We got the engine out of my '71 MGB last Saturday. It wasn't nearly
as difficult as it was last time, partly because I have so much more
recent experience, and partly because I've got the air compressor now.
If I liked my air compressor a lot previously, I *love* it now. It
made several previously awful jobs fast and easy.
For all the people who gave advice of one kind or another, here's
what I ended up doing:
I jacked the car up and put the front wheels on my ramps. I like them
too; oddly, I've never put the car up on them before, having used them
only to get the race car up onto the trailer. I wish I could say I'd
never use jackstands again, but I'm sure I'll have suspension work to
do one of these days and the wheels will have to come off. Till then,
the jacks are the way to go.
With the car thus lifted off the pavement, it was relatively easy for
me to get far enough under it to get to all the bellhousing bolts, and
with the air wrench, they come off in five seconds each instead of five
minutes each. Unfortunately, the starter still has to be frobbed by
hand -- or rather, I couldn't find a place from which I could get
the impact butterfly to drive everything necessary to make it go.
Maybe it's time for air tool #2, a small air ratchet. But while I was
twiddling the lower (fine-threaded) starter bolt, I was glad I decided
not to try to do the pistons in place. I was to be even more glad a
little later.
We got the motor out -- Kim undid the motor-mount bolts and two of the
bellhousing connections (big plus for little hands!), and she steered
and braked while we rolled the M.G. backwards with the engine on the
hoist. We took a few minutes to clean off some of the gunk that had
been under the B, leftovers from the leaking tappet cover. Once more,
air tools rule -- I used a garage cleaner and a broom to work it into
the crud, then Kim poured hot water onto that, and after sweeping the
guck out into the driveway we blew it dry with the air hose. I put
two of our scrap pieces of particle board down, and then lowered the
motor onto it.
Over on its side, it's amazing how much oil remains in the tappet
gallery; looks like a cup or so when it spills out on the floor.
Oh well. Tim zipped the 1/4" bolts out of the pan with the air
wrench, and then we were faced with the problem of the gaskets.
Eventually I was able to separate the pan from the gasket; boy,
that Permatex stuff sure holds things tightly...
There was a lot of silver in the bottom of the oil pan. Tim wondered
what it was; later I realized it was the leftovers from the piston.
More in due time. We set about pulling the conrods off the crank,
made sure they were marked, and then got to the #4 piston, the one
that had blown.
It was horrible. There were two sections missing from the face of
the piston, each about 3/8" long and all the way through from the
rim of the piston to the inner wall where the rings rest. But that
wasn't the worst. Compression heat had blown in through these
gaps and actually eaten away everything between the rings (and a
few sections of the rings as well) through a couple of 2" sections
of the circumference. The top of the piston looked chewed up,
in retrospect probably from ring chunks being hammered against it.
The good news is that there is no visible scoring or other damage
on the cylinder bores. And of course I'm not using that head, so
I don't care (for now) what it might have done to the combustion
chamber. In fact, the bores still have all the machining marks
visible; I probably won't bother with the dingle-ball hone, as it
still looks fresh and new. Oh, and I blew out all the oil passages
to make sure there were no chunks of ring sitting anywhere. I
think I'll drain the first sump of oil before it's been in the car
for any length of time, just in case...
We ordered the parts today; UPS Next-day Air costs only $13 extra,
so we'll have the goodies by Thursday. With the upcoming three-day
weekend, I should have the car running by next week. A big difference
from last year, when everything dragged on and on and on...
I'm still trying to figure out what to do about my exhaust system.
I may just paint what I've got and reinstall it with proper sealing
rings (one was missing completely) held in place with exhaust system
paste. It's complete, and usable, and I like the sound of the Ansa
that's in the car. That's easiest and of course cheapest.
But with luck and a good deal more hard work, this car will be back
on the road by the end of the month, and ready for its smog test after
the rings have some running-in time. (Again, any advice on how to
get the rings to seat most quickly will be gratefully accepted; no,
Roland, I don't think *I* would run them without oil either...)
If anything, it should go back together more smoothly than it came
out, hence my subject line, one of the Big Lies of all technical
writing.
--Scott "Yeah, and childbirth is just conception in reverse" Fisher
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