Do you have a S38 leaking valve cover?

[M5BB]

This leaking valve cover issue was driving me nuts so on Saturday I decided to examine the problem.

What seemed strange to me was that others were complaining of the same issue.

So what is common about our cars and the problem?

The gasket……

But more than that there is nothing that can be done about the gasket as least right now.

I removed the valve cover and checked everything for flatness.

All pretty good with only a few thousands from end to end. Not anything that shouldn’t be pulled down for a seal.

I was then thinking about the fact that acorn nuts can only tighten till they bottom out so I measured the height (with a digital caliper)from the cam box sealing surface to the bottom of a nut installed on the stud.
I then measured the thickness of the valve cover with the gasket and washer.
I got a number which represents the amount of compression that would be achieved with the acorn nut bottomed out on its stud.
This number was .028. Now that’s about what a sparkplug gap would be.

Not much crush of the gasket.

I decided to get either thicker washers or double up with 2 on each stud. This about doubles the crush number.

I have a good local hardware store and was able to get some 7mm flat washers.

I used two washers per stud and installed the valve cover.

I could feel the crush as I tightened it down.

The leak is gone.



My thought is that as gasket materials improve the supplier of these gaskets has allowed the thickness to become smaller not realizing that we have a limit on the ability to tighten the (acorn) nut that holds the valve cover down.

Just my thoughts.

Any way I don’t have a leak and you can’t tell that there are two washers on each stud.

HTH

Gary Beck

[bojangles]

are you sure that the studs were tightened into the cam tray all the way?
If the studs are not in all the way then the nut will bottom out before the valve cover is tight.
If the nut bottomed out on the stud, then you should be able to continue tightening by driving the stud deeper in.

maybe the studs were changed some time ago for longer ones?

I dont have this problem at all... seems strange to me.

[M5BB]

Could be but how can you drive a stud deeper when it is bottomed out?
As far as I know mine have never been removed.
How long has it been since you bought a valve cover gasket?
Maybe not your problem but i know of at least 3 others.

[JW in VaBeach]

Haven't had this problem yet but thanks for the info.

[Philo]

Hi Gary.., followed your post on Yahoo S38. Mine still leaks and I've already tightened the nuts again, replaced the gasket, checked the cover for straightness... so what's next, goop the valve cover gasket with Indian Head ?

I haven't gotten to that step yet since my last valve cover gasket didn't leak..., so I'm kind of miffed why she's leaking now. But that was with the flat b35 valve cover rather the the b38 cover I have in place due to the coil on plug setup. So.., my situation complicates things since we have different covers.

So what's the common denominator ?
* thinner spacer washers.
* change in spec with the castle nuts
* change with gasket material

I'm not really sure.., the next thing I'm going to try is tighten the castle nuts down again. Then check the new spacer washers against the old ones in the hardware drawer.... after that.., if I still have a leak, I'll try the Indian Head.

[M5BB]

Phil, not sure what to tell you but it's thicker washers under the castle nuts that you want because the castle nuts can only tighten till they bottom out.

You need more compression.
I think the gaskets have gotten thinner.
I know the ones I'm using now have a different composition than the ones 4 years ago.

[Philo]

I also noticed in the ETK that the castle nuts for the b38 valve cover are a different part number and three times more expensive.

I'll put on regular nuts and see if that solves the problem.

Thanks Gary... How's that new garage ?

[Jeremy]

It's possible that the original valve cover gasket was dc'd and the part superseded by a later part that fits but is slightly different. S38b38 being the last one that they made that's the surest bet for the part that replaced the earlier one if this is the case. It might be worth it to see if b38 spec studs and castle nuts are any different dimensionally than the earlier fasteners.

The washers are likely the less expensive and less troublesome solution, however.