Northern Lights — Injector Service (SP-11)
Repair & overhaul · Fuel injectors
From a Northern Lights operator's manual covering: M40C3, M944, OM944T3. Check it applies to your exact model before use.
Applies to: Northern Lights M40C3, Northern Lights M944
Before you start
- Do not use pry bars to remove injectors from the cylinder head.
- Overtightening can damage injectors.
- Do not use your hand to check for leaks.
Procedure
- Check injectors every 500 hours at a Northern Lights dealer or local injection repair station.
- Clean loose dirt from around injectors and fuel lines.
- Relieve high pressure by loosening delivery line flare nuts at each injector.
- Remove delivery lines as an assembly; do not remove spacers; cover all openings.
- Remove return line retaining bolts, washers, and return line.
- Loosen injector retaining nuts a little at a time and remove the injector and injector seat.
- Install new injector seal washer seat and injector; evenly tighten retaining nuts.
- Reinstall return line with new sealing washers and tighten bolts.
- Reinstall injection lines and tighten flare nuts at injection pump; leave loose at injectors for bleeding.
- Bleed injection lines, tighten flare nuts at injectors, start engine and check for leaks.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Injector retaining nuts: 18.1 to 25.3 ft/lbs (24.5 to 34.3 N·m)
- Return line bolts: 13.0 to 15.9 ft/lbs (17.7 to 21.6 N·m)
- Flare nuts at injection pump: 19.5 to 23.9 ft/lbs (26.5 to 32.4 N·m)
- Flare nuts at injectors: 14.5 to 17.4 ft/lbs (21.0 to 23.0 N·m)
Full service-parts list: Northern Lights M40C3 →, Northern Lights M944 →
Source: Northern Lights operator's 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.