2007 Evinrude E-Tec 75, 90 HP outboards Service Manual, Page 246Get this manual
MIDSECTION EXHAUST HOUSING
Cleaning and Inspection
WARNING
Wear safety glasses to avoid personal injury, and set compressed air to less than 25 psi (172 kPa)Clean all parts with parts cleaning solvent and dry with compressed airAll nut and screw threads coated with thread locking material must be thoroughly cleaned before assemblyWhen using thread locking product, be sure to prime the threads with Locquic PrimerExamine the upper and lower thrust mounts, and replace if deteriorated or damagedBefore checking the exhaust housing for distortion, thoroughly clean the top and bottom mating surfaces and remove all sealer and corrosionCheck the exhaust housing for distortionPlace the housing on surface plateUse dial indicator to check flatness by measuring the run-out on the top edge of housingThe maximum allowable run-out is 0.009 in(0.228 mm)If you do not have access to dial indicator and surface plate, seek the services of machine shopDO NOT attempt to straighten distorted housing; replace it