3.2 Carrera Rebuild - Case Halves, washers

[MikeMorgan]

Hi. I just bolted my engine case together after weeks of worrying about the Loctite and whether I could do it or not. Well, I think it worked out OK but....

With 25 ft-lbs of torque on the case nuts (M8) the aluminum washers crushed substantially, which I had read, they are supposed to. I've been reading in the forum that I probably should have not used the ones in the Pelican hardware kit but some others with harder alloy.

My question is, should I not worry about them as they are supposed to squish or should I replace each stud with a new type washer and new nyloc nut?

Thanks

Mike in Dallas
__________________
Mike

[Trackrash]

The case perimeter nuts should be torqued to 18lbs, which is 25nm. There should not be any major distortion to the washers at that torque. I guess at 25lbs the washers would be ruined.

[MikeMorgan]

Gordon, thanks. I feel like an idiot; I got the numbers transposed from the Bentley book and got my Nm and ft-lbs crossed. I wonder if I should leave it the way it is now for a while and let the Loctite set up and then change out each nut/washer one at a time.

Any thoughts, Anyone?

Thanks again

Mike

[Walt Fricke]

Mike - leave it alone. Yes, next rebuild may require replacing the crushed washers. Yes, they will be a modest pain to pry off. No, this won't affect the integrity of your motor. No, your nuts don't have to be replaced. No, don't worry about your studs. Torque specs for things like this are quite conservative. The major stresses on the case are carried by the case through bolts, which are calculated to act like a big enough spring to keep the bearing webs always in contact with each other. Not much of that stress gets applied to the smaller case studs.

While you gain no benefit by over torqueing these studs, neither are you apt to suffer any detriment operationally. Yes, you might keep an eye on them in case one shears and the nut and part of the stud goes AWOL. But I'd not worry about it. None of the studs broke, so none are likely to do so in the future.

I've always used thin steel washers for this application - the sealing capabilities of a crush washer really aren't needed. For valve covers, you really need the stronger aluminum sealing washers, because covers come off relatively often to check valve lash, and prying crushed ones off maybe doubles the time for the work.

Let the sealant cure and move on.

[proporsche]

hi Mike
are you talking about the around the case nuts and washers?If yes there should not be an aluminium washer but steel washer.
No silicon type nut either.
Steel washer and steel lock nut type nut...
on this locations...
this nut with the washer torgue as you know now 25 nm...
http://cdn1.pelicanparts.com/catalog/images/SuperStock/900-910-022-02-OEM.jpg

Ivan
here is a detail of an engine i am doing now..with the correct nuts



here are the correct washers

[Tippy]

Originally Posted by Walt Fricke

Mike - leave it alone. Yes, next rebuild may require replacing the crushed washers. Yes, they will be a modest pain to pry off. No, this won't affect the integrity of your motor. No, your nuts don't have to be replaced. No, don't worry about your studs. Torque specs for things like this are quite conservative. The major stresses on the case are carried by the case through bolts, which are calculated to act like a big enough spring to keep the bearing webs always in contact with each other. Not much of that stress gets applied to the smaller case studs.

While you gain no benefit by over torqueing these studs, neither are you apt to suffer any detriment operationally. Yes, you might keep an eye on them in case one shears and the nut and part of the stud goes AWOL. But I'd not worry about it. None of the studs broke, so none are likely to do so in the future.

I've always used thin steel washers for this application - the sealing capabilities of a crush washer really aren't needed. For valve covers, you really need the stronger aluminum sealing washers, because covers come off relatively often to check valve lash, and prying crushed ones off maybe doubles the time for the work.

Let the sealant cure and move on.

Yes, the voice of reason.

OP, worry about other stuff, you're fine.

[MikeMorgan]

Thanks Everyone for the replies and advice. I think I will take Walt's advice and leave as is and not worry about it for now. Maybe next time.

As for the nuts and washers, I used the ones from Wayne's harware superkit and it states that Outercase Mounting Hardware should be M8 Nylon Self-locking nuts and Aluminum Washers.

Regards from steamy Dallas. Feels like 140 in the garage!

[proporsche]

I have never ever seen on 911 engine nylon nut in my 30 years of working on engines. Unless someone put them there so it is everyone choice....There are no nylon nuts and alu. washers on 911 Carrera engines.... ever;-)

Ivan

[Walt Fricke]

I've put nyloc nuts on my engine case studs, but Porsche only put them on the valve covers (or is it just the aftermarket kits which have them).

I've always used the thin steel washers for this job, but when helping a friend put a case back together I switched his aluminum washers (maybe they were magnesium - not overly malleable like some aluminum alloy washers), he later looked up in the parts manual for his model, and lo and behold the 72-3 parts manual shows 22 aluminum washers for this application. But the '74-7 manual shows steel washers here, so I expect Porsche kept that up for later models.

The take away from this is no one should worry if he used aluminum washers which crushed.

[Trackrash]

Interesting that my '78 SC motor had aluminum washers apparently from the factory. I don't believe the case had been split before. I always thought it was odd to use aluminum washers under torqued nuts.

[Flat6pac]

Ive always seen nyloc nuts on the permeter of factory 911 factory builds until the last couple years of Carrera the they changed to prevailing torque nuts. Replacing prevailing torque nuts with new seems to eat the threads too much.
The bag of new PT nuts I find make nice exhaust stud nuts if the threads are questionable..
Bruce

[proporsche]

Hi Bruce.. our shop then only used the steel nuts back in the 1980`s, there could be a reason i could not see nylon nuts and have been using on rebuilds only steel nuts.When you said later Carrera`s used the lock nuts .My 911 had already steel nuts and steel washers...in 1985...before i took it a part...

Ivan

[Walt Fricke]

While I don't think the Nylocs hurt anything, neither do I think they help. I've never seen one of these case bolt nuts back off. Have any of you seen that? I suppose if the builder spun the nuts on by hand, and then missed getting a wrench on one of them, it could fall off. But that doesn't seem like something a change of nut type would help much. And I suspect that one of the 22 or so nuts missing would not lead to a leak, eithr, though I don't volunteer to test this.

Proper application of the sealant, so it surrounds the stud holes on the case halves, should prevent any oil at all migrating to and along the studs to get past the nuts/washers. I've not seen weeping there (other than that pesky IS stud, but that is a special case and it is not a periphery stud).

Valve covers are different.

[proporsche]

Walt..2x well said....i am just being ...super-genau..;-)
Ivan

[Walt Fricke]

Well, puenktlich also means precise or accurate. which fits.

[proporsche]

hi Walt ..that what i said originally but my German wife has corrected me to this,super-genau...

[gtc]

PET shows aluminum washers and nylok nuts for the case perimeter.

[Flat6pac]

But until just recently steel perimeter washers came I'm the bottom end kits, not aluminum.
If you keep the sealant inside the bolt perimeter you won't have to worry about leaks on the centerline .
Bottom trailing edge of centerline there is a spot that needs extra sealant because metal runs out of sealing surface.
Bruce