crg53

I have a small oil leak on the lower left side valve cover. The leak is around the stud and nut. With everything cleaned off, I started up the engine and ran it for some time, and you can see oil bubbling out on the top side of the nut, it looks like it is making its way up the thread. What is the best way to fix that little problem?

demonfish

if i remember correctly, the studs are outside the gasket?

id take the cover off, machine it flat, new gasket and replace...

elbeee964

You remember correctly, oh' Man of Magenta.
There's only a thick, plain washer under each of the valve cover stud/nuts. There's is no seal at the stud penetration through the cover.

Valve cover sealed areas are leaking past seals into these non-oiled stud areas.
Sorry.

Disassemble, and appraise nearby seals and sealing surfaces. (Nuts reinstall to 7 ft-lbs) <--- Corrected! (was "in-lb", should have been "ft-lbs".) Sorry for the stupidity on my part.

demonfish

...with new washers...

and maybe some sealant on the gasket

crg53

Thanks guys, now I know what I will be doing this weekend. The strange part was, that after I shot the engine off and let it cool down, the drops of oil disappeared, and they did not drip onto the floor.

elbeee964

You think that's neccesary?
Seems if the existing washers weren't 'scuffed' or radically blemished, that they'd be good for reuse.

(But this wouldn't be the first time I was wrong today... or the 54th.)

dfinnegan

What's up with the valve cover nut washers? Mine are thick. Seems like maybe a quarter inch thick. I ordered new ones, as they never come with the seal kits, and the new ones were like regular old (thin) washers.

Are these supposed to be thick or thin?

demonfish

i thought they were like crush washers and should be replaced - could be wrong though?

Duck

The ones on my valve cover were thick and not crush washers (not sure what value crush washers would be). Since the stud is outside the seal, it does not seem that the washers are that critical. I could be wrong. I reused my washers, but also using billet valve covers lower and upper.

dfinnegan

Yeah, I've been reusing my washers, but they are getting a little long in the tooth so I thought I'd order new ones. I'm back using the old ones as the new ones were so thin I figured they were just wrong.

J richard

The washers are single use and should be replaced with the gastket, they are aluminum and will crush, The factory valve cover kits replace the nuts and washers, I'd try just replacing the washer and the nut first.

dfinnegan

I've purchased the factory kit (I think!) from Sunset each time. I always get new nuts, but have never gotten new washers.

Really, they crush under 7 ft-lbs? I'm surprised. Mine don't look crushed. Just dirty and a bit corroded.

Guess I'll have to go back into the PET and get the "right" part number rather than just asking for the "valve cover washers".

Cheers

elbeee964

My work books are at the office, so I can't do the engineering numbers right now.
Will write more on these washers when I have those numbers in hand...

*************************
Edit
7 ft-lbs torque applies about 1775 lbs of load under a 6mm nut.

For the thick aluminum alloy washers I threw away from my last valve job (.551" od x .251" id x .124" thick), this came out to be a compressive stress under the nut's contacting surface (.372"od x .252" id) of approx. 30.2 ksi.

On the valve cover side of the washer that load is spread across the entire washer surface, so the compressive stress is approx. 9.4 ksi.

Figure an average -- not super aviation alloy -- heat treatment for that thick washer's matl.
So, I'll use 6061-T4 properties: Fcy = 14 ksi [mil-hdbk-5h]

So, you'd expect to see an impression of the nut onto the washer, but no embossing of the 'lower'/valve cover side.
(And as I'm looking over this old washer from my valve job, that's exactly what I'm seeing. --Shazam!)

My opinion:
The washer's material and thickness are required to spread the loads from a concentrated to a diffuse, lower, level of compressive stress onto the rather wimpy valve cover's alum. aly. surface. This is accomplished by a near-disposably inexpensive thick, aluminum washer.

Therefore, the washer's thickness is crucial to spreading/diffusing the load's application onto the valve cover.
If a thin washer -- whether steel or aluminum -- is used, I'd venture to say you'd risk embossing the valve cover material adjacent the stud. ...Or, since the valve cover is cast -- ie, not the strongest of aluminum conditions, void/discontinuity-pocked, and fracture-prone -- you'd risk cracking the valve cover with a thin washer.
So, always use a thick washer.

Reusing old (thick) washers I'd posit is a very low risk compromise. No biggie.

(If I didn't have replacements for *my* valve job, *I* wouldn't become nail-bitiingly nervous over doing that... That said, being OCD, I'd always argue with the supplying valve kit distributor to include new (thick) aluminum washers with the kit. Why? Because I'm paying good money and I want to see nice, shiny pieces, that's why!)

An emergency fix of stacking thin washers to get the same thickness would work, too... I guess... (-- but never on my car.)

crg53

Hey, thanks Elbeee, that is a very clear explanation. So the way I see my little problem is that the oil is getting past the valve cover gasket where is surrounds the stud and then making its way up the thread past the nut, and the thick washer is there to spread out the load, not as a sealing unit. Is there an o-ring under the washer or is it metal to metal contact?

dfinnegan

Thanks, Lonnie! That was a great explanation. As an engineer who's lost his slide rule, I appreciate the technical detail.

Cheers!