Re: Low Compression 1990 200TQW IA Stage I

[Peter Kollias <pkollias@syrisscientific.com>]

Igor,

You mention, among other remedies, "hot tank the head" and "magna flux".  Would you
mind giving me a brief run down on what these two processes are?

TIA
Peter Kollias 5ktq (still going....)

four.rings@mcione.com wrote:

> Forhan, Thomas wrote:
> >
> > The bad news: 100/110/115/65/110, with a 25% leakdown on all five
> > cylinders. Also, light oil leakage at #4 sparkplug. Oil consumption is 1qt
> > per 2500 miles, no radical change over time.
>
> Should be a lot higher on your late 200 w/ 8.4:1 CR. The #4 is really screwed.
> Bentley sez compression should be 123psi to 144psi for a brand new MC
> engine (my guess is that the lower value is for my single knock MC
> w/compression ratio 7.6:1 and the higher value is for a late dual knock
> MC w/compression ratio 8.4:1 ). Wear limit is 92psi, max delta between
> the cylinders should be no more than 44psi.
>
> You can do just the valve job but what if after you assemble the motor (with all
> new head studs and EM studs/nuts!!!) the #4 does not come on par with the rest
> of them? You'll need to pull the head again and do the rings.
> OTOH, what if just the valve is burned on the #4.
> In any event, pull the head and examine the valves/seats. Then rotate the crank
> and examine the cylinder walls for scoring.
>
> > 116000 miles total.
>
> Just broken in.
>
> > I bought the car used at 82K , unknown history.
> > Switched to Mobil 1 and added  IA Stage I chip and spring mods, within a
> > few months of buying it.
>
> No problem here.
>
> > Struggling through the archives, seems like rings are unlikely. It sounds
> > like one or the other of (1) a complete valve job (2) just guides (3) just
> > the guide seals.
>
> With the 25% leakdown and such a low compression I'd suggest a complete valve
> job: hot tank the head, magna-flux it, cut the valves, replace the guides/seals.
>
> > I'd appreciate any and all thoughts, and I am particularly interested in
> > estimates of the time needed to R+R the head. Anyone know what the flat
> > rate books suggest?
>
> Sorry, can't help you with this. I've done all the heads myself.
>
> Igor Kessel
> '89 200TQ - 18psi (TAP). Head work done this past Spring.
> Some previously lobotomised fleet:
> '89 Mirage
> '85 5000s
> '84 M-B 220
> '86 Lada 2107
> '84 Lada 2105