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Easy head gasket question
by
1slowvw
on 09 May, 2012 13:33
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Hello folks, I'm back from a long diesel hiatus (although I was a pretty hard core lurker on the site before).
I'm preparing to re-assembly an AAZ I had put together years ago that has recently come back to me. Unfortunately I'm hours away from a torque wrench and the car. I do however have the motor here, a new head gasket and bolts.
What I'm wondering it will it hurt it to put the head on with the bolts snug and let it sit for a few days until I get home to torque it down to spec.
I can't see this hurting the gasket but I figured I would ask the pro's first. Assuming this is still where the north american IDI pro's lounge about.
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#1
by
CrazyAndy
on 10 May, 2012 20:55
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Since they're single-use bolts I wouldn't risk it. If it's dust getting into the cylinders you're worried about, I'd suggest just laying some blue painters tape over the deck if it's clean enough. It won't leave any residue on the sealing surface.
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#2
by
JamesT
on 10 May, 2012 22:31
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I'd go for it. Just make sure you snug them to a lot less than torque spec. Just enough to keep the head on. They're one use only bolts because they stretch when torqued. Not torquing them means no stretch.
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#3
by
theman53
on 11 May, 2012 04:40
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I wouldn't put it on. For no other reason than the torque settings are not only to clamp the head on but they are even so it doesn't warp. If you feel confident to put it on evenly then no harm done, but I don't even store my heads laying flat just in case of warpage.
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#4
by
745 turbogreasel
on 11 May, 2012 12:23
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Unless the head is wet, I don't see the difference between waiting 30 seconds or 30,000.
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#5
by
R.O.R-2.0
on 11 May, 2012 12:40
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I'd go for it. Just make sure you snug them to a lot less than torque spec. Just enough to keep the head on. They're one use only bolts because they stretch when torqued. Not torquing them means no stretch.
im with James...
GO FOR IT..
i have a set of WASTED head bolts that i use EXACTLY for this purpose.. i have 11mm, 12mm, and 16v head bolts, all used..
they are more used as TOOLS now, rather than fasteners..
i would just set the head on, and tighten the bolts hand tight with the triple square bit..
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#6
by
JamesT
on 12 May, 2012 00:42
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How could a head not torqued fully sitting on the surface on which it was made to mate to warp?
If these heads were that susceptible to damage, they probably wouldn't stand for 30 years of heat cycles and hammering.
And I don't store my heads flat either, but not for fear of warpage, but because I don't want it to sit on a valve.
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#7
by
92EcoDiesel Jetta
on 12 May, 2012 06:21
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How could a head not torqued fully sitting on the surface on which it was made to mate to warp? If these heads were that susceptible to damage, they probably wouldn't stand for 30 years of heat cycles and hammering.
And I don't store my heads flat either, but not for fear of warpage, but because I don't want it to sit on a valve.
x2. some people are just neurotic lol
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#8
by
R.O.R-2.0
on 12 May, 2012 11:11
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How could a head not torqued fully sitting on the surface on which it was made to mate to warp? If these heads were that susceptible to damage, they probably wouldn't stand for 30 years of heat cycles and hammering.
And I don't store my heads flat either, but not for fear of warpage, but because I don't want it to sit on a valve.
its not possible for the head to warp, when its sitting on the deck its supposed to mate to..
you have to get these heads REALLY HOT to warp them.
and with the head bolts barely more than hand tight, the engine isnt going to be over heating, or running for that matter..
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#9
by
theman53
on 12 May, 2012 13:54
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Do what you want. My machinist said never to put your head flat unless it was torqued down to it. Metals bend, especially if let sit over time. Me and my luck, I try to do everything the machinist says. Not because it will happen everytime, but I don't want to be the 1 in 1,000
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#10
by
745 turbogreasel
on 12 May, 2012 14:14
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I'm gonna go put all my warped heads upside-down
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#11
by
smutts
on 14 May, 2012 12:32
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Run flat out, there must be something like 2500 psi plus in those cylinders, (no I don't know the exact figure), if that head will stand up to that then how the hell will it warp laid flat?
The reason head gaskets blow due to the wrong tightening order is that the gasket can't flatten out properly and buckles, not that the head is cast out of cheese. But then again I put my shoe on the wrong foot this morning.
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#12
by
clbanman
on 18 May, 2012 09:29
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Metal can stress relieve and move just sitting for a length of time. Mind you this tends to me more shortly after some type of process application (welding, machining, etc.). We have actually done CMM measurements and other verifications on our frames showing this taking place. For most of the heads we are discussing, they have gone through heat cycling and enough time that the effect is probably minimal, but for example, if the heads were freshly milled, there would be potential for this to happen. Would it be enough to cause head gasket problems? That I can't say for sure.
Another example: my boss (in a previous job he had) produced large steel castings that needed to be stress relieved prior to machining. They did vibratory stress relieving but found that just putting the castings outside for about a year accomplished the same purpose.