What is the Torque for 911 Valve covers

[kyriakos59]

Please someone advise on the torque needed for tightening the valve covers, upper and lower for a 1974 911 Carrera CIS. 8 Nm from Wayne's rebuilding book seems very low. My tool also starts from 12 Nm.

I have applied 30 Nm. Is it too much ? What are the consequenses for a higher or lower torque than the proper one needed ?

[kidrock]

Wayne's book is correct. Tightening the valve covers should be done in a crisscrossing pattern, starting from the middle of the covers and working your way to the outer portions.

8Nm is correct; however, sometimes it is not tight enough. Start at 8Nm, drive for 20-50 miles, and check for drips (which usually originate from the lower covers). If you have any drips, slowly and carefully increase the Nm a couple of pounds.

30Nm is probably too much, and may warp your covers.

[mca]

If you go too low you will have TONS of oil blow past the cover gaskets. Once the oil hits your exhaust it will look like your car is on fire.

Too high may pinch the gasket too much or possible warp the cover. Also leads to leaks.

I have the silicone reusable gaskets and I think that I use 10NM ... or just visually look at the squeeze of the gasket.

[Peter Zimmermann]

Originally Posted by kyriakos59

I have applied 30 Nm. Is it too much ? What are the consequenses for a higher or lower torque than the proper one needed ?

Something to consider. The following is an excerpt from a copyrighted work written by me on this very subject. Cheers!

A Logical Discussion:
Topic: Rocker/valve cover retaining nut torque for Porsche 911s built between 1965 and 1989.

Rocker covers evolved through four generations; (1) aluminum upper and lower (6-nut type) used from 1965-67, (2) magnesium upper and lower (11-nut type) used well into the ‘70s, (3) aluminum upper and lower (11-nut type) used on most ‘77s, early Turbo Carreras and early SCs, and (4) aluminum upper covers with heavily reinforced lower aluminum covers often called Turbo covers.

Gaskets also evolved; originally made of cork, then graphite composition, then a version with a silicon bead (lower) as well as ultra-thin, firm, self-sealing gaskets that ranged in color from green to almost blue. Hardware, always 8mm, stayed the same with one exception – very early 2.0 911s were frequently seen with non-locking upper cover nuts used in combination with wavy-type lock washers.

That’s the history. It is fact that the early cork gaskets could squeeze out from between the early covers and cam housings, especially under a heavy hand tightening the nuts. As a side note, my shop used cork gaskets (lowers were available for both 6-nut and 11-nut covers) to help seal up leaks caused by warped magnesium covers. Those covers were never “torqued,” just tightened by feel and using the visible gasket edge as an aid.

Along came lean burn engines, thermal reactors and excessive heat, which, in a way, was responsible for the development of the superior gaskets that we have today.

All the while, a plate (used through about mid-’83) on the bottom of the engine, usually referred to as an oil screen cover or a sump plate, saw fewer gasket changes; from thin paper to graphite, then to an improved even thinner graphite. No change to the torque spec for its 6mm (quantity 8) nuts was made – that held at 10Nm (7 lb/ft). Think about that for a moment; tiny 6mm nuts, each used with a wavy lock washer, tightened to 7 lb/ft.

Back to a set of rocker covers, sealed with graphite upper and lower gaskets. Those gaskets were quite firm, and about 1/3 the thickness of cork versions, it made sense that more torque could be applied. Certainly the hardware was up to the task, after all, it was identical to the crankcase perimeter hardware and the chain case to crank case hardware – 8mm Nylok nuts and aluminum sealing washers. Specified torque for that hardware? 25Nm (18 lb/ft).

The period through which gasket technology changed was interesting for my shop. Many of my customers bought new cars, and some opted to have us perform the required 1,000 mile service, rather than have it done at the dealer by an unknown (yes, Porsche pre-approved this and all warranties remained intact). We noticed, while doing those jobs, how tight the factory-installed rocker cover nuts were, and realized it was due to the new gaskets, and eventually better lower covers. We re-checked the Spec books (by this time we were servicing SCs), and decided that the “All bolts (fasteners) on crankcase and camshaft housing, M8 = 25Nm” had to take precedence over the note about a “cover, M8 = 8Nm” which co-incidentally appeared in the torque spec list with the camshaft bolt/nut spec. So, we used 18 lb/ft on a large number of cars, new and old with the latest gaskets, discovered that dis-assembly at the next scheduled service was perfectly normal, and made that spec routine for all except the cars that used cork gaskets.

We have now reached the point where the latest version sump gasket became identical to the chain case, crank case gasket. To review, the torque for the 6mm sump plate nuts is 10Nm, the torque for the 8mm chain case nuts is 25 Nm. The rocker cover gaskets that have been available for many years are thin, firm, and self-sealing. Rocker cover hardware is 8mm. Why would one consider 6 lb/ft – ONE LESS than the considerably smaller 6mm sump plate nuts, reasonable and appropriate for that 8mm hardware?

One must conclude that the 6 lb/ft spec; (1) was a typo (M8 instead of M6) that turned into a monster, (2) was a correct spec, but for original rocker covers using cork gaskets, or (3) was that it referred to the [3] 6mm bolts that secured the “cover” at the end of the camshaft inside the chain case, and two mistakes were made – one a typo and one in translation.

My personal belief is that #3 above is correct because; (1) the reference to a “cover” with “M8” hardware appears with the torque spec for the bolt/nut on the camshaft, and (2) that “cover” is called a “chain case cover” in later Porsche repair manuals, is noted to have, and is secured with 6mm hardware, and recommended torque is 8-10Nm (6-7 lb/ft). FYI: Later factory technical spec lists do a far more thorough job elsewhere as well. Not only did they finally correctly define “cover,” they itemize the specs for M8 hardware on the crankcase, M8 hardware on the cam housings, M8 hardware on the chain case, and included a spec not seen before – “Valve cover to camshaft housing.”
Logic.

With regard to this thread, 30Nm (about 22 lb/ft) is a bit high, but the OP's instincts are correct. The primary problem with the higher torque is that a chance exists where the aluminum sealing washers will collapse into the stud threads, making cover removal at the next adjustment interval extremely difficult.

[T77911S]

just my thoughts.

the washers are desigend to flatten. at 7lbs, does any of that happen? dont the washers provide some sealing too?
the gasket can make a difference too. i have the reusable ones. the last time i had the covers off, i torqued to 7lbs and thought there is no way this thing will not leak. so i tried more torque. and, as siad above, the gasket will squeeze out, not good either. so i went with a torque that was on the edge of starting to squeeze the gasket.

[Peter Zimmermann]

Originally Posted by T77911S

the washers are desigend to flatten at 7lbs, does any of that happen?

Absolutely incorrect. Taiwanese washers might flatten at a low torque, but proper German washers will hold shape to at least 20lb/ft. The two washers are distinctly different in appearance, the crappy washers are shiny, the good washers are a dull gray. Wrightwood Racing kits and all factory-approved kits come with the good washers. If you have doubts which you have put the head of an 8mm bolt in your vise, slip a washer onto it, install and tighten a nut against the washer. Use a torque wrench in small increments to learn when the washer crushes.

dont the washers provide some sealing too?

That's why they're called sealing washers. They seal the base of the Nylok nut to the cover. Any oil that walks along the stud threads, past the washer, will be stopped by the plastic insert in the Nylok nut.


the gasket can make a difference too. i have the reusable ones. the last time i had the covers off, i torqued to 7lbs and thought there is no way this thing will not leak. so i tried more torque. and, as siad above, the gasket will squeeze out, not good either. so i went with a torque that was on the edge of starting to squeeze the gasket.

No comment. I can't imagine a professional using a "reusable" gasket. I've never seen one, and would never consider using one.

Start in the middle, snug by hand lower/upper, lower/upper, working toward the outboard ends. Repeat with torque wrench at 15 lb/ft. Repeat again at 18 lb/ft.

[Formerly Steve Wilkinson]

"No comment. I can't imagine a professional using a "reusable" gasket. I've never seen one, and would never consider using one."

The thick orange silicone gaskets are indeed reusable, and they're widely used, and reused, by "professionals" in the general aviation industry,where valve-cover gasket leakage is not an annoyance, as in the Porsche world, but a potential disaster. I had them on the Lycoming engine in may last airplane, a Falco, and have them on my 911. Reused both times.

You'll also need a small low-torque wrench to get accurate numbers like the ones being suggested (correctly) for valve covers. The big one that you use to torque your lugnuts will be laughably inaccurate if you're trying to achieve seven or even 15 foot-pounds.

[Peter Zimmermann]

Originally Posted by Formerly Steve Wilkinson

The thick orange silicone gaskets are indeed reusable, and they're widely used, and reused, by "professionals" in the general aviation industry,where valve-cover gasket leakage is not an annoyance, as in the Porsche world, but a potential disaster. I had them on the Lycoming engine in may last airplane, a Falco, and have them on my 911. Reused both times.

Airplanes are also something I know nothing about. But I do know that my above "Logical Discussion" post was written using 30+ years in the trenches tuning, servicing and repairing 911 automobiles. We never had VC leakage problems, other than warp issues, which were corrected by VC replacement.

I appreciate your comment about torque wrenches, but I think that it goes without saying that a 3/8th" drive wrench is required for torque in the 15-20 lb/ft range.

[T77911S]

to provide sealing, dont they have to crush? and if the crush point is 20lbs as you say, then they are not being used properly, no?

i thought the nylon part was on there more as a locking device, to prevent the nut from backing off due to low torque.

i had both 3/8 and 1/2 inch wrenches cal'd last year. the cal guy comes in jan, will have them done again.

i have been reusing mine. i have been having problems with valve adjustments (i had a rocker come lose so i keep checking it) and there is no way i am putting new gaskets on every time, since these are not leaking. but then i guess i am not a profesional so it is ok. its always nice to say what you would do if you have deep pockets or it is not your money.

[Peter Zimmermann]

Originally Posted by T77911S

to provide sealing, dont they have to crush? and if the crush point is 20lbs as you say, then they are not being used properly, no?

High quality sealing washers, by their nature, are cut accurately to work within a known torque range by conforming to the two involved surfaces. Don't forget, the same washers are used on crankcase perimeter bolts/studs, which are also tightened to 25Nm. When I say "crush," I'm not talking about the soft metal conforming, I'm talking about the junk washers completely collapsing into the threads of the studs.

i thought the nylon part was on there more as a locking device, to prevent the nut from backing off due to low torque.

They actually end up being dual purpose. Early 2.0 911s did not use Nyloks originally, the covers were installed with regular nuts and wavy-type lock washers.

i had both 3/8 and 1/2 inch wrenches cal'd last year. the cal guy comes in jan, will have them done again.

Calibration is good! My wrenches are SnapOn, and it's getting close for me to do the same.

i have been reusing mine. i have been having problems with valve adjustments (i had a rocker come lose so i keep checking it) and there is no way i am putting new gaskets on every time, since these are not leaking. but then i guess i am not a profesional so it is ok. its always nice to say what you would do if you have deep pockets or it is not your money.

Don't get me wrong. I can only speak from the view of a professional 911 technician, even though my career began as a DIYer (I was building cars in my dad's backyard before I had a driver's license). You do what works for you, I've just tried to address the OP's post and correct some very flawed information that's out there.

Which washers are in your cabinet?

[Walt Fricke]

Peter

The orange silicone valve cover gaskets seem to work fine, and are, indeed, reuseable. They are sensitive to torque, sort of like the cork gaskets, because they are so flexible. The only issue I have had with them is that the engine needs to be cold for them to be removed, or they will tear while you are lifting them off the studs. But I think this flexibility and softness (squishability?) may be part of why they seal so well.

And most folks won't have occasion to try to remove a valve cover on a hot engine.

I'm not a shop owner or shop mechanic, but if I took my car (with these gaskets) to a shop for a valve adjustment or something, I'd expect not to pay for new gaskets. And I'd want the old ones to be reused (unless torn).

Thank you for posting the history of Porsche 911 gaskets. I have come to believe that Porsche specs, like any large amount of information, are subject to the occasional typo.

Walt Fricke

[vulcan300]

I recently had my second brush with a Victory Motors car at the shop (Cars purchased from that company are now banned from my shop). After removing all the bolts on the passenger side lower cover I found that the cover would not come off, which is unusually as I usually have to be careful so the cover doesn't fall right off. On closer inspection I found that some cheap flimsy washers had been used at the last valve adjustment and the washers had indeed crushed in the stud threads. It took 6 solid hours of very patient picking, twisting and tearing to remove every on of those damn washers without damaging he studs or the covers. The moral of the story is DO NOT use cheap thin washers when replacing your covers or you'll be very unhappy the next time you have to do a valve adjustment. Proper washers should be around 1 mm thick and should not squish into the thread when torqued.

As for torque I agree that one can go higher than the 10 N-M referenced in the Porsche service manual. However I've used 10 N-M many times along with one time use gaskets with the silicone bead and have not had any trouble with leaks.

[Wayne 962]

We sell the OEM kits that come complete with the gaskets and new hardware. These are nyloc nuts that go on the end of the studs and attach the valve covers to the camshaft housings. The Porsche spec is indeed very light. In my 101 Projects and Engine Rebuild book, I recommend tightening them to spec and then tightening them further as needed.

Gaskets will compress over time, and even if you crank it down right after a valve adjustment, you may need to retighten later on. I have used the regular, stock gaskets and the newer rubber ones. I do like the rubber ones, although tightening them down too tight can damage them. I usually don't actually torque these, but get out my 1/4" driver and tighten them down "light snug tight" with two fingers. This has worked pretty well for me, as I've never had any leak after doing this.

With the older-style magnesium covers, if you torqued them down too much, you could contribute to warping and easily cause them to leak. I don't think that's an issue with the aluminum ones, but I think the spec is reflective of the old mag covers that used to be over-tightened.

The bottomline? Tighten them down lightly and then increase if they happen to leak.

-Wayne

[T77911S]

i usually buy the kit as wayne stated, as most probably do. i used the rubber ones for the first time just recently. actually, they came on a 3.0 i bought along with the turbo valve covers so i pulled mine off and put these on my 2.7. at first i torqued them and then went back and tighened them some more, just to the point i could see it was compressing the gasket.
my old set was actually leaking at the stud. that was with the gasket that had a green bead on it i think, and of course new washers and torqued.

as for pro's reusing them, thats not their money so it is easy to say use new ones, plus they likely have them in stock and dont have to order every time they take off valve covers.

still. at 6-7lbs does the washer do anything over a standard steel washer?

[sc_rufctr]

Originally Posted by T77911S

... at 6-7lbs does the washer do anything over a standard steel washer?

The Alloy washers conform to the nut and rocker cover surfaces to create a seal. (even at 6-7lbs)
But more importantly (IMO) the alloy washers won't damage the rockers as the engine goes through its heat cycles.
A steal washer doesn't have the same compliance as alloy so I would continue using alloy.

On a side note I once owned a Fiat 500. (2 cylinder air cooled engine in the rear)
That engine had a steel rocker cover on top of the engine with a cork gasket.
You could only tighten the two nuts finger tight because any tighter and the gasket
would be cut by the rocker cover as the engine warmed up.

The problem is the alloy head expands at a greater rate than the steel studs and rocker cover.

At least our P cars have alloy covers but the steel studs still expand at a lesser rate than the covers.

I have always liked the steel spring holding on the air cooled VW engines rocker covers.
That seems like a good solution...

Anybody have experience with these engines?
Do they tend to leak at the rocker covers?

[peon77]

We call it German "specs" GudenTiecht

[Peter Zimmermann]

Originally Posted by Walt Fricke

Peter

The orange silicone valve cover gaskets seem to work fine, and are, indeed, reuseable. They are sensitive to torque, sort of like the cork gaskets, because they are so flexible. The only issue I have had with them is that the engine needs to be cold for them to be removed, or they will tear while you are lifting them off the studs. But I think this flexibility and softness (squishability?) may be part of why they seal so well.

And most folks won't have occasion to try to remove a valve cover on a hot engine.

I'm not a shop owner or shop mechanic, but if I took my car (with these gaskets) to a shop for a valve adjustment or something, I'd expect not to pay for new gaskets. And I'd want the old ones to be reused (unless torn).

Thank you for posting the history of Porsche 911 gaskets. I have come to believe that Porsche specs, like any large amount of information, are subject to the occasional typo.

Walt Fricke

Thanks for the explanation, Walt. The reusable gaskets may satisfy a need for some people, but I wasn't taught that way, and teaching old dogs new tricks...

Regarding torque specs, I'll say this one more time, with a couple of qualifiers. For 911s built through the '89 3.2 liter Carrera, that use 11-hole, aluminum lower covers, and use-once super-thin greenish blue gaskets, or green gaskets with a silicone bead, the torque spec for the 8mm Nylok nuts, used with proper German aluminum sealing washers, is 18 lb/ft.

It has nothing to do with heat cycles, or anything else. My shop buttoned up thousands of 911s using 18 lb/ft, many we didn't see until the next 15K service was due (many of our customers would have the in-between service done at an oil change only facility, or they would do it themselves). NONE had to return for follow-up tightening, NONE leaked, NONE had stripped hardware, NONE had hard-to-remove covers/washers, ALL were assembled using new gaskets, new washers, and new Nylok nuts.

[Gunter]

"GudenTiecht" is nowhere to be found in a German Dictionary, along with "Furbar"

Don't know where that nonsense came from.

Back to the Valve covers:

First priority: Clean mating surfaces thoroughly,
Second: Check covers for warp,
Third: Use Nylok nuts and Alu washers,
Fourth: Tighten gently from the center out, re-check/tighten after running for a while.
I tighten the bottom row just a tiny bit more than the rest, just by feel, without a torque wrench; no leaks.

I use ordinary paper gaskets and been re-using ordinary gaskets for years by doing what we've been doing for Industrial applications for years:

Smear grease on both sides of the gaskets before installing; they will seal and won't stick or break next time you open the covers.

It's a simple solution, try it, you'll like it.

[Wayne 962]

Originally Posted by T77911S

still. at 6-7lbs does the washer do anything over a standard steel washer?

Can't recall exactly, but I believe it was Jerry Woods who told me that the aluminum hardened washers are used to prevent electrolysis / metal transfer interaction that would interact between a steel washer and the aluminum case.

-Wayne

[OnAir]

Hi,
OK I am not a car mechanic but I am an engineer with quite a lot of mechanical background.
Can somebody please explain - why do the valve cover gasket kits need sealing washers under the nuts?

If the gasket is working, the threaded studs should be dry shouldnt they?

Doesnt really make sense to me but I stand to be corrected.