Just change the fluid and filter for my sons 05 MCS Automatic 120k miles. Now when I put it in drive it lunges hard and downshifts fairly hard. Could it be that I didn't put enough fluid back in it?? Would that cause this issue??

 

I remember your other post about a fluid change. When you changed the fluid did you see any metal shavings in the old fluid? Did you use a or our guide to do the fluid change? It could be a level issue, but I'm not too sure. I know in our article it states to heat up the fluid to between 35*-45*C (95 to 113 degrees F) as this is critical to getting the level right. The fluid level must be at the correct temperature to register correctly at the overflow pipe. You can review our tech article here and see if it may help you a bit if you didn't already. Otherwise, definitely check that level and I did run across this thread here about the Aisin transmission with lots of information with symptoms people dealt with when theirs failed. May not be your issue, but maybe see if some of the advice given will help with your diagnosis. Hopefully someone will have some other advice for you as well. Good luck.

 

from the Pelican article "With the plug in place, start the car, put your foot on the brake, and cycle the car through each gear, holding there for 5 seconds each. This will help to circulate the new fluid through out the transmission. Once you have cycled through all the gears, you'll need to re-fill the transmission. Shut the engine off and make sure the fluid being added is up to operating temperature. Re-fill the transmission until fluid again starts to drip past the overflow tube. Once it stops dripping out, the transmission level is correct. Now re-fit the inspection plug to the bottom of the overflow tube with a new crush washer and torque it 27Nm (20 ft/lbs.). Now all that's left is to lower the car down off the jackstands and you're done."

I think this is probably an overlooked step. The transmission fluid change is one of those items that always scares me. You have a working unit and then after a bit of fluid change, you are in a bit of trouble. It really can't be very many things that went wrong, wrong fluid or not enough in all the right places.

 

Yeah I performed the steps to a tee...the whole reason for doing the change was due to the tranny slipping a couple times while my son was driving. So we parked it till I could get the stuff to do the fluid change. Researching it seems that the tranny in this particular year and model mini is pretty durable, buy the Valve Body tends to fail before the tranny will. I'm hoping it was a simple fluid change that it needed. It has 120k miles on the clock. I may not have got the temp up correctly when I initially introduced the new fluid. I only drained maybe 2.5 to 3 qts of fluid when I drained the old fluid.

 

Sounds like a fluid level issue. I would do another change to see and drive it again. In all of the posts I've read, they say you need to do at least three changes to get about 80% new fluid into the trans without dropping the pan.

When you did your change, was it one drain, or the procedure of multiple changes?

 

I changed the filter and fluid just once. So what you're saying is just change the fluid now two or three more times after running it for a few miles for each interval??

 

According to all of the posts I've read, Yes. When you drain the trans without pulling the pan, you only get about 50% out. Then you drive it for a bit and it mixes together and you drain and fill again, as many times as you want to. The more you do, the higher the percentage of new fluid in your trans, but with rapidly diminishing returns. That's why most people stop at three.

It's an in-efficient way to do it, but the only way if you don't drop the pan or pull the transmission.

 

Yeah I REALLY hate to buy a new Valve Body or a rebuilt tranny if I don't have to....the valve body is cheaper, but still $$$$ if it doesn't fix the problem. I'll do a couple more fluid swaps and see what happen

 

Check out this thread:

https://www.northamericanmotoring.co...ion-fluid.html

The first post has a pdf link to a guide and info on why so many changes. The third post has info on letting the car drain overnight to get about double the amount of fluid out per change. If all else fails and it is your valve body, many people seem to have luck with a rebuilt from Revmax.

 

These are the magnets from the pan. The right is one I cleaned the left is what both looked like when I dropped the pan. That look about normal for 120k miles on the tranny?? No metal slivers...just gunk on the magnets.

 

98 times out of 100, if you were experiencing transmission problems before a fluid change, they will be there after a fluid change. Unless your problems were low fluid before, new fluid to the proper level won't fix it. There is no magic in the fluid. It is a preventative maintenance job, not a therapeutic one. I think multiple fluid exchanges to get most of the old fluid out is just going to be a waste of money and get no where with your transmission issue. The gunk on your magnet lookss normal.

 

True, fluid changes after problems seldomely work, but sometimes they do, so it's a cheap gamble if you can do them yourself.

Pocketmaster, if you dropped the pan that quickly it seems you might have the ability to replace the valve body itself it that's the problem. Do a search and look for the post(s) that give info on what to check on the valve body. One of the solenoids seems to come loose or rotate in the body and cause problems, but I don't remember the details. The post also included pictures of the solenoid.

Bringing the transmission to be rebuilt with you doing the R&R is also cheaper, but if you have any issues in the future they might blame you for doing something improperly.

 

This is after one tranny fluid cycle. Drain and refilled, drove the vehicle about 20 miles. Drained it again and this is what it looks like. The left is fresh fluid, the right is what it looked like after 20 miles. Doing another cycle now. Got 2.75 qts out after allowing to drain over night

 

What ended up being the fix?

 

It sounds to me like it may have had problems that a fluid change would not fix. Fluid changes won't fix it if it has bad clutches or bands. If it was driven low on fluid or slipping for any amount of time, it may have overheated the clutch packs and may need a full rebuild.

*EDIT* NEVERMIND! I just realized this is a 5 year old zombie thread.