Hello members,

I have a 2014 IS350 F sport AWD for the past 3 years and have loved the car with minor to no issues. Recently I have noticed that the car will start to vibrate for a quick 2-3 seconds when initially driving the car for the first time of use during the day, ie.. in the morning when I'm leaving to go to work, and during my afternoon drive back home. I start the car and allow it to warm up, once I pull out and begin driving i'll feel a lite shuttering or vibrating from the front of the car as i'm coasting at about 20-25 mph, this only last for 2-3 seconds and then goes away. Once the car appears to have been driven for some time it never happens again, until of course the car has some for some time (several hours) and once again is being driven. I took the car to a dealership and was told the transmission has an issue and needs to be replaced, however I've never experienced any issues with the transmission or received any codes/errors. Has anyone experienced a similar issue or know what may cause this? Also as a bit of additional detail, I noticed the issue after having the vehicle serviced for replacing a front differential seal that was apparently leaking. All thoughts are welcomed.

 

When i first starting reading your post I was thinking a transmission is, before you mentioned the dealer suggested a transmission issue.
And by that I mean perhaps it was in need of a fluid service...perhaps the old dirty fluid was causing some type of torque converter shudder that you were feeling.
This shudder would not throw a code and could stop as the vehicle warms up.

Then you mentioned the seal, so of course that seems like a logical culprit.
Do you know if it was a side seal or the pinion seal?
And when you say coasting, do you mean you are very lightly on the gas to maintain speed, or you're completely off the gas and the vehicle is rolling on it's on? My guess is the latter.

Based on your issue and that a seal was replaced, I would guess the pinion seal...because to replace the pinion seal the input flange has to be removed, the crush sleeve also has to be replaced when the new seal is installed.
After the flange is reinstalled it has to be torqued to a specific spec is order to preload the pinion bearing and to crush the crush sleeve (hence the name). If this is not done properly, then odd things can happen, like weird vibrations.
Add to that if you feel the shudder on decel, or coasting without the throttle being applied, this could also be a diff. issue...which brings me back to m pinion seal explanation.

 

Hello Sasnuke,

Thanks for the reply and input, for clarification the dealership replaced the oil seal on the front differential as it appeared to be leaking, and the vibration only happens when coasting and the foot on the accelerator, and not deceleration. The thought had crossed my mind to flush the Transmission fluid to see if there is any effect on the drive ability of the vehicle. So far this weekend I flushed the rear diff, and topped off the front diff as the drain bolt stripped and I was unable to flush the system, yet to no available because the vibration was still felt even after the top off. Next step is to flush the trans fluid, maybe drop the pan and do a filter change.

 

Given the age of the vehicle it wouldn't be a bad idea to change the transmission fluid.
Flushing it is going to be a challenge as there is no way to flush the tranny. The cooler is located on the side of the transmission, so connecting a conventional flush machine would not be possible.
Transmission flushes and drain-and-fills have been discussed on several threads on here, so I won't bother rehashing all that info.
As for the filter, there is no filter. The transmission has a strainer, which is like the filter, but actually has a stainless steel mesh, rather than an element of some kind.
So really it doesn't trap particulates, but rather stops them from re-entering the tranny once they drop into the pan.
The idea is that the particulates will stay in the pan and be expelled when the fluid is replaced.

Going back to the front diff. I should have mentioned it has 3 oil seals...2 side seals and 1 pinion seal.
They basically all do the same thing...keep the oil in.
If the diff. wasn't removed from the vehicle for the repair, then likely it was the left oil seal or the pinon seal.
If the diff. was removed, then it could have been the right oil seal.
There was a thread on here where the owner had a front diff. oil leak...I honestly can't remember which seal it was exactly, but I'm pretty sure it was the pinion seal.

Let us know what happens after you change the fluid. Keeping in mind there is a specific process to set the level correctly as there is no dipstick. You may want the dealer(or a shop with the right tools) to do it to save the headache.
Also a drain-and-fill will only get about 1/3 of the total fluid...even if you drop the pan you won't get much more...it will still be about 1/3. You could check the magnets inside the pan and the inspect the strainer if the pan does get removed though.

 

Seems like the vibration is caused by rotation. Is it happening in your front end, or rear end area? Try filming a drive with a go pro underneath the car. I am experiencing something similar with my 2011 AWD IS350, and I filmed below the underbody while driving. I too had a vibration while coasting 20-25mph, and getting up to higher speeds around 55-60mph. None when the car was decelerating or on acceleration. It was accompanied by a low howling noise that seemed to come from the LH front end. I was able to prop my car on quickjacks covering all four ends and carefully put the car in drive. That may help isolate and pinpoint the noise for you if you do the same. Be safe if you try that, or have a mechanic look at it for you. I found out my LH drive shaft and front differential area was making the low howling noise as well, while being up in the air. Upon inspecting the joint connecting the LH driveshaft to the front differential, I found some play between them shaking by hand. There was also grease leaking out of my LH driveshaft inner boot outer clamp area. My mechanic is taking a look at the end of this week to see if more serious issues are happening with the front differential, but making sure the bearings and connections on the shaft are intact should be a giveaway as a cause of vibration.

 

From your post it's difficult to tell if it's engine related or driveline related. You say when you first drive the car but then you say while coasting.

Can this vibration be replicated at idle, or only while driving, in gear AND when you hit the gas? After you hit the gas? During hitting the gas? Or none or all the above? And ONLY at 20-25 mph?

My first thought is driveshaft/support bearing/coupler issues, meaning excess wear causing play which will cause vibration at certain speeds. But would need more info to make a better guess on a forum.

 

My turn to chime in - I have had two IS350 (2015 and 2017) and I have experienced the same thing when driving the vehicle after sitting for several hours too. It is hard to explain but for me, the shudder would happen closer to 85-90 km/h (50-55 mph) for a few seconds but would go away as soon as I would provide a bit more pressure on the accelerator. I am wondering if that is what "shopgirl1" is experiencing too? I am now driving an 2019 RC350 and have experienced something similar so I am not worried about it and assume that it is just a function of the fact that I don't drive the vehicle hard enough (lol).

I think, and I could be wrong, but when she says "coasting", she doesn't mean what we all refer to coasting as "letting the foot off the accelerator pedal" but I could be wrong.