Well, I've gone and bought another car. The smoke on the MG was getting very
bad and my girlfriend needs a reliable sensible car to drive while I set
about rebuilding the MG's engine, so I've bought a small Renault Clio for
her to nip around town in. This should take the pressure off the MG and
allow me to take my time over it in the garage during the long winter
months.
Just to recap...
The MG's (78BGT) engine is smoking badly. I *thought* the smoke was
'external' to the engine, ie: oil dribbling down from the rocker cover onto
the exhaust manifold, but the other day, when we picked the clio up, I
followed Kim who was in the MG and 90% of the smoke is coming out of the
exhaust. Any speed above ~50mph causes massive amounts of white/blue smoke
to be emmited. There is also some smoke in the engine bay and this seeps up
through the gearstick area and through the air vents. Originally I thought
the smoke was gearbox/OD oil leaking onto the hot exhaust, but after a
compression check showed 11-11-6-11 bar (165-165-90-165 psi) I came to the
conclusion that a piston ring has gone. This is causing massive amounts of
blowby gas and also burning a lot of oil.
I have two choices now...
1) Remove the head and sump pan and lift out the pistons and renew the rings
(and do the big end bearings while I'm in there)
or
2) Lift out the whole engine and rebuild totally.
Having just spent all my money on the clio, option (1) is more attractive.
The engine is pretty rattly above 3k and the oil pressure is low, but
fitting new bearings should sort both of these problems (worn bearings = big
gaps = low oil pressure = more wear etc etc).
Looking at Brown and Gammons web site http://www.ukmgparts.com/ (very good
site BTW, with online spares buying etc)
they have all the bearings I need and also have piston ring sets. A couple
of decisions need to be made here...
- Replace the lower half of the 3 inner main bearings too?
- Thrust bearings? (revs drop when clutch dipped) these should be able to be
slid out, unless they have a lug on the top (A series has the lug on the cap
only I think so allows thurst change with crank in situ, not sure about B
series though)
- The crank is original and not reground, but will no doubt have some slight
wear. Would I be better off fitting -0.010" bearings instead of standard?
- I could get a set of pistons and rings. This is a lot more money though.
When I did the head swap I found the bores were not too worn, and didn't
have a very pronounced step at the top. The pistons could have worn around
the outside, especially in the left-right 'slap/slop' direction
perpendicular to the gudgeon.
If I was to pull out the whole engine, can I disconnect the gearbox and just
lift out the block? Ideally, I'd like to renew the oil pump. Is it hard to
get at? Engine out job only, or possible in situ? I suspect it is on the end
of the cam, under the gearbox housing.
An help of advice is gratefully received!
scott
**********************************************************************
This email and any files transmitted with it are confidential and
intended solely for the use of the individual or entity to whom they
are addressed. If you have received this email in error please notify
the system manager.
This footnote also confirms that this email message has been swept by
MIMEsweeper for the presence of computer viruses.
www.mimesweeper.com
**********************************************************************
///
/// mgs@autox.team.net mailing list
/// or try http://www.team.net/cgi-bin/majorcool
///
|