PWL216 889 #1 Posted June 16 (edited) I picked up a C-85 and noticed the gear shift was sluggish when moving through the gears. I checked the transmission dipstick and saw it was overfull, was an awful brown color and stunk! Damn, water in the tranny. No shifter boot cover - the likely culprit. I drained the tranny of a gallon of fluid vs the two quarts it’s supposed to have. I assumed there was still contaminated gear oil in the case, so I decided to try and flush it…with MMO. Was this a good choice? I had it, so I figured why not give it a shot. I did three flushes, using two bottles of MMO. After the last pass there wasn’t much of the contaminated oil showing, so I stopped flushing and added new transmission gear oil. The process seems to have worked as the sluggishness is gone. It shifts really well. I’ll be taking it for a ride later to test it. How do you do a transmission flush? Edited June 16 by PWL216 Share this post Link to post Share on other sites
rmaynard 15,434 #2 Posted June 16 Well, I wouldn't waste Marvel Mystery Oil when regular diesel or kerosene would do just fine. 2 1 Share this post Link to post Share on other sites
Ed Kennell 38,131 #3 Posted June 16 I use kerosene. Fill it and drive it slowly for a few minutes in tight circles using all gears to scrub all the gear teeth. Raise the front end and drain it. If it looks dirty, repeat till it looks clean. Then fill with 90w. gear oil. I save the dirty kerosene and mix it one to five with used motor oil to treat fence posts, fence boards, trailer deck boards, trailer springs, etc. 1 2 Share this post Link to post Share on other sites
squonk 41,067 #4 Posted June 16 Biggest thing is how rusted the needle bearings got. Those tin can bearings are the most robust units you run across. I would run it a while then drain it again. I would add some Lucas oil stabilizer to the next fill 1 Share this post Link to post Share on other sites
ri702bill 8,316 #5 Posted June 16 (edited) My in-the-cellar setup... Reverse rotation E-lectric motor. Work it thru all the gears - flush with diesel & drain twice..... Edited June 16 by ri702bill 5 5 Share this post Link to post Share on other sites
peter lena 8,608 #6 Posted June 17 @PWL216 , initial viewing , drainage , driving around with a cleaning / flushing agent . initial front end lift , to enhance drainage , like diesel fuel / hi mileage ATF fluid , and road time on cleaning out the crud . regularly check my , differentials , their are no surprises , always clean / clear / full. also put miles and every gear option into use . local CUL DE SAC , is like a prefect mechanical gear run . new shift boot , greased INSIDE the boot, so it effortlessly slides over the irregularities of trans case , wide TYE WRAP on top of shifter boot ,holds prefect setting , for long life . been using lucas climbing gear oil , also get after any related linkage / lever movement areas , make the rust run out . also do a regular once over , after every usage , top up fuel , 1 OZ of STA BIL fuel storage , check trans fluid , find having a regular check over , has given me solid status as to solid operation . that check over is similar , yet different , in cold weather , basically adding , plug in battery tender / heat bulb reflector under engine . @ri702bill totally agree with your trial / test set up . making a change , usually helps things out , pete 1 1 Share this post Link to post Share on other sites
