Diesel engines operate with significantly higher compression than gasoline engines. Diesel engines produce high-pressure exhaust gases that result in pulsing, vibration and noise production that are typically louder than gasoline engines. Sound waves and vibrations transfer to the cabin of the van from both the engine and the exhaust system. Sound output control, vibration dampening and installation of sound blocking materials will help reduce the noise levels of diesel vans.
Install a resonated exhaust tip on the end of the tailpipe. A resonated exhaust tip contains a sound dampening lining that will reduce the total sound output from the exhaust. Reducing the sound output from the diesel engine exhaust flow will dampen the noise in the van.
Remove the seats, carpeting, trim, ceiling upholstery and any plastic covers from the doors and interior of the van. Install CLD tiles -- constrained layer dampener tiles -- or other sound dampening mats on the bare metal to reduce sound vibration transfer. Overlay the bare interior with sound blocking sheets to reduce sound wave transfer. Replace the covers, upholstery, trim, carpeting and seats.
Inspect the exhaust pipe hangers. Remove any hangers that are directly welded to both the exhaust system and the van. Replace the hangers with free-hanging or rubber-ended hangers to reduce vibration transfer to the chassis of the van.
Replace the exhaust system's muffler with a muffler designed to reduce sound. Diesel engines installed in vans typically have higher displacement than other engines. The greater the engine size, the more exhaust gases are produced during operation. Mufflers designed to control sound will significantly reduce a diesel engine's total sound output.
Affix a sound-dampening liner to the underside of the van's hood and engine shroud, if equipped on the interior of the van. Sound wave control in the engine compartment will reduce the total sound heard both in the cabin and outside the vehicle. If possible, install the sound dampening mat on the firewall.
Free-hanging or rubber-ended hangers may require professional installation. Many muffler repair shops will provide this service.
When installing sound-dampening mats or pads in the engine compartment, be sure the mats are rated for high temperature areas. Melting, noxious fumes and fire hazards may result from use of non-approved materials.