[Supras] Question about head gasket (hopefully last)

[t72pwrd]

While I appreciate the answer, and it does make good sense, do you 
understand that I was trying to be flippant?   I expected a flippant reply. 
Relax a little bit.  These cars are a lot of fun, have some!



----- Original Message ----- 
From: <berniek at technicaldevelop.com>
To: "t72pwrd" <NHOLDEN1 at woh.rr.com>
Cc: <Supras at supras.com>
Sent: Sunday, June 04, 2006 8:35 PM
Subject: Re: [Supras] Question about head gasket (hopefully last)


> Your last question relates to why most head gasket failures involve 
> cylinder
> #6 rather than #1.  I believe the reason involves greater heat, higher
> temperature at the rear of the engine, as it is further removed from the
> water pump.  In years past, inline engines had steel water distribution
> tubes within the block.  From all appearances, that does not appear to be 
> so
> with the 7M.  Higher temperature at the rear of the engine is also 
> reflected
> in part in greater cam journal wear (complete disappearance of the soft
> "mystery coating") on the exhaust side of the engine at the rear, probably
> from thinning of oil.  I've experienced this, as have others I've
> corresponded with.  One other problem I've had and others have written 
> about
> is a slow coolant leak from between the head gasket and the block, again 
> at
> the rear of the engine.  This, too, would indicate presence of higher cold
> to hot temperature differentials at the rear of the engine as opposed to 
> the
> front.
>
>            BernieK
>
>
> ----- Original Message ----- 
> From: "t72pwrd" <nholden1 at woh.rr.com>
> To: <berniek at technicaldevelop.com>; "Craig Thommes" 
> <cthommes at adelphia.net>
> Cc: <Supras at supras.com>
> Sent: Sunday, June 04, 2006 7:35 PM
> Subject: Re: [Supras] Question about head gasket (hopefully last)
>
>
>> IIRC the 1/2J motors came with MHGs from the factory.  I think that was
> the
>> biggest reason they don't blow as frequently as a 7M with a composite
>> gasket.
>>
>> Don't worry about adding fuel to a flame war, this list can certainly
>> withstand it.  I actually miss the frequency of the flame wars from a few
>> years back.  They were entertaining, fun to engage in, occasionally
>> educational and always resolved peacefully :-)
>>
>> BTW, if it was "cumulative end to end differential expansion" why doesn't
> #1
>> blow too?  Put that in your pipe and smoke it you lousy &#@!#$$%^%!  LOL!
>>
>>
>> ----- Original Message ----- 
>> From: <berniek at technicaldevelop.com>
>> To: "Craig Thommes" <cthommes at adelphia.net>
>> Cc: <Supras at supras.com>
>> Sent: Sunday, June 04, 2006 6:24 PM
>> Subject: [Supras] Question about head gasket (hopefully last)
>>
>>
>> > Inline 6 cylinder engines are probably the longest which use aluminum
>> > heads and iron blocks.  Other engines have shorter heads, which
> minimizes
>> > cumulative end to end differential expansion or head warping.  Most 7M
>> > gasket problems happen at the sixth cylinder, apparently due to
> cumulative
>> > differential expansion.  My JDM engine showed deep grooving in the head
>> > and block around the stock gasket crimped rings, especially at the 
>> > ends,
>> > presumably from tendencies of the block and head to "walk" with respect
> to
>> > each other due to thermal cycling.
>> >
>> > I do not want to add fuel to a flame war here.  I just want to know 
>> > what
>> > the consensus is regarding life to be obtained from a 7M with a Cometic
>> > gasket (mine was special ordered as 2 mm thick).  I'll be running 14 
>> > PSI
>> > boost and ARP head studs.  I'd like to be able to get 150K miles with
>> > periodic retorquing if needed.  Got that from the stock head gasket 
>> > with
>> > 72 Lb-Ft. retorquing at 8 PSI.
>> >
>> > Just out of curiousity, what did Toyota do in the 1J and 2J engines to
>> > eliminate the problem?
>> >
>> > Thanks.
>> >
>> >        BernieK
>> > _______________________________________________
>> > Supras mailing list
>> > Supras at supras.com
>> > http://supras.com/mailman/listinfo/supras_supras.com
>>
>>
>>
>