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[Abiton]

So, rather than hijack other peoples' threads, here's one of my own.  I'm not trying to be 'difficult' here, I just don't understand.

Every other day on here I read about how overtightening the bolts that hold the plastic camcover(s) on can cause the cover(s) to warp.

Now please look at this picture (4-pot item, I think) of the inside of a camcover and explain to me how, with the metal insert, and the surrounding of solid plastic cylinder and the reinforcing ribs; overtightening the bolt could possibly cause the cover to warp.  I'm guessing that V6 covers have substantially the same construction.


The O-rings have, what, 0.5mm of squish before the plastic and/or metal insert bottom out on the cam caps and can go no further.

The only danger I can see in overtightening these bolts is cracking a camcap, not warping the cover, and I've never heard of that happening either.  Tighten them evenly, and in a sensible sequence, sure, but can the 8Nm really be critical?  I just can't see it myself.

Educate me peeps. 

[Entwood]

I'm probably well wrong and TB or Mark will correct me ... but I believe that if you overtighten then as the centre is pulled down on to the bolts, the edges splay outwards, so destroying the seal made by the gaskets.

If you over tighten anything... it has to give somewhere and I believe , in this case... it is the sides flexing that occurs first.

 :-/ :-/ :-/ :-/

[Abiton]

But the top of the camcaps stop it going down too far.  If they didn't the o-rings wouldn't have anything to seal against.

[dave10]

i blame the gaskets themselfs because before you put the cover back on you can wiggle the gasket left to right so when you fit the cover back on the engine one part of the gasket could slide left and another part slide right causing a slight twist in the gasket which will be alot harder to compress causing the warping

[feeutfo]

only ever layed eyes on my own cam covers, and had similar thoughts. Also seen The Boy post hes never seen warped covers. My only thoughts where, another of those myths, similar to the one about fitting carlton rear bushes, or localised damage directly around the bolt holes possibly twisting the brass insert in the cover from overtightening, but as you say, they do seem sturdy enough.

End of the day though, bolts only need to be tight enough to compress the gasket.

[Bionic]

Entwood has got it right, they can be splayed out by overtightening the centre bolts but if a torque wrench is used - as recommended - then the problem does not arise.
 :yOld saying - If a jobs worth doing its worth doing right!
The second most important thing is that none of the aftermarket joints are worth a damn! They will leak in time regardless of what you do. Only the VX ones fit as they should and do what they should. You get what you pay for in other words.
When you do it remember to replace all of the o rings under the bolt heads too or the bolts might just weep.
GudLuk

[mudflap]

All the torque wrenches i have seen are for sockets, is there a special adapter tool for hex bolts?


.

[Andy B]

All the torque wrenches i have seen are for sockets, is there a special adapter tool for hex bolts?


.

You just use Torx sockets instead of hexagon sockets. 

[amba]

Just buy a set of torx sockets to fit 3/8 drive or what ever size you require.3/8 seems the best size for most jobs...

[Auto Addict]

If the cam cover bolts couldn't be over-tightened, then Vx wouldn't quote the 8Nm figure.

 

[Marks DTM Calib]

If you over tighten the bolts a few things happen:

1) You strip the threads in the alloy cam cap.....not good, you then get a leak!

2) You can crush the metal insert (its not mega strong), seen this a few times, this in turn splays the surrounding plastic out and distorts the cover.......you then get a leak.

THE major issue is point 1......I found a few like this on a 2.6 I had to do the cam cover gaskets on and this car had recently had the same job carried out by an ex-member on here.

I have said it quite a few times but....manufacturers dont use torque wrenches during assembly for no reason as it adds cost....plus, those who dont use a torque wrench obviously consider themselves to have a greater level of experience and knowledge than the original designers....

[megaomega123]

I slightly over tightened one of mine on previous omega and managed to strip it very quickly. As said, torque values are given for a reason and usually follow harsh testing of the values and the characteristics of over and under torquing an item.

[Abiton]

Well, thanks for all the feedback.

I did buy a torque wrench for this job, which has been useful many times for other things since.

My impression remains that the covers are very, very unlikely to suffer any distortion through 'normal' levels of tightening on these bolts.
Stripping of threads in camcaps I can see being a major setback though.

 

I don't consider myself more knowledgeable than virtually anyone BTW, I've just seen the thing and drawn my own conclusions.  The reason for the thread was not to attack anyone's beliefs, just to find reasons.  Thanks for all of your assistance with this.