Leaking a lot of oil all the sudden

I saw some dummy pack his luggage on a Commando at 0:darkthirty one morning, accidentally pinched off the breather tube that was run along the frame rail with a bungee cord wrapped around it...

DogT said:

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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My oil was was half way in the middle of L and H. Rode for 50 miles and it blew oil all over the back fender and swing arm. Looks like it came from the oil tank cap. The oil cap gasket looks to be made of cork. Can you get a replacement without having to repace the cap? Also, I have the oil tank breather hose vented to a plastic bottle in the battery case which has no pressure relief. There was almost no oil in the plastic bottle. It is a pretty cheezy fix so I thought it probably wasn't completely airtight and would allow oil to flow from the breather to the overflow bottle. Could that be the problem if it's not just a bad gasket on the oil tank cap?

First, you don't want to block the oil tank breather from the air, that's why it's called a breather. 2nd since you put the breather into a closed bottle and none of the oil made it's way into the catch bottle, you've pressurized the tank, thus spewing out the filler top. You can put an extra gasket in the filler cap, it may help, I did and I still have drippage. You can use a large pill bottle like this, but your breather comes from a different location than mine. But that catch bottle needs to be vented. You can buy a nice AL one for about $30, do a search here on catch bottle. I found a flanged plastic fitting that fit into the 3/8 hose and drilled a couple of holes into the top of the pill bottle top.



Dave
69S

Humf, Every now and then I get carried away and over fill my Combat's so oil shows half way between L-H so just have to let it seek its natural max level, 1/4" end of 1972 dip stick and clean up the mess then keep better hand control on oil so just touches or a bit short of touching dip stix. All the other points apply too of course. Once ya get good enough to have a fully fettered Commando the rest of life just doesn't seem so hard to handle.

1974BlueCommando said:

My oil was was half way in the middle of L and H.

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Some Commando dipsticks have the "L" & "H" marks too high.

1974BlueCommando said:

Looks like the culprit is the top of the oil tank. It must have too much pressure from somewhere. Any ideas what to try?

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Make sure the vent tube is clear and routed without restriction and check the oil after warmup. This will give the oil in the sump to return for a valid reading.

There were 3 differing dipsticks over the years , hpefully not interchanged ,err on the side of low.

The short kind are just too short which leave their marks above natural max level. I've though about hooking a chain and magnet as dip witness and ferric dust collector, but so far just peer in with a light, when not much wet sump. After rides is the best time.

1974BlueCommando said:

I have the oil tank breather hose vented to a plastic bottle in the battery case which has no pressure relief. There was almost no oil in the plastic bottle. It is a pretty cheezy fix so I thought it probably wasn't completely airtight and would allow oil to flow from the breather to the overflow bottle. Could that be the problem if it's not just a bad gasket on the oil tank cap?

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Doesn't this explain it all. Oil tank breather with no escape to the atmosphere?

DogT said:

1974BlueCommando said:

I have the oil tank breather hose vented to a plastic bottle in the battery case which has no pressure relief. There was almost no oil in the plastic bottle. It is a pretty cheezy fix so I thought it probably wasn't completely airtight and would allow oil to flow from the breather to the overflow bottle. Could that be the problem if it's not just a bad gasket on the oil tank cap?

Click to expand...

Doesn't this explain it all. Oil tank breather with no escape to the atmosphere?

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+1, failed engineering. Same result as my cryptic, sarcastic self-inflicted failure described above.