Seats, Rear - How To Fix Water Leak, Prevent Wet Back Seats

How To Repair Water Leak / Wet Back Seats
By KidKoala

My girlfriend now owns a Celica VVTI, which is a lovely car but it has suffered with a water ingress / leak problem that took a fair bit of detective work so I thought it is best to write it up.

We first noticed the problem when a friend sat in the back, and got a wet bum!

This car was getting wet on the right hand rear seat behind the driver.

I stripped the interior out, and found a pool of water under the rear bench on the right hand side (unsurprisingly) and the seat foam was pretty wet too.

Searching online was of little use, some suggestions of boot/trunk seals and rear quarter lights.

I put a hose over various bits of the car, and eventually saw water dripping in around the area of the wheel arch, and tracking along the seam sound deadening into the seat base area.

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After some detective work it was apparent the water was coming in through the tailgate gutter somehow, so I checked the area on the outside to see what could be leaking.

There is a rubber cylindrical bung on the top right hand side of the boot/trunk opening/gutter, and in this case the bung was loose in the hole and able to move around a fair bit. I'm guessing the rubber went hard and shrank over the years.

You could potentially buy a new bung from Toyota, but I wanted an instant fix. I ran some VW sealing cord/putty round the perimeter of the bung, and popped it back in to make a perfect seal.

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I then used the hose again, and there was much less water ingress, but still it was coming in steadily.

I was out of ideas, so had to strip the rest of the interior out (the plastics around the rear quarter light, and boot/trunk plastics).

I then got my girlfriend to spray the car with the hose, and I sat inside looking for leaks.

About 3" into the width of the rear quarter light (above it) there is a metal seam where 2 skins meet with ridges in it.

Water was leaking between the two seams and coming out of a ridge in a slow drip.

Sorry for the appalling photo, I forgot to take an actual one of the drip at the time.

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At first I thought maybe it was the quarter-light seal, but just spraying this excessively with the hose showed no signs of water ingress.

I traced the rough path of the water by looking at the arrangement of the panels, and decided the only places it could possibly be coming in from was the roof gutter, where two seems meet in the top right hand corner.

I ran this past my friend who was a Toyota mechanic for a long time, and he said that other Toyota's used to go on this seam, but not the Celica, so I guess this is a rare case but I doubt I'm the only one with the problem (especially as these cars get older).

I have used some brush on seam sealant over the dodgy seam, and will paint it soon so it is inconspicuous.

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Whilst in the boot/trunk doing all this, I noticed a fair bit of water there too - I traced this back to the boot/trunk seal, which was in great condition but leaking from underneath.

Due to trapped water in here, there was a bit of rust on the lip in various places, so I removed it with a Dremel flap wheel, panel wiped it and then touched it up with Hammerite rust prevention and restoration paint. No one sees any of this as the seal/plastics in the boot/trunk cover it all up.

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Toyota originally sealed these with black silicone from the factory. I pulled the seal off and ran a bead of RTV silicone along the lip of the bodywork, then refitted the seal.

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It's mostly back together now, but keeping the seats out to confirm tomorrow with a hose that it's all spot on.

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Hopefully the car is now leak free, and rust free for another 13 years at least!


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