Datsun Roadster Forum-311s.org

Just want to verify, as I'm going to retorque my head bolts. Does the valve cover gasket need any sealant or is it just a pressure fit seal for U20? I'm always afraid to tighten those 2 big cover nuts too tight and I'm seeing a bit of oil seeping at the corners.

I use sealant gasket-cover, but just hand-tighten the nuts as far as I can (I have strong hands).

Permatex #2 was recommended , for the 1600, it stays pliable.
Linda

I don't use anything, and am very nice to the big bolts... hand tighten only until snug and firm but they WON'T feel tight (like they can't move more), otherwise you risk breaking the cover. Wipe both surfaces free of oil (head and gasket) first.

By "hand tighten" I mean I am using a 24mm socket with a 10" ratchet, but turn with my hand on the socket end until snug and a bit beyond but not much. They have never loosened up.

Also check top of head surface for flatness. I have never used sealant on a U20 cover, 1600 yes but a u20 gasket should seal fine without it.

Probably the thing that most people miss with sealing a U-20 valve cover is that the cover with only 2 nuts holding it down is easy to over tighten and cause a leak because of this. There are two other problems, in many cases the heads top surface is not flat. When the head becomes warped and you remove take it to the machine shop for repairs they do not always cut the top of the head to match the bottom. This causes 2 problems, one the cam does not turn freely in the head and can sometimes break because of this. And 2 when they do cut the head as per Rallye Enterprises and others, you only cut the head flat to the end of the cam tower portion of the head. This results in the head dropping away at both ends more at the front that the rear. In addition when the heads have been taken apart and put back together the studs do not always get put in correctly and hit the underside of the valve cover.
The best thing to do is before putting the gasket on put the valve cover in place and look at how it sits. Then if it falls off on the ends as I have described, there is a simple fix to get a good seal. Place heavy string in the gasket groove at the areas that you need to push down to closer to the head and then you will get even sealing pressure on the gasket. If the valve cover is high centering on a stud, this too is an easy fix. When you find this problem put some grease on each of the suspect studs set the cover on and pull it back off, the stud or studs that touch will leave a grease mark inside the cover. To fix this put a plastic bag over the head and poke thru the plastic where the stud hits only. The bag will act a seal then lay heavy nonflammable cloth over the plastic bag and grind the stud down till it does not contact the head with no gasket on the valve cover. The plastic bag will keep grinding grit out of the engine.

Dave

I like the heavy string idea! Good call.

After checking for flat surfaces, if it seems OK, I always use a very thin bead, 1/8" of black RTV in the groove of the cover gasket before putting it on the cover, then a thin bead on the outside of the gasket where it touches the head. Put the cover in place and wiggle the cover and finger tighten nuts so the gasket just makes contact, let sit overnight to cure the rtv, then tighten nuts a little bit more by using a socket, but only turning the socket by grabbing it like a screwdriver handle, no ratchet, usually about half a turn before I start to get nervous, as Mr. Premo said, VERY easy to overtighten, causing a cracked valve cover.

I do as Greg suggests. Hand tighten the big nuts....always with that little voice in my head saying "not too much, not too much" no sealant needed. This has worked great for many years on both of my u20 cars. My Solex B cam has a leak problem. First it leaked on the dizzy rear side. I moved it around and now it leaks on the intake manifold. Its a new gasket. Thinking of trying an older gasket. Maybe the gasket needs to take a set - get some high heat cycles before it settles ? Anyone had this experience?

Tightening is not the answer and i really don't want to,use sealant. leaks are minor...so hoping it will find its level and seal.

Ya, I edited my earlier post as I don't really use the length of the 10" ratchet; I keep my hand on the socket end.