Crankcase Pressure
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Road Master
Joined: Nov 2013
Posts: 852
Likes: 54
From: Dallas tx
Crankcase Pressure
Has anyone got any ideas what might cause excessive crankcase pressure? A guy I ride with is having troubles with his oil tank dipstick blowing out. He has an 08 Heritage. I've looked it over and can find nothing wrong. The bike runs good, compression is good (no blow by) and the bike is not over filled with oil. He's even replaced the dipstick, thinking that the fit had gotten loose over time. Along with this it seems to be making his rocker box seals to start to wreap, but that may not be related..
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Joined: Jan 2014
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From: Central California
Excess crankcase pressure is typically caused by a less than optimal ring seal.
With the oil cap or breather hose off, put your hand over the opening, and rev the engine a bit. If you can feel a good amount of air coming out, chances are the motor needs some help. Then move on to other diagnostic tools, such as doing a leak-down or compression check.
With the oil cap or breather hose off, put your hand over the opening, and rev the engine a bit. If you can feel a good amount of air coming out, chances are the motor needs some help. Then move on to other diagnostic tools, such as doing a leak-down or compression check.
Thread Starter
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Road Master
Joined: Nov 2013
Posts: 852
Likes: 54
From: Dallas tx
Excess crankcase pressure is typically caused by a less than optimal ring seal.
With the oil cap or breather hose off, put your hand over the opening, and rev the engine a bit. If you can feel a good amount of air coming out, chances are the motor needs some help. Then move on to other diagnostic tools, such as doing a leak-down or compression check.
With the oil cap or breather hose off, put your hand over the opening, and rev the engine a bit. If you can feel a good amount of air coming out, chances are the motor needs some help. Then move on to other diagnostic tools, such as doing a leak-down or compression check.
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Road Master
Joined: Nov 2013
Posts: 852
Likes: 54
From: Dallas tx
What do you mean by umbrella valve? That's a new one to me. Since there's no blow by on the rings I am kind of suspecting the crankcase vent not working properly and that's why I asked about it. But he'll, I don't even know how to find them..
Last edited by Pitbull_Dallas; Feb 17, 2016 at 02:34 PM.
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Joined: Jan 2014
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From: Central California
The umbrella seals are in the rocker box and prevent excess oil from blowing out the vent tubes that connect to the air cleaner. Even if those were bad, it wouldn't cause the dipstick to blow out.
Maybe if the head vents were blocked completely by someone who installed solid bolts rather than the hollow ones, that might cause the dip stick to blow out. That would mean no where else for the excess pressure to go.
Maybe if the head vents were blocked completely by someone who installed solid bolts rather than the hollow ones, that might cause the dip stick to blow out. That would mean no where else for the excess pressure to go.
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Road Warrior
Joined: Jun 2013
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From: Louisville, KY
Also, don't fill it above the 75% mark.
Last edited by 1004ron; Feb 17, 2016 at 03:37 PM.