Water leaks

General information

If water penetration occurs after body repair, the cause can be determined using the checks described below. A systematic and logical procedure is required to find the places where water penetration occurs. Before starting to perform extensive checks, a full inspection should be performed.

Visual inspection

• The following signs may indicate that there are leaks:
• Check the clearance and installation accuracy of auxiliary parts such as hood, tailgate, doors, etc.
• Check sealing elements such as plugs, rubber door seals, etc. for correct installation and possible damage.
• Check the water drain holes for blockages.

To obtain additional information about the presence of possible leaks, various tests can be used:

• Testing using a water hose
• Test by pouring water
• Road test
• Testing using ultraviolet lamp
• Checking using a special mirror
• Testing with chalk (powder)
• Testing using a smoke tube

Testing using a water hose

NOTE: Never direct the water jet directly at the rubber seal.

• Perform a water hose test with the help of a second person (inside the vehicle).
• Use removable spray tips (water nozzle to provide a fine spray of water).
• Start at the lower end and spray the entire area, gradually moving up.
• The following is used for testing using a water hose:
  • Softened water (with added liquid soap)
  • Special mirror
  • Testing using ultraviolet lamp

Water dousing test

• Additional checks can be performed at the car wash.
• Some leaks start here or just appear here.
• The interior of the respective vehicle should be checked using lighting during the washing procedure.

Road test

If no leaks are found when performing the above checks, road tests should be performed on wet roads.


Road tests in various conditions:

• At different speeds.
• On various road surfaces (from asphalt to cobblestones).
• With the vehicle loaded or unloaded.
• Driving through puddles (water splashes).

Testing using ultraviolet lamp

• Wet the outside of the area to be tested with clean water.
• Prepare the test fluid (see Operating Manual) and apply it from the outside using a suitable water spray.
• Illuminate the relevant area from the inside using an ultraviolet lamp.
• The test fluid will make the leak visible.

Ultraviolet lamp

Advantages of ultraviolet lamp:

• There is no need to dry wet areas before testing.
• The location of water entry and its route can be accurately identified.
• There is no need to remove most of the auxiliary components from the vehicle.

Checking using a special mirror

To see hard-to-reach places, you can use a special mirror.

Special mirror

Advantages

• Switchable light is built into the mirror area.
• The angle of the mirror can be adjusted manually using the handle.
• The connector between the handle and the mirror is flexible.

Checking with chalk (checking with powder)

This test checks the clamping and bearing surfaces of the seal.

Performing the check:

• Sprinkle the door seal with powder or cover it with chalk.
• Coat the seal bearing surface with a thin layer of grease.
• Close the door slowly and open it again.
• Check the width and continuity of the imprint on the door seal.

Testing using a smoke tube

Checking for leaks.

• Set the interior ventilation control to maximum.
• The assistant introduces smoke into the area being tested (in the passenger compartment) using the appropriate tube.
• The second assistant determines where the smoke is coming out.

Other testing equipment

When leaks are detected, other equipment such as stethoscopes or ultrasonic measuring devices can be used.

Repairing a leak using recommended tools, accessories and materials

Tools and auxiliary equipment:

• Dry, absorbent cloth
• Removable spray tip
• Backlight, fluorescent tube
• Mirror.
• Compressed air
• Sealing Protrusion Installation Tool
• Vacuum cleaner for wet/dry cleaning
• Compressor for sealant
• Interior trim remover
• Blade or pocket knife
• Wedge (wooden or plastic)
• Heat gun
• Ultraviolet lamp
• Special mirror for detecting hidden leaks
• Stethoscope
• Testing device using air supply
• Ultrasonic measuring device

Materials: (refer to Spare Parts Microfiche)

• Sealant (tape and plastic compound)
• Universal label
• Flange Sealant
• Sealant for sealing windows
• Waterproofing (PVC)
• Waterproofing with foam plastic
• Double-sided adhesive tape for waterproofing
• Butyl tape for waterproofing foam
• Methylated spirit (available)
• Polyurethane adhesive
• Silicone remover
• Tar remover

Water leaks according to mileage or operating time

Increased mileage has an impact on the problem of leaks in the car. Possible influencing factors:

Maintenance and care of seals:

• Lack of maintenance, inadequate maintenance or improper maintenance
• Using the wrong materials

Damage to seals:

• Due to ageing, wear and tear or improper handling/installation.

Heavy vehicle contamination:

• Heavy contamination of the vehicle can seriously impair the functioning of the water drainage channels and rubber seals.

Factors depending on the service life:

• External factors
• Ultraviolet radiation
• Extreme climate conditions

Corrosion can have serious effects on the bodywork, especially as a result of:

• Light or heavy rusting of the seal holder
• Rusting of sealed welded seams of the body
• Perforation corrosion

Water leaks after body repair

If a car has a leak after body repair, the following points should be taken into account in particular:

• It is necessary to check the correct installation of auxiliary elements and their seals (e.g. rear lights, etc.).
• The doors and the boot/tailgate must be checked for correct alignment. The corresponding seals must not be damaged and must be installed correctly.
• Check that the welds are sealed correctly.
• The correct installation of the rubber sealing rings should be checked.
• The seals of windows equipped with rubber seals must be installed accurately and in contact along the entire perimeter.
• Windows with direct glazing must have a correct and complete adhesive connection.

Water drainage system

If a vehicle has water penetration, the areas where water enters or drains should be checked first.

Pos.	Spare Part No	Name
1	-	Water drain, front
2	-	Water drainage, side and rear
3	-	Draining water from the roof hatch
4	-	Water drain tank

Water Ingress, Diagnosis and Corrective Action: Front of Vehicle Interior

Windshield (installed using rubber)

Diagnostics:

• Water ingress into the A-pillar area

Cause:

• An old or improperly installed seal can cause the rubber seal to not tighten properly or not tighten properly on the windshield or window frame. This allows water to pass between the rubber seal and the windshield or between the rubber seal and the window frame.

Corrective action:

• Seal the problem area by applying window sealant between the rubber seal and the windshield or between the seal and the window frame. Wipe off any excess sealant immediately.
• If a new leak is detected after the required leak check, the rubber seal should be replaced.

Windshield seal

Pos.	Spare Part No	Name
1	-	Window frame sealing
2	-	Window sealing

Windshields (straight glazing)

• Diagnostics: Water ingress into the A-pillar area or instrument cluster area
• Reason: Tears in the sealant bead
• Corrective action:

NOTE: Repairs must be carried out in accordance with established methods (Microfiche Service/TIS CD, group 42/501-11).

• Breaks in the sealant bead can be found from the inside using compressed air. A leak can be identified from the outside by escaping air.
• The second method of checking is by testing with water. The outer covering should also be carefully lifted using a plastic wedge. The leak should be detected from the inside, involving a second assistant.

Water Intrusion Diagnostics

Pos.	Spare Part No	Name
1	-	Testing using compressed air
2	-	Testing with water

Side windows

Fixed door windows (installed using rubber or direct glazing) can suffer from the same problems as the windshield, so the same corrective actions should be used.

Windows doors

Door seal

Diagnostics:

• Water leaking into the lower part of the door interior trim or into the lower trim panel area.

Cause:

• A waterproofing or foam flashing installed behind the interior door trim is designed to channel any water that enters through the door drain holes or downward or outward. If the waterproofing or foam flashing is damaged or improperly installed, water may leak into the vehicle's interior.
• Additionally, the drain holes may become clogged with leaves, dirt, or excess cavity protection material. Water collects in the door and leaks into the vehicle's interior.

NOTE: If the flashing or foam flashing is damaged, it should always be replaced.

• Check the waterproofing or foam waterproofing for damage or improper installation.

NOTE: When removing foam waterproofing, the butyl tape should be cut with a knife.

• If the waterproofing is to be re-glued, double-sided adhesive tape should be used. For foam waterproofing, butyl tape is used.
• Before installing waterproofing or foam waterproofing, check the drain holes for blockages.

Corrective action:

NOTE: When installing butyl tape, do not touch the mating surface (this will reduce adhesion).

• Remove the interior door trim.

Door seal

Pos.	Spare Part No	Name
1	-	Drain holes
2	-	Waterproofing with foam plastic
3	-	Interior door trim

Door seals

Diagnostics:

• Water ingress into the lower trim panel area

Cause:

• Insufficient clamping force between the seal and the door.

Corrective action:

• Check the clamping force:
• The easiest way to check the clamping force between the seal and the corresponding supporting surface is the paper tape test. This involves placing strips of paper at various points between the door and the seal and closing the door completely. If the paper can be removed without much resistance, the clamping force is too low.
• Adjust the clamping force:

NOTE: When adjusting the clamping force, always take into account the alignment of the edges of the corresponding elements.

• The clamping force is usually adjusted using the door lock counter part. When making the adjustment, the alignment of the distances from the door to the wing or from the front door to the rear door should be taken into account.
• Another adjustment method is to change the position of the seal mounting flange. The clamping force increases as the flange moves toward the door.

NOTE: Do not move the flange too far towards the door as this may reduce the sealing surface area relative to the door.

• Check the supporting surface:
• Apply chalk evenly to the seal surface. Cover the door support surface evenly with Vaseline.
• Close the door completely, the lock should work. Open the door. The chalk imprint (support surface) can be identified by the film of grease.
• The supporting surface must be at least 5 mm wide at all points.

Checking the seal

Pos.	Spare Part No	Name
1	-	Panel flange is bent too far inwards: small bearing surface
2	-	The panel flange is adjusted correctly: correct bearing surface
3	-	Check the clamping force using paper tape

Other reasons:

• The door seal must completely seal the door where it meets the body.
• Water can penetrate directly or indirectly into the vehicle's interior if the seal is damaged somewhere.

Corrective action:

• A damaged or worn door seal should always be replaced completely.
• When replacing the seal, please note the following:
• Always install the seal first in the small radius area (corners).
• Then fix the seal evenly on the flange by tapping it lightly with a rubber mallet. Twisting of the installed seal is absolutely not allowed.

NOTE: The specified seal length should not be reduced.

Adjusting the door seal installation

Another reason:

• The door seal is attached to a welded flange around the entire perimeter. If this welded flange is deformed or damaged at any point (usually in areas with small radii), leaks may occur at that point.
• A stretched seal retainer can also cause leaks.
• In both cases, water penetrates into the vehicle interior under the seal holder.

Corrective action:

• Straighten the warped weld flange using a hammer and anvil, preventing and, if necessary, repairing any damage to the paintwork.

NOTE: If the seal has a connecting joint, it should always be located at the bottom of the door frame.

• A stretched seal holder must be straightened manually. If this is no longer possible, the seal must be replaced.

Leaks through door seals

Pos.	Spare Part No	Name
1	-	Correct seal holder
2	-	Stretched seal holder
3	-	Sealing of the connecting joint

Roof hatch

Diagnostics:

• Water ingress into the roof hatch opening

Cause:

• The sunroof is installed in a water catch basin. Water flows out through the water catch basin, water drain holes and drain hoses. The drain hoses run down on both sides through the A-pillar and the C-pillar.
• Drain holes or drain hoses may be clogged with leaves, dirt, skid plate material, etc.

Corrective action:

NOTE: For a sunroof, the outer rubber seal and the lock actuator or latch mechanism should be checked first.

• Check the water trap for leaks.
• Check the drain hoses for leaks and to ensure they are properly connected to the water trap.
• Check the drainage system for blockages and, if necessary, blow it out with compressed air.
• Check the outer seal and correct adjustment of the sunroof.

Roof hatch

Pos.	Spare Part No	Name
1	-	Roof
2	-	Roof molding
3	-	Water trap with drain

Apron panel and heating/ventilation

Diagnostics:

• Water ingress into the front of the footwell

Cause:

• The apron panel is sealed in several places relative to adjacent elements, such as the connection to the A-pillar or the floor. These seals can be destroyed.
• The heater and ventilation system housing are connected to the apron panel. The through zone is sealed with foam waterproofing, which is attached to the housing.
• The body has drain holes to allow water to drain.
• If the foam waterproofing is defective or the drain hole is clogged, water may leak into the front of the footwell.

Sealing the heater and ventilation housing

Corrective action:

• Seal welds with damaged seals.
• If a leak is detected in the heater or ventilation system housing, the drain holes should be checked first.

NOTE: Damaged foam waterproofing should always be replaced.

• To inspect the foam flashing and its supporting surface for damage, it may be necessary to remove the housing.

Checking the foam waterproofing and drainage holes

Pos.	Spare Part No	Name
1	-	Waterproofing with foam plastic
2	-	Water drainage holes

Other reasons:

• Bolts and holes for routing cables and hoses should be checked for leaks in the area of the apron panel and instrument panel (rubber sealing rings in particular).
• If the footwell area is wet, you should also check the door hinge seals, door light switch, and cable routing holes.

Door Light Switch Seal

Rear Gutter Seal

Diagnostics:

• Water ingress into the side area of the ceiling lining

Cause:

• The outer roof panel is sealed at the weld seam where it connects to the side panel. This sealed weld seam can be covered with trim tape or a socket.
• In the case of station wagons and hatchbacks, there is an additional seal against the rear roof cross member.
• Water can penetrate here if there is a gap in the sealed weld.

Corrective action:

• Remove trim strip or socket. Inspect and reseal sealed weld.

Sealing the gutter

Luggage compartment seal

Diagnostics:

• Water leaking into luggage compartment

Cause:

• The luggage compartment lid seal matches the door seal.
• If water penetration occurs, the seal should be checked for damage and the seal retainer should be checked for proper installation.
• The clamping force and bearing surface of the cover should also be checked for leaks.

Corrective action:

• The lid is adjusted using the mating part of the lock or the lock.
• Rubber hard stops are installed on both sides of the luggage compartment opening. They are usually adjustable and the clamping force can be changed.
• The small radius sealing areas of the luggage compartment lid are also problem areas.

Check the seal for correct installation position

Another reason:

• The seal does not attach evenly around the perimeter of the cover due to deformation or unevenness of the weld flange.

Corrective action:

• Check the seal and the bearing surface.
• Straighten a warped or uneven weld flange.

Uneven weld flange

Another reason:

NOTE: The seal retainer covers the defective weld.

• Leaking weld on weld flange (through penetration). Water can enter the luggage compartment under the seal holder.

Corrective action:

• Pull the seal away from the seal retainer.
• Seal the leaking weld using sealant.

Welds with through penetration

Folding tailgate

Diagnostics:

• Water ingress into the rear area of the headlining

Cause:

• The tailgate leakage issues are consistent with the door issues.
• In addition, the area to be sealed must be much larger. The openings for the distribution of cables and hoses must also be sealed.
• The rubber sealing rings for the wiring holes must be checked for damage and correct installation (completely disconnected).
• The tailgate hinge mounting points may leak.

Corrective action:

• Check the rubber sealing rings and replace them if necessary.
• Check the hinge attachment points and re-seal them with sealant if necessary.

Check the cable and hose routing holes for rubber sealing rings

Forced air extraction

Diagnostics:

• Water ingress into the side area of the luggage compartment

Cause:

• The forced air suction for the car's interior is often located in the lower area of the side panel of the luggage compartment. The ventilation system housing is sealed with foam waterproofing from the body side.
• The rubber flap of the forced air exhaust must be able to move freely.

Corrective action:

• Remove the forced air suction. If necessary, detach the bumper.
• Check the sealing area between the body and the housing, as well as the rubber flap.
• Replace damaged foam waterproofing if necessary.

Check the forced air exhaust seal

Rear window

Diagnostics:

• Water ingress into the luggage compartment area

Cause:

• Leak through the rear window.
• Check for leaks in the same way as you would for a windshield leak.

Reversing lights

Diagnostics:

• Water ingress into rear luggage compartment area

Cause:

• Leaks through the reverse lights. There are two ways to seal:
• Sealing with foam waterproofing
• Sealing with plastic sealant
• If the reverse light is leaking, it usually means that the seal was not installed correctly.

Corrective action:

• Remove the reversing light. Check the housing and glass for damage. Check the plastic seal for leaks.

NOTE: Sealant should always be removed when performing repairs.

Check the seal of the reverse lights

Panel joints with sealed welded seams

Diagnostics:

• Water ingress into the luggage compartment area

Cause:

• Several panel joints must be installed during manufacturing in the wheel arch and luggage compartment areas. These joints are sealed with sealant.
• Uneven application of sealant may result in a rupture in the sealed weld.

Corrective action:

• Open the sealed weld.
• Find the leak in the sealed weld.
• Reseal using sealant.

Possible water penetration at panel joints in the luggage compartment