
Completion of new cylinder heads (OHV)
Information on diagnostics
Valves run in valve guides, they are shrunk into the cylinder head and fitted with sealing rings. If lubrication juice runs into the skirt of the combustion chamber, replacement of the valve stem seals should be considered. When mounting the valves, apply some oil to the skirt. A valve spring compressor which compresses the springs can be used to install valve heads and springs – meaning the valve cotter halves are easy to insert. The valve then still has to be ground in. For this purpose, either the sealing area of the valve or the valve seat are thinly coated with abrasive paste. You can find more detailed information and instructions on valve assembly/replacement in OHV engines (the designation for engines where the camshaft is mounted in the crankcase in this context) in this article.
Checking the components
Preparation

NOTE
Carefully clean the mounting parts to be re-used and replace any defective used parts.
Checking used valves





Checking the rocker arms


Checking the valve guide clearance

Guide values for the valve guide clearance
Valve stem Ø | Intake valves | Exhaust valves |
6 – 7 mm | 10 to 40 μm | 25 to 55 μm |
8 – 9 mm | 20 to 50 μm | 35 to 65 μm |
10 – 12 mm | 40 to 70 μm | 55 to 85 μm |
Measuring the valve recess

If the valve recess is too small, check whether the correct valve is being used. Replace the valve if required, or rework the valve seat insert until the prescribed recess dimension is achieved.

An excessively large valve recess leads to diminished compression. If the valve recess is too small, the valve may collide with the piston during operation.
Valve tightness test
Vacuum test

Grinding in valves

NOTE
New valves may already exhibit radial eccentricities due to damage in transit. It is therefore also recommended to check new valves for concentricity.
Mounting the components
Mounting the valve stem seal


NOTE
The use of protective bushings is recommended to ensure that the sealing lips are not damaged on the sharp edges of the valve cotter grooves.

Valve stem seals with metal supports must be carefully and lightly tapped into place using a plastic hammer. The seal is in place when you hear a different (deeper) tapping sound.
Mounting the valve springs

Video - COMPLETION OF CYLINDER HEADS FOR UTILITY VEHICLES
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