| Description and Operation Water leaks can occur after body repair work, but can also occur on new vehicles. The test methods described below allow the various causes to be identified. In all cases, a systematic and logical procedure is required to locate water leaks. General When searching for faults, it must be taken into account that water can enter the vehicle passenger compartment in various ways and under different conditions. Therefore, it is sometimes not sufficient to perform a water test on a stationary vehicle. Before beginning extensive checks, a thorough visual inspection must be carried out. The following points are to be taken into account in the process: - Check the clearance and accurate fit of ancillary components such as the trunk lid and doors.
- Check for correct installation and possible damage to sealing elements such as blanking plugs, seals and rubber door seals.
- Check that the water discharge are not blocked.
Testers NOTE:Further test methods and testers are set out in the "Wind noise" chapter. Water leaks and wind noise can have similar causes. This means that test methods and testers can be used for both types of problem. The alternative tests are as follows: - Stethoscope.
- Smoke pipe.
- Ultrasonic detector.
- Powder test.
Test method Water leaks in the vehicle passenger compartment cannot usually be located at the first go, as the water frequently distributes itself across larger areas. For this reason, the passenger compartment must be dried before the leak tests. Any ancillary components that block the view must be removed. Water test During the water test, the vehicle is sprayed with water at the suspected location of the leak. At the same time, a second person checks the passenger compartment for places where water enters the vehicle. - Start in the lower area and spray the whole area, working upwards in stages.
- Use a water spray nozzle with a variable water jet.
- In difficult cases, improve the free flowing of the water by adding a small amount of rinsing agent.
- Use a special mirror in areas with poor visibility.
- If necessary, use a contrast agent and UV lamp.
Washer test Certain leak problems only appear in a car wash or can only be simulated there. The concerned area of the passenger compartment should be inspected with a torch during the wash procedure. Road Test Some leaks only appear when the vehicle is moving. If no leaks are detected during the above-mentioned tests, road tests should be carried out on wet roads. - At various speeds.
- On various road surfaces (asphalt to cobbles).
- With loaded or unloaded vehicle.
- Driving through puddles (splash water).
Test with UV lamp As already indicated in the water test section, a leak test can be executed with a UV lamp and a special contrast agent. The advantages of using contrast agent are: - No need to dry out wet areas beforehand.
- The water entry and its subsequent path can be seen more clearly.
- No need to remove most ancillary components from the vehicle.
NOTE:The equipment manufacturer's instructions must be followed when using a UV lamp and contrast agent. Procedure for using a UV lamp. - Wet the test area with clear water from the outside.
- Prepare test liquid and apply it from the outside using a suitable water sprayer.
- Illuminate the relevant area from the inside using the UV lamp. The test liquid will make the leak visible.
Chalk/powder test In this test, the contact area of the seal is checked. To do this, the door seal is coated with powder or brushed with chalk. A thin layer of grease is applied to the contact area of the seal. The door must then be slowly closed and reopened. The width and continuity of the imprint can now be checked on the door seal. Smoke test This test can be used to detect leaks visually. The process is as follows: - Set the ventilation blower in the passenger compartment to the highest setting.
- Close all doors so that a slight overpressure can build up in the passenger compartment.
- Move the smoke pipe along the outside of the body to the areas to be checked.
- Leaks can be detected through the irregular movement of the smoke.
Stethoscope test This procedure is very similar to the smoke test. Instead of the smoke pipe, move a stethoscope past the areas of the body that are at risk. Leaks can now be detected acoustically. Ultrasonic detection With this test, a leak can be found electronically. The procedure is as follows: - Place the ultrasonic transmitter in the vehicle.
- Completely close the vehicle.
- Search the exterior of the vehicle using the detector.
- The detector provides a simple indication of a leak.
Sequence | Stage | Testing | Result | Action | | 1st | Ask customer for a detailed list of possible reasons for the water entry. Does this information allow the cause of the leak to be identified? | Yes | Dry out the vehicle and repair the damage. Perform a water test as a check (see test method). | | | | No | Step 2. | | 2nd | Perform an initial visual inspection on the vehicle. Look for signs of water entry. Can the cause of the leak be identified immediately? | Yes | Dry out vehicle. Repair damage. Perform a water test as a check (see test method). | | | | No | Step 3. | | 3rd | Is it possible that water is getting into the vehicle through a seal (door seal, trunk lid seal)? | Yes | Check the seal for damage. Check the creation of the seal using the chalk test (see test methods). Step 4. | | | | No | Step 5. | | 4th | Is the contact area for the seal adequate? | Yes | Step 5. | | | | No | Perform work as described under Areas with possible water leaks - Door seals. Dry out vehicle. Repair damage. Perform a water test as a check (see test method). | | 5th | Before starting any further work, use the VIN to look for model-specific information in eTIS. Perform Oasis query and check TSIs. Does this information allow the cause of the leak to be identified? | Yes | Dry out vehicle. Repair the damage using the information found. Perform a water test as a check (see test method). | | | | No | Step 6. | | 6th | Establish the extent of the damage. To do this, expose wet areas. Remove parts. Investigate the suspected area for signs of water. Does an investigation of the suspected area allow the cause of the leak to be identified? | Yes | Dry out vehicle. Repair leak. Perform a water test as a check (see test method). | | | | No | Step 7. | | 7th | Check exterior areas (seals, seal welds). Check interior areas: Signs of water, plugs, seal welds. Can the cause of the leak be identified? | Yes | Dry out vehicle. Repair leak. Perform a water test as a check (see test method). | | | | No | Step 8. | | 8th | Perform water test or ultrasound test. Can the cause of the leak be found? | Yes | Dry out vehicle. Repair leak. Perform a water test as a check (see test method). | | | | No | The water entry may only occur under dynamic driving conditions. This requires intensive tests to be repeated with the corresponding climatic influences (rain). | Possible complaints and corrective actions NOTE:Water leaks and changed vehicle acoustics can have similar causes. For this reason, information from the Wind noise or Noise, vibrations, roughness chapters may be useful in identifying the fault. An outline of the possible complaints due to water leaks is provided below. The causes of water leaks and the possible remedies are presented using selected examples. They are intended to provide troubleshooting tips and suggestions for the user but do not represent an exhaustive faults list. Glued windows A broken pasted seam can cause water to enter around the window. A broken pasted seam can be located using a water test or by carefully blowing compressed air onto the inside of the window seal. Corrective action Broken pasted seams -Arrow- can be sealed from inside using PU adhesive. If this seal does not resolve the problem or the broken pasted seam is too extensive, it is necessary to remove the window and glue it back into place. Door seals If water appears at the bottom of the door, it is possible that the door seal behind the door trim is damaged. If the door is intact, water can enter through the window weatherstrip and flow out through gaps on the underside of the door. If the door seal adhesion is faulty or the door seal is damaged, water can get into the interior. Fastening bolts could be loose or clips incorrectly positioned on door modules. Corrective action Depending on the door seals used, different sealing methods can be used. NOTE:The drainage holes on the underside of the door may not be blocked - if they are, clean them. Defective films and foam seals must be replaced. Once the adhesive surfaces have been cleaned, plastic films must be stuck with double-sided adhesive tape or replaced. Leaky foam seals are sealed with Butyl tape or replaced. Plastic door modules are fitted with a weatherstrip, which cannot be replaced. Seal the leaky point with Butyl tape or replace the part. Door weatherstrip Leaks can be caused by badly fitted seals. In particular, areas with radii -Arrow- must be thoroughly checked. Door seals can develop leaks due to: - Damaged or expanded seals.
- Ageing.
- Insufficient contact pressure.
- Inadequate contact area for seal on body part.
- Uneven welding flange thickness.
- Kinks.
The contact pressure of a seal can be determined using a strip of paper. If a strip of paper trapped in the closed door can be pulled out easily, the contact pressure is too low. Corrective action Replace damaged or aged seals. Prevent kinks. The contact pressure can be changed by adjusting the catch bolt or correcting the panel flange. Realign uneven welding flange thicknesses. Properly repair any paint damage that occurs. Rubber grommets / plugs Rubber grommets or plugs are fitted at numerous points on the body. They are frequently used as seals for cables, hoses or actuating links. Rubber plugs are frequently used for gaps caused during production. Leaks can be caused by badly fitted or damaged rubber grommets and plugs. Damaged cable insulation can also cause leaks. Where components are bolted on, water can enter if there are inadequate seals at the connection point. Corrective action Correctly fit rubber grommets / plugs. During fitting, ensure that the sealing lips are not trapped and are applied properly. The contact area of the rubber grommets / plugs can also be sealed with PU sealing compound. Replaced damaged rubber grommets and repair damaged cable insulation. Heater housing/ventilation Loose Butyl sealing strips, damaged sealing surfaces or a trapped carpet can cause leaks around the heater housing / ventilation -Arrow-. Badly positioned or badly fitted hoses can also be responsible for water entry. Water drains must not be blocked. NOTE:A large quantity of water flows through the water tank. If there are leaks in this area, it is essential to ensure that the water drainage mechanisms function correctly. Drainage openings may not be blocked or stuck. Leaves and other dirt must be removed before troubleshooting. Corrective action Before the actual repair, make sure that the water drains are not blocked or stuck. Remove the heater housing / ventilation and fit a new Butyl sealing strip. Damaged sealing surfaces must first be adjusted. A trapped carpet must be removed. Seal welds PU seal welds are applied to welded or riveted connections -Arrows- to seal the interior of the vehicle. Incorrectly applied or damaged seal welds can allow moisture to penetrate into the interior of the vehicle. It is also possible that seal welds that visually appear to be intact in terms of their shape and size actually have poor adhesion. Corrective action Incomplete seal welds must be supplemented with PU sealing compound. Damaged seal welds must be removed and re-applied properly. Make sure that any residual moisture is effectively removed before a new seal is applied. Attached parts The add-on parts include: - Exterior mirros, handles, controls.
- Mouldings, roof mouldings, lettering.
- Roof aerial, roof rack or connections for roof rack systems.
- Bumper mountings.
- Injection nozzles, door contact switches, bump stop rubber.
- Control unit seals.
- Tail lamps.
- All kind of screwed connections (pedal block, door and tailgate hinges)
Add-on body parts must be fitted with seals, grommets or sealing compound to prevent water entry. However, even when a sealing system is fitted, the screw thread may still cause leaks. Corrective action Seals must be tested and, if necessary, replaced. Check contact surface and adjust if necessary. Points sealed with sealing compound must be thoroughly cleaned and the seal replaced. Check grommets and replace if necessary. At all screwed connections, seal the thread with an appropriate sealing material. | 
