Quote:
Originally Posted by 1QuikWS6
Just a thought (I'm not totally up on newer BMW engines) but can you simply knurl the existing guides as we did on muscle car V8's?
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Yes you can. In fact BMW makes two sets of valves for the M52: 5mm and 6mm. Normally you'd need to replace valves anyway so you'd get the larger ones and bore out the guides slightly. I think that's the way BMW wants you rebuild the head. I talked to several shops and they said that's a really risky thing to do because there a good chance the valve guides are most likley not true. With the tolerances being so tight on the N52, here's a good chance of a significant amount oil getting through. They said its safer just to replace the guides since they're so cheap.