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How to Repair Your Sunroof

Intro…

This guide is about repairing your sunroof (sometimes called a moonroof). It applies to most vehicles fitted with a tilting glass sunroof. The same faults can apply to any vehicle, Renault, BMW, GM, Ford etc. The vehicle used is in this article is a Land Rover Discovery; (It has two sunroof’s – ‘Double trouble’!).

Sunroof Repair - Tilt and Slide
Sunroof Repair – Tilt and Slide

The Causes (and Fault Finding):

  1. Sunroof Frame to Vehicle Roof Seal.
  2. Drain Tubes (their fixing points).
  3. Drain Tubes.
  4. Sunroof Glass (rubber seal).
  5. The Fit or Function.

How to Repair:

Sunroof Component Parts (Tilt and Slide)
Sunroof Component Parts (Tilt and Slide)
  1. Sunroof Frame to Vehicle Roof Seal.
  2. Drain Tubes (their fixing points).
  3. Drain Tubes.
  4. Sunroof Glass (rubber seal).
  5. The Fit or Function.

This type of sunroof comes in two halves, the top half containing the glass and opening mechanism, the bottom half acts as a drip tray (and may have the motor attached).

Note: If the drain tubes are working well you may only see faults in certain situations (the way the vehicle is parked, the amount of rain)? If the sunroof to roof seal has gone, then water may bypass the drip tray and the drain tubes and enter the vehicle directly through the roof seal.

The Causes (and Fault Finding)

Take note if your vehicle tends to leak more when parked in a particular position, as this may aid diagnosis of the fault?

1. Sun Roof Frame to Vehicle Roof Seal

Sunroof Repair - Tilted Sunroof
Sunroof Repair – Tilted Sunroof

This is where the two halves of the sunroof clamp the roof between them and form a sandwich-type seal.

The seal between the sunroof and the vehicle roof can dry out, allowing water to pass through.

Although the sunroof may show no visible faults, water can pass through the roof seal (the joint between the top of the sunroof and the car roof itself).

The drip tray (the bottom half of the sunroof) may not see large amounts of water unless there is a fault in the sunroof opening itself, or the drain tubes are blocked.

Fault Finding:

If you can see no visible fault and the amount of water entering the car via the roof started with a trickle and has been steadily increasing…    The fault may well be the roof seal?

  • Leak test the roof seal.
  • With the sunroof closed, pour water onto the roof, so it runs towards (but not on top of) the sunroof.

2. Drain Tube Fixing Points.

Sunroof Repair - The Drain Tube Fixing Point
Sunroof Repair – The Drain Tube Fixing Point

The drain tube fixing point may be a plastic moulding fixed to the sunroof ‘drip tray’ with a mastic. As with the sunroof seal, it can dry out, the seal can fail and water can leak onto the headlining.

In addition, the drain tube fixing point can:

  • Become brittle and break off.
  • Become blocked.
Fault Finding:

If you can see no visible fault and the leak is in one particular area?

  • Pour water in the drip tray (the bottom half of the sunroof) through the open sunroof to simulate a leak?

If the drip tray (the bottom half of the sunroof) is not storing water and the water is clearly running away, there may be a break in the drainage system.

Sunroof Repair - Fully Opened (Tilt and Slide)
Sunroof Repair – Fully Opened (Tilt and Slide)

3. Drain Tubes.

These fix to the sunroof drain tube fixing points and are routed across the roof and down through the bodywork, and allow any water to drain through a hole in the underside of the vehicle onto the floor.

Fault Finding:

If the leak is in one particular area, or the drip tray (the bottom half of the sunroof) fills with water?

  • The drain tube may have become blocked by leaves and debris.
  • The drain tube may have a hole or broken joint.
  • The drain tube could be routed incorrectly or kinked.

4. Sunroof Glass (rubber Seal).

This is the seal between the sunroof and the glass. If there is a problem with the rubber seal there should be obvious visible signs:

  • Perished rubber.
  • Failing to seal / Compression (you can check this by watching the rubber compress as the roof closes).
  • Dirt, plant growth etc.
Fault Finding:

You should see a visible fault, such as perished, shrunk or broken rubber. The drain tubes should carry away any water that gets past the rubber seal unless it is excessive, or the drain tubes are blocked or broken.

5. The Fit or Function.

If someone has played around with the sunroof (e.g. the glass) and it is not fitted correctly, then this can lead to faults and then leaks.

Fault Finding:

Visual inspection for fit and finish?

How to Repair

You may be able to carry out some of the repairs without removing the headlining. But, if you’re going to go the whole hog, you may want to consider taking it out! This isn’t usually difficult but needs a fair amount of time and perseverance with removing lots of fixtures and fittings (and working out how it comes apart). Most roof linings should have some give and shouldn’t break or kink too easily if you are careful. You can also try to loosen part of it to gain access, e.g. one side, the front or back?

  • Tools: The usual screwdrivers, small spanners sockets etc, torx allen keys or sockets.
  • Materials: Clean cloths, mastic/sealant, Araldite (a resin type glue).

1. Sunroof Frame to Vehicle Roof Seal

Removal:
  1. Refer to your vehicle manual.
  2. Remove the headlining (feel free to try and carry out a repair without removing it, but it may be a struggle).
  3. Release the drain tube pipes (beware, the tubes can break off!)
  4. Release the sunroof motor connectors and earth connection (if fitted).
  5. Undo any screws that hold the motor to the sunroof drive (if fitted)
  6. Undo the screws holding the ‘drip tray’ to the sunroof frame.
  7. Lower the drip tray.
  8. The sunroof can then be removed, (there is no need to remove the glass).

Note:

when removing the sunroof, the rear edge of the sunroof may have to be lifted first to clear the hole.

Replacement:
  1. Clean the roof edge and sunroof mating surfaces to provide a good bond and seal.
  2. Apply a good quality sealant or vehicle mastic. (The good quality silicone may contain a higher percentage of silicone and less ‘filler’ material).
  3. Replacement is the reverse procedure. Check for correct fitment and position as you go.
  4. Do not over tighten the screws; let the sealant do its job.
  5. Check the drain tube fixing points (even if they don’t leak) – See 2. Drain Tube Fixing points below.

2. Drain Tubes & Their Fixing points

Sunroof Repair - Drain Tube Repair
Sunroof Repair – Drain Tube Repair

Note: Araldite (a two-part epoxy resin type glue) is very good for re-sealing and provides for a more rigid fixing, (beware; the drain tubes can break off if you try to remove the pipes! Araldite can also be used to fix these too!).

  • Ensure the repair area is dry and clean.
  • Clean the area around the plastic to metal joint to provide a good key for the glue. You can roughen it up with some sandpaper. (Remove any old excess mastic that will prevent the glue from providing good adhesion).
  • Apply the Araldite ensuring the joint is well covered. Apply a second layer of glue if needed.
  • Allow the glue to dry thoroughly before testing for leaks.

3. Drain Tubes.

There are only two drain tubes fitted to these particular sunroofs. These are all towards the front end of the sunroof and operate to some extent independently.

Drain Tube Locations.

The drain tubes exit the vehicle via the roof pillars (‘A’, ‘B’ or ‘C’ posts). Water from the sunroof travels down these drain hoses and through a hole in the vehicle onto the road.

Sunroof Repair - The Drain Tube
Sunroof Repair – The Drain Tube

On the Land Rover Discovery (2 x sunroofs), the rear sun roof drain tubes exit near the rear lights. On the front sunroof, they disappear down the ‘A’ posts by the windscreen.

You need to ensure:

  • The tubes aren’t blocked (you can pour water into the sun roof gully and watch it run out on the ground).
  • The route the tubes have been run is not higher than the drain tube fixing point itself.
  • That the tube fixing point on the sunroof isn’t broken, as they can be brittle.

4. Sunroof Glass (rubber seal)

This is an easy item to change if you can get hold of one. It appears only to be sold as part of the sunroof assembly? However, I have seen the seal rubber sold individually on e-Bay.

Before you go down this route and spend hard earned cash, is it the seal causing the problem? It should only be the cause of the problem if it is dirty, damaged, or has an inherent defect? This should normally be visible.

The root cause of water ingress in a sunroof is often via:

  • Item 1. The sunroof to roof external seal.
  • Item 2. The drain tube fixing points and any problems with the drain tubes (Once the water is in).

To remove the seal, simply open the sun roof and carefully pull it out of the recess.

  • Check for damage and cleanliness.
  • Check the sealing rubber compression (you can check this by watching the rubber compress as the roof closes).

Note that you may see water on the seals from condensation running off the glass sunroof, or water running in from outside when the window opens.

5. The Fit or Function.

If parts of the sunroof (such as the glass or frame) have not been fitted correctly, then this can lead to faults and then leaks.

All you can do is re-fit and repair as necassary.

Testing

Sunroof Repair - Fully Opened (Tilt and Slide)
Sunroof Repair – Fully Opened (Tilt and Slide)

You can test for leaks by pouring water into the drainage ‘drip trays’ and watching for water running out under the car. Note that:

  • The drainage holes from the sunroof may be at one end (on the Land Rover Discovery it’s towards the front of the car) and operate to some extent independently on each side. For checking, the vehicle will need to be parked fairly level.
  • Pouring water in the drain does not check the sunroof to roof external seal. With the sunroof closed, pour water onto the roof, so it runs towards (but not on top of) the sunroof.

To check the overall water integrity of the car (for the sunroof), you may need to leave the car parked in the rain for a day.

Try to replicate the previous fault conditions, such as parking the vehicle on a slight slope (nose up or nose down?), etc.