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Registered
Join Date: Jun 2001
Location: France
Posts: 95
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valve guides
When I read previous messages, i'm really surprised about the fact that one of the weaker part of 911 engine seem to be the valves guides, maybe even before early chain tensionner.
I've never been told about it here, in France. Can fuel be responsible for this difference? My car is 200,000 km and has never been rebuild, in spite of hard use (average speed about 200 Km/h (125 Mph), high revs...) compression ratios are still good, but I planned to change rings and valve spings and seals, but not the Guides. Is it possible to do it myself or is special tool required? is there a way to know if valves need to be replaced? |
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06-12-2001, 07:24 AM
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Registered
Join Date: Sep 1998
Location: Bremen, Germany
Posts: 162
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Welcome European user, 200 kmh sounds familiar.
For changing the valve guides, the heads have to be removed, the old guides to be bored out, new ones to be fit in (freeze/heat and press), valve seats to be ground, valves ground in, and everything put back together. That can only be done at a specilized shop. But replacing the guides is not that expensive. To tell if it is necessary try the following: Get under load up to about 4000-4500 RPM (Acceleration, best in high gears). Lift your foot until about 2500 RPM is reached (engine braking only). Then give full throttle and look in the mirror: Excessive blue smoke: time for replacement. If you plan on re-ringing anyway, thats the point to do the valves as well! But do that only if your engine case is not leaking yet... BTW: most old cars' engines with >150k km driven in Europe will need new valve guides. Its not a P-car symtom. Have you been behind an old 3' or 5' BMW recently? They are used to smoke LIKE HELL! Jens '76 2.7 CIS with '73 body conversion |
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06-12-2001, 08:52 AM
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