TRANS, HOW TO FLUSH & ANYONE PUT DRAIN PLUG PAN ON?

[bdv]

HAVE A HYDRAMATIC TRANSMISSION WITH PART # 8684198 5 STAMPED ON SIDE BELIEVE IT IS A 4L80E BUT AM NOT SURE HOW TO CHECK. HAVE READ I SHOULD REPLACE FILTER AND SCREEN. SHOULD I REPLACE ANYTHING ELSE WHILE I HAVE PAN OFF? WHAT DOES IT TAKE TO REMOVE/REPLACE REPLACE FILTER AND SCREEN? I AM ALSO THINKING OF REPLACING PAN WITH: “Part# is 8685921 for the 4L80-E oil pan with the drain plug. cost $32.55 Part is listed as a 2WD but fits a 4X4. Only difference is the drain plug”. HOW SHOULD I FLUSH REFILL TRANS FLUID TO TAKE ACCOUNT OF THE FLUID IN THE TRANS COOLER?

THANKS FOR THE HELP BRENT

[DickWells]

Hi Brent: I'm not an authority on this, but I (finally) flushed my 4L80E last year, and this is how I did it.
I drained the old fluid from my alluminum deep pan, pulled the pan, changed the filter (it's simple), and put the pan back on, then re-filled the pan with about 8 quarts, I think, of new fluid. Then I separated the cooler line (bottom), and pushed on a piece of clear tubing, started the engine in park and had my wife run it while I watched the fluid pump through from the cooler and torque converter. I had her shut it off after every couple of quarts, then re-filled and re-started until the fluid ran nice and clear. Then I filled her up to the full mark, and I was done.
Around here, it costs at least a hundred bucks to have a professional do a flush job. I've read in the DP that the above proceedure is permissable. I probably wasted about four quarts of new fluid. That's a long ways from 100 bucks. I used to just change the filter and the fluid that I lost with a simple drain. I noticed that the latest job has kept the fluid looking fresh for a LOT of miles, so I'll probably do it the same every year or so from now on.
As you can see in my profile, I have a deep pan with a drain plug. With that alluminum finned pan, and the factory cooler, I seldom see more than 170 degrees temp. Usually 140. I've never seem more than 210, towing up mountains in the heat.
Hope this is good info for you.
Dick Wells

[moondoggie]

Good Day!

I bought a spare tranny pan from a tranny shop & welded a drain plug fitting on it. I threaded it the same as the engine oil drain plug - I'll never have to guess in the future what drain plug to buy if I need one, it's the same as the oil drain plug. I sure wish I knew you could buy one with a drain plug in it - I think I paid $20 for the used one I bought; then again, it was fun making the simple part on the lathe at work... smile.gif

My fluid was totally cooked. I bought my pickup with 80K miles on it, never did anything to the tranny until > 210K miles. I'd have been ashamed for anyone to see what drained out of my tranny - it looked like really dirty diesel engine oil, I don't think there was a hint of red or pink to it. I did a tranny splash, repl. the filter, & installed the pan with the drain plug. Then every oil change I dropped whatever amount of tranny fluid came out (5 quarts or so, I think). If you do the math, after several of these, you have > 99% new fluid; I'd allow folks to see my tranny dipstick now, she's the right color. :D

I'd have done like Dick Wells said, that's the best way, but I don't trust my mechanical ability to do it right. Plus, with how long it had been since the fluid had been changed, I was scared of all new fluid loosening up some crap that would then make my tranny quit tranny'ing. I had an 84 Sub once that I put some tranny flush stuff in, & within a week, no tranny. :(

Blessings!

[Kennedy]

Look closely, I found the 2wd pan to be slightly shallower.

I drilled a hole thru and welded a 1/2" NF nut inside the pan. If you are looking to get maximum fluid removal, you can slot or drill the nut. This works great, BUT it relies on the seal more heavily and fluid comes out as soon as you start to losen the plug.

[slagona]

I use the same method as Dick stated above. Drain and Drop the pan. Change the filter. Put the pan back on and refill with new fluid - however much came out is about how much I put in at this point. I have at least 24 quarts on hand to do the entire job. Get a 5 gallon pail, undo the top transmission line on the passenger's side of the radiator. Put one end of the hose (I used clear) on the end of that metal line and the other end in the five gallon bucket. I had marked my bucket with lines indicating each 1/2 gallon. Now, start the truck, keep it in nuetral, and as fluid drains out, keep addding about the same amount of new fluid in the fill tube. It is handy to have a second person sitting in the truck to shut it off in case of emergency.... But I have done it solo - it's pretty easy to keep up with the amount being pumped out. Just keep the truck running and keep adding new fluid as old fluid pumps out. When it becomes clear, you've flushed everything out and are done..... Shut the engine off, run the transmission through its paces, and check the fluid level after that. There used to be some really good threads out there on this procees, try searching to see if they are still there....

--Scott

[JohnC]

Here's how I do it. First, remove the line going into the top of the radiator. This is the feed from the trans to the cooler (4L80E, others DO vary!) Stick a piece of 3/8" hose on the line and put it into a 5 gallon bucket. Run the engine at idle until the fluid stops coming out into the bucket. This pulls most of the fluid out of the cooler into the pan and pumps it up into the converter. Next, drop the pan, which is now nearly empty and easy to handle, and change the filter. Clean the pan, put it back and add in 7 quarts of new fluid. Run the engine at idle again until the fluid stops coming out. Now the clean fluid is up in the converter and nearly all the old fluid is in the bucket. You may refill the pan and run a little more into the bucket, but it's hard to control at this point and the rewards are negligable. Anyhow, refill the pan, reconnect the upper cooler line and check the level per the owner's manual. It's easy, no mess, and you'll get 99% of the old fluid out and not waste more than a quart or 2 of the new stuff.

Don't need no stinkin' drain plug...