Honda BF75 oil leak when fully tilted

"I have a 6 year old BF75 whic

"I have a 6 year old BF75 which has sprung a leak when the engine is put on full tilt. It seems to come from what appears to be a small vent nipple on the front of the engine. Otherwise the engine runs very smoothly and does not burn oil. (Ninety mile trip - no oil loss, but moor up and tilt and within minutes oil everywhere.) There is no water in the oil. Does anyone have any idea what is going on?

Chris}"

"I am pretty sure the nipple i

"I am pretty sure the nipple is a vent for the block.

Here is the obvious question...is your oil at the proper level?

Have you changed your oil lately? And did this start shortly thereafter?

Is it possible that the oil is coming from somewhere else and running to the nipple and dripping there? Oil is very deceptive.

Since the oil filter is in the same area...is it tight? Is it possible the old o ring was left on when the oil was changed. That will cause a leak when you tilt the motor.

A way to check to see exactly where the oil is coming from...you should clean the entire area with something like brakeclean. Let it dry. Then get some powdered spray antipersperent and spray all over the area...leaving a coating of dry powder.

Tilt the motor up and the white powder will change very quickly, letting you know exactly where the leak is. You know that the leak can be anywhere from the nipple on up (or to the side...especially is the motor was turned to one side or the other when raised).

There may be something else commercially available to do this. Your motor will smell very feminine for a while.

As for the nipple...
If you have a small hose or a bendy straw, remove the oil cap, connect the hose/straw to the end of the nipple and gentle blow into it. Feel any restriction? I do not know if there is any sort of valve on the other side. I can not tell from the service manual."

"If it's like mine, there

"If it's like mine, there is a chamber up front near the starter and vent hoses attached which run down to the oil filler/dip stick area. These had spring wire clamps which liked to cut the hoses. Check there for leaks."

"Thanks a lot. The fault star

"Thanks a lot. The fault started one day out of the blue on a trip around the Hebrides ie not after oil change. Oil level is correct and leak is not from filter. I will do what you suggest, but it will have to wait a while - swine flu has got the better of us! I will let you know when i get to the bottom of it..."

Good luck with the flu!

Good luck with the flu!

"Pull your starter out and loo

"Pull your starter out and look into the chamber below. If you see a puddle of oil there, you have a lower crank seal that has gone bad. Honda had some tech bulletins on that a few years ago.
Nick"

"I think the bulletin that is

"I think the bulletin that is being referred to is (bulletin #47) for water dripping from the flywheel cavity vent tube due to the seals in the mount case letting water in from the bottom. It would eventually get to the starter and cause a failure.

However, it seems the basic theory could be correct concerning the lower crank seal with evidence being seen in the starter area."