can cause damage.
When I replace these lines, how much fluid can I expect to lose?
What's the risk of damage by draining that amount and topping off?

Any info and advice would be greatly appreciated!

Thank you!

 

[4R005]

If yours is a V8, this was what I did when I had the same problem. First off, you need to locate fill plug ( passenger side roughly 2/3's way up from tranny bottom, 24 mm socket ) and make sure you can loosen it. Then locate two other plugs at bottom of tranny case. One is the drain plug and the other is connected to a vertical tube inside case and is use to indicate correct fluid level when you are filling up the tranny after a drain or a top-up operation. When fluid run out out of this tube the correct level of fluid is reached in tranny. Vehicle is level etc etc. Also check cooling lines from tranny case to rad also. Mine also leaked there as well. Advise not to drive if you are not sure how long leak had been. Ask me why I say this. A $ 4200 complete rebuilt of my tranny is why when all fluid was lost from the leaks. If you are handy and have a flaring tool & a tube bender its an easy & economical job to replace all lines from tranny case to rad & from rad to oil cooler and back to tranny. I did all that prior to having my 4R towed to tranny repair shop. Believe steel tubing size is 3/8".

 

[rdruss]

IMO, don't fool around with DIY tubing, buy the OEM tubing or get from Dorman. If you haven't noticed puddling of ATF on your driveway you probably haven't lost much. Put a drain pan under the area you are working on and catch whatever small amount of fluid escapes. After you finish installing the new lines drain your trans pan and replace the same amount that comes out, probably just under 4 quarts and add back another few ounces over that amount. Drive your 4Runner and if it performs well, drain the pan again after a few more drives and replace what comes out, do it again after a few more drives and you're good to go.

 

[Guitarplaya39]

Thanks for the info guys.
I ordered the correct part online, but I'm just hoping it arrives before it's too late. No puddling yet, but it's definitely all over the skid plate. Kicking myself for not noticing how bad the rust was earlier.

 

[4R005]

The tranny in my '05 was a sealed system , so no dipstick to check fluid level. Wife drove into town for groceries ( 30 minutes round trip ). The 4R stopped 200 yds from our house on the return trip ( no forward gears and only reverse at a crawl pace, barely. Repairs consisted of all new clutch discs, planetary gears , solenoids etc and torque converter. Had no indication of leak(s) cos our circular driveway is all gravel ( country living ). I believe major fluid loss was during drive into town when fluid was recirculated ( pumped) thro' system.

Do not know if your vehicle is equipped with a dip stick or not. Without a DS, fluid level is unknown and you will not know how much fluid is still in tranny case. Good luck.

 

[Drcoffee]

These steel tranny lines usually rust up under the radiator and are no more than 2’ in length. Save time, money and aggravation. Buy Gates 3/8” transmission hose and high quality stainless steel hose clamps. Using a mini pipe cutter and cut the steel lines back to where its still solid and rust-free and hose clamp the new rubber lines in place. Route it so it is secure and avoids rubbing. It will never rust again and costs much less.

I had a 8” section that was about ready to break from rust. I cut it back to solid steel and havent had an issue since then. With the failure rate as high as it is, they should be stainless pipes not paint steel.