2007sc430

After getting fed up with the dealer "leak specialist" who couldn't figure out why there was water getting into my trunk I decided to do a little investigating myself. First a little on the design of the most rearward seal on the roof (this is the source of all the water coming into the trunk). There is a large outer channel that takes some of the water and sends it to the side trunk channels and out the back, and there is a smaller inner channel that runs under this rubber which drains the residual water so that there is none sitting in the large outer channel. This inner channel drains out of a hole on the bottom of the seal just down from the C-pillar and into the same side trunk channel (if you open the top halfway you can see exactly what I'm talking about). The problem is that the tube connecting the two fills with water during a heavy rain or carwash (as it is designed to do) and if there's any other leak from that tube, some of the water won't make it to the drain hole, and instead it will come out from the inside/interior aspect of the seal (which drains into the interior of the trunk).

First I tried sealing the inside/interior aspect of the seal the best I could but of course it's impossible to see where the breach is since it can't be inspected visually. Every time I applied some black silicone, the water just channeled around it and into the trunk. Finally I took the drastic measure of completely sealing off the inner channel (on the exterior aspect) and it seems to have fixed the problem (I hit it with a hose for a couple of minutes and trunk stayed dry...success!!!!). Now, all of the water is forced to drain down the main outer channel, although there are plenty of residual droplets left in there that have nowhere to go until they evaporate. Especially on the inside corners (just under the corners of the rear glass..ie: the most inward part of the C-pillar) there is water that just sits there.

Can anyone think of how this may become an issue down the road? Was it a bad idea to seal off a channel that was designed by Lexus to clear up the residual water? Shame on Lexus engineers for allowing water to drain INSIDE of a seal, opening up the possibility that any breach would send a small amount of water into the trunk (no pun intended).

Thanks!

By the way, a lot of you may not even notice the water in the trunk since it is a small amount and most of it drops into the carpet close to the trunk wall and over the wheel well. I had the car for almost two years before I realized the dampness. I urge all of you to check it after a heavy rain.

lexie

I have the exact same problem like you described and I also studied how the water channel works.. It usually happened at the right side and made my carpet all wet. It happened at high speed.

What I did was to apply some gasket foam tape on the trunk rubber gasket ( to make it thicker) just near by the inner channel area and it seemed the leaking problem has been solved for now.

JohnnyCake

This is good information. If you could illustrate with pictures, that would probably help people in the future who find this thread.

grabber2

Good info....however, I don't drive in rain & garage keep. I wash it many time & luckly, no leak to the trunk

2007sc430

I will try to take some photos although I'm a little embarrassed by the sloppy-job I did in applying the silicone (it's not noticeable from the outside so I didn't care too much to make it look neat). Garage queens fare better b/c they aren't exposed to the elements which degrade rubber. I try to garage it as much as I can but it still bakes in 80-95 degree weather and very high UV rays for most of the year (I live in Miami). The rubber seals don't stand a chance against this. They tend to get dry, discolored, and crack.

I use Klasse on the body which does a good job but there aren't too many options to protect the rubber that last through the rain. I've tried Griot's (washes right off), and I have bottle of Aerospace 303 that I will apply soon. I just have my doubts that any product applied to rubber can withstand a good rainstorm.

genec220

I have the same problem in my '02 unfortunately. I have reached my breaking point with it. So much so that I called Pohanka Lexus today. THAT is a whole 'nother story but it provides a point of reference of my frustration. If anyone can post some pictures, it would really help me resolve this. I'm not really familiar with the correct terms of the different parts being described. Please don't be embarrassed by your work. I bet it is better than Pohanka would have done, and YOU fixed the problem. A water leak is a tough one to fix.

I have isolated the leak to be on the right side, around the lower part of the rear window so it is right in the area you are describing.

Thank you in advance for your help.

nwcn98

I had a similar problem and ended up having the real window seal replaced. No issues since.

townsville

I had the same problem on my '02 SC430. Mainly on the right hand side. very frustrating. Finally solved by putting a layer of all weather gasket tape on the front rubber strip on the trunk lid i.e. to make it thicker and seal up against the rear window lower strip. Solved !

ozlex01

I had the same problem 06 LS430. It actually fried my rear computer box which had to be replaced a year ago. Same thing happened this weekend and found water standing in the left well in trunk. Drying it out now . Hopefully it did not damage the computer again. First symptom was the fuel lid pops open after switching off the car.

tromly

Wow, what has happened to Lexus quality?

bacardi11

iTrader: (1)

I've had this problem for years. i'm going to do what (nwcn98) did and be dome with it.

Moonstruck

Does anyone use weatherstrip lubricant on the weatherstripping on your cars, especially the stripping between the roof panels? As our cars get older the stripping will deteriorate and cause the roof to leak. Water in the trunk is one thing, water inside the car would suck. Please share with me the products you use to keep your weatherstripping in good shape.

ShawnOk

iTrader: (1)

I started this thread a while ago. I have 303 but left it in Oklahoma, so i tried glyecerol (another recommendation from my research) and it was too messy. I don't recommend it on the gaskets. Got on the actual body in some places. Tough to clean up. Just too greasy. https://www.clublexus.com/forums/sc-...intanence.html

johnbella

Ok,,for anyone that has a sc 430, problem solved for leaking water in boot

1st of all...the rubber seal that is on lower rear window edge has an inside channel,,,when water runs along there,,such as rain,,or hose if yr testing,,u will notice an inside channel,,one person was spot on abt that bad design from lexus,,but it was desingned simply for overflow,,,
u can block that innner running section of tube,,i will load pics and show u exactly,,,simple use black silicon,if possible,,,dont over do it,,,clean all residue around it,,,after applying let it dry out properly,im talking abt both sides of rear window,,done where window seal meets up with boot seal,,if u open roof half way,,u will see what i mean,,,,the rubbet around bottom of pillars,,,on both side,,have an inner channel,,thats where u block it off with silicon,,please try it,,let me know,,i will do my best to try and install some pics,,im new to this im not too sure how to load pics here,,maybe i need some help here,,,heheheheh,,ok,,cheera and good luck,,,
u might want to reove yr rear seat completely,,it might have built up with water

Harold57

Good to know. Welcome to the forum John.