potential tranny issue

628 Views 7 Replies 5 Participants Last post by robs, Oct 5, 2011

robs

Discussion Starter · Jun 9, 2011

I think my transmission is doing something weird. FYI this is my wifes vehicle that I am now driving so I can't really tell what should be considered normal. She's pretty useless when it comes to seeing if the feel has changed

Anyway when cruising above 50MPH (>2K rpm) or so I let my foot off of the accelerate to coast. The rpms drop to idle and after the truck slows done a bit, the rpms move back up to 1800 . it doesn't do this all of the time just every once in a while.

Switching gears is very smooth and there is no noise. Fluid is at the correct level and doesn't look bad. Was thinking about a filter/fluid change but i hear this can cause more problems than not. Anything else I should check?

02 Rodeo Sport 3.2l V6

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CatFuzz

· #2 · Jun 9, 2011

This sounds normal to me. When the RPM's jump up, it's downshifting to the next lower gear.

99 Rodeo, 3.2L Auto, Manual hubs, "Trooper lift".

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ABS and traction control are for people that don't know how to drive.

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Ramblin Fever

· #3 · Jun 10, 2011

Agreed.....sounds normal to me too.

That said, how many miles are on the truck? Has the fluid/filter ever been changed?

It never hurts to change the fluid/filter, just do NOT do a flush, and do not try to change too much ATF at one time - i.e. don't do too many drain/refills too close together if the fluid's been neglected.

I change my ATF every 15k miles with a drain/refill procedure; I have 200k on one rodeo and 350k on the other rodeo - both original automatics.

Make SURE to use only Dex 3 if at all possible; these transmissions don't care too much for the new Dex 6

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robs

Discussion Starter · #4 · Jun 10, 2011

Thanks for the responses. All of the vehicles I've ever owned are manual. I only drive my wifes Pilot here and there on the weekend. I need to start paying more attention to it. As funny as it sounds, I don't have a real good background on how these transmissions should behave

Truck has 105K. My wife remembers taking it into NTB for a fluid top off a few years back when the 1-2 shift was very rough. Don't know if they replaced the filter and/or did partial.

I think I will go ahead and drop the pan and replace the filter. Given the mileage how much metal on the magnet should be considered normal? Would the presence of any shaving signal a problem?

Thanks!

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robs

Discussion Starter · #5 · Jun 16, 2011

Bear with me here guys.. I still think something is not right. Another symptom is that when just cruising above 50 or so the truck is in 4th. If I press the accelerator hard, the tranny down shift into 3rd and then immediately shifts back into 4th so I don't get the pickup I need. It feels like it's having a problem with the 3rd to 4th transition. The change is smooth but just not expected. Are there any sensors that control these shift points or something else I should look into.

I know if I take it into a mechanic and tell them this, they will immediately want to rebuild/replace. I'm hoping to have as much info as possible as I don't know much about these systems

Thanks

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Mediamonkey11

· #6 · Jun 16, 2011

robs said:
Bear with me here guys.. I still think something is not right. Another symptom is that when just cruising above 50 or so the truck is in 4th. If I press the accelerator hard, the tranny down shift into 3rd and then immediately shifts back into 4th so I don't get the pickup I need. It feels like it's having a problem with the 3rd to 4th transition. The change is smooth but just not expected. Are there any sensors that control these shift points or something else I should look into.

I know if I take it into a mechanic and tell them this, they will immediately want to rebuild/replace. I'm hoping to have as much info as possible as I don't know much about these systems

Thanks

See what happens if you have it in power mode when you do this, sounds like it's just eager to be in the higher gear so as to save fuel. If you floor it, does it stay in the gear? I mean floor it....

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SurferJoe

· #7 · Jun 16, 2011

OK - taking you foot off the throttle and it going into a 'coasting mode' is wrong. There is no engine braking that way and that's not the way it's supposed to work.

Once a transmission is settled into OD or even Manual Drive and the TCC comes on, then you are essentially locked up in a direct-to-the-wheels-from-the-engine mode.

If you didn't have TCC hooked up, then of course you'd go into freewheel and that's not the way it's supposed to work.

FYI: ANY manually selected position will apply both the friction pack/device for that gear and also at the same time apply the braking band or clutchpack. That's the way it's supposed to work.

IF the unit is making upshifts to whatever range you have selected and you suddenly take your foot out of the throttle before all the called-for shifts are accomplished, then the unit is commanded to (either) go directly to the upper gear selected and also at the same time apply the braking frictions for that gear..........

..........and at the same time to 'burp' the TCC so the shifting shock is not going to happen .....

.............OR it will go into freewheel and just gently apply the upper gear that's selected as soon as the correct for that gear roadspeed is achieved.

It's a little complicated - but if you are settled into the chosen gear and it's anything but LOW/ First or Reverse - then the TCC will lock the convertor and you'll get engine braking while the throttle is released.

Anything less is wrong and indicates a bevy of possible reasons as to WHY.

1) TCC sprag is blown - or rolled over
2) Forward sprag is blown - or rolled over.
3) TCC qualifiers are not met
4) TCC annular seals are blown or leaking badly.

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robs

Discussion Starter · #8 · Oct 5, 2011

I know this is an older post but just wanted to close it properly. Learning more about how these transmissions work I realized that when this occurs the lockup clutch is not engaged so what I'm getting is normal. When the lockup clutch does finally engage I get full engine breaking as expected. I tested this by using advice on another post and lightly pressing/holding the brake pedal to release the lockup clutch. When the tcc is released the rpms flare up a couple hundred.

Basically what I am feeling is not a gear change but the lockup clutch engaging and disengaging. The problem is between the steering wheel and the drivers seat. Hardest problem there is to fix.

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