Cam In Head Engine Longevity by
William R Blankley
more by William Blankley
Thank you, Tony
Massey, for your information. You confirm my theory that
the Manta thrives on hard use and regular maintenance. My
experience has been that at about 50K miles the bores
have lost maybe 3 tenths of a thou. going on to maybe a
thou at 100K. By this time the piston ring grooves are
about on the limit for wear. Replacing the rings helps a
lot. Certain makes of aftermarket rings are relieved so
as not to foul the wear ridge at the top of the bore,
Replacement Opel rings are an expensive waste of time,
causing damage unless the bores are honed To remove the
ridge. However, what really causes the problems is the
build up of carbon in the inlet ports. I have had two
engines in this state, the terminal stage of which is
characterised by idling on three cylinders, the deposits
can build To perhaps 3 to 4 millimetres, the loss of
performance is so gradual that it usually goes unnoticed.
My experience of the
CIH engine is that at 50K one might as well change the
clutch plate, strip the engine, decoke, clean, replacing
such items as timing chains and oil seals and generally
make good well before the trouble starts. What is the
point or pleasure of driving a Manta with a hangover?
There is another CIH
problem, if the car is left unused the rings will seize
in the grooves. Again this is prevalent at 50K. Oil comes
out everywhere, even from the air inlet. Why? Because the
Positive Crankcase ventilation cannot cope with all the
gas blowing past the rings. The PCV normally keeps the
engine crankcase under sufficient suction to ensure that
air leaks IN rather than oil out. Two things To do: first
try an oil change to a decent oil (Esso EX2 or Mobil 1)
before really DRIVING the car for lots of miles of
shopping and motorways To get it stinking hot. If this
proves useless but fun then its stripdown time folks.
Summation, every 50K
pre-emptive strike time. At 100K Zero Hour the entire
vehicle. Sure, you might be lucky, but I like to know. To
every rule an exception of course, thank you Tony.
William
R Blankley
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