I'm having trouble figuring out this trunk leak. There's water coming in from behind the trunk liner on the right hand side, up at the top around the lower corner of the rear window. The gasket isn't the problem; no water is leaking into the cargo area itself.

When I first noticed water, there was a good inch or two in the spare tire well and the space just behind the right tail light. I drained it out, and now I might find anything from a little moisture to a small pool of water in the side compartment area, depending on how much it rains. I'm not sure how long the water had been there. The car has 67k miles and was always kept in a dry garage. I had only had the car for a couple weeks when I first noticed the leak. Fortunately the water never damaged the radio tuner module (I think that's what that is) in the bottom of that compartment.

There are some rusty water trails in the trunk below the corner of the rear window. Could it be a broken seal around the window? I'm not aware of any water getting into the passenger compartment.

I don't have pictures on hand but I'll get some if needed.

 

Could be window seal, could also be sunroof drain. Sunroof drain could be clogged or may be split.

 

Sorry, I can't give any advice on where to look, but it is wise to have it taken care of. The Amp is located in the trunk and doesn't like moisture.

 

No sunroof on mine. I guess what I'll do is have the window resealed, unless anyone has another idea.

 

I had a Sequoia that leaked and I found it by doing a smoke test. Yep, a smoke test with a smoke machine. You might want to try that before chasing it with money.

 

I do happen to have a fog machine, but won't that leave residue in the cabin/trunk?

 

Depends on what you use to create the smoke. I used old sheets to cover my leather and dash just in case when I did mine. Windows can be cleaned easily with a warm soapy water solution.

 

I wonder if your rear window was replaced but not resealed correctly? On the driver's side bottom of the rear window is the Lexus logo and glass information. See if yours shows Lexus or a non-Lexus aftermarket brand like PPG, Pilkington, Fuyao, etc? Even if it DOES say Lexus doesn't mean your rear window is original. I've had my front windshield replaced, and fought with the insurance company to get Lexus glass, so my front did get replaced, yet it says Lexus. Curious what your rear is...

 

It just occurred to me to use dry ice in distilled water. That would still produce some water vapor, but the distilled water won't leave residue. Might give that a try.

 

I don't think it's been replaced, but I'll take a look.

 

Nope, I was wrong. It was replaced after an accident in 2009. It appears to be genuine Lexus glass, or at least it's marked as such.