JackzRunner

Hi all,
First of all what a great forum, it seems very helpful. Now for my problem: I have a 95 4runner V6 4x4 with auto. Since I have had it since 2000, I think there seems to be some auto tranny clutch slippage. For example, in all the gears from 1st to 4th (not overdrive) there is slippage but it “locks” in 5th gear/overdrive. By slippage I don’t mean the engine revs and it doesn’t go at all, it goes normally but there seems to be a 500-600 RPM slippage since gears 1-4 never “lock” like overdrive does. And by lock I mean that when a transmission upshifts, the RPM’s decline and lock there. So, when you step on the gas the RPM’s go back up slowly again until it upshifts again. But with the 4runner, even after it upshifts, you can press the gas and it will go up another 600 or even 1000 RPM without downshifting. It seems the engine revs faster and then the transmission slips until it “catches up”. I’m not sure if this is making sense. But it had always been this way and I would not have thought it was a problem but when I went to change my transmission fluid, it was dark as motor oil even though it had only been about a year since I last changed it and even then it was as dark as oil. And I have never towed anything or done anything crazy with the transmission, just normal driving. Oh and it shifts smooth considering it has 130K.

Also, I know this slippage is not mechanical, since I can hit the O/D switch and turn it off thus making the tranny “lock” in 4th gear. This way once I hit 35MPH, it goes into 4th gear and the RPM’s drop down to 2,000. And it seems to make a lot more power this way. For example, there’s this hill I pass by everyday and it always revs at 2500 and pulls at 30 MPH going uphill. But when I turn off the O/D and lock into 4th gear, it now easily goes up the same hill with the SAME amount of throttle at only 2000 RPM and going 40 MPH and still accelerating! My 3.slow all of a sudden becomes a 3.fast (almost on par with my Infiniti I30).

So my question is: is this normal? And if it is, why does it slip when it can make so much more power when it doesn’t? And no I am not “lugging” the engine. And what about you guys with the manual? What are your RPM’s on certain speeds? Sorry for the long write up but I thought I’d make it worthwhile as this is my first real post.

Thanks
JackzRunner

regularguy412

The A340 series of transmissions have only 4 forward gears : Low, 2nd, 3rd and O/D. The transmission also has a locking torque converter. This is what you may be calling '5th' gear. When you press the O/D Off switch, you lock the tranny from going into O/D. Howerver, it is still possible for the converter to lock up , under the right operating conditions ( dependent upon tranny fluid temp and engine load).

It would take pages of posting to describe all the variable situations, conditions and scenarios that the transmission 'could' be in , since the system is designed to try and keep the engine in its optimum operating range regardless of hills, wind resistance or vehicle loads.

The one thing I got from your posting is that you feel that -- when the tranny upshifts , the shift does not feel firm or positive,, it's like it's sliding into the next gear, not 'dropping' into it. The A340 is a hydraulically controlled transmission. It uses solenoids in the valve body to upshift or downshift between gears,, and to lock or unlock the torque converter.

The 'sloppy' shifting can be due to : weak solenoids, gummed valves attachted to the solenoids or low hydraulic pressure.

Obviously, it is very important to have the right amount of fluid in the tranny. Check the fluid level on level ground, engine warm to operating temperature , engine idling and in neutral (parking brake set). Too low fluid will cause low pressure,, too high fluid causes foaming and can also cause low pressure or overheating.

If the fluid is OK, you will likely have to test the solenoids for proper actuation, and also check the valves that the solenoids push or pull for sticking. If all that is OK, you likely have hydraulic pressure loss. This could be due to worn seals inside the transmission or the pump losing efficiency.

You can check the solenoids and the valve body with the tranny still in the 4Runner. To fix seals or the pump, you'll have to pull the tranny and transfer case.

MIke in AR