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95 pathfinder/terrano2/mistral transmission


Dino3310
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Hi Guys

Ive got the 95 td27 with auto transmission... i think my tranni just died?

about 2 months ago i did a fluid flush after it stuttered a bit in o/d, the fluid that came out was looking a off being a bit brown instead of reddish, after the flush its been running great ive done around 2000klms and its been running as it should but today i went for a 20 minute drive into town all was well but when i left town the o/d wouldnt work and 1st wouldnt work so im guessing that was limp mode, after arriving home i checked fluid levels(all good) let it cool down then went up the road a little and now the torque converta aint working too as i have to flick her into neutral to stop her stalling at near stand still, when i managed to get her back up my drive i drained a couple liters of oil to see what she looked like figure it should still be a reasonable color since been new oil 2 months ago but no it was a dark chocolate brown in color!!!!

 

does this sound like a stuffed transmission?

 

cheers

Deano

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Sounds pretty stuffed to me. Dark brown fluid says that trans got hot. Unless you've been towing fully-loaded tractor trailers up mountain passes since you changed the fluid, I'd guess something failed inside the box and caused it to overheat; then, as the fluid degraded, the clutches started coming apart and the debris started jamming up passages or solenoids.

 

There's a diagnostic on US models where the light in the "power mode" switch flashes to tell you what the TCU thinks is wrong with the trans. Might be worth checking, though it sounds like it's probably too late in this case.

 

Make sure you flush the old fluid and crud out of the cooler lines and replace the cooler before replacing the trans. You don't want the gunk the dying trans spat up getting into a fresh trans.

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cheers mate

yeah i havent done any towing, just easy driving mainly flat roads and just cruising, no heavy loading.

i just did the 'self diagnostic" procedure as per in the manual, its has a long light on the 7th flicker which the manual says its the 'Torque converter clutch valve is short circuited or disconnected'

im pretty sure its a bit more than just that LOL

 

i'll start looking around for a low mile 2nd hand one, ive looked at fully reconed ones but there cost is ridiculous

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I would need to look and see how these are arranged, but on most Auto transmissions there are shift solenoids. One solenoid will work two gears. 1st and od might be the two that are paired on a solenoid. You may have a failed solenoid. There should be ports to hook up pressure gauges, then you can see if the solenoid is shifting back and forth.

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In hydraulic systems, if the fluid is ported through a small opening with a sharp edge under high pressure, it will heat the oil, sometimes to the point of burning it. I have seen this when the lands of spool valves don't shift far enough to clear the oil passage.

 

Since it was stuttering in OD, I wonder if the solenoid wasn't shifting fully, causing the burning. A bit of crud can cause the solenoid to stick, or if it is an electronic tranny, a faulty solenoid coil.

 

Remember, this is all speculation on my part based off what I know of Ford transmissions, heavy equipment, and industrial hydraulic systems. It needs verification by the Nissan manual and some testing.

Edited by Citron
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I don't know nearly as much as I should about how these slushboxes work, but I have heard of bad solenoids in general causing overheating. The torque converter heats the fluid whenever the lockup clutch isn't engaged, so if the lockup clutch stays open all the time, I'd expect that to dump some extra heat. (Enough heat to roast fluid in that short of a time? No idea.) I'd expect it to drive reasonably close to normal without lockup (you might not notice on flat ground if you don't watch your tach) and I don't think a failed lockup solenoid would trigger limp mode, either--a guy on here cut in a switch on his so he could kick it on/off at will and I don't remember his computer pitching any fits. (Limp mode holds it in third, BTW.)

 

A friend of mine got lucky with the slipping trans in his S10. He did some research, opened it up, and found a broken accumulator spring. He replaced a few small parts and it's been fine since. But the key there was that he caught it early. Even if yours started as a bad solenoid, the failure of first and overdrive, followed by the torque converter locking up, sounds like the damage has spread.

 

Definitely do your research. Take a good look at the fluid you drained out. Check it for chunks. If it's burned but clean otherwise, maybe it's worth tearing into, at least enough to drop the pan and see what's stuck to the magnet inside.

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The solenoids I was referring to are for shifting. Once you drop the pan you can usually find some bolts to drop the valve body and the shift solenoids are in there. At least on the stuff I am familiar with.

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I'm +1 for digging into the thing. Burned oil can be replaced and unless your slipping, you've still got clutch material left. Your issue might be simple enough with replacing the lockup clutch solenoid and/or shift solenoids.

 

My experience with a toasted trans is that they are violent and loud. Grinding snapping and loud popping/banging jerking slamming...

 

I'd drop the pan and see what is in there.

 

 

Sent from my iPhone using Tapatalk

Edited by onespiritbrain
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  • 2 weeks later...

went into town heading to my mates workshop..... tranny ran fine, after half an hour or so driving it played up a little. i figured it must have been the oil from the change i did as i didnt have any problems before that or maybe there was a bit or crud in the system blocking a gallery, so i went straight to the auto store and brought some dexron3 oil, i got enough to fill it twice as i wanted to flush all of the old @!*% out. got home and flushed it till the ugly oil was gone and only the good stuff coming out.

did a short drive to check level and the a 3hour drive and shes running sweet, check dipstick oil level good and oil color perfect so im very happy with the results and learnt a lesson on using correct spec oils.

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Nice! Definitely keep a close eye on it moving forward but hopefully your flush was all it needed. What did you fill it with before?

i didnt know at first as a mate gave me a 20litre container of the stuff he uses at his job, been in my garage for the last 6months.

when i realized it could be the oil i got a hold of him he said it was 'Castrol super Torque'

so far so good, dipstick shows clean oil, truck running sweet...... well until the alternator decided to die yesterday..... it never ends with this thing, must be at that age where everything needs replacing around the motor lol

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power steering..................................

making a prick of a noise, graunch/crunching sound at around 1500-2000 rpm then disappears, it has been building for a while. there No whining or humming like the classic air bubble its a metallic grinding sound like something spinning and catching.

anyway i pulled it apart as i suspected one of the vanes had come out and was grinding around, i was wrong it looks tidy and everything in its place.

where im stuck at is, is there a bearing or a bush at the front and how the hell does the front pulley nut come of, is it one of those reverse threads and ive been trying to force it tighter or do i need to give it more muscle. the front bush/bearing seems to be my last port of call to check as everything else seems to be fine.

 

anyone know where a schematic diagram of the pump is online

 

cheers

Dino

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And you're sure it's the PS?

well mate after tonight i think i can say i totally misdiagnosed this one.

i put the pump back together and back in the truck started her up and it made the noise again soooo i took the belt of again and started her up only this time i hopped out and revved her from the throttle linkage on the injector pump...... thats when i noticed the alternator belt and pulleys weren't turning properly, to the point i could stop it altogether by stopping the fan by hand {not recommended} so i then took the alternator belt of and found i could turn the crank pulley by hand and very easily. so im thinking that the pulley key has sheared of which might have been started by the ac unit seizing a couple years back and it gradually wore out what was left...... i think that makes sense, ill find out tomorrow when i get some time to get into it.

on a positive note; i got to find out how the internals of the PS pump work and look like :-)

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