Random oil burn/plug foul

[KiwiBrumby]

A couple of nights ago after work I started my Brumby and looked in the mirror to see a cloud of oil smoke coming out from the exhaust, it stopped after 5 to 10 seconds and then when I drove off I was running on three cylinders.

Got home and checked the plugs, the one nearest the firewall on the left side of the car was black and sooty but not what I would normally think of as oil fouled, the other three were good.

I cleaned the dirty plug and put it in the front right hole and the one from that cylinder where the 'dirty' plug had been.

Fired up and still only had three working cylinders so check that spark was getting to the left rear plug, it was.

Next thing for no reason all four were going so took the Brumby for a drive, gave it a bit of a thrashing and not a a suggestion of misfiring etc, all good!

Next morning all was still good.

I have experienced this oil burning thing about two times previously but never had issues of plug fouling then.

I use the Brumby pretty much daily and it has always runs well, uses virtually no oil and am puzzled by this fouling thing.

Any ideas????(If it's any clue the left side of the motor is lowere than the right by a bit due to parking angle here - we drive on the left)

 

TIA  

[KiwiBrumby]

WELL, I experimented by parking on a level surface while at work over the last two days and wouldn;t you know it - no smoke on start up!

 

So my theory is that when I park for 10 hours with the left side of the Brumby lower than the right by a bit that 'somehow' oil drains to the lower side combustion chamber(s)

 

Anybody else have a similar occurence?

[1 Lucky Texan]

maybe valve seals are leaking?

[skishop69]

Black 'soot' is usually not oil consumption. It's fuel fouling.Oil burning usually shows dark brown or black and looks 'tacky'. My guess is your getting fuel from the carb after shutdown. Fuel level too high or a leak. Texan has a good idea too. You could have bad valve guides or seals, but that usually shows oil consumption. I'd put in a new set of plugs and check the color after driving for a week and compare them.

[Al Zhiemer]

It could be valve stem seals, usually the first sign is blue smoke on start up, unusual for valve stem seals to just collapse like that. Even when parked on a level surface, it should still blow some blue smoke. If its an intermittent issue, it may be worth popping the rocker covers off and checking that one of the valve stem seals hasn't moved the next time it happens.

Have you tried parking the opposite way around to see if it affects both banks of cylinders?

Does it do it when parked on any angle with the left side lower than the right?

Has the engine got above normal operating temp?

 

Cheers,

Al

 

[KiwiBrumby]

OK, today I parked back where the oil smoke occurred, i.e. where the Brumby has the left side quite a bit lower than the right.

Sure enough after work when I fired it up there was a pall of smoke!

 

In answer to above by Al, the motor was cold, the Brunby had been sitting for 6 hours

And to park with the ground sloping the other way would mean finding such another location near my work as  parking in my usual parking spot facing the other way on the street is a no-no, ticket material! 

 

PS No further plug fouling has occurred

Edited January 10, 2019 by KiwiBrumby

[el_freddo]

Sounds like oil slipping past the rings after shutdown. 

To mimic the lean to the RHS you could park on that level space then drive up on to a brick that’s placed under each wheel on the LHS. Then leave it over night/a few hours etc. 

Cheers 

Bennie