Lotus Elan and Lotus Elan Plus 2 Forums

easy way to check is a cylinder leak down on a warm engine


this is something you muist attend to straight away lest you pass out
and stuff it raising the values of the rest of our cars...not the way i
want to see it happen


since i just mentioned i drive a alfa super this is a pretty common
alfa problem made worse by an aftermarket exhaust tip, the direction it
points and the length it extends makes a difference


i believe it has been mentioned already; also check for oil leaks on
the exhaust what is coming out around the engine may be oil dripped on
to an exhaust pipe and burning off as it gets hot, you'll still get the
fumes as it continues to burn.

back to the leak down; if you haven't a proper guage but have a source
of compressed air bring a cylinder to TDC (else the engine rotates
under pressure) pressurize the cylinder through the spark plug hole.
pull off the oil filler and listen, lots of hissing from air means the
rings are gone and the combustion is blowing into the crankcase...may
be part of the oil leak problem...open the throttle and listen for air
escaping past a poor valve seal, like wise listen at the exhaust
outlet. do each cylinder in turn to get a good seat of the pants feel
for the internal condition of valves and rings.

cheers,
scott



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I've done more investigating, smelling and sealing.

I taped over a couple of gaps in the firewall and a larger crack in
the fiberglass created by the PO hanging the exhaust from it. I've
noticed that I have a number of different smells, mostly exhaust and
burnt oil. I don't have any oil on the garage floor, but do believe
that oil is likely dripping onto the exhaust from the rear crank
seal, causing part of the smell.

I also noticed that plugs 1 & 2 have seeped oil onto the top of the
engine. What is causing that? These are also the plugs that have a
habit of fouling. On the engine, the PO wrote: The guides are new,
valves are original. When the block was apart, we checked the rod
bearings, ok, but did not pull the pistons. Is this a rings issue or
values, or both? Thanks. Dan '70 S4 SE



--- In ***@***.***, scott potter <twincamracing@y...>
wrote:

Howdy dan,


likely seepage from the cam cover finding a low spot


it is not unusual after having a fresh top end for the increased
cylinder pressure to cause blow by the rings...after the top end seals
well the pressure wants to leak out, or down

plug fouling on one and two sounds pretty indicative of the above

down and dirty run a compression test on each cylinder and follow up
the first compression reading with a shot of oil from a squirt can if
the compression reading jumps way up its rings

alternatively, go back to a previous post about how to do a leak down
test. dual guage leak down testers are less than $100. and can give you
a definitive answer to how much leakage is in each cylinder and where
it is leaking

cheers,
Scott

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