The back side of my drivers side valve cover is leaking oil. They are the LG4 vlave covers and I think they were from an 85 305. I have a 74 350 in there now with the LG4 valve covers. The first time I put them in I used a calk gasket without any sealer and it leaked, today I put in another calk gasket with permatex sealer and it still leaked. Does anyone have any ideas on this. I was thinking maybe the valve covers warped or does a 70s engine use different valve covers, but I dont think so. I also have those 3 inch long metal bars that the valve cover bolts go through that distribute the torque of the bolt more evenly. Any help would be appreciated because this oil leak is driving me nuts and my car has been kicked out of our driveway becuase of its leaks.

Thanks,

Matt

 

The valve covers are the same as anything from the '70s.

Try this... take them off and see if the flange is flat. I betcha its not. Around the bolt holes, I bet its kinda bent in because they were over tightened.

Easy to fix though. Just put them on a hard block or somthing and pound them back flat. Problem solved.

 

Also check to make sure the machined surface on the heads are flat, and minus any deep scratches or gouges. Like air adam said though, it's probably gonna be a warped or dented valve cover flange.

 

I cleaned up the underside of my valve covers so they were spottless then flattened em out,then cleaned the head where the valve cover sits and then just used silicone around the valve cover with no gasket.set em in place with the bolts loosely in and let the silicone set.Never leaked again

 

Try using the neoprene gaskets. They seal much better than the cork. (also do not push out of place while being tightened as bad......) and best of all..... Reusable. (to an extent)

 

Thanks for the info guys. I'll go out there soon to see if my valve covers are warped. Do you guys recomend a brand of valve cover gaskets to buy becuase I just bought the generic ones from straus.

Matt

 

My personal favorite are the cheap cork ones, never had one leak myself. If you are looking for a "better" one, try the fel-pro rubber gaskets, they dont use sealant.

 

I just switched to Mr Gasket Ultra-Seal gaskets because the regular cork ones I put on when I swapped my heads were leaking on the drivers side. So far I have had the Ultra Seals on for about 3 months with no problems at all.

 

ive always used the cork gaskets also and never had a leak

i would suspect as stated before they have been over tightened at one time or another and the covers need some straightening

and remember do not tighten these down too tight they only need like 3 or 4 ft.lbs of torque to tighten them up

here check this out ...

http://www.boxwrench.net/specs/chevy_sb.htm

 

99.999999% of all cork gasket leaks come from 2 things. Insufficient cleaning of the mounting surfaces or overtightening. As a matter of fact, the passenger side valve cover has been taken off my car three times, and i have the same cork gasket on. If you put sealer on the valve cover, and stick the gasket to it and let it tack up. Then clean the head real well. No sealer on the head at all. This way you can pull the cover and still reuse the gasket, most of the time.

 

I just get the rubber gaskets, and use black silicone to 'glue' them to the bottom of the valve cover. Once they are cured, put them on the heads, tighten them up and they never leak. That way, they can be removed and reused a couple of times too, if needed.

Course getting cast aluminum valve covers usually fixes most sealing problems too