Operating temps

[Daniel Ciobota]

Mike,

 I agree with the hot temps playing havoc with gm aluminum heads.  I just had
mine redone (1st time in 120k miles), and they had to machine them .010" to get
them straight again.  Lucky for me, the seats were ok, and guides were fine
too... the reason for rebuilding?  Busted head gaskets (surprise!).  I think
some gm engineers should be tied up and dunked in 240deg antifreeze mix, that
might change their thinking about what temps to design the cooling system for.
;-)

Daniel


Mike Rolica wrote:

> Not trying to get anybody all riled up.. Just looking at it from a
> machinist's point of view.  You may think there is no damage but what us,
> the machinist sees is a different story.  Hmm a connection? Almost all L98
> alum. Heads I've machined, the deck is out 15-20  thousands of an inch out
> of flat and the seats are pounded in, ESP exhaust . You also see that the
> deck and cylinder walls tend to be out of flat and out of straight
> respectively.  I can guess within about 10 deg F how hot the engine has been
> run when it comes in for the 2nd rebuild. (That is if I had prev. rebuilt
> it, i.e. line honing decking boring planing the heads.  Not disagreeing that
> higher temp does not get more power. I agree that too low is bad too.
> 165-195 seem to be a good range provided you can get oil temp up.  This is
> where oil cooler/warmer is good. But on stock gm blocks/ heads high temp
> plays havoc on their "shape". Due to that cylinder thickness, deck thickness
> is fairly thin. Now if you used a bowtie block that had been annealed you
> can run your 240-260 no prob or if you have used reg. block and fill block
> half full of block cement to prevent the cyl walls from going crooked and
> busting.  Fords are even worse .. :-)  ESP 3.8 v6 heads   I hate them!!!!
> All of them are like bananas within 60 000km and the seats pounded so bad
> that have to put new ones in to get a seat, valve guides all wore ect ect
> ect.:-)    BTW  it also depends on what you run your clearances at and your
> rpm ie rod,pist-wall, main valve-guide.
> Mike Rolica
> EXT. 260
>  :-)
>
> -----Original Message-----
> From:   Daniel Ciobota [SMTP:dciobota at hiwaay.net]
> Sent:   Friday, September 24, 1999 7:47 PM
> To:     gmecm at efi332.eng.ohio-state.edu
> Subject:        Re: Operating temps
>
> Well, since this is a gm ecm list, and we're talking gm operating temps, the
> stock L98 corvettes (84-91 models) had fans that kick in at 230deg... on hot
> summer days with ac on, it's not uncommon to see operating temps on those
> cars
> climb up to 240 before coming back down.  This happens regularly on those
> motors, with no damage to them.  Btw, the boiling point of 50/50 antifreeze
> is
> somewhere around 265deg... synthetic oil starts to turn to tar at 470deg I
> believe.  Oil temps run regularly to 260deg on those cars as well.
>
>  Just another (gm) datapoint.
>
> Daniel
>
> Mike Rolica wrote:
>
> > DRUGS!! LOOK WHAT THEY DO!!  The highest thermostat I've ever seen is 195
> > deg at 280, serious engine damage occurs!  Mine runs at 212 max! oh by the
> > way  my 1999 vw golf vr6, the first fan kicks on at 203 off at 195  second
> > kicks on at 212 off at 200.  At 220, the ecm kills the motor!  Been there
> > too.
> > Mike Rolica
> > EXT. 260
> >  :-)
> >
> > -----Original Message-----
> > From:   David Cooley [SMTP:n5xmt at bellsouth.net]
> > Sent:   Friday, September 24, 1999 3:15 PM
> > To:     gmecm at efi332.eng.ohio-state.edu
> > Subject:        RE: Operating temps
> >
> > At 02:52 PM 9/24/1999 -0400, you wrote:
> > >DO THE PISTONS EVEN SLIDE IN THE BORES AT THAT TEMP? MIGHT BE KINDA HARD
> ON
> > >RINGS AND STUFF, BE PRETTY TIGHT!  DE HEADS (ESP. ALUM.) MIGHT LOOK LIKE
> > >BANANAS :-)
> >
> > Ya Know,
> > Any new vehicle you buy with an electric fan runs at 220 to 225 before the
> > fan kicks on. 240 isn't that hot compared to 220-225...  Oil temp (without
> > a blocked cooling jacket for the water...) will probably be within 10
> > degrees or so of the water temp.  This has been the case since the
> > early-mid 80's.
> >
> > ===========================================================
> > David Cooley N5XMT Internet: N5XMT at bellsouth.net
> > Packet: N5XMT at KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068
> > We are Borg... Prepare to be assimilated!
> > ===========================================================