2. Oil burning: About 1 quart every 3,000 miles.
To me that's a positive indicator. Many times someone will want to put a fresh set of
heads on an engine that's burning a quart every 500 miles, and unless it's a clear case
that
only the valve stem seals are the root cause of the excess oil consumption then I
usually tell them not to do it.
Especially if the oil burning is combined with low oil pressure at a hot idle. Even more
so if the engine sounds like a diesel on a cold start due to piston slap.
3. Overheating: About 5 months ago, my idler tension pulley burnt out on the freeway, kicked the serpentine belt off, and my truck overheated. I replaced all the parts, but I'm wondering if this was the start of my problem...
I think so. In the bathtub curve of the service life of a SBC, you can accumulate a lot
of miles on one of these (even though all the gaskets/mating surfaces are no longer in
brand new unworn condition) ...IF it never overheated. A good overheat can easily stress
a vintage head gasket to failure. But IF the overheat is promptly corrected, oftentimes
the overstressed head gaskets will wait to fail until a few more miles have accumulated.
And I think that this is where you currently are. As the talent in here will tell you, be
extremely suspicious of any potential heat-related cracking in those heads. Meanwhile,
I've seen a lot of blocks soldier on after a overheat w/no real problems, especially if it
was a 1-time event like your serpentine belt failure would cause. To understand why this is,
all you have to do is visualize where all the combustion heat is concentrated. (Exhaust
valves, combustion chambers, and piston tops vs everywhere else.) IF you use a
really savvy machine shop that has worked hundreds of sets of SBC heads they will
be able to guide you as to whether your heads are good candidates for a rebuild, or
if a new set of heads is a better long-term investment.
4. Smooth operation: The truck runs great overall, the ONLY thing I can think of is that at very low RPM (like coasting through a parking lot on cold start) sometimes the truck will 'lug' or 'lurch', almost like you're about to stall a manual transmission (the truck is auto). It's noticeable because it will jolt you a little bit.
I do agree an engine replacement is optimal, however spending $1k to have a truck that runs around town vs $5k+ for a new motor is a better scenario for me at the moment (just had our first kid, literally yesterday).
CONGRATULATIONS! Becoming a dad is by far the best gig I've
ever had. So good that even engine building
became a way to save money (in order to do right by my daughters) as opposed to being the ultimate
destination, if you know what I mean. (I'm the guy who would rather work on something cool on
the engine stand rather than be stuck on a cruise ship power noshing...with no engine building books
to pleasure read. :0)
And since you aren't running your business off of this truck while it's constantly loaded to the max GVWR,
if you can take a large, good flat file across the engine block surface and get everything to clean up to the same
overall color (especially between the center cylinders) then I think that you will be able to put a good-enough
long-term fix on this engine to cover your 'runs around town' needs.
Thank you again for the advice. I will vacuum out all the gasket debris in the cylinders, examine the cylinder walls, clean the pistons (not sure with what yet), and proceed with my cylinder head project (valves, etc.)
I think an affordable set of brass brushes that you can put on your drill (see attached) will give
the ability to clean up the piston tops without causing any damage. Just bring each piston pair
up to TDC and take your time. Use a little solvent if needed, but otherwise these will give you the
kind of results pics that you would want to share with us. :0)
And a large, fresh file may seem like a luxury, but that's how all us shade tree mechanics were able
to visually prove to ourselves that we caught the head gasket failure in time before the block deck
was permanently damaged.
Best of luck. And again congratulations on your newborn. Way cool.
