Oil pump or filter?

AZMatt

AZMatt

Joined
Mar 8, 2015
Messages
33
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Hi all,

68 N15cs. Problem started with excessive oil blow by out the breather. Found that the crankcase had almost a quart of oil when I drained it. After a ride the blow by resumes. Now suspecting oil pump is not returning to oil tank properly.

The PO installed a commando style oil filter on the return line to the tank. I'm thinking of removing it to free any restrictions. Do the N15 pumps not have enough pressure on the return line for a filter? Or should I leave it and take apart the oil pump to see if it's worn?

Thanks.
 
Triton Thrasher said:
Does the crankcase fill with oil while parked, or while riding?
Click to expand...
It fills during a ride. Then I get a steady to fast drip out of breather hose. I have the anti drain valve installed to prevent wet sumping so that shouldn't be an issue.
 
Sump plug screens clogged? If not, I suspect the oil pump.

Re: in-line oil filter ..... the scavenge side of the pump is capable of developing high pressure as the feed side. The resistance of an oil filter (assuming there is no unusual blockage in the filter or head) should be nothing for the pump to handle.

Does the scavenge pump deliver a strong stream to the oil tank? The stream should be more or less steady, with only a bit of a waver.

Slick
 
texasSlick said:
Sump plug screens clogged? If not, I suspect the oil pump.

Re: in-line oil filter ..... the scavenge side of the pump is capable of developing high pressure as the feed side. The resistance of an oil filter (assuming there is no unusual blockage in the filter or head) should be nothing for the pump to handle.

Does the scavenge pump deliver a strong stream to the oil tank? The stream should be more or less steady, with only a bit of a waver.

Slick
Click to expand...

Thanks. That's what I needed to know. I prefer to keep the filter fitted. I'll take the pump apart and see what I have. It appears to flow back steadily to the tank however after a good ride it just can't keep up and fills the crankcase.
 
AZMatt said:
It fills during a ride. Then I get a steady to fast drip out of breather hose. I have the anti drain valve installed to prevent wet sumping so that shouldn't be an issue.
Click to expand...

What sort of anti drain valve do you have fitted, could be your problem?
 
M
AZMatt said:
Hi all,

68 N15cs. Problem started with excessive oil blow by out the breather. Found that the crankcase had almost a quart of oil when I drained it. After a ride the blow by resumes. Now suspecting oil pump is not returning to oil tank properly.

The PO installed a commando style oil filter on the return line to the tank. I'm thinking of removing it to free any restrictions. Do the N15 pumps not have enough pressure on the return line for a filter? Or should I leave it and take apart the oil pump to see if it's worn?

Thanks.
Click to expand...
Matt, I would look at the oil pump. On another thread it was mentioned that the return oil pump gears wear faster than the feed ones. The fellow posting his thoughts said that contaminates in the oil cause wear on the gears.
Question, are you in AZ?
John in Texas
 
Do the obvious.

Bypass the filter. If that makes no difference, then the filter was not causing your problem.
 
Thanks guys. I bypassed the filter and it made no difference. I will be taking apart soon to inspect the oil pump. I've heard from another Norton owner that it could be a seal on the crankshaft under the timing cover. And John in Texas-I just moved from Arizona to Nashville.
 
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