SharkSkin

Yes, I would... absolutely. When the gasket is first torqued down, it compresses and conforms to the minor surface irregularities in the head and the block. Essentially you then have surfaces mating with equal pressure over the area that's compressed. You can never re-align all of the parts so that all of these microscopic features line up the same way again. So what will happen, when re-torquing, because the metal has already been deformed into a specific shape(again on the level of barely visible to microscopic), when you attempt to deform it to the new shape there will inevitably be places that are under more pressure than designed, or less. It's the areas that are under less pressure that are at higher risk of becoming a leak path. Sometimes it's fine, sometimes it's not. Do you feel lucky?

GlenL

I feel lucky. That's what keeps me goin'!

Are the head gaskets going back in with the same head and block?

m21sniper

Sharkskin gave a good explanation as to why it's considered a no-no(and really, it is considered a no-no among engine builders).

Composite gaskets are designed to perfectly take shape with the mating surfaces once. Once the gasket has been crushed it does not 'rebound' if you take it out...so the next time it's crushed it will not perfectly seal the mating surfaces unless you perfectly re-align it(which strikes me as impossible from a practical standpoint).

Of course 'perfectly seal' and 'seal' are different things, so odds are it will work for a while....but not for as long, and maybe even not at all.

If you want to reuse your headgaskets you should just get some copper shim type gaskets. You can use those over and over, and because they're generally slightly thinner, you also get a slightly higher compression ratio, and therefore, slightly more power. Copper shims also transfer heat better, so they do have their advantadges.

AO

Hell, it's not my car, so, I'd...

6.0-928S

When I was first taught to build engines I was told never to install a crushed gasket. There is no 'spring' or resistance to crush left in the gasket. The second time it is used, to get the proper torque it must be crushed further which deteriorates the gasket. I'm not a scientist but I'm 52 now & I've built a lot of engines (although the vast majority are domestic the theory is the same) & never had a blown head gasket on a NA engine. I have always used a used head gasket to do my setup measurements, including my current 928 stroker build in progress. My opinion FWIW.
Hammer

Jim bailey - 928 International

When you drain the oil on a 928 you are supposed to use a new crush washer... perhaps that makes it clear.

mark kibort

yes, that does make sense, but i never change the washer (who would have guessed. im thinking Anderson doesnt even run one to save weight!

hey, you never answered my question regarding the oil pickup for scots car. should we go old style with the large pickup , vs the newer stuff that looks like a ladle (sp?) with a screen on the bottom?

thanks,

Mk

Jim bailey - 928 International

Mark you would be correct about Anderson because he drains his oil by opening the valve on the bottom of his remote oil tank. As far as oil pickup preferences very generally most later designs are better than the early or else why would Porsche change it ? You have to figure they were trying to make it better or cheaper.

mark kibort

thanks!

mk