Unusual Automatic Transmission Symptoms Options

[realthumbz]

Hi guys

I'm having some issues with my recently acquired 1994 NJ 3.0 (6G72) Paj's auto transmission. By way of background, i've given it the mother of all services, so mechanically it's in excellent shape except for the tranny.....

Ordinarily the car performs very well. From time to time however I'll be in 'drive' and driving along at suburban speeds (40-60 kph) and push the accellerator and find the engine RPM increases, but the car's road speed does not, ie, the transmission feels as though it's slipping.

Accellerating harder will provide a little bit of 'driving force', however 'slipping' is the best way of describing what's happening, as I look for somewhere safe to pull over.

From the side of the road I can select reverse (which engages immediately it's selected), however when I select 'drive' again, there is no feeling of drive 'engaging', however if I then push/feather the accellerator a little, the transmission does eventually start to provide some weak 'driving force', with some continued slip, then after a few more seconds it seems to engage and normal drive seems to return. At this point I can even accellerate away with full power and there is no longer any slip evident at all!???!

After the first time this happened, I resolved to service and safely flush the transmission by a very very reputable transmission shop (I've known these guys for 10 years). These symptoms did not return for these guys, and they didn't return for several days, however as I was returning home from work this evening, the symptoms as described above returned.

There is plenty of spotlessly clean, rose colored oil in the tranny (first thing I checked.... yes... with the motor running), and the service guys said that while the old oil was dark, there was no metalic residue in the pan.

Yes it seems worse when the car is hot, and these symptoms have never occurred when the engine is cold. The engine's thermostat is a brand new aftermarket unit, and the guage always sits exactly on the half way mark.

Also, there are no nasty noises coming from the tranny, however when the engine is at operating temperature and I select 'drive', there is always a very slight delay before it engages (I know this is not ideal).

So.... please guys, feel my pain, and those of your with experience / knowledge in this area I'd very much appreciate it if you can shed some light on this...
cheers guys

[Aldee]

hmmmmm...when its hot it slips....it sounds like the oil cooler isn't working properly. there are two hoses the connects from the radiator to the tranny...that might be the culprit, the hoses might be blocked. if that doesn't solve the problem then the worse would be your torque converter.

[realthumbz]

Thanks for your reply Aldee

I know those hoses are in good shape and that there are no blockages as I've removed the radiator recently to replace the harmonic balancer ($$ouch$$) water pump / cam belt and all associated oil seals.... plus the guys that did the transmission flush used these hoses to do the transmission flush (after they removed the pan to inspect for sediment etc).

The thing that seems to stump even the most experienced guys i've spoken with about it, is that after the transmission 'slips' for a few seconds, when full drive returns there is no trace of any slippage!

With absolutely no personal experience with the engineering side of auto transmissions, I have an indulgent suspicion it may be something to do with the overdrive gizzmo.....

anyone else have any suggestions??

[Benckj]

Just a couple of things you may not have thought of.

Tranny fluid. The Mitsis take a special type which I belive is only avaialble from the dealer. It is like three times the prices so even repuabale tranny shops don't buy and put is a similiar product. It doesn't work and you will have problems with your torque converter slipping.

Electrical connectors. I had numerous problems with my tranny that was found to be intermittant problems with multiple connectore leading to/fro the ECU. Take some time to remove and clean (with emery cloth and contact cleaner) each connector. This is a common problem that many mechanics never check.

Have you looked at the fault codes? Tranny over temp or others may come up if you are having problems. Download the codes and do some homework.

There is a previous thread on the overdrive and problems with the double sensor and aucuator from memery. Try searching to see if it is of some help.
Jim

[off-roader]

I would guess they put in the wrong tranny fluid as well. Mitsu auto trannys are pretty reliable.

As has been said, it does use special fluid and the wrong fluid will destroy the internals of the tranny.

[realthumbz]

Thanks Benckj and off-roader.

I have spoken at length with a number of people about the type of ATF that goes into Mitsubishi transmissions. A number of different auto shops have told a consistent story with regard to the transmission in my '94 Pajero/Montero. That being that its a transmission that was used in volvos, toyota hiaces and cressidas and others besides. For clarity, my engine is the 3 litre 6G72. There is evidently more concern about the type of fluid that goes into the larger transmission that mated up to the later 3.5 litre V6s.

I did have a look for electrical connectors that plug into the transmission but found very little. I will have it up on ramps again this weekend, so will give it a jetwash and have another look.

I have never 'checked' error codes, so it's probably time I had a crack at this. I'll try to search for some instructions on how to do this and hopefully some sort of key for interpreting them. If you guys have a link to this type of info at hand it'd be great if you could steer me in the right direction.

thanks very much again for your suggestions.

[BavarianSigma]

Thanks Benckj and off-roader.

I have spoken at length with a number of people about the type of ATF that goes into Mitsubishi transmissions. A number of different auto shops have told a consistent story with regard to the transmission in my '94 Pajero/Montero. That being that its a transmission that was used in volvos, toyota hiaces and cressidas and others besides. For clarity, my engine is the 3 litre 6G72. There is evidently more concern about the type of fluid that goes into the larger transmission that mated up to the later 3.5 litre V6s.

I did have a look for electrical connectors that plug into the transmission but found very little. I will have it up on ramps again this weekend, so will give it a jetwash and have another look.

I have never 'checked' error codes, so it's probably time I had a crack at this. I'll try to search for some instructions on how to do this and hopefully some sort of key for interpreting them. If you guys have a link to this type of info at hand it'd be great if you could steer me in the right direction.

thanks very much again for your suggestions.

G'day to downunder!

some weeks ago i bought a used Sigma with basically the same engine and transmission. After a while of driving around i started to observe the exactly same problems as you stated above.

After some sleepless nights i developed a theory: the metal dust swimming in the transmission oil gets attracted by the magnetic field inside the solenoid valves (electronic pressure reducer). Finally the pistons gets clogged and they get an additional friction, so they fail to operate smoothly.

So far my theory - next week i will screw the solenoids, and then i can prove or discard my theory...

BTW, do you have some -hopefully good news- from your transmission?

[manybrews]

the transmission in your montero is built by aisin-warner. They are owned by toyota, and now are the largest tranmission manufacturer on the planet.
they are also nearly indestructible. Not only used in mitsus, toyota, and volvos, but jeeps, kias, suzukis, etc.etc.

youre explanation is a tough one. In 18 years of working for mitsu, Ive seen exactly ONE of those need to be rebuilt.

if its similar to Americas monteros (and im sure it is), the transmission is electronic, but only partially. The electronics tell it when to shift, but do not alter pressure. For that, there is still a throttle cable heading to the transmission from the throttle itself.
I would check that. check it at the throttle and see if the outer housing has torn from its mount. Although honestly, even if it has, it shouldnt cause a total slipping condition.

unfortunatly, a guess from me is that you are suffering a mechanical failure. You should have the pan removed and checked for debris.

[BavarianSigma]

I removed the pan, removed the valve plate. Cleaned it carefully. Checked and cleaned the solenoids. But there was no indication this parts could have been the source of trouble.

Finally i attached a LED to the DCCSV (damper clutch control solenoid valve) - and voila: the transmission computer switched on and off, making me feel something is slipping from time to time. My car's predecesasor has screwed the throttle position sensor. Now, having adjusted the TPS, the problem has gone.

Greetings...

[KiT TeUnG 2549]

More so , Aisin-AW (not Aisin Warner) made transmissions for the Pajero , as well Mitsubishi also made its own transmission on most Pajero's and Tritons and RWD vehicle models (not Montero's which were exported to the United States) which unlike the Aisin-AW models which for that year in sum used a detent cable , the Mitsubishi variants were fully electronic and not partially electronic like the Aisin model.