Detroit Diesel — Check Rack Freeness and Spray Tip Concentricity
Testing & diagnosis · Fuel injector
From a Detroit Diesel service manual — check it applies to your exact model before use.
Procedure
- Place injector in Tester J 29584.
- Hold control rack in no-fuel position and depress follower to bottom of stroke.
- Slowly release pressure while moving control rack up and down.
- Rack should fall freely.
- Adjust dial indicator to zero and rotate injector 360 degrees; note total runout.
- If total runout exceeds .008 in, loosen injector nut, center spray tip and retighten to 75-85 lb-ft.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- .008 in total runout
- 75-85 lb-ft
Source: Detroit Diesel service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.