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From: bcking@inmet.UUCP
Newsgroups: net.auto.tech
Subject: Re: Engine Rebuilding
Message-ID: <102000016@inmet.UUCP>
Date: Wed, 11-Dec-85 20:26:00 EST
Article-I.D.: inmet.102000016
Posted: Wed Dec 11 20:26:00 1985
Date-Received: Sat, 14-Dec-85 23:39:21 EST
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Nf-ID: #R:isrnix:-64100:inmet:102000016:000:4888
Nf-From: inmet!bcking    Dec 11 20:26:00 1985


**  Reface this wine with your sausage  **

There's a lot of variability in engine rebuilds.  In all cases you will
be trading off either your time or someone elses time (read: your money)
for one or more benefits.  To answer your questions point by point:

> How sucessful are engine rebuilds (assume they are done as well as
> possible)?

>   I've heard that a proper engine rebuild can restore an engine
> to new or better performance.  I've also heard that you can never restore
> an engine 100% with a rebuild - things have stressed, warped, etc. (after
> 100k miles) and that you cannot expect to get the same amount of mileage
> out of a rebuilt engine as you got from it when it was new.

An engine rebuild can indeed restore an engine to new or better than
original.  Any low rent engine rebuild/swap shop can deliver close to
new performance for another 30K miles or so.  If you want the engine
completely worked over it will probably last a whole lot longer than
the original did.  I don't know about Volvo engines or the going rates
in your area, but to get an American V8 rebuilt here in New England will
cost anywhere from $800 to $3500.  You could spend a whole lot more if
your looking for high performance modifications and parts.

A cheap rebuild generally involves decarbonizing the head(s), knurling
the valve guides, replacing bad valves, new oil seals, new rings,
a look at the carb, and a look at the distributor.  They never do bearing,
rod, or crank work, and if the head needs to be decked they'll try a
thicker head gasket instead.  These guys guarantee their work for about
a month or 1K miles, so they play the odds that no major bottom end
failures will pop up in that time.  It's a safe bet- unless something
is seriously wrong with the engine when they take it down it's not very
likely to blow up for a long time.

You're buying a whole lot of psychological benefit with a cheap rebuild.
The car runs noticably better once it's done, because they only rework
the parts which will make the most difference.  You feel better when
you see your neighbors in the morning and your car isn't choking the
county in a blanket of blue fog.  And you didn't spend that much money
to keep your rig rolling for another few seasons.

By contrast, a complete rebuild involves bringing ALL engine tolerances
back to their original or better values.  Balancing (matching components
for optimum fit and uniformity) and blueprinting (optimum assembly) can
make the engine last longer than a (typical) new one does and deliver
better performance to boot.

In addition to checking and replacing all worn parts, a top rate rebuild
will aslo include a careful check of the block, head(s) and other major
cast parts for cracks, and remachining of the block or head surfaces that
need it.

> My car is beginning to show some oil consumption (more than 1qt every
> 1200 miles) and at first I thought of dedicating this christmas to
> rebuilding it.  Now I'm considering only taking off the head to replace the
> gasket (it does leak) and having the valves/head machined (new/knurled guides
> of course).  I have a feeling (from looking down into other engines of it's
> type) that most of the oil loss may be from valve leakdown and not ring
> wear.  All compression specs are at or above the factory specs (I may
> have some carbon around the rings to help me along).  My major objective
> is to recover oil consumption (or lack thereof) with minimal engine
> trauma and greatest longevity.

> If I recondition the head will the added pressure (from well-sealing valves,
> etc.) simply accelerate the wear in the bottom end?  Is it silly to do
> partial (top end) rebuilds?  Am I being penny-wise and pound foolish?

If you want the cheapest route to keeping the car going for another few
thousand miles, I'd recommend just driving it until it really NEEDS work.
Then figure out if the rest of the car is worth the money for a rebuild.
If you just want to get another 30K or so out of it, you may want to just
do the top end.  I'd check this out with someone who really knows the
pathology of Volvo engines.  It's possible that your particular engine
wears out the bottom end before the top.  This is rare, though.
Having the engine rebuilt by a cheap and dirty rebuild shop will yield
the same end result.

If this car is your baby and you expect to keep it forever, you might want
to track down a volvo restoration shop for the rebuild, or for pointers
on your engine's peculiarities if you intend to do it yourself.  It's a
whole lot easier to find both good advice and good shops to do work on
American V8s because they've been used for racing for such a long time,
but I'm sure it's possible to dig up the same sort of expertise for your
Volvo.  Good luck.

R.M. Mottola
(Currently unemployed, but not for long.)

(Response posted for me by a friend.  This too shall pass.)