Tranny's blues from Mexico

[geezerpower]

I am sorry for reposting this but I am new to the forum. I posted this same message in the new members forum but I believe that this is the right place to do it. Again, my apologies for reposting.

Here is my story:

I’ve just bought a 95 Pathfinder 4x4 auto.

When I checked the tranny the oil was new, the dealer told me that it was recently serviced at a Nissan dealer.

Unfortunately there was no warranty since I bought it “as is”, I took her home, about 65 miles away into Mexico, on my way home at about 70 mph there was a rough down shift from OD to direct and the tranny got stuck.

I took it to my mechanic and when he opened it, he told me that it was clear that the tranny had been recently rebuilt, lots of new parts… even a new turbine, but the gears of the planetary were gone. He replaced all the damaged parts with original Nissan parts, and, based on my experience with other trannies he added an aftermarket oversized transcooler.

It worked like a charm for a day but again, less than 50 miles away, while I was still testing the tranny, exactly the same failure, going up in a gentle slope at about 70mph the same rough downshift and the tranny got stuck in 3rd gear.

I helped the mechanic to remove the tranny and I wanted to see with my own eyes the interior, everything looked fine, the clutch was new…etc, but the gears of the planetary were toast.

I am desolated; I haven’t been able to drive the car for a whole day since I bought it!!

My question is: What can cause that kind of failure? At first it looked like if the tranny went into fail-safe mode but there was substantial damage to the gears and no indications in the dashboard (no blinking). Unfortunately I have no Nissan dealer in town to take the car, so I must make do with local mechanics.

I would appreciate it any suggestions you could give me for the mechanics to look for.

 

:help:

[FLApathy]

maybe the first time it was rebiult they forgot to put something back in like a stop and it let something slip off, im not sure this is the first ive ever heard of something like this

 

 

try gettinga picture of the tranny, like a parts sheet and mark off all the parts, kinda long hard process but hey

Edited July 23, 2005 by FLApathy

[jj big shoe]

Waaay outside chance, but cheap & easy:

Check the ECU codes? Maybe some bad sensor or something will pop up.

Yo no sais, amigo. Buena suerte.

[FLApathy]

yeah excatly jj thats what was thinking but for some reason i typed the other thing i typed and not what you typed

[lgranch]

I can not think of anything that the computer could do that would toast the gears on the planetary!!!. The ability to down shift is designed into the tranny, even from 4000rpm. The engine may have a minor problem but the planetary should hold.

 

This is also not a heat related issue. There is no way the tranny fuild can breakdown in less than 100 miles and cause this gear failure.

 

Right now there are only two things that I can think of. 1) is a complete lubrication failure. 2) Mechanical mis-assembly on rebuild.

 

At this point I do not think that I would spend any money on rebuilding the tranny in the Pathy. There is some form of mechanical damage that has been done during the first rebuild. I would replace the tranny with a used unit. Have your mechanic look the used unit over for signs of wear and replace the soft parts.

 

I am making this statement thinking that this is happening in 2 wheel drive based on the speed you are reporting. If this is 4 wheel drive then there are obvious causes.

[geezerpower]

Thank You guys for the ideas.

Right now, my mechanic is looking for a decent salvaged tranny, he will replace all the soft parts with the ones of the failed trannies (after all there was no damage to the clutch assemblage and it was new). Once the car can be moved, we will take it to a specialized garage to run a complete diagnostic of the electronic components.

Igranch, I think your diagnostic is accurate (and yes I was driving in 2wd, I haven't had the opportunity to test the 4wd yet), most likely it was your first option, lubrication failure, since it is not likely to have the same mis-assembly twice. But the question remains, how come that one moment the tranny was working properly, shifting up and down very gently at very reasonable RPMs and all of a sudden there was that rough downshift it went from 1200 to something like 3000. what do you think we should look into? specially since we will have to use some parts like the box of valves or the pump from the old one.

If you don't mind, I will keep the thread open and (eventually) I will be able to share with you (hopefully) the end of this saga.

Again, thank you.

[lgranch]

Yes please report back. One of my pet peeves on this forum, is people do not report back when they find a solution. Yes some do, but others, es-specially with unusual problems do not.

 

A complete lubication failure could be a pump problem, or more likely a pump drive problem. A shaft is worn or something and the gears for the pump fail to contact when under load. So when a mechanic looks at in the static mode, he would have to recognise the wear as serious. Because he only will see enverything work like it should due to no load. A transmission dyno test would detect this problem. But who does tranny dyno tests..... a few.

[geezerpower]

Hi guys:

I am posting what is likely the end of this saga.

Since my mechanic gave me a warranty on his job and his pride was hurt for the failure of the repair, he took on himself to look into junk yards until he found a very good tranny and was able to purchase it for me in $200. He checked all the tolerances based on the CD of the Electronic Service Manual for the Pathy that I bought on e-bay and with my help and his son’s we put the new-salvaged tranny and did not charge me a penny for the job. Boy!! Talk about honor!!

I have only been able to test the tranny for a day now, I took my Pathy to a 60 mile drive at high speed and everything looks fine so I am confident that this time we did it right.

With my mechanic we took apart the old pump and everything was all right, the whole thing appeared to be new. javascript:emoticon('')

smilieThe mystery of the two consecutive failures may lie in a hair line crack almost impossible to see with the naked eye that we found inside the old case, tjavascript:emoticon(':idea:')

smiliehe theory that we developed is that when the fluid was cold and more viscose there was little or no leakage and enough pressure inside an ATF duct to keep everything going, when it reached certain temperature and the ATF lost density, it started to leak from the duct into the interior of the case and the pressure went down. The two consecutive failures could be explained because he used the old case in the rebuilding because it looked so good (the external metal was still shiny like if it was brand new).

Anyway, hopefully from now on I will be able to tell you stories of my travels in my Pathy through Baja. Thank you for your help.

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smilie

[88pathoffroad]

Wow.....just...wow. Thanks for the information, geezerpower.

[lgranch]

Excellent !!1 . This is exactly the type of informational feedback that I like to see. I would never had suspected a cracked casting as a portionof this type of failure.. Thanks again for the reply

[Vsicks Pathy]

It's true. We learn something new every day.