Part N-umber
Body Repairs - Water Leaks - Water Leaks
Description and Operation
General Published: 11-May-2011
If water leaks occur after bodywork repairs, the cause can be established using the checks described below. A
systematic and logical procedure is required to locate water leaks. Before beginning extensive checks, a thorough visual
inspection must be carried out.
Visual Inspection
- The following characteristics may indicate existing leaks:
- Check the clearance and accurate fit of ancillary components such as the hood, tailgate, liftgate, doors, and so
on.
- Check for correct fit and possible damage to sealing elements such as blanking plugs, rubber door seals, and so
on.
- Check water drain holes for unhindered flow.
Various tests can be used to provide further information on possible leaks:
- Water test
- Washer test
- Road test
- Chalk (powder) test
Practical execution of tests and checks
Water test
NOTE: Never aim a jet of water directly at a rubber seal.
Carry out the water test with a second person present (in the passenger compartment).
Use variable washer nozzles (concentrated water jet to fine spray mist).
Start in the lower section and spray the whole area, working upwards in stages.
Washer test
Further tests can be carried out in the washer system.
Some leaks originate here, or only occur here.
The relevant passenger compartment should be checked using a torch during the wash procedure.
Road test
If no leaks are located during the tests above, road tests should be carried out on wet roads.
Road tests under various conditions:
- At various speeds.
- On various road surfaces (asphalt to cobbles).
- With loaded or unloaded vehicle.
- Driving through puddles (splash water).
Chalk test (powder test)
In this test, the clamping load and the bearing surface of the seal are checked.
Performing the test:
- Dust the door seal with powder or coat with chalk.
- Coat the bearing surface of the seal with a thin film of Vaseline.
- Slowly close the door and open it again.
- Check the width and continuity of the imprint on the door seal.
Other test equipment
Other equipment such as stethoscopes, UV lamps, special mirrors or ultrasound measuring instruments can be used to
locate leaks.
Rectifying the leak using recommended tools, auxiliary equipment and materials
Tools and auxiliary equipment:
- Dry, absorbent cloths
- Variable washer nozzle
- Torch, fluorescent tube
- Mirror
- Compressed air
- Seal lip installer
- Wet/dry vacuum cleaner
- Sealing compound compressor
- Remover for interior trim
- Cutter blade or pocket knife
- Wedge (wood or plastic)
- Hot air blower
- Special mirror for concealed leaks
Side windows
In the case of side windows, the same problems can arise as for a windscreen. The same corrective actions must therefore be
used.
Door seal
Diagnosis:
- Water ingress in the lower part of the interior door trim or in the rocker panel area.
Cause:
- The water shield fitted behind the interior door trim exists to drain off water that has entered the door via the
drainage holes, either downwards or outwards. If the water shield seal is damaged or has been fitted incorrectly,
then water can get into the passenger compartment.
- In addition to this, the drainage holes can become clogged with leaves, dirt or excess cavity protection agents.
Water gathers in the door and ingresses into the passenger compartment.
- Check water shield for damage or correct fitting.
- If the water shield needs to be re-bonded, then approved seam sealer should be used.
- Before the water shield is installed, the drainage holes must be checked for unhindered flow.
Door seals
Diagnosis:
- Ingress of water into the rocker panel area
Cause:
- Insufficient clamping load between seal and door.
Corrective action:
NOTE: When adjusting the clamping load, the profile alignment of the relevant components must always be taken
into consideration.
NOTE: Do not realign the flange too far in the direction of the door, as this can reduce the bearing surface of the
seal to the door.
- Check clamping load:
- The easiest way to check the clamping load of a seal to the respective bearing surface is by means of a paper
strip test. This consists of trapping strips of paper at various points between the door and the seal, and fully
closing the door. If it is possible to pull out the paper with no great resistance, then the clamping load is too
low.
- Adjust the clamping load:
- The clamping load is normally adjusted using the striker. When doing so, the edge alignment from the door to
the side panel, or from the front door to the rear door must be taken into account.
- Another setting method is to realign the panel flange for the seal mounting. The clamping load is increased by
moving the flange towards the door.
- Check the bearing surface:
- Apply chalk evenly to the surface of the seal. Evenly coat the bearing surface of the door with Vaseline.
- Close the door fully, the lock must engage. Open the door. The imprint of the chalk (bearing surface) can be
identified in the film of Vaseline.
- The bearing surface should be at least 5mm across at all points.
Other causes:
- The door seal must completely seal the door where it meets the bodywork.
- Water can ingress directly or indirectly into the interior of the vehicle if the seal is damaged at any point.
Corrective action:
- A damaged or worn door seal must always be renewed in full.
- When renewing the seal, the following must be taken into account:
- Always fit the seal first in the area of the narrow radii (corner points).
- Next, secure the seal to the flange evenly by tapping lightly with a rubber hammer. The installed seal must not
be kinked at any point.
NOTE: The prescribed length of a seal must not be shortened.
Other cause:
- The door seal is attached to the welded flange all the way round. If this welded flange is uneven or damaged at
any point (usually in areas with small radii) then this point could be subject to leaks.
- A stretched seal carrier can also cause a leak.
- In both cases, water gets into the vehicle interior under the seal carrier.
Corrective action:
- Align the deformed welded flange using a hammer and anvil block, prevent and, if necessary, repair any paint
damage.
Sliding roof/tilting roof
Diagnosis:
- Ingress of water at sliding roof aperture
Cause:
- The sliding roof/tilting roof is installed in a water trap. The water drains off via the water trap, water drain holes
and drain hoses. The drain hoses lead downwards on both sides via the A-pillar and B-pillar.
- The drain holes or drain hoses can become clogged with leaves, dirt, underbody protection and so on.
Corrective action:
