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Join Date: Jan 2003
Location: San Francisco Bay Area
Posts: 1,194
Valve Guide Wear Effects?

I understand the basic symptoms of valve guide wear and even have a worn valve guide and valve from a friend's 993. My question is this - what happens to the engine when valve guides wear? I know that oil can get by the guides into the combustion chamber and cause burning oil and consumption issues. But what bad things happen to the engine?

This is what I have been told, but I want to understand better the issues:

1) Worn valves can fail to cool the combustion chamber properly and can cause the valves to heat up to the point of metal failer.

2) Worn valves can allow fuel to get into the cylinder and wash down the oil causing the cylinders and or pistons to wear prematurely.

Is this correct? What else happens? Thanks for helping with what may be a stupid question.

Old 07-14-2003, 05:19 PM
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emarsh's Avatar
Join Date: Jun 2003
Location: Central Texas
Posts: 100
Worn guides can hammer out the seats as the valve goes where it wants to, not where the guide says it should go.
1979 911 Targa
406ci Chevy powered '88 Fiero GT
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Old 07-14-2003, 05:30 PM
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Join Date: May 2002
Location: Portland, Oregon
Posts: 8,932
I just had my worn guides replaced. Done to the excessive wear, I neded to buy 12 valves. The machine shop noted that several of the valve stems were thinning as well as the damage to the valve ends.

I also noted that prior to the rebuild, I was adding oil every 200 miles and my oil always had that yellowish goop in the filler neck. With 200 miles on the rebuild, all I see is oil in the oil tank.

I am sure I was approaching a catatrophic failure but luckily for me, I took care of it while the damage was limited to the valves only.

1970 VW Sunroof Bus - "The Magic Bus"
1973.5 911T Targa - "Smokey"
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Old 07-14-2003, 07:39 PM
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Old 07-14-2003, 07:39 PM

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