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Re: need big time help


>OK folks.  The mechanic just called and this is his take on the
>smoking/misfiring engine.  I had switched it to Mobil One 5w30
>with factory filter about 2000 miles ago.  He thinks that the Mob1
>is too thin for the engine and that it "queered"

We need to revise Webster's best on this .

>the engine.
>Basically oil was getting into the cylinders and causing it to
>run rough, and ultimately a lot of oil, causing it to smoke

If the engine was too loose for 5W30, I could see it burning some oil that
got past the rings and valve seals.  It probably would have shown a low oil
pressure as well, assuming that the bearings were as worn as the rest of
the engine.  The amount of smoke you describe, however, and the suddeness
of it, sound as if something gave way abrubtly.  Possibly an oil ring or a
valve seal.

>He says my only options are a) rebuild and b)
>replacement, he recommends the latter.

I think I'd need a bit more detailed diagnosis than "queered" before I
would spend that kind of money.  If, for example, it is valve selas that
have gone, you're looking at a head job.  It should be easy to determine
what has died with a leak down or compression test.

>I suggested flushing the engine and running a thicker oil,
>because as I pointed out, none of the engine tolerances should
>really have changed.  He's going to dump some 10w40 in and see
>what that does and call me back.  Does this make sense?

I don't think it will work, since it sounds like a more sudden and
traumatic failure than the wrong oil.

>I guess I'm looking for feedback overall.  Is this a possible
>scenario?  He claims he's seen several engines do this

"This" would certainly require some additional definition before you'd get
anywhere with Mobil.

>on Mobil
>One.  If so, Mobil's footing the bill for this if I have any say
>in the matter.  I also wonder why it ran fine for 2000 miles or
>so then suddenly did this.
>Postmortem... he just called and reports that the #1 and 2 plugs
>were soaked in oil, but #3 was dry and... the plug tip was ripped

I can't figure that one.  What would cause the plug tip to be ripped out,
yet still allow the engine to run?  Could the tip have broken out fiht, and
fouled the engine?

>His guess is low oil pressure.

If low oil pressure was the culprit, the engine may have been too worn for
5W30.  If so, I don't think the fact it was Mobil's 5W30 would make much
difference.  Nor would the fact it was synthetic.

>At this point, he said it's
>not even worth putting oil in the engine.
>Oh, and that half-joke about sticking in a turbo engine?  He said
>the conversion runs about $6000 total.  A standard replacement
>should run $500-800 for the motor and 15 hours of labor ($900
>at $60/hr).
>| Dan |
>Dan Simoes                                dans@ans.net
>ANS                             http://coimbra.ans.net/dans.html
>100 Clearbrook Road                     (914) 789-5378 (voice)
>Elmsford, NY 10523                      (914) 789-5310 (fax)

Richard Funnell,
San Jose, California
'83 urQ
'87 560 SL