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ELIMINATE THE SHAKES, RATTLES AND ROLLS.
Nothing can be more irritating for your customer than a rattle, wind noise, or a vibration that makes driving their car unpleasant. This is especially true if the vehicle is relatively new. Nothing can be more frustrating for you than trying to pinpoint the cause. Diagnosing Noise, Vibration and Harshness (NVH) issues can be made easier by performing some simple tests. NVH problems associated with the body of the vehicle are the focus of this month’s Body Repair.
BUZZ, SQUEAKS and RATTLES
Buzz, squeaks and rattles cover a wide range of issues, but these annoyances can drive your customer crazy. If you can diagnose and correct these problems (known as BSR’s), you will be your customer’s savior.
Many BSR complaints, such as loose trim, can be corrected using various tapes or lubricants. Tapes including foam, flock and anti-squeak, can be used to eliminate noises caused by metal, plastic and vinyl components.
BSR’s can be caused by several conditions and can be easily corrected.
✔ Tighten loose fasteners to specifications
✔ Replace damaged or missing clips
✔ Replace damaged trim panels
✔ Properly re-install incorrectly installed trim panels
Wind noise is the result of most air leaks. Air leaks can be caused by poor sealing, improper body component alignment, body seam porosity, or missing plugs in the engine compartment or door hinge pillar areas. All body sealing points should be airtight in normal driving conditions. Moving sealing surfaces will not always seal airtight under all conditions. At times, side glass or door seals will allow wind noise to be noticed in the passenger compartment during high cross winds.
Note: As is also the case with water leaks, over-compensating door or glass adjustments to stop wind noise that occurs under severe conditions can cause premature seal wear and excessive closing or latching effort.
Before performing any wind noise tests, verify that floor and body plugs are in place and body components are aligned and sealed. If component alignment and sealing is necessary, refer to the appropriate service manual for the vehicle being repaired.
Road testing the vehicle to check for wind noise is pretty straightforward. Drive the vehicle to verify the general location of the wind noise. Apply masking tape in 6-inch lengths along weatherstrips, weld seams, moldings, or door seams. After each length is applied, drive the vehicle. If noise goes away after a piece of tape is applied, remove tape, locate the problem and repair the defect. The example (Figure 1) illustrates the use of masking tape to find the location of wind noise.
Some veteran techs, who have a lot of experience diagnosing wind noise, will use the smoke screen as a diagnostic tool. Smoke is directed along the door seam and a second person inside the vehicle looks for smoke entering the passenger compartment. The second person inside the vehicle can also use a stethoscope or chassis ear to detect difficult to diagnosis buzz, squeaks and rattles while driving down the road.
Water leaks can be caused by poor sealing, improper component alignment, body seam porosity, missing plugs and blocked drain holes. Centrifugal and gravitational force can cause water to drip from a location away from the actual leak point, making it quite difficult to locate the source of the leak.
All body sealing points should be water tight in normal wet driving conditions. Water flowing downward from the front of the vehicle should not enter the passenger or luggage compartment.
Moving sealing surfaces, such as side glass or door seals, will not always seal water tight under all conditions. For example, minor leaks can occur during hard driving rain, or high pressure washing. If you can go through a car wash with no leaks, you’re good.
Note: Overcompensating on door or glass adjustments to stop a water leak that occurs during severe conditions can cause premature seal wear and excessive closing or latching effort.
Before performing any water leak tests, verify that the floor and body plugs are in place, body drains are clear and all body components are aligned and sealed. If component alignment and sealing is necessary, refer to the appropriate service manual for the vehicle being repaired.
A simple test to check the integrity of a door seal is to place a piece of paper (a dollar bill works very well for this test) between door seal and door frame. Be sure that the piece of paper does not overlap both door seals. With the paper in place, tug on the paper (Figure 2). The paper should pull out with some resistance. If there is no resistance, or the paper is not held in place when the door is closed, the seal is bad.
Note: This paper test can also be used to locate the source of wind noise.
To detect a water leak point-of-entry, do a water test and watch for water tracks or droplets forming on the inside of the vehicle. If necessary, remove interior trim covers or panels to gain visual access to the leak area. If the hose cannot be positioned without being held, have someone help you with this water test.