My oil consumption rate has taken a nose dive in the last couple months.
I am now getting about 200 miles to the quart. I know zero about
combustion engines and so am hoping that the cause of my problem can be
pin pointed on the net. New gaskets have just been installed on the sump
pan, the engine bearer plate and the timing chain cover. After a long
run or idling in place for 20 minutes, the facts are as follows:
1) Virtually no leaks under the car. In my garage I put a fresh piece of
kraft paper under the car, continue running the engine and find one drop
of oil on the nut at the bottom of the sump pump, one at the bottom of
the spin on filter (a modification) and a drop or two on the paper under
the cotter pin of the bell housing. No oil on the sump pan itself.
2) At idle, I get smoke. Today the TD idled for 20 minutes and by the
time I returned, the TD was bellowing out LOTS OF SMOKE. The garage was
suffocation.
3) When driving, no smoke is visible in the rear view mirror nor by
friends following close behind. Only when I stop at a light and then
start up again is there a few small puffs.
4) Spare Plugs are badly sooted and fouling even after a short run. All
plugs are wet with oil.
5) Compression is 160, 160, 152, 160 psi. This is a MkII. Max reading
should be 150, but then, I know the head was milled by the previous
owner back in 1978 but I do not know by how much, so compression may be
a bit higher than the book.
John Twist says in his tech manual, "If the MG burns oil, there may be a
bluish smoke from the tailpipe, or the car may smoke embarrassingly at
idle, but more often then not there is no visible smoking. If it is not
smoking appreciably, yet consumption has reached a quart or two per
tankful petrol, it is the RINGS."
OIL CONTROL RINGS: New rings and pistons from Moss were installed by a
local machine shop one year ago. There is only 12,000 miles on the new rings.
VALVE SEALS AND GUIDES: New guides and seals were installed during
restoration in 1978. The car has been driven about 20,000 miles since
then.
Because the valve seals and guides are 22 years old, I initially
suspected them. However, I have heard that there is not enough oil
pumped to the top of the engine to lose a quart every 200 miles. Is this
a true statement or could this be my problem?
Others have said it must be the oil control rings on the pistons, but
then, these are new.
I am hoping that I can get some guidance before I start pulling pistons,
valves etc. Thanks for whatever help can be rendered.
Stu Keen
1951 MGTD MkII
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