Detroit Diesel — Check Bearing Pre-Load (Camshaft And Idler Gears)
Adjustments · Camshaft Gears and Idler Gears
From a Detroit Diesel service manual — check it applies to your exact model before use.
Procedure
- Ensure the bearings are clean and lubricated with engine oil before checking the pre-load.
- If a new bearing has been installed, work in the bearing by rotating the gear back and forth several times.
- Tie one end of a piece of lintless cord around a 1/8" piece of wood or soft metal stock; place the wood between two of the gear teeth.
- Wrap the cord around the gear several times.
- Attach the outer end of the cord to spring scale J 8129.
- Maintain a steady pull on the cord and scale 90° to the axis of the hub and note the pull required to start the gear rotating.
- Make several checks to obtain an average reading.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Pull within 1 lb minimum to 5 lbs maximum and does not fluctuate more than 2 lbs 11 ozs
- On 8V engines only, preload on idler gear is 1/2 to 3 lbs (maximum)
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.