This seems to be a very common problem, and I will continue to try and investigate the drains. However it looks to me like the sunroof isn't quite flush with the roof. Anyone else have this problem and know if that might be contributing to my problems?

Here's the full story: didn't notice a leak until a month after I got the car. I wasn't driving it much but maybe I opened the sunroof and that did something? It started leaking on the passenger side. I took it to the lexus dealer, they cleaned the drains and said they fixed it. However, a couple weeks later we had a heavy rain and this time the right side was fine but the left side was incredibly wet. I took it back and they claimed some of the drains were messed up due to body work (there's no evidence of any bodywork on this car) and they couldn't fix it without removing headliner which would be insanely expensive. If that was the case, they should've told me the first time, or at least refunded my money, but they didn't. My theory is that when they cleaned the drains, they were able to clean the right one, but knocked the left one completely off. So I probably need to remove the headliner and investigate. But this sunroof does look low...

 

That can be fixed via shims one example
https://www.lexuspartsnow.com/parts/...277-20040.html

diagram
https://www.japan-parts.eu/lexus/us/...glass/2#63277C

The roof is drooping probably due to wear in the mechanism so the shim fix is more of a band-aid but will help. Dropping the headliner is not all that hard.

 

You probably need to do 2 items. One is to fix the drooping and the other is to clean all 4 drains.

I haven't noticed any leak until the day when a very strong typhoon attacked our part of Japan several years ago. My 98 Celcior's sunroof was not drooped but I noticed that both the liner and the floor were wet. I had to clean drains of 4 corners using a compressor. 2 drains at the front side can be found and accessed easily but those 2 rear side were not. There is a way to access those as is explained here but I hesitated to remove the head liner. In stead, I used a bore camera and a copper pipe to find the rear drain holes. With these I was able to access 2 rear holes easily and succeeded to clean all drains. You can find my method at the post #8.

 

Thanks so much for the suggestions. I will look into the shims and attempting the drains again.

 

I finally had time to look into this. There were already 4 shims on the right side and a metal shim plus a homemade wooden shim on the left side. I tried to add some washers which has helped a little, but there's a limit to how many you can add before you reach the end of the screw.

What can you do when you've reached the limit of how many shims you can put on there and it's still too low?

 

Means the mechanism is worn out. I've done sunroof repair (using salvage yard parts) it's one of my least favourite.

 

oh man, maybe i should just permanently seal it. i mean, if i ever manage to get it to not leak, i'm going to be too scared to use it.

another option would be to make sure the drains are clear, and jam something in there to prop it up to the correct height and just not use it.

 

propped it up and sealed it with dicor lap sealant. we'll see if it holds.