Leaky valve covers ?

[Jeff Balazs]

Now that I have my engine running I have a few small oil leaks to deal with around the valve covers. What do you guys like to do for a fix on these? I have new gaskets and fiber washers on.

Thanks for your input.

Jeff

[HanksB3B]

Jeff,

The gaskets used to be cork now I think they are a rubberized material. Tightening the heck out of the special screws is not necessarily the answer because there is a tendency for them to "dish" and actually work in reverse of doing what they are supposed to do.

Possible Alternates:

1. Make your own gaskets from 1/8" cork? (make a router template?)

2. Use gasket cement (works but not my favorite) to glue the rubberized type to the cover plate and no gasket cement on the block side?

Hank

[Plymouthy Adams]

personally I would check the borders of the cover plates..making sure they are not dished already and ensure the four sides are on the the plane..

[ggdad1951]

my replacement was cork!

[Jeff Balazs]

Hmm.... I had one off the other day and it did not appear to show any distortion.

It had a small drip going so I tried smearing some permatex on it and refitted it. Of course now it is leaking in a slightly different spot.

It has a new Felpro gasket. When I ran the truck again yesterday the other cover started dripping too.....and I was careful not to disturb it when working on the rear one Sunday.

I have another set of valve covers and some new rubber gaskets from VPW I guess I can try them and see if there is any improvement.

Jeff

[52b3b Joe]

I had to retighten mine a few times after I got mine running. I don't know if the heating and cooling does something to it, but now mine don't leak anymore once retightened.

[Jeff Balazs]

Took out one of the thumb bolts on the front cover just now. It looks like it is leaking from around the bolt holes. Turns out the seat area of this bolt is not flat. If I put a flat washer on it it wobbles significantly. So instead of the cover being dished it is the sealing surface on the bolts. Looks like some sort of rubber washer arrangement would probably work.

Jeff

[Don Coatney]

There should be no pressure above atmospheric in the valve chamber unless your engine has excessive blow-by and all crankcase vent holes are plugged. And all splash oil should drop into the crankcase assumimg the drain holes are open. I have found that cork gaskets work the best in this application. Pictured are the cork gaskets I am using in my Desoto long block engine as the rubber gaskets I tried failed.

[ggdad1951]

as Don shows there should be some washer gaskets on the bolts.

[Jeff Balazs]

Yes I had those washer gaskets. Problem was (I think) that the surface that they seal against on the retaining bolt is distorted. Of the 4 bolt 2 had significant distortion......almost 1/16" You would never get a thin hard fiber washer to seal that much. After about 15 minutes of running time they began to weep oil around the bolt hole.

I have made a fix from a rubber washer and a hardened steel washer which I think trues up the sealing surface for the fiber washer. I will let you know when I have tested it for a while.

Jeff

[Jeff Balazs]

OK my fix appears to have worked. Ran for 25 minutes...no leaks at all.

Funny how small things like this can mess with you. To look at these retaining bolts you would think the sealing lip was true....and they probably were back in the day. Well one less thing to fuss with now.

Jeff

[greg g]

over tightening is the most common cause of leakage other then a failed gasket or bent parts.

[Plymouthy Adams]

over tightening is the most common cause of leakage other then a failed gasket or bent parts.

actually I have found that overtightening is actually the root cause for bent parts and gasket failure due to over squish..kind of a three part package

[Jeff Balazs]

Yes I agree. I am sure that these distorted retaining bolts were caused by just that. Two were good and two were not. Not a huge problem but one that was not as visible as a tweaked sheet metal cover either. The valve covers themselves seem just fine and the main rubber gaskets are working. Of course these covers are not in the easiest location to get to. And that is probably why they got the "rough" treatment in the first place.

Jeff