Automatic box

[shug243]

Hi. I have an issue with my terrano. Everything changes up and down ok. But when on motorway the revs shoots up and the engine races, this happens at about 70mph. And when I back off the accelerator and sit about 60mph all is fine. I have checked the oil, no discolouration and no smell and overdrive is off. I'm thinking solonoid. Can anyone tell me how to access them to test them. Thanks

 

[jonela]

Overdrive should be 0N at all times except when using it to engine break or on long hills where box starts to search

 

[Sweety]

Take it for another blast along the road with O/D switched on to see if it happens:thumb2 also not having the O/D switched on you'll be using more fuel

 

[jonela]

Are you sure o/D is off, the light on the dash comes on when O/D is disengaged ,not when it is engaged.

 

[rustic]

First of all Welcome to the best 4x4 site for all things Nissan.
For reference, how long have you owned the vehicle, and has this just recently happened?
There are many owners of the automatics, so I'm sure you will get a solution soon.
:thumb2
Rustic

 

[shug243]

Had it over a year. And it has been happening the last couple of months. Od switch light is off. I'm sorry for the confusion

 

[briggie]

don't assume that just because the od light is off , that overdrive isn't engaged ..... next time it does it press the od button and see what happens ....also do you have the sport / power / economy switch ? .......... failing that go to quick links and download the full workshop manual for the r20 ...... the auto section has full diagrams and diagnostics for auto boxes ( AT section )

 

[shug243]

I do have the economy switch. Thanks

 

[AlexD333]

Urm sorry am I the only one or is it just me, clutch slip?

Or friction plates slipping of some kind... :nenau

 

[Barrbeast]

Urm sorry am I the only one or is it just me, clutch slip?

Or friction plates slipping of some kind... :nenau

It's an auto dude :augie

 

[AlexD333]

It's an auto dude :augie

Autos can still slip :thumb2

 

[AlexD333]

An article I may have not written myself :augie

"First, the components in your transmission may be overly worn causing them to literally slip when they are trying to make gear changes. This can cause erratic shifting, or allow your engine to over rev as it changes gears. The components in your transmission may have become worn from normal driving. As these components operate, they will wear down with normal use, but there a few ways you can help them to last a little longer. First, change your transmission fluid regularly. This will make sure there aren’t suspended particles in the high pressure fluid that can be abrasive and wear down components prematurely. Also, when your vehicle is cold, operate your engine at a lower RPM by driving slower. Automatic transmission fluid does a better job lubricating things when it is warm so keeping engine speeds to a minimum while your transmission is still cold can help it last longer. Also, if your vehicle has a performance shift option, it can accelerate wear of the shift components as it causes the transmission to operate at high pressures and make harder shifts, so only use it when necessary.

The other possible cause of your transmission feeling like its slipping would be due to low fluid pressure. If the fluid that operates the shifting mechanisms is low for some reason it can cause your transmission to not fully engage and feel like it is slipping. Low fluid pressure may be due to bad fluid pumps, clogged transmission filters or a low transmission fluid level" :thumb2

 

[Barrbeast]

Autos can still slip :thumb2

But they can't have clutch slip

 

[AlexD333]

But they can't have clutch slip

Fair enough :thumb2

 

[solarman216]

OK to throw a spanner in the works yes they can have clutch slip/band brake slip it is how an auto works, in this case I suspect the lock up clutch in the fluid flyeheel , it gets its oil feed through the main shaft and it is a known point of wear such that when very hot the oil leaks at a greater rate than can be supplied, so under high load your lock up clutch is slipping dropping back to 60 lessens the load so for now it can cope, the next stage as wear progresses is loss of reverse gear , sorry but think your box is on the way out, could be wrong of course, hope I am but I have stripped one of these boxes and seen it first hand, Rick

 

[solarman216]

Autos can still slip :thumb2

Correct Alex well done, Rick

 

[shug243]

Thank you for that. If it was wear and tear would I not smell the clutch burn. And the colour being brown or black. Which it isnt

 

[shug243]

Thanks for all ur input. The jeep has only done 90.000 miles. And there is not any smell or burnt fluid. But what I will do is give it a oil change and clean the filter. And change the solonoids if I can. All your help is greatly appreciated

 

[AlexD333]

Actually yes I a agree with the above statements too, if it was slipping bad I would have thought you'd smell it, even at 60mph?

The fluid being burnt I'm not sure if it would be with just a lack of fluid to certain plates..

What's the next step chaps? How can we further diagnose? And can the level be topped to see if symptoms disappear :nenau

 

[AlexD333]

Correct Alex well done, Rick

Doesn't happen very often