Petrol in the engine oil , new petrol tap or rebuild it ?

[hollo]

I gave my 350LC a bit of TLC today and did lots of little jobs I've been putting off for too long . Anyway when I drained the engine oil , it smelled very strong of petrol . Every time I park it up , I always turn the petrol tap off and if it's for any length of time I also turn it off before I get home , so the carbs are dry .

So petrol must be leaking from though it's off .

So my question is , what's best to do ? , get a re-bulld kit for it from Norbo or get a new pattern tap ? , does anyone have any experience of either ?

Thanks

Mike .

[Dave B]

Petrol in the gearbox/ transmission oil? That's not good. If the petrol tap is leaking, and the float valves are not closing fully, then petrol will leak into the crankcase. The mystery is how it is getting from there into the gearbox. The obvious suspects are the crank seals, which is bad. Otherwise it could be the horizontal joint between the crankcase halves leaking, and that's worse.
What worries me most is that the crankcase would need to be holding a very large volume of petrol for it to reach half way up the cases, and I would expect that much petrol to cause a hydraulic lock when you try to start the engine.
On your original question, if ther is no sign of corrosion on your original tap, rebuild it. If there is, you need a new one.
Cheers

Dave

[midlifecrisisrd]

Most likely the Rh crank seal failing

May not be the tap at fault.

On the piston down stroke the crank area has positive pressure to push the fuel up through the transfer ports.

This will allow fuel mixture to pass through a failing seal.

3 ways to check

1 - buy a leak test kit from maccas but this will involve carb and exhaust removal

2 - remove the fuel pipe and place the end into a glass jar with a hole drilled in the cap for the pipe with a tight fit.

Leave over night and see what's in the jar after 24 hours. No fuel, no leak.

3 - with the bike running fit a longer crankcase breather pipe and put into a bottle full of water. Rev the nuts off it and see if it blows bubbles in the water

Lots of bubbles means the seal is leaking or joint between cases halfs is leaking

Steve

[hollo]

Thanks Steve , as I'm a simple chap I'll have a play and test your suggestion 2 first , as it seems to be the easiest.
So if I have a R/H crank seal failing , I take it the same will happen ( I'll get petrol in the engine oil ) when the engine is running . So it will happen when I'm riding the bike ? . If this is the case , I take it replacing the R/H crank seal is a big ( and expensive ) job ?.
Where would I find the crankcase breather pipe ? , as if I draw a blank with option 2 , I'll try option 3 . Are there any other Symptoms of crank seal failing ? , as the bike is running as good and crisp as it always has.

Thanks for your help
Mike .

[midlifecrisisrd]

Hi

The crankcase breather pipe is on the top case at the rear of the engine

If you need to change the seal it's an engine out and splitting the cases

Steve

[hollo]

Bugger , lets hope it just the fuel tap.

Thanks again for your help and suggestions Steve

Mike .

[hollo]

Well , GOOD NEWS , it's the tap . I connected up the two tap outlets to the clear bottle as per the pic

and only after a minute I could see petrol dripping out , and after 10 minutes there was a fair amount of petrol in the bottle . If it makes any difference , it coming from the outlet at the back of the tap , as the pipe connected to the side outlet wasn't dripping at all .So I'll contact Norbo for a rebuild kit , and then I should be sorted.

As ever , it's not all peachy , as I managed to still petrol on the cases and partially strip some of the paint off , which is a sod, but I'd swap this for having to have the crank seal replaced any day.

Thanks again for the help and advise.

Mike .