Resealing, Rebuilding and Maintenance
Most owners of 911 based Porsches are very interested in their
cars and the intricacies of the engineering, design and technology that allow
the cars to function. They are more apt to want problems or glitches taken care
of promptly and fastidiously. Fortunately, the cars are not fraught with a
multitude of inherent problems.
Over the past 25 years of caring for and
repairing these fine automobiles, by far the most common problem I see is
related to engine oil leaks. The basic design of these air cooled engines finds
the pistons, liners, cylinder heads and camshaft housings, "hung"
from the crankcase, not bolted to a block with a head gasket as more
conventional water cooled engines. The lubrication system must provide a flow
of oil to and from the outer extremities. The system is also of dry sump
design. It doesn't utilize an oil pan, but uses a remote mounted reservoir and
a two‑stage oil pump whose job it is to pull the oil from the reservoir
and push it through the engine to the oil cooler(s) and back to the reservoir.
There are over 44 different points from which oil can leak.
Resealing a 911 engine involves, in most
cases, removing it from the car and a lot of disassembly and inspection of
these areas. Depending on the mileage, year and use of the car, several
decisions need to be made for a proper repair. Do we split the case and do a
thorough rebuild including cylinder head refurbishing, new crank main and rod
bearings, new layshaft bearings, timing chains and any equipment upgrades that
might make a more serviceable engine, or do we just disassemble it to the case
and replace any and all gaskets and seals which could or are causing leaks.
Since even a "simple" reseal is
very labor intensive, it makes sense to do as much as possible during the
repair that is called for. This initially costs more than the basic repairs,
which are needed; however, it is less expensive in the long run.
Attention to detail and a thorough
understanding of the engine's design and function are the keys to a successful
repair.
Kurt Hertel