Northern Lights 984K / M984 — Injector removal and installation
Repair & overhaul · injectors
For the Northern Lights 984K / M984, from the Northern Lights operator's manual.
Applies to: Northern Lights M984, Northern Lights 984K engine
Before you start
- Do not use pry bars to remove injectors from the cylinder head.
- Overtightening can damage injectors.
- Escaping diesel fuel under pressure can penetrate skin.
Procedure
- 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 without removing the spacers; cover all openings.
- Remove return line retaining bolts, washers and return line.
- Loosen injector retaining nuts equally a little at a time and remove the injector.
- Remove the injector seat and cover the holes to prevent debris entering cylinders.
- Install new injector seal washer seat and injector; evenly tighten retaining nuts to 162 - 243 ft/lbs.
- Reinstall return line with new sealing washers; tighten bolts to 8.7 - 9.4 ft/lbs.
- Reinstall injection lines and tighten flare nuts to 18.2 - 25.3 ft/lbs; leave loose at injectors for bleeding.
- Bleed the 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 162 - 243 ft/lbs (2.24 - 3.36 kg-m)
- Return line bolts 8.7 - 9.4 ft/lbs (1.2 - 1.33 kg-m)
- Injection line flare nuts 18.2 - 25.3 ft/lbs (2.5 - 3.5 kg-m)
Full service-parts list: Northern Lights M984 →
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.