Gen III vibration

[JAVYPRO]

Hi Guys,
My wife's GEN III, 2001 XLS, has developed this vibration as if you are driving on pavers BUT the crazy thing is that it only does it in 4th gear. You can be driving normaly no vibration at low speeds and all of a sudden bbbrrrrrr like driving on pavers, now when it does that take your foot off the gas pedal and it goes away OR downshift to 3rd and it will ot vibrate.

I am thinking the culprit might be an engine support or transmission support. So I just checked the transmission support and it is fine so it coult be one of the engine mounts. The one on the passenger side is easy to check but the driver is not.

Have any of you had this issue? what was it?the mount?

Thanks,
Javy

 

[Inyo_man]

When was the last time you swapped out the transmission fluid?
If it has been a while, or you never have...then I'd suggest you perform a fluid flush on the transmission.
There are good threads on this, be sure to do a complete flush, not just a drain and fill.

I have installed new motor mounts...mine were completely broken in half. Although it did not produce the type of vibration that you are suggesting.
When you crawl under the rig to examine the mounts, look with a flashlight and see if there is a visible crack/line in the rubber. If so, you likely have
broken mounts. Installing new mounts was a few hour project.

 

[SONICMASD]

What RPM does it do it in? Gen3s are notorious for doing it around 2000-2500rpm. If so you can try removing the rubber counter weight by the transmission and/or replacing the transmission cross member bushings.

https://www2.pajeroclub.com.au/forum/showthread.php?t=54443

 

[coffeegoat]

I did the cross member bushing within the past year, the instructions/pictures are on my build (in signature). In my case it was related more to speed than RPM, and new tires fixed it, but the bushings are cheap and take like 15 minutes to swap. The counter weight is also quick to remove, but I haven't tried that one.

 

[sidecardog]

I am having the same issue. Just started recentlly. Does it at low RPMs in 5th gear, like when I'm just starting to climb a gradual hill and the engine hasn't shifted down into 4th yet. If I give it a little gas and get it to shift, the vibration goes away. I'm due for a fluid exchange so I'll do that and see what happens.

 

[Michael Brown]

+1 to Inyo's comment on the transmission fluid.

My 2001 did exactly this while I was in college. Especially around 40-45mph going uphill. Less throttle or more throttle with downshifting would stop the vibration.

It is actually the torque converter in the transmission shuddering. This happens over time when the fluid degrades. The shop we were using would performed several fluid flushes, which only stopped the issue temporarily. It would always return because they would put the old fluid back in.
After they messed up the vacuum hoses, I stopped using them entirely. After college, I completely changed the fluid to fresh, new SP-III @ 160k miles. There is an easy procedure for this using the internal pump to remove/flush fluid. It takes ~10qts doing this method.
With new fluid, I never had the issue come back. Truck ran better than ever for another 15k miles until I hit a patch of ice on the highway.

 

[JAVYPRO]

Michael,
That is awesome encouragement. I need to get this done but how or what is the procedure to remove all the fluid? to be honest, I do not trust these "flush" jobs at the regular oil change chain stores and the dealer are, well you know, way overpriced.

Thanks,
Javy

 

[Inyo_man]

I would not recommend taking the rig to a shop for this procedure. It is quite simple...having someone to help does make it go faster.
If you are so inclined, I'd also suggest changing the filter in the trans. pan. Although this does add another step in the process, if it's never been changed, you might consider it.

https://www2.pajeroclub.com.au/forum/showthread.php?t=15879

Cheers

 

[coffeegoat]

I agree with Inyo man - do this at home, on the side of the street, whatever. With another person it's really about a 15 minute job to do a full fluid flush, and if you buy SPIII on Rock Auto (PN: AISIN ATFSP3) it'll only cost you ~$50. It always takes me longer to pull the skid plates on/off than it does to actually do the fluid swap.

 

[Inyo_man]

I have only used Mitsubishi Motors AFT SPIII.
Is the Aisin the same fluid repackaged?

 

[coffeegoat]

I assume so, it's what gets recommended on the Mitsubishi Facebook group, I've used Hyundai and Kia SP III with great results.

 

[coffeegoat]

Oh, and eneos

 

[Michael Brown]

It was OEM fluid for KIA, Hyundai, and Mitsubishi. Aisin is just the transmission manufacturer who originally used the fluid.
I used the Aisin fluid for my last change, but I have also used the KIA and Hyundai OEM branded cases. Aisin is the original transmission manufacturer where Mitsubishi got the design (like Chrysler using/producing our ZF designed 8-speed under license). Aisin specified the requirements for SP-III fluid so any SP-III will work. They all should have a translucent ruby red color when new. As the fluid gets old, it picks up material from the wearing parts and turns brown/black. The torque converter starts to struggle as the fluid gets even older. A flush will remove some of material, but the fluid itself has lost its original properties.
Dexron, Dex/Merc, or any other fluid will have incorrect properties which will cause the transmission to act strange or cause damage.

PS. Also make sure to check the correct fluid level on the transmission dipstick after the flush/fill procedure and again once the transmission is warm. Too high or too low will cause problems, but I always get 10-12qts so I have a couple to add if it is low.