Aisin 50/51SN Problem between 3th and 4th gear

voorn12 · Post by **voorn12** » 18 May 2021, 13:26

Hello,

My Auto: Volvo XC90 2.4 D5 2005year Euro3 120kw

Gearbox: Aisin Aw 50/51Sn

I have problem with my gearbox. Something not good between 3th gear and 4th gear. I added video of my problem.

This is video for my problem:

I need help. And I will wait answers.

Thank you.

Post by **SuperHerman** » 18 May 2021, 20:39

Have you inspected the B4 servo? Investigate this and see if it could be the source of your issues.

voorn12 · Post by **voorn12** » 19 May 2021, 00:26

SuperHerman wrote: ↑18 May 2021, 20:39 Have you inspected the B4 servo? Investigate this and see if it could be the source of your issues.

I was removed b4 servo. But everything looks good.

Guys please help me.

voorn12 · Post by **voorn12** » 19 May 2021, 07:09

And i have one more question.

I can drive with this car or not?

Post by **SuperHerman** » 19 May 2021, 08:04

Have you checked the level and condition of your transmission fluid? There should be a dipstick.

If you have done a drain and fill did you find any shiny metal particles? At your miles it is rather rare for a transmission hard part to fail. Worn clutch discs possible, but the color of your transmission fluid would be instructive. A drain and fill, if not done, should be performed. Changes may not be immediate, but you should notice some improvement if the transmission fluid has never been changed.

Regarding driveability - have you tried driving it using the manual mode to see if you can work around the issue?

If you have a proper scanner you can watch the transmission in action. It may be that you have a solenoid that is failing and/or is sticking or it could be the valve body has some bore wear causing excess pressure loss. Which solenoid is problematic can be deduced by looking up the solenoid function chart for the 50/51SN.

Assuming you have no tools to do a proper diagnosis, start by checking your fluid level and condition. If warranted change it. Try operating the vehicle in manual mode.

voorn12 · Post by **voorn12** » 19 May 2021, 10:30

SuperHerman wrote: ↑19 May 2021, 08:04 Have you checked the level and condition of your transmission fluid? There should be a dipstick.

If you have done a drain and fill did you find any shiny metal particles? At your miles it is rather rare for a transmission hard part to fail. Worn clutch discs possible, but the color of your transmission fluid would be instructive. A drain and fill, if not done, should be performed. Changes may not be immediate, but you should notice some improvement if the transmission fluid has never been changed.

Regarding driveability - have you tried driving it using the manual mode to see if you can work around the issue?

If you have a proper scanner you can watch the transmission in action. It may be that you have a solenoid that is failing and/or is sticking or it could be the valve body has some bore wear causing excess pressure loss. Which solenoid is problematic can be deduced by looking up the solenoid function chart for the 50/51SN.

Assuming you have no tools to do a proper diagnosis, start by checking your fluid level and condition. If warranted change it. Try operating the vehicle in manual mode.

Oil level good.
Before was very dark oil in gearbox, black colour.
Now Its new oil inside gearbox.
I flushed my gearbox two times, with gibbons method. But doesn't help.

I have VidaDice 2014D. But I'm still learning how it works.

Post by **SuperHerman** » 22 May 2021, 22:36

What happens when you shift the car manually?

Post by **Roger_850T** » 23 May 2021, 11:17

I just went through this on my V70, same transmission. You should search the site for V70 transmission issues, you'll find lots of good discussion.

To summarize though, there are a number of steps to take, keep going down the list until you fix your issue. They are:

Replace the transmission fluid, reset the counter.

Re-do the transmission adaption procedure. (Makes the Transmission Computer re-calibrate it's adaptation.)

Rebuild the valve body

Rebuild the transmission.

I just finished putting in a rebuilt valve body. I had it rebuilt by Level 10 Transmissions. https://www.levelten.com/ I'm happy with it so far, although I'm going to re-do the adaption procedure because the N-D shift is not to my liking. But I had the exact same flare and slam between 3-4 that you have, and that's now silky smooth.

I'll post links to the V70 threads if I can find them again, but meanwhile use the forum search.

Also, I believe the B4 Servo Cover issue is not applicable to you - that was just some of the early transmissions. You can confirm by checking the transmission serial number, the first three digits are the year (2 digits) and month (letter) of the transmission manufacture. The first 3 digits of the serial number on the affected transmissions will be between 01C (March 2001) and 01L (December 2001). Since your car is 2005, it should be long after the issue was fixed, unless someone replaced your transmission with an early unit.

Roger