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Excessive Tranny Problems


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Hey all... I had the clutches and gears changed in my tranny 2 weeks ago. The mech. assured me everything was fine, but sunday morning while driving, the tranny geared down to 2nd gear as soon as I reached 120km/h... I managed to drive home stuck on 2nd gear and later when I started again, it worked a bit better, but I'm only getting 1st, 2nd and 3rd.... no 4th and no reverse... does anyone know if this is a mechanical or electrical prob ? And should I do any more repairs or change it entirely ? Also, I'm in Trinidad and am having difficulty finding another tranny....

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Sounds like it went into "limp mode". When you shut off the ignition and turn it back on again, it will reset the tranny computer and should work properly again. The Nissan auto transmission is entirely controlled by the tranny computer. From the sounds of it, someone at the mechanic's shop did something wrong. If they simply reused the stock tranny cooler, it may be clogged. That's a very common problem with Pathfinders. It's easily fixed by using an aftermarket external transmission fluid cooler and completely bypassing the stock cooler inside the radiator.

 

By the way, it's not "4th gear" on an auto...it's simply overdrive. The torque convertor locks up to provide direct drive at higher speeds.

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88 you're right about 4th being overdrive in an auto - but the Nissan automatic IS a 4 speed - it just happens to have an over drive ratio for the 4th gear (unlike bmw 5 spds that have a 1:1 final drive ratio that ISN'T overdrive)... it also is a lock-up

 

not to be a pain in the behind, but felt like clarifying...

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I had the clutches and gears changed in my tranny

autos dont have clutches'

 

anyways sounds like the shop you took it to did something wrong, take it back to them and make them fix it at there expense

 

 

btw: no reverse is a good sign of a worn auto tranny

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Do too. The clutches(multiple) in an auto go inside the sprag/drum assembly and have steel friction discs inbetween them. There are anywhere from 4 to 6 clutch discs inside an auto, depending on manufacturer, construction and application. :)

 

http://auto.howstuffworks.com/automatic-transmission11.htm

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Hey guys... thanks a lot for all the response... I already have an external cooler... the van came with it. I spoke to the mech. and he said he eventually did get reverse, but only for a moment. I'm wondering if it could be an electrical problem, since basically everything mechanical was already changed... :confused:

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I'm sure this is probably not it, but since I don't know how competent your mechanic is, I'm going to put my neck out on the chopping block and ask if the cable was adjusted on the shifter. Sometimes the more bvious problems are the hardest to find. :hide:

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Good question denisb... I would like to think that he did. But one can never be sure unless it's done by oneself... Although he did assure me that everything checked out fine....

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Very interesting!!!!

So there goes who evers theory that disconnecting the lock up would over heat the trans!!!

Not likely!!

Ok, I'll say it again, pathy auto trannies are not designed to run unlocked for a long perioid of time. Anytime the torque convertor is not locked up it will be slipping and therefore generating heat from fluid friction.

 

I never said it will destroy your tranny, but it will generate extra heat and wear (especially on your ATF), and I would guess if you are running it hard offroad you would have a much greater chance of overheating your tranny...

 

If you don't believe me, see here:

http://65.166.200.170/ubbthreads/showflat....true#Post315854

 

and here:

 

http://65.166.200.170/ubbthreads/showflat....true#Post256855

 

and here:

 

http://65.166.200.170/ubbthreads/showflat....true#Post312257

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I figured it was temp sensitive since every Pathfinder I've driven doesn't shift into lock-up when it's -30 unless you've driven around A LOT. When I first got my car I counted 5 gear changes...one from about 0-15, one from 15-25, one from 25-35, one from 35-45 and then really low one (I'm guessing lock up) from 45+. I always was interested in why the 4spd seemed like a 5spd. Anyway, I don't know anything about these trannies except I have noticed they tend to overheat A LOT when driving down newly graveled roads and into a wind. Too much resistance I guess. And, they also seem to lose reverse at about 125k or so. At least the 3 my parents and I have owned and the numerous ones people we know have owned. But I bet 88offroad doesn't have to worry about lock up since I think he's the one with the picture with his reverse lights on. :P Hey, at least I think I'm funny.

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Well guys... I bought another tranny today... it's in the shop now, so I hope this solves my problems. Again, thanks for all the views and comments... will keep you all posted of the outcome and hopeful progress... Guess no more turtle watching for a while... :lol:

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