Cummins/Onan B43 / B48 — Cylinder Head Removal and Installation
Repair & overhaul · cylinder heads
For the Cummins/Onan B43 / B48, from the Cummins/Onan service manual.
Applies to: Cummins/Onan B48
Before you start
- Torquing or removing cylinder heads when hot (above 700 deg F [37 deg C]) will result in head damage.
Procedure
- Use a 1/2 inch (13 mm) socket wrench to remove cylinder head bolts and lift heads off.
- Clean out all carbon deposits; do not damage the outer sealing edges where gaskets fit.
- Use new head gaskets and clean both the heads and the cylinder block thoroughly where the head gaskets rest.
- Place a head gasket on the cylinder head and align the stud holes with those in the cylinder block.
- Carefully install the cylinder head on the engine.
- Follow the head torque sequence shown in Figure 28.
- Graphoil head gasket: tighten all bolts to 5 ft-lbs (7 Nm), then 10 ft-lbs (14 Nm), then torque to 14 to 16 ft-lbs (19-22 Nm); recheck.
- Asbestos head gasket: tighten all bolts to 5 ft-lbs (7 Nm), then 10 ft-lbs (14 Nm), then torque to 16 to 18 ft-lbs (22-24 Nm); recheck.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Graphoil head gasket 14 to 16 ft-lbs (19-22 Amazon eBay FridayParts $39.99 Nm)
- Asbestos head gasket 16 to 18 ft-lbs (22-24 Nm)
- Remove cylinder heads for carbon cleaning and gasket change at least every 200 hours (400 hours on unleaded fuel)
Full service-parts list: Cummins/Onan B48 →
Source: Cummins/Onan 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.