Montero shudder/vibration in 4HI Only
 

Hey guys I recently started using 4hi and 4WD on my Gen 3 Montero and I found a vibration so I am hoping you all might be able to help me track it down. Here's the issue, I get a shuddering vibration when I accelerate in 4HI and it's more evident when accelerating up a hill. Heres the catch though, it only vibrates in 4HI.. In 2Hi the truck is buttery smooth. I'm assuming this means it is related to the front driveline so I took it to a couple shops and they said the front propeller shaft and u joint looked fine.. I replaced the front U-joint anyway because it looked old and was easy to do but the vibration is still there. So what do you think it could be? Should I replace the front drive shaft completely? Have the transfer case looked at? front differential? I'm familiar with the 2-3RPM vibration from other threads, but that also occurs in 2WD. This is more of a shudder pulsing vibration that occurs from 2kRPM all the way up to 5KRPM.

When I bought it I put new oil in both differentials (Valvoline 80W-90 GL-5) and transfer case (Pennzoil Synthetic 75W-90 GL4), only the front differential had black oil in it. I'm hoping you have some ideas for me because this shudder is driving me nuts. I love this truck and want it be as reliable as possible (it only has 84,000 miles on it)
Thanks for any advice you can give me guys!! I appreciate it
-Chris

Front drive shaft might be out of balance. There are small weight welded to it to balance, if one of them fell off it will vibrate when turning. Check if you have any shops in the area that can do drive line balancing.

Christo........I would be interested to hear what you find out. Hunter mentioned a welded weight to balance the shaft......glad I just learned about that.

My first thought was that maybe the output seal on one side was shot, allowing some play and hence the vibration.....but I think you indicated that there were no leaks, so I guess that can be ruled out. How about the inner front wheel bearings? If they are worn-out, maybe that would cause the vibration. I think I made some posts with pics of tearing down the front hubs to access the inner wheel bearings and cleaning/repacking. Seems that often the inner bearings are neglected since they are much harder to get to......mine were almost greasless and just had a rusty film keeping them from squealing......just needed a good soaking in gas and repack with good grease.

thanks HunterD that’s what I’ve heard too. Unfortunately there’s no driveline shops Where I’m at. I called a shop and they can mail me a whole new driveshaft for $250. If trying to rebalance the one I have is close to that I might just go for a new one. Is there any chance the front differential or transfer case could make a vibration like that too? I just don’t want to start throwing parts at it. Thanks man

Thanks for the suggestions man. Hopefully I’ll be able to pin it down. Are you saying the output seals on the transfer case? I wonder how I could test that? No leaks that I can see either. I was also thinking motor or transmission mounts could be bad, but I would assume those would vibrate in 2wd too which it isn’t right now...

Uh Oh more Issues
 

Hey guys in an attempt to eliminate my 4wd vibrations I took it upon myself to replace the front drive shaft. By the way this was way trickier than I thought.. I had to unbolt half of the exhaust and still barely squeezed the dang shaft out. These are not designed to be an easy replacement...



Anyway I got the brand new front shaft in and took it for a drive in 4H. The vibrations were better but still lingering. So I decided to drive it hard for a bit to see if the new driveline needed to be worn in. Sadly the vibrations all came back and I started to notice a burning smell from under the car. I remembered this smell from driving hard in the snow a few months ago (should have checked into it then). So I babied it home and got under the car. It was still smoking and I could see oil flung all over the new driveline, exhaust and transfer case. Looks like the transfer case seal is leaking now and probably was before, but I never noticed. I’m thinking the output bearing might be bad too? and could be the cause of my vibrations. I made an appointment at a local shop this week so I will update the thread of what I find. However I am still curious if anyone agrees with this diagnosis or has any tips for me before I take it in. I like to know what I’m getting into before handing my car over to a shop. Is there anything I should do to make sure I don’t get bamboozled? Would getting a used transfer case be better than having them try to “fix” the one I have? I have uploaded a photo so you can see the oily mess. As always thanks for any advice you can give me! Cheers 🍻

https://cimg8.ibsrv.net/gimg/mitsubi...735520592.jpeg

Christo......alot of work, and frustrating to see the oil leak after the test drive. The oil is leaking from the transfer case, right? Did you happen to check the transfer case oil and differential level before taking the last test drive?
I guess your best bet is to let the shop look it over and give you the exact problem.....then decide what steps to take.
Good luck.

$2400 Repair?!! Uhhhh
 

So I finally found a shop that took the time to narrow down my vibration issue. After a test drive and finding metal shavings in the differential oil, they said they highly suspect the vibration is coming from inside my front differential. They then quoted me $2400 to rebuild the front differential and also replace the half axles which they said are "loose"... I told them I couldn't afford that haha and took the Montero back home to do some research. So my question for you guys is, what options do I have? Is it worth rebuilding a differential? Or Is it easier to just replace it with a used one? Sadly I don't have much knowledge about replacing differentials at all... but I am willing to learn if that means saving $2400. I seem to remember other owners on here doing 4.3 to 4.9 differential swaps from a junkyard like it was no big deal. Curious what you guys think I should do!:eek: Thanks for the input!

Did the shop find "metal shavings" or "metal pieces" in the differential oil? If it's just small shavings, replace oil and drive. Do you have to be in 4wd? Drive it in 2wd as long as you can. While doing that, be on a lookout for a replacement transfer case from a junk yard.
Any idea what may have caused the wear? Was it driven in 4wd on paved roads? Was Montero driven hard 4-wheeling? It's surprizing that t-case would fail out of the blue like that.

I agree with Hunter. Keep your eyes open for another Monty for sale, and sometimes you can snag them for less than $1k or less. Use it as a parts vehicle and you will have a ton of parts to get you thru the future.