1992 Mitsubishi Pajero Auto transmission oil levels

ROB TRUSCOTT

MEMBER
1992 MITSUBISHI PAJERO
2.5L
4 CYL
TURBO
4WD
AUTOMATIC
102,000 MILES

The dipstick for the auto gearbox has two sets of marks. The lower end of the dipstick is marked - cold. The upper end of the dipstick is marked -hot. When the engine is cold, the oil level should register on the bottom level and after running for 10 miles or so, when tested with the engine running, the oil, on the gearbox dipstick should register on the upper (hot) level. However this is not happening. There is no oil showing on the dipstick at all when tested 'hot running', even though it has started off at the correct cold level. The oil in the gearbox sump seems to disappear when hot instead of registering higher up on the dipstick. So the opposite is happening to the levels.
This would seem to indicate that there is insufficient transmission oil in the gearbox, but recently on ascending a steep climb, the transmission lost power, the A/T warning light came on as the oil in the gearbox overheated. This would seem to indicate that there is too much oil ! What do you think is happening. How can I correct this.
There are no Mitsubishi agents in my area, and probably none in Zimbabwe, so I am stuck with this problem and will be very grateful for any helpful advice. I am 75 years of age and extremely short of funds !
Many Thanks

4 Replies

CARADIODOC

MECHANIC
33,871 POSTS

When you're checking the level cold, is that also with the engine running? If not, that's why it's reading higher. With the engine running, some fluid hangs up in the clutch packs and the level on the dip stick will be lower. That's the accurate reading. Be sure to shift into all the gears first, then leave it in neutral or park to check the level.

The fluid has to read higher when it's warm because it expands. If it reads low when warm, use that reading to determine if you have to add fluid. Warm is normal driving conditions.

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Wednesday, June 18th, 2014 AT 2:38 AM

ROB TRUSCOTT

MEMBER
3 POSTS

Okay - I have done that. I have checked the level -cold - with engine running, having first run the selector through all the positions. I then checked and found that the dipstick indicated - no oil.
This would seem to indicate that there is insufficient oil in the gearbox, even though under normal load the gears are changing satisfactorily.
Does it mean that when the gear box was under load up the steep climb the
overheating was due to insufficient oil? And not too much as I had thought?
Thank you so much for replying

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Wednesday, June 18th, 2014 AT 3:22 AM

CARADIODOC

MECHANIC
33,871 POSTS

It sounds like the level is low. That will cause slippage in the clutch packs, especially on a hill because the pump will suck up air instead of fluid. Air can be compressed so there won't be sufficient fluid pressure to keep the clutch packs engaged solidly. The resulting slippage will make the engine speed up while the vehicle will not, and the clutch plates will get very hot. That can damage them very quickly.

While low fluid level will cause problems first on hills, over-filling the transmission will cause problems at high speeds. The fluid can reach the rotating parts and get whipped around. That whips air into the fluid, which, again, can be compressed. That is less common but it is why we need to check the level accurately so neither condition causes slippage of the clutch plates.

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Thursday, June 19th, 2014 AT 12:33 AM

ROB TRUSCOTT

MEMBER
3 POSTS

Thank you very much for your good advice. The oil levels are now correct after having checked cold with engine running and adjusted accordingly. The dip stick is now showing correctly in the hot position with the engine running after a 20 kilometer drive.
Many, many thanks
Rob.

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Thursday, June 19th, 2014 AT 2:55 AM