ENGINE NOISE

The underside of the bonnet or engine cover is sometimes covered in a trim panel, but it is rarely capable of blocking vibrations and noise transmitted through it. One solution is to fit thick soundproofing material to the underside. This must be fire retardant and selfadhesive. The underside of the bonnet must be clean to allow the material to be stuck to the single skin area of the bonnet panel. If possible, the original trim should be refitted.

Engine blankets are available for a number of vehicles (mainly diesels) to help absorb the sound of the engine from travelling through the bulkhead and into the cabin. These are often fitted between the back of the engine and the bulkhead, secured with cable ties.

The engine undertray is sometimes designed to absorb sound and many of them are lined on the inside with soundproofing material.