So is there a heat exchanger inside the radiator for the transmission? Do I need to ask them to replace the radiator so that this doesn't happen again?

 

Correct. Definitely something to ask them about or at least see what they are speculating as to the cause.

 

Called this morning to get more info... They are replacing the transmission, radiator, all new lines, coolant flush thru the engine, and adding a trans cooler. I definitely want to see the old trans/radiator to take some pictures... This is nuts!

 

I was thinking about your problem more and there is a recent '14 on one of the 460 FB sites that had the same thing happen.

 

meh, it happens. Congrats on getting a resolution and getting it fixed!
You're within the powertrain warranty, so it's not a big deal big picture, right?
If this is was was widespread, even 0.05% of the units sold we'd certainly hear more about it cause they'd be on this forum or ih8mud or expedition portal complaining.
stuff breaks (Even on one of the most reliable vehicles sold), nothing is perfect, likely just a defective part in one of the interfacing systems which keep coolant and AT fluid separated.
I had a timing cover leak on my 2017 at 25K miles, it happens. Get it fixed and move on.
The moral of the story for me with this post is if I had a major drive line vibration issue as you've been dealing with, I'd be doing a drain and fill on my AT fluid (this is how they caught your issue) or checking my coolant level regularly to make sure it wasn't noticeably dropping (it could drop for other reasons like a coolant valley leak which also wouldn't be noticeable but that doesn't yield a vibration, just lowering coolant level).

 

This wouldn't be a big problem to me if I had the car for a few years... I just bought it in June, and it needs a new transmission? C'mon... That means the dealer didn't really give it a thorough "161 point inspection" like Lexus boasts about in every ad... I am discussing a buy back with Lexus Corporate. This trans replacement doesn't give me much confidence in keeping the car long term

 

That's fair to feel that way although have you read the checklist Lexus uses to Certify a vehicle? It's pretty vague and isnt geared towards catching complex internal problems like this... they essentially kick the tires and do a visual check and take it for a short test drive around the block.... you invested money in chasing issues with the tires, so if nothing else, I'd try to Lexus to reimbursement for that and or get free service for the life the of the vehicle, preventative and corrective. Tell them that's the only way you're not gonna pursue legal recourse to have them buy it back or give kbb good +10% on trade of a new 2021 gx... you have options but alas, its warrantied and ultimately nothing to be concerned about long term. Sounds like they're fixing it right. Good luck.

 

I haven't been on the road much for long distance trip lately due to covid. I noticed some minor vibration inside my 2015 GX on highway (65 to 80 mph). My stock tire is at 4/32nd and I do 38 psi. I did have a minor lean to right which is not uncommon for gx. I can hardly feel any vibration for in town local driving. My wife also feel the minor vibration but she never noticed the lean.

​​​​Is this more of alignment issue or something more serious? Thank you.

​​​​​​

 

Do you feel it throughout the vehicle or through the steering wheel?


The wheels might need to be balanced again. Look for a shop that has hunter road force machines. Toyota/Lexus suvs and trucks seem to have this issue quite often.

 

I agree on checking the balance. But since your tires are on their way out, maybe a new set of balanced tires and an alignment check would be helpful.

 

I felt the vibration mostly thru steering wheel. maybe I shall drive the gx more often. guess the guy having million miles on the truck would never feel this.

 

Wheel balance. Has to be done with the Road Force like Obsidian stated.

 

I opened a case with Lexus for a buyback in August. They replied yesterday saying that "the car does not suffer from any material or workmanship defects". They told me to contact NCDS if I don't agree with their determination.

One of the issues I had were fixed but the other still remains; the transmission had a vibration when the TCC locked up at cruising speed. This was due to engine coolant contamination. The transmission was replaced with a reman unit. My second issue is with the engine; it suffers a vibration at 1300-1500 rpms in park and while cruising with light throttle/tip in. I plugged in my OBD scan tool yesterday and ran Mode 6 to see misfire data on each cylinder individually. Cylinder 5 showed 2 counts over an extended period of time; no counts during my test. There were 0 counts on all other cylinders. This is interesting... when I got the car in June I started digging and found that Cyl 2 and 5 had misfire data. I replaced the plugs with OEM Denso. There was no change to how the car ran. Does this mean the coil for Cyl 5 needs to be replaced? Could there be a failing injector? Dealer and Lexus will not help anymore... The car is "operating without fault"

 

Let me start with saying I'm not a mechanic(only performed basic maintenances), but could you temporarily move the coil pack from a good cylinder to a bad cylinder and see if the probably follows the suspected coil pack? If so, you have your answer without buying a new one to find out. Just a thought.

 

I will try this when I get home... Great idea!