1999 GMC Sierra 1500 Pickup Owner's Manual - Page 297

Cleaning Your Diesel Engine yousprayorpourwateroranyother liquid onyourenginewhen it is armorhot, or when it isrunning,you could causeserious damagl o it. youever clean theengine,clean it onlywhen it is cold. Noise Control System ThefollowinginformationrelatestocompliancewithFederalnoiseemission standardsforvehicleswithaGrossVehicleWeightRating(GVWR)ofmore than10,000pounds (4 536kilograms).Seeyourmaintenanceschedulefor informationonmaintainingthenoisecontrolsystem to minimizedegradation of thenoiseemissioncontrolsystemduringthelife ofyourvehicle.The noise controlsystemwarranty is given in yourWarrantybooklet. Thesestandardsapplyonly to vehicles sold in the United States. Tampering With Noise Control System Prohibited Federal law prohibits the following acts or thecausingthereof: 1.Theremovalorrenderinginoperativebyanyperson,otherthanfor or purposesofmaintenance,repairorreplacement,ofanydevice element of designincorporatedinto anynew vehicleforthepurpose of noise control, prior to its sale or delivery to the ultimate purchaser or whileit is in use; or 2. Theuseof thevehicleaftersuchdevice or elementofdesignhasbeen removedorrenderedinoperativebyanyperson. Amongthoseactspresumedtoconstitutetamperingare Insulation: Removalof noiseshields or underhoodinsulation. Engine: the actslisted below. Removalorrenderingenginespeedgovernor, if so equipped,inoperative so as to allowenginespeed to exceedmanufacturerspecifications. Fan and Drive: Removalof fanclutch, if so equipped, or renderingclutchinoperative. Removalof fanshroud, if so equipped. Air Intake: Removalofair cleanersilencer. Reversingaircleanercover. 6-1 9