Valve guide bushings — design description (BMW X5 E53)

The valve guides are made of a special brass alloy based on bronze and are pressed into the cylinder head. The parameters of the intake and exhaust valve guides are the same. The valve guides, cooled with liquid nitrogen to a temperature of minus 150°C, are pressed into the cylinder head, which has a temperature of 30 - 50°C. The valve guides are not supplied as spare parts. Checking the wear of the valve guides is especially important for engines with a long service life (car mileage).

The gap check should be carried out using a measuring device (see fig. 6.55), similar to gasoline engines, and should be no more than 0.5 mm.

Parameters	Size, mm
Inner diameter:
nominal	6,00
admission
inlet	from 0.0 to +0.015
outlet	from +0.015 to +0.03
Maximum clearance rod/bushing	0,50

Information taken from this resource «BMWMAN.ru»