re-use never run head gaskets??
#16
Originally Posted by GlenL
If you torqued it down and then removed the head, would you get new gaskets?
An engine builders trick to to re-torque the head multiple time to make sure the gasket is fully crushed and the studs are all at the same force. Seems like that's what oyu've got: a pre-crushed gasket. It's not bad to have lost "fresh springiness" as that's absolutely what you _don't_ want.
An engine builders trick to to re-torque the head multiple time to make sure the gasket is fully crushed and the studs are all at the same force. Seems like that's what oyu've got: a pre-crushed gasket. It's not bad to have lost "fresh springiness" as that's absolutely what you _don't_ want.
#18
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.
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.
#20
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.
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#22
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
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
Originally Posted by 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.
#23
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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.
#24
thanks!
mk
Originally Posted by 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.