rstl99

I brought my recently acquired 2004 GX to Lexus dealer to have them replace the fluids in the diff and transfer case (yes, I'm getting too old to crawl under a car and do that myself). Their records indicated that the transmission fluid had been replaced there a few years ago, so I didn't get that done. I had noticed a bit of wetness under the transmission and it looked like tranny fluid. I asked them to check it. They said the pan leaks a bit, probably corrosion on the lip where the bolts attach. They said not to worry and "just keep an eye on it". There's some rust on the bolts, but nothing worrying. I found that odd, but maybe it's another of the weak aspects of this vehicle, leaking transmission pans. I don't recall reading anybody listing this as one of the few repairs they've had to do on their GX over the years. Anyway, I'll bring it in and get the pan replaced, I can't live with knowing my tranny is slowing leaking fluid, and not having a dipstick to monitor the level (thanks Lexus!). Oh yeah, my 1989 Toyota Cressida is still on its original transmission pan and no leaks... ;-)

chiph9

I'm in Texas, so no rust here. I don't like spots on my garage floor, so I'd get it fixed, personally. Plus there's the whole not knowing how much fluid has been lost issue.

Chip H.

rstl99

Yes, I definitely will get it fixed, especially for the latter reason you indicated.
I'm not convinced I need a new pan, so it may be just the seal leaking. I'll ask my indie Toyota mechanic to have a look at it and advise.
He can also advise me on the small leak in the left hand side exhaust manifold (probably the usual crack these engines develop there).
Lexus dealer wants too much money to address these issues, so I'm hoping he can do it for a cheaper cost (if needed).
I attach a couple of pics of the oil pan. Rusty bolt heads and drain plug, but I don't see serious rust on the pan requiring replacement of it...

rstl99

Crawled under the truck and was able to see the area of the transmission pan that is rusted and likely leaking. It must be replaced, I see that now.
Too bad Toyota didn't put stainless bolts holding up the pan, which wouldn't have rusted like the stock ones have, thereby causing the pan lip to rust. Oh well, at least now I know.

470reasons

LoL! I was going to suggest re-torquing the bolts. But, after seeing that picture - don't even breath on it. That is some nasty rust.

rstl99

Yeah, welcome to the rust belt!! ;-)
Oh well. Took it to my indie mechanic and will see what he can do for me.
A friend of mine had a similar issue with the oil pan on his Dodge truck. He welded the rusty area, POR15'd it, put a new gasket on it, and all was fine. When I was a young man I'd fix stuff like that, now I pay someone else to do it...

08gx470v8

Thsee pictures make my stomach cringe to think about. I really wish this car had a transmission dipstick so I could monitor th second most important fluid in the car after motor oil (and excluding brake fluid of course).

rstl99

I have a new pan seal etc on order and my indie mechanic will replace it.
As you suggest, Lexus's decision to remove the transmission dipstick strikes me as somewhat irresponsible on these vehicles. Not only for those of us in the rust belt who can encounter what I have, but for those who venture offroad with these capable trucks, and may dent or puncture the pan and not be able to monitor a possible leak.

When I asked the Lexus dealer to look at a possible transmission leak that I had noticed dripping (I had brought the truck in for them to replace the fluids in the diffs and transfer case), they informed me of the pan rust and leak, but said it wasn't serious yet, and "keep an eye on it". How, without a dipstick? They did give me a parts list for the replacement which was useful to me in ordering parts online (significantly cheaper than dealership cost).

I also wish that Lexus had put stainless bolts on that pan (and the engine as well), since I think it's the rusting bolts that eventually led to the rusting pan and leak.

So I suppose the lesson is, for those of us northern brethren who live in the rust belt: check your pan bolts every now and then. Or grease them to prevent them rusting.

470reasons

Thanks for posting this thread. I'm in the 'rust belt' and never gave the trans pan bolts a second thought. Will start taking anti-corrosion measures NOW! Hope your pan bolts unscrew without snapping. Did you order a new pan????

rstl99

Yes, I ordered a replacement Toyota pan and bolts. I thought of getting hardened SS bolts to prevent future rusting, but figure the original bolts lasted 12 years and that I likely won't still be driving the truck in 12 years, so stock bolts are good enough. They're painted black so should resist rusting if some anti-corrosion is applied once in a while.
My mechanic will be replacing the pan, I don't crawl under a vehicle to do that stuff any more (I'm 60). He said he'd need to remove some of the exhaust system to get at the pan.
So yeah, have a look at your bolts once in a while and rust treat them if you can, before the next snow-salt season!
Cheers.