SW20 MR2 T-Top Leak Repair Silicone Method

[GDII]

As this is a very common problem but no specific post exists on this forum at least I thought I'd share the silicone sealant repair method for fixing the the SW20 MR2 leaking T-Tops.

The reason why these seals leak with old age is that rubber shrinks when it gets old and is not looked after. The culprit is the rubber on the car and T-Top pulls away from each other in the vertical join at the outer edge at the door glass opening up a gap for water to either drip or come streaming into the cabin. This can wreak seats and floor pans due to sitting water in the seat fabric and foam or carpets.

The goal here is to build up the gap with black silicone bringing the mating surfaces back together tightly sealing the T-Top as if new.

Things you are going to need:
A leaky T-Top SW20.
AP Cleaner or Methylated Spirits. You can use a decent dishwash liquid in water.
Old drink bottle with push cap filled with water.
Microfibre cloth and/or an old tooth brush.
Black silicone window sealant such as Permatex or CRC.
A cling film such as Glad Wrap.
Painters masking tape.
Vaseline or a grease.
Can of V and reading the nutritional values optional.

Before starting make sure you either have a garage space or the weather isn't going to rain in the next day.
Having a friend help with step 4 and 5 will make it easier and having the car in a garage out of the wind is also an advantage.
Also make sure the roof of the car is clean for step 5.

Step 1:
Remove the T-Top panels from the car and set aside.

Step 2:
Clean the rubber around all the door window glass and under the T-Top panel. Take this time to give the rubber a good clean up. Most of the time there will be built up dirt and dust in all the channels and surfaces. One thing to check is that the drain channels and drain tubes are free of dirt and debris and they drain to the correct place.

To clean this area grab your AP cleaner. I use a spray bottle such as a used Mr Muscle/AJAX or similar bottle with a decent concentrate of Sunlight dish soap and an old tooth brush and microfibre cloth. Give the rubber a good scrub but not to hard to ruin the surface. The area we are most concerned about can get delicate after 29 years. Wipe off the dirt with the microfibre cloth and dry the rubber once it is all clean. Use the water bottle with clean water to gently fill up the channel around the main T-Top glass seal. If this does not drain check that the upper part around the rubber seals hasn't been blocked with dirt. If these drain freely and correctly the rear will drain out the vent behind the rear quarter window and the front should drain out behind the front wheel. If you find water in your car you have either a damaged or disconnected drain hose and you will need to fix this.

Once the rubber is dry wipe the area from the outside at the door glass to the locating lugs with the Meths and a microfibre cloth removing any grease that might be present from the initial clean. See area in the images below. These images show an already repaired seal but it does show the extent of silicone normally needed to fix the leak.

Step 3:
Do the same to all the rubber of the T-Top panels. It's a good chance to clean the glass around the edges too that contact the roof seal.

Step 4:
Prepare the cling film and masking tape and your friend. Make sure you are out of the wind to help application of the cling film prior to taping it down.

Step 5:
Place the T-Top back on the car and examine the size of the gap of the vertical join between the car rubber and T-Top rubber. This will determine how much silicone to use. Not all cars are the same, some have large gaps and some have small gaps. Remove the T-Top again and place in a convenient place so you can apply silicone and get it back on the car easily without getting the silicone everywhere.

As you can see here, this seal has opened up while the others are nice and close.

Step 6:
Apply the black silicone to the car rubber in the areas shown below. Do not load it too much but use enough to fill half the gap based on step 5.

Step 7: Apply cling film over the silicone and tape it to the roof and inside the car to hold it in place. I have sometimes wet the roof a bit to help the film stick down while working on it but make sure the tape doesn't get wet too. Make sure the cling film is held in place as best as possible by the tape to ensure it doesn't wrinkle too much. Create a relief hole for the T-Top locking pin to go through the cling film.

Step 8:
Apply a similar thickness of silicone to the T-Top as in step 5 in the areas shown below.

Step 9:
Place T-Top panel back onto car as per normal. You really only have one shot at this otherwise it gets very messy. Ensure the cling film doesn't move too much. It shouldn't if taped down securely. Even if the film does move both sides of the silicone should make the same contact pattern as each other and seal together well. Make sure the door glass is in the up position and the cling film is on the inside of the glass. Then close the door and leave the car at least 24 hours. After the 24 hours is up you can cut away the excess cling film but leave it between the new silicone faces for another day. After day 2 remove the T-Top panel and apply Vaseline or some grease to both faces of silicone to prevent the shiny faces sticking together while it is still fresh. We don't want them to pull each other off the rubber.

This should stop the leak and look OK if done well. This method has been successful for me for 8 years + and I have not redone it. As you can see in the photos some faces of mine don't even have silicone on them.

A massive thank you to Clanfever/Olaf for using the write up text to create the series of photos for this. Very well followed Sir!

[ClanFever]

It's so easy! It's like 1 2 3... 4 5 6 7 8 9! But I am an idiot and managed to do it to two different mr2s and had no more leaks! Thanks for the tutorial Phil, it did make it so much easier

[Frankcp]

Nice technique, do you think it would work using urethane instead of silicone ? :

[GDII]

As long as it has some flex in it and it's not going to stick together once the plastic film has been removed, it should be ok. Essentially what you are doing is filling the gap in the two halves of the rubber to close the gap from the rubber shrinking over time.