Valve Guide: Service and Repair

REPLACING VALVE GUIDES

Removing

Working from the camshaft side, use a facing cutter to mill projecting valve guides until guides are flush with cylinder head. With a sharp blow with a hammer, dislodge each guide and use a press to force out toward combustion-chamber side.






Installing

The holes which accommodate the valve guides in the cylinder head will have been made slightly wider by removal of the old guides. New oversize valve guides must be installed and machined to fit (see table of sizes).

1. Measure valve-guide holes in cylinder head.
2. On a lathe, machine the oversize valve guides to the correct outside diameter to fit the hole in the cylinder head. The squeeze for intake and exhaust valves must be 0.06 - 0.09 mm.
3. Dust machined valve guides with talcum powder and, working from the camshaft side, press guides into cylinder head with improvised mandrel.

4. With a broach or on a precision drilling bench, bore valve guides out to size "g" = 9.00 - 9.015 mm. If no other tool is available, a reamer can also be used to enlarge the valve guides.
Important: Always set or clamp the cylinder head at the correct angle before pressing in and boring the valve guides.
After replacing valve guides, check bearing pattern on valve seat and remachine valve seat if necessary.






Table of sizes for installing valve guides:

Valve guide Outside diameter Hole diameter
*Valve guide Cylinder head

Standard size (series) 13.060 13.000 - 13.018
Oversize 1 13.260 13.000 - 13.200

* Machine outside diameter of valve guides to fit diameter of hole - take squeeze into account.