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Registered
Join Date: Dec 2007
Location: Just a little north of 13669/Nation's capital
Posts: 1,289
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Need expert opinons on cam lobe wear
The pictures attached show the worst of 3 camshaft lobes on my 86 that exhibit some pitting. The rocker faces are absolutely perfect. Should I worry about this pitting? The car has 103,000 on it, runs great, doesn't burn any oil. I do have another set of cams and rockers but if this is not going to develop into something bigger, why bother to change them out.
 
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12-30-2008, 04:55 PM
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Manassas, VA
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Are the cams original to this engine? It almost looks like welding porosity rather than pitting. The off color around the area is interesting also.
I think that since it is a localized issue and the rocker arm surfaces look good, leave it alone until it requires a rebuild. Good Luck, Mark
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1991 964 Polar Silver Metallic Turbo Coupe |
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12-30-2008, 05:57 PM
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Max Sluiter
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Have you been using reformulated oil rather than Brad Penn or Swepco or something else with adequate ZDDP?
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1971 911S, 2.7RS spec MFI engine, suspension mods, lightened Suspension by Rebel Racing, Serviced by TLG Auto, Brakes by PMB Performance |
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12-30-2008, 08:21 PM
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Registered
Join Date: Dec 2007
Location: Just a little north of 13669/Nation's capital
Posts: 1,289
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Thanks for your answers. I think the discoloration is more a trick of the camera and light I was shining at the spot and also my finger wiping the area clean of oil. The car is fairly new to new to me and it appears that the engine has not been opened, at least any time recently. I have added a ZDDP additive since owning the car.
Last edited by brighton911; 12-31-2008 at 02:46 AM.. |
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12-31-2008, 02:42 AM
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Registered
Join Date: Jun 2006
Location: Virginia Beach
Posts: 556
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The cams will only get worse. You are thought the surface hardening. Price of cams vs price of new bearing if the metal from the cams goes through the engine. Make sure you don't have an oil restriction while you are at it. Change the cams.
Good luck with what ever you decide, Happy New Year, Rusty |
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12-31-2008, 05:03 AM
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abit off center
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What rusty said, If you check the hardness of the cam in that area you will find it rather soft. I have also found that after refacing rocker arms about 2 to 3 times they need to be hardened again if you only take of the min amount.
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______________________ Craig G2Performance Twinplug, head work, case savers, rockers arms, etc. |
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12-31-2008, 05:24 AM
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Somewhere in the Midwest
Join Date: Oct 2001
Location: In the barn!
Posts: 12,499
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Pitted cams like that is not uncommon. I've seen more on 3.2 than other engines, but it's a manufacturing defect for sure....the conditon of the lobe in the picture would make me want to get a new cam....
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12-31-2008, 06:37 AM
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Registered
Join Date: Jul 2001
Location: Portland Oregon
Posts: 7,007
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Having seen plenty of such things, I have a whole pile of cams just like those here,...
 Provided that the spray bars are not plugged up, what you see is due to using today's oils with insufficient ZDDP for these engines. Those cams can be repaired, but be sure to replace the rocker arm(s) if you do so.
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Steve Weiner Rennsport Systems Portland Oregon (503) 244-0990 porsche@rennsportsystems.com www.rennsportsystems.com |
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12-31-2008, 04:20 PM
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1991 Porsche 964 Turbo 3.3L
1971 Porsche 911S
1969 and 1986 Porsche Targa and Coupe 1720cc and 3
