Leaking a lot of oil all the sudden

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1974BlueCommando

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I rescued a 1974 Norton a year ago. Ran great last summer, almost no oil leaks. Took it out for the first tiem this year and oil is blowing out all down the bottom, onto the kickstand, the back fender, the frame, the back tire. I can't tell where it's coming from. How do I track down the source. Doesn't seem to leak when its not running. Any ideas would be appreciated
 
You probably wet sumped. All the oil from the tank drained into the motor when it sat. When you started it up, it had nowhere to go but out the seals. Did you top it up before you started it too? That would have led to way too much oil.
 
I'd suggest washing off the oil and then firing the bike up and looking for the leak.
 
1974BlueCommando said:
I didn't add any additional oil. What does it mean wet sumping and how do I fix it to stop the leaks?
Click to expand...

When a bike has some miles on it there is some wear in the oil pump.
It sometimes is enough that over time the oil from the tank by gravity seaps down through the pump into the crankcase.
Sitting over the period you described could have allowed so much oil to accumulate in the crankcase (which is really ment to have maybe half a cup in it) so that the crank plows into it and blasts the oil up and out every place it can.

Did you check oilbefore starting? If you did and saw oil low it could have wet sumped and topping tank would make situation worse.

If wet sumping but only after sitting quite a while probably no big deal, however if happens quickly probably means reconditioning pump. There are threads on this site that describe how to do that.

Putting a valve, either automatic or manual in line down from oil tank is done, however there are differing opinions on this site as to whether it is advised since it opens the possibility that the valve will fail or not be opened accidentaly with all the negative consequences you can imagine.
 
The bolt that holds the bottom of the oil tank in place . Rubber anti -vibration bit with it , cooks the rubber hard ,then the brazed part of the lower tank cracks. It's a bugger to get at and fix. Spray with detergent wash to observe the leak source after the wash ,use a good flashlight too.
 
two other things to consider, if most the oil in the sump and ya top off oil tank before a start, the tank over fills and puks out excess via the vent pipe. Other thing could be the bottom of the oil tank fastener area has finally cracked though but that would not mess much forward of the oil tank. It can be tricky to run just long enough to see where it starts yet not so long its blown around to confuse again. Check primary oil level ain't filling up from the crank seal.
 
Also maybe check your auto chain oiler to see if operational or maybe the method used to block off has failed. The oil filler /level check cap has also been known to let oil onto back portion of bike ,like everyone says clean oil off start up and look closely with good light.
Craig
 
Thanks for all the responses. Chain oiler is sealed off at the tank with a rubber fitting. Oil tank was refurbished by Colorado Norton Works so the bottom bolt was removed and replaced with a rubber pad. I checked the oil tank prior to starting and the oil tank was very low so oil did leak down into the motor. I did not add additional oil because I knew it had leaked down into the engine. Sounds like it was wet sumping. The oil tank is now full. Will it stop blowing oil everywhere or do I have to replace gaskets and seals in the engine?

Filler cap was on tight.
 
I had a similar problem that turned out to be a blocked oil pump return passage. A long string of silicon sealant between the pump and engine case blocked the return line and built up pressure so that oil pumped out through the crank case breather line.

Quite a mess.
The fix was to remove the timing cover and oil pump and clean up.
 
I'd suggest cleaning it up first. Then trying again and see if it still leaks, that is if the oil from the tank hasn't all gone into the engine again. You can remove the sump bolt, drain what oil is in the engine, put it back in the oil tank and go from there. If it doesn't leak now, you know it's because of too much oil in the sump while starting. You probably need to read up on modifying your breathing system. Simplest is comnoz sump breather.

I put a manual ball valve in the oil feed line from my tank with a micro-switch that cuts off the ignition, so I can't start it unless the oil line is on. One of these days I'm replacing the micro-switch with a proximity switch and a relay. Some don't like that either because it keeps the cam to dry for start up. I have noticed that since I put the valve in the line, and I don't have any wet sumping at all any more, all the leaks are gone from my engine. And I'm using the original beather off the drive side cam, but I did take the breather that went into the air filter into a catch can.

Dave
69S
 
I'll try DogT's suggestion first, clean the engine and drain the sump prior to start and then look for oil. It that's not it, I'll try Bob Z's potential blocked oil pump fix.

Thanks for your help.
 
Clean oil leak initiation is a lot harder to see than dark dirty oil, so some dust with talcum in suspected area to see it wetted soon as possible not to get fooled by oil showing up more further down. I'd had to decrease and decrease my distance to find oil till only ~100yd interval to see the begining of it.
 
hobot said:
Clean oil leak initiation is a lot harder to see than dark dirty oil, so some dust with talcum in suspected area to see it wetted soon as possible not to get fooled by oil showing up more further down. I'd had to decrease and decrease my distance to find oil till only ~100yd interval to see the begining of it.
Click to expand...

NAPA sell some dye that glows under blacklight. It works quite well for finding leaks, I don't like to leave it in the engine for very long. I worry about it compromising the quality of the oil in the engine, so I'd drain it our after you figure out where the oil is coming from.
 
There is a procedure that you can consider before you start it the next time the bike has been sitting for a few months. The easiest thing to do is to drain whatever is in the sump and put it back in the tank. It's a good idea to hold back a half a cup or so and divide it up between each of the valves. The oil you pour over the exhaust valves will drain down onto the dry cam lobes and on the intake side it will drain into the timing chest to help lube the chain and the rest. Ride it to heat the oil then change it.

You may have blown out the main seal in the primary. Check the level in the primary before to ride it. If the level is very high then the oil in the crankcase was forced into the primary past the main oil seal. Drain it and replace it with the right amount. If the seal is shot you can replace it without taking the engine apart, but the primary would have to come apart to get at it. I've found from personal experience that, overall, it's less trouble to drain the sump.
 
Oil tank vent tube should be open to air or with check valve so no pressure build up in tank. Bad cap seal would let oil spray return get out of course.
 
If your oil tank is pressurized, something is blocked or your breather system is not working right. Move the oil tank breather to the air but watch it to see what comes out. Wet sumping will do that too. Or did you have too much oil in the tank, it only needs less than full mark, more towards low.

Dave
69S
 
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