I recently was driving my GX 470 on a 300 mile trip. 240 miles into the trip and for no apparent reason, suddenly the truck sounded like it had a flat tire. I pulled off the road, determined tires were fine, then drove on the shoulder for about a mile. You could hear the gears, which sounded like metal on metal. We stopped had the truck towed to the nearest Lexus dealer. They told us the transfer case was bone dry causing the gears to grind and fail.
How could the fluid simply disappear? There was no sign on the garage floor proir to or after the issue. Could a seal have broken? I thought that would be rare....no one can tell us what happend, only that it was $4,800 to fix.
Any ideas?????

 

$4,800! Yipe! Sorry to hear this. Definitely sounds like a leak, but shouldn't there be some warnings signs? Warning lights? Something?

 

$4800 you will have to change your username to POORDOG. No warranty? That is weird. Was there a smell of burnt fluid?

 

Gear oil by its nature will leak lower than normal oil (given the same size leak). However, the leaks can occur on the tops or sides of the transfer case and you may not see dripping or even the telltale sign of an oil stain anywhere until it is too late. It's not the first time I have seen such a case on CL or elsewhere. Gear oil is one of those things that can run 100K, but I would look to change it every 30K. I examine the level around every 15K for both the transfer case and the rear differential. The transfer case is the more important one to watch though in terms of the consistency of its fluid (it gets a really bad rotten egg smell when it's really old).

 

There is a warranty on the transfer case seal, but only if you replaced it in the first 90,000 miles. I found my leak at 94,000 miles, called Lexus Customer Care and they wouldn't budge -- they offered a $500 discount instead.

You can find the recall/warranty with some google-ing.

Mine leaks and I had quotes around $2k to get it fixed. A local mechanic that I trust told me to instead just make sure the transfer case fluid is checked when I have my oil changed.

 

If there isnt obvious leaking how do you tell if the transfer case needs a seal replacement? Im not very mechanicaly savy but is there an area to check for evidence of oil leaking? What warranty would cover the repair? I have an after market warranty on my 04 but sounds like Lexus would pick it up with under 90k. Does this sound right?

 

$2k to fixed it ? wow thats just outrageous price. i got quoted $550 to fixed it.

so i guess as long as the fluid is full, we don't need to fix it then ? this is what i've been doing also, i've just kept refilling it every few months or so. Way cheaper to refill it than fixing it :x

 

That's exactly what you do. I used to have a leak on mine in my RX300 and took care of it when I had the transmission out a few years ago. Before that was using a 75W140 gear oil to slow down the leak (which was incidentally on top), though we did replace both of the side seals, too.

If I don't see leaking, I usually smell around for a sulfur smell...sometimes these leaks won't stain. We have a 4Runner that's similar (only RWD), but I do take a look at the rear differential about every 3 months or so.

The transfer case issue is noticeable with low or old fluid, because you may notice a longer interval between gear changes. I noticed this particularly in 1/4 mile racing as it was much quicker after changing out the fluid.

 

I have been told that there is some sort of plastic part/plug in the transfer case that can fail in higher mileage GX470s causing you to loose all the fluid and ruining the transmission. It apparently can be repaired/replaced but I have no additional information. Can any one assist?