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Oil in crank case

PostPosted: Tue Aug 01, 2017 3:28 pm
Hi All,

Just got my LML out of the garage - 2/3 month lay up , and had trouble kicking over. eventually about 250ml of synthetic rock oil 2 pushed out of the exhaust and over the block paving.

The refill tube glugged right down when I topped it up.

It went well for 25 miles after that and its running ok, not weak etc.

I might have left the fuel on, but could have switched it on 'auto pilot' as I was messing about reconnecting the battery.

Is it anything to worry about? its due for a full service - cables gear oil etc and i'd get them to look at it if its an issue - I just haven't the time right now to even think about repairing it myself

Thanks in advance


Re: Oil in crank case

PostPosted: Tue Aug 01, 2017 7:08 pm
by retroden
I have always found that there tends to be a build up of two stroke oil in the carb/air box. Whether this is peculiar to the reed valve engine models, I am not sure. But as a precaution I always switch the fuel tap off when not in use and I let the engine idle with the fuel tap turned off before parking it up. This seems to help but does not totally cure it, even though I have changed all the reed valve ,carb and air box gaskets.
I think that this is why some people opt to do away with the auto lube system and premix instead..

Re: Oil in crank case

PostPosted: Wed Aug 02, 2017 6:50 pm
by Shaunbond
Your float needle sound knackered. If you left the petrol on and the needle is shot, fuel will pass through and flood your crankcase, eventually getting up to the exhaust port and your exhaust. The petrol will evaporate and you'll be left with the oil. Although the amount you say is a hell of a lot.......

Re: Oil in crank case

PostPosted: Sat Aug 12, 2017 9:40 am
Cheers gents, its only got a couple of thousand miles on the clock.
I'll clean the carb and keep the fuel switched off - no recurrence since though

Re: Oil in crank case

PostPosted: Sat Aug 12, 2017 11:14 pm
by Philos
My 150 leaks 2 stoke oil into the engine as well when it's left for a while. This problem seems very common, and from my limited reading up on it, it has something to do with a one-way valve in the autolube system not shutting off completely. To be honest, I'm not going to worry about it because it's not going to do any damage apart from being a little hard to start after a lay-up and wastes a little oil. I look at it as insurance for my engine, because over the winter months it's well protected from rust internally by all the oil inside!

This problem of the 2t oil seeping into the engine has nothing to do with the fuel system though and nothing to do with leaving the fuel lever on or not. The 2t oil and fuel systems are completely separate apart from when they enter the engine. It's always recommended to turn off the fuel lever after use in case the float chamber needle valve leaks, cuz that'll flood the engine with fuel and eventually leak out the exhaust pipe.

Oil in the in the carb body is from spit-back which is common on 2 strokes and nothing to worry about. A great way (I read here) to remove the build up of oil in the bottom of the carb body was to suck it out with a syringe with a little tubing attached.

Hope that all makes sense.

Re: Oil in crank case

PostPosted: Wed Aug 30, 2017 10:40 am
cheers mate, I tend to use it in fits and starts. runs well though