[HappyMint]

I took the car to Mitsu a few days ago and they changed the rear diff gear lube, but I guess I wasn't clear enough and they didn't change the ATF fluid. Today I went back and watched their "evo tech" who went to special training for mitsu on how to work on Evos bleed the ATF fluid from the system. He even had another tech sit in the driver seat while on the lift and turn the steering wheel left in right while bleeding it. I went up and asked him about it and I was told that he was trained at mitsu school to bleed the ATF fluid from the rear diff when it was changed.

I was under the impression that this was simply a drain and fill just like the gear lube in the rear diff? I mean even the service manual doesn't seem to indicate that the ATF fluid needs to be bled. I also saw him in the trunk area with the side latch working with the fluid reservoir? Did he do more than the typical change? I asked him to show me where he was draining from and he showed me the bolt and it's pretty clearly marked as the torque transfer/ATF fluid.

I'm so confused!

 

[mantella]

There should be 2 drain plugs one for the normal diff fluid and 1 for the spIII atf fluid. i would check you repair sheet since they may have only changed the one that most do not.

 

[dragon831]

Isn't it the AYC that requires all that trouble? The other 2 are just drain and fill jobs I think.

 

[mantella]

2 plugs on the rear diff. 1 drain and refill the 2nd one is a bleed it item which is the ayc

 

[SiliconTek]

The rear 2x 10mm drain plugs are drain and fill only.

 

[dragon831]

^^^^
as per http://forums.evolutionm.net/mitsub...on-x-maintenance-service-how.html#post6750417

page 79

 

[HappyMint]

I'm aware of the fact that there are 2 drain and fill plugs, but it seemed like he was bleeding one of those 2 plugs (the ATF one). He showed me the plugs and they're labeled on the diff what the drain and what the fill plugs are. Is it even possible to bleed the drain and fill ATF III one? Where exactly is the third one that requires bleeding? Any idea? Is it also labeled?

Maybe I can get under the car and take a pic sometime soon to show you what he changed.

 

[SiliconTek]

You NEVER need to bleed the system unless you either remove the pressurized lines, replace a component, or a failure occurs. Under normal circumstances it is fill only.

 

[HappyMint]

So bottom line is, there are only 2 drain and 2 fill plugs on the rear diff? It's not like there is another spot there to drain/fill and he just drained / filled the wrong spot? Bottom line is I'm trying to figure out if he drained/filled the right thing and if I need to go back or redrain / refill myself.


At this point I don't care if I paid extra for him to do unnecessary bleeding, I just want to know if I need to change some fluid that has been missed twice now.

 

[segfault]

Yes, there are two drain and fill bolts. One for gear oil and one for ATF like you think. Both are simple drain and fill, no bleeding. The bleeding he did was unnecessary as it is only if you detach either of the two lines that lead from the pump to the rear diff unit. Those are the two nipple things you're thinking of.

 

[mantella]

unless you had a problem with the ayc pump or somnething only a drain and fill is needed. some people have had problems with leeks and such in the trunk or cold weather problems and have had to bleed the system along with a ayc reflash.
on the bright side if they did not charge extra for it I would think it may be a good thing. Most likely a wast of time but hey the more fluid changed the better.

 

[HappyMint]

Thx for the heads up fellas!

 

[discogodfather]

It's a complicated system. The AYC has three parts:

1) The open diff gear oil side
2) The Clutch paks pressurized (hydraulic side), this is the same circuit as the actual hydraulic unit (two lines going into the back, plus bleeders, this is ATF)
3) The torque transfer gears (this is in the center housing and is a separate fluid and completely sequestered from the ATF that is used in the clutch paks.) They sit in an ATF bath but they are just lubricated by it, the fluid is not pressurized.

When we service the diff, we drain the gear oil out of #1 and #3. Both fluids have no pressure and have air at the top of their respective chambers, and need no bleeding at all. #1 and #3 have two sets of fill/drain plugs that you see on the diff.

Like Silicon said, #2 has no service requirement unless there was heavy failure or the lines where removed, etc. That is just hydraulic fluid than actual goes into the diff, makes it's way behind the pistons that drive the clutch paks, and pushes. It does not spin or have any friction, and as long as the reservoir for the hydraulic unit (ACD/AYC pump) is filled, should not need any bleeding or maintenance. Once you break the lines in that system, it needs to be bled.

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