Here's an update on the oil burning/compression problems.
I've had several discussions and suggestions off list with an assortment
of ideas for me to try. Here's what I've done so far.
First, I drained the suspect gasoline (I think this was not in the
original post, but after further discussion, the thought occurred that
the pinging started soon after filling up from an unknown source. Thought
was that ethynol having a lower vaporization point coming in contact with
hot spots from carbon build-up might be causing detonation.) I then
filled up with 93 octane BP and a can of "104" octane booster.
I drained the 2000 mile old SAE 30 oil, changed to a new felt filter
element (old sure had a lot of sludge for only 2000 miles. Must be the
metal particles from the new parts wearing in), flushed and refilled with
Castrol GTX 20W-50 to exactly the full mark. There was no smell of
gasoline in the old oil, so at least any possible leaking around the
rings isn't allowing gasoline by into the sump. I wiped down the
underside of the car to eliminate any oil drips so I could try to
identify where oil might be dripping.
Changed oil coated and carbon caked spark plugs to a new set of Autolite
404 (cross reference for MGA manual's recommended Champion N5.)
I started the car up and it ran pretty well, but was definitely not
getting full power in the center two cylinders (the low compression
ones.) There was absolutely no pinging or signs of poor timing, but I did
lean out the mixture a touch. It bogs down a lot at low RPM, has fair
performance at mid RPM range, and I'm keeping out of the upper RPM ranges
until I know what all happening in there.
I drove it to work (local) all this week in semi-rural traffic at speeds
up to about 50 MPH. I've kept an eye on the oil level, and for signs of
coolant in oil or oil in coolant. There is still a little oil leaking
under the car, and it is darker, so must be from the engine/tranny joint,
as the engine oil is still clean.
Performance during the week might have very slightly improved, but
nothing dramatic. There is still the lugging at low speed and loading
conditions, so if there is any carbon build-up on the valves keeping them
open, it is not getting any better. I suspect I have a blown head gasket
between #2 and #3 cylinders. I put together a couple of fittings to
perform a blow-down test on the cylinders, and will do that this weekend.
As for the oil burning: Nothing here has improved at all. I zeroed the
trip odometer when I changed the oil, and last night I added about 90% of
a US quart to bring it back to exactly the full mark on the dip stick.
Odometer reading was 98 miles! The oil in the sump is still pretty clean,
and there is no gasoline smell. There is very slight blue smoke when
driving after warm-up. It is more noticeable when looking back down the
road than from the tailpipe. Almost like a very light fog. After shutting
down for a while (maybe 1/2 hour so engine is still hot, but car has been
setting for a while) I get quite a bit of blue smoke when accelerating or
revving the engine. This goes away after several minutes. When starting
from cold, there is an oil burning smell, but no noticeable exhaust
smoke. The fellow that followed me to work the other day said I sure
smelled like I was burning oil, but he only noticed the blue smoke after
starting from a light after idling for a minute or two. There is almost
no oil on the engine other than a very tiny bit coming around the filler
cap. More a slight ring of vapor coating than any blowing by the cap. The
rest of the engine is completely clean and dry of oil (except the
dripping at the rear as noted above.)
I plan to do the blow-down test this weekend to try to determine if it is
rings or valves, and I hope to be able to keep an eye on the fluids and
keep topping up the oil and driving until the weather changes and I can
pull the head.
If this brings a flash of insight to anyone, or if you see a flaw in my
reasoning, I would appreciate the input. Thanks to everyone who wrote
with ideas and suggestions, and especially to Barney for repeatedly
trying to help me better explain what I was seeing.
Thanks,
Steve
Steve Morris Avon, Ohio
1958 MGA 1500 Red/Black
NAMGAR #5987
http://www.en.com/users/smorris/mga/
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