Valve guides — checking and replacing (BMW 7 Series E32)

When restoring a cylinder head with leaky valves, it is not enough to treat the valves and valve seats or replace them. It is very important to check the valve guides for wear. This is especially important on engines with high mileage. Worn valve guides do not ensure uniform valve seating and cause increased oil consumption. If the wear is very significant, the guides must be replaced in a workshop.

Remove the valve.

Remove any deposits from the guide bushing using a fine awl.

Insert the new valve from the combustion chamber side. The end of the valve stem must be covered by the guide bushing.

Check the play by rocking the valve back and forth.



To check, apply a steel ruler or dial indicator to the valve plate. The clearance should not exceed 0.5 mm.

If the clearance is too large, you can turn the guide bushings and install repair-size valves with an increased stem diameter.

Caution: If the guide bushings are turned or replaced, the valve seat must also be treated.

If the guide bushings are so worn that they can no longer be machined, replace them.

Press out using a mandrel on a press towards the combustion chamber.



Heat the cylinder head to 50°C and cool the new guides to -15°.

Install the guide bushings on the press using a mandrel. Dimension A should be 13.5 mm.



After pressing, the guide bushing hole must be reamed to the required value.

(You can find the original version on the portal www.bmwman.ru)