Valve cover leaks
#1
2nd Gear
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Join Date: Mar 2002
Location: Mechanicsville, VA
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I just had my 74 2.7 rebuilt to RS specs with PMO carbs. I changed to turbo vavle covers with the new type (green) gaskets and I still had leaking. I tried the gray graphite gaskets and still have some leaking. I was wondering if anyone had tried the silicone gaskets that Performance Products sells ($69.95)? I am even considering putting C2 style covers on if I have to but that requires changing the studs. Please help if you know a fix.
Thanks
Thanks
#2
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I have been using the silicone reusable valve cover gaskets for two years with good results. You just have to be careful when removing them to do a valve adjustment; they could get snagged on one of the studs and rip.
I assume you have cleaned the mounting surfaces for the gasket (heads and covers). Sometimes residual gasket material will be stuck to the mounting surface and cause a leak. Did you replace the nylock nuts and washers on the valve covers? They should be replaced each time you remove the covers. Finally, it is very easy to over torque the valve cover nuts. The valve cover nuts have a very low torque (like 10 lbs); overtightening these nuts can also cause leaks.
Bruce
I assume you have cleaned the mounting surfaces for the gasket (heads and covers). Sometimes residual gasket material will be stuck to the mounting surface and cause a leak. Did you replace the nylock nuts and washers on the valve covers? They should be replaced each time you remove the covers. Finally, it is very easy to over torque the valve cover nuts. The valve cover nuts have a very low torque (like 10 lbs); overtightening these nuts can also cause leaks.
Bruce
#3
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Something else to consider - Wayne Dempsey comments in his "101 Projects" book that sometimes the casting process can leave the turbo valve covers slightly deformed. He recommends that if you're still getting leaks, to have the valve covers milled flat at your local machine shop, so they will be completely flat when bolted to the car.
#4
Instructor
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I have been struggling with this myself. First I used the standard gray and it leaked. Switched to a greenish gasket with silicone bead, the leak still persisted but somewhat better.
Had cover checked for flatness on a surface plate and was maybe within .002. Will most likely try and machine next time off .
Had cover checked for flatness on a surface plate and was maybe within .002. Will most likely try and machine next time off .