Scott, have you done a compression test on the engine? When I bought the
1980 MGB I'm going to drive for the first time tonight (I hope), it also
smoked from the breather (as well as everywhere else) very bad. I did a
compression test before buying the car and cylinders number 2 and 3 were
low. I thought it was a head gasket, but it turned out the head gasket was
bad, but the head was also cracked in number 2 cylinder. I replaced the
head and now it's running fine with no smoke. Hope yours isn't this
extreme, but I would definitely recommend a compression test on the engine.
Keep us informed of your progress.
Ken
-----Original Message-----
From: owner-mgs@autox.team.net [mailto:owner-mgs@autox.team.net]On
Behalf Of scott beavis
Sent: Wednesday, October 24, 2001 4:02 AM
To: MGs (E-mail)
Subject: Update on "bluebell" (re-named "smokey joe")
Finally got round to spending a few hours on the MG (78BGT) on Sunday. There
has always been a slight clunk sound when coming on and off the power at
very low speed, so I changed the diff oil. Interestingly, my 1/2 square
socket drive fitted the drain and fill plugs fine. No need to make up
special tools! I also crawled underneath and painted some 'black protector'
bitumen paint on any rusty bits, like the front valance and the front of the
leaf springs. Need to do a full waxoil spray soon, ready for winter. I
usually mix 2:2:1 waxoil:old oil:petrol and spray that *everywhere*
underneath. As well as doing the diff oil, I adjusted the valve clearances,
cleaned the plugs and did a compression check. One cylinder was down a bit,
but I think that is just my poor valve grinding, as it was like that ever
since doing the head swap. Whilst I was underneath and in the engine bay I
set myself on a mission to figure out why on earth the MG was smoking so
much. It is more than just the usually puff of blue smoke when caning it.
The rings are pretty worn I know, and there is quite a bit of blowby gas,
but after about 5 miles at high speed there are clouds of white/grey smoke
out the back. This has gone on for months and I think I may have *finally*
figured out what is causing it. Normally the car is fine, for around-town
driving, but any sort of motorway journey results in a fog screen. It is so
bad that we are having to use my racing mini to go and visit my parents down
in the west country (Devon, UK, we live up near London). The mini has no
radio, no heater, bucket seats, 4 point harnesses and hard suspension. My
girlfirend is not best pleased! My first big breakthrough was a couple of
months back when I looked into the cause of our "1 minute to engage"
overdrive. I found that all the gearbox oil had leaked out, due to "finger
tight malcolm" OD sump plate bolts (PO, not me!). I really thought I'd
solved the mystery then. High speed = hot exhaust + overdrive in = oil
leaking onto exhaust = lots of smoke. But, much to my annoyance the next
motorway trip was smokier than ever. What the hell is going on here?! I also
thought it was due to the crank case breather getting oil onto the manifold.
That was duely re-plumbed back into the carbs. This makes the car run a bit
crap and ofcourse any oil mist is then burnt, making smoke. I tried plumbing
the vent to dump all the way over on the right hand side, near the ign coil,
but still it smoked.
Then, the other day I made an interesting observation. Driving down a local
dual carraigeway at ~60mph, OD in, no smoke, at the bottom of the hill I
went round a roundabout. Whoooosh! Massive cloud of white smoke out the
back. It was as if the swerve motion had slopped the sump oil and some had
come out over the exhaust manifold. I am 99% sure the smoke didn't come out
of the exhaust pipe as 1) the engine didn't splutter, 2) it was white not
blue and 3) I could smell/see smoke inside the cabin. When I got home I
checked the tappet chest covers and the mech fuel pump blanking plate bolts.
All were ok, but I torqued em up a bit more. Then I noticed a wet 'spray' on
the heater hoses. Mmmm...what's that? It was oil. Eh? This was right up high
on the engine, alongside the rocker cover and the hoses had oil ON TOP, not
underneath. This looked like oil had been somehow spraying out of the oil
filller cap. There was also a lot of oil on the lip of the rover cover and
oily tracks down the head. The rocker cover gasket is new and seated ok. It
almost looks like oil has been coming out of the filler cap and under the
rocker cover T-bars. Surely the rocker cover can't be pressurising that
much? Surely it can't have that much oil in it? Maybe oil is collecting on
top of the rocker cover on the straights and then on the roundabout it ran
down the side onto the exhaust manifold? Maybe at high speed it builds up
and then after a few miles it runs down.
I am now tempted to plumb in a vent pipe from the rocker cover to a bottle
and see what I catch. There is a small screw on the 4th rocker piller which
controls the oil delivery. Is it ok to 'turn it down a bit'? When I remove
the cover there is a lot of oil on top of the head.
Anyone had this kind of problem before?
Scott
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