Crankcase pressure
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From: NorCal
I don't believe you'll notice much if anything at idle. You'd need to crank it up a bit.
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From: San Diego, CA
Are you talking about the breather assemblies that go in the rocker boxes....??? If so, it's not a difficult job, just time consuming. You have to remove the fuel tank, the rocker covers, the Breather assemblies, then reassemble everything....
If you have (can borrow) a leak down tester & a compressor... it will take about 15 minutes to do a leak down test and it only requires removing the spark plugs..
If it passes the leak down test, you know you need to dig deeper into the breather system.
If the leak down test shows bad rings, you can wait to replace the breathers when you take off the jugs for new pistons/rings...
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From: Montreal
Are you talking about the breather assemblies that go in the rocker boxes....??? If so, it's not a difficult job, just time consuming. You have to remove the fuel tank, the rocker covers, the Breather assemblies, then reassemble everything....
If you have (can borrow) a leak down tester & a compressor... it will take about 15 minutes to do a leak down test and it only requires removing the spark plugs..
If it passes the leak down test, you know you need to dig deeper into the breather system.
If the leak down test shows bad rings, you can wait to replace the breathers when you take off the jugs for new pistons/rings...
If you have (can borrow) a leak down tester & a compressor... it will take about 15 minutes to do a leak down test and it only requires removing the spark plugs..
If it passes the leak down test, you know you need to dig deeper into the breather system.
If the leak down test shows bad rings, you can wait to replace the breathers when you take off the jugs for new pistons/rings...
Thank you,
Today my new oil cap blew off after 5 min of riding and broke into pieces on the floor, this is the 2nd one. Brought it to the dealer, I have no idea what else to do. They say some vent is blocked, ill let you guys know what they find! Keeping my fingers crossed that its nothing major 🤞
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,061
Likes: 11,080
From: San Diego, CA
Thank you,
Today my new oil cap blew off after 5 min of riding and broke into pieces on the floor, this is the 2nd one. Brought it to the dealer, I have no idea what else to do. They say some vent is blocked, ill let you guys know what they find! Keeping my fingers crossed that its nothing major 🤞
Today my new oil cap blew off after 5 min of riding and broke into pieces on the floor, this is the 2nd one. Brought it to the dealer, I have no idea what else to do. They say some vent is blocked, ill let you guys know what they find! Keeping my fingers crossed that its nothing major 🤞
Please remember to report what they find...
The breather assemblies in the rockers, control the crankcase venting. They are pretty simple and I've not heard of them failing before.. Most breather assembly problems come from being assembled wrong with the rubber butterfly valve put on wrong, and actually then blocking the crankcase pressure from escaping through the head/breather bolts, etc... I'm very curious now, what they will find. Whether it's these breather assemblies themselves, or some of the hoses/passages after the breather assemblies they think are blocked...
FYI......
Forgive me if you already know this, but here are a couple of pics of the breather assembly in the rocker boxes. It's located between the rocker arms. The first pic is the breather assembly unit. It was just before I removed it, so the two bolts that hold it in place are missing. The second pic is with the top of the breather removed, exposing the rubber umbrella valve. That valve directs the pressure through the entire breather system.. from crankcase to air cleaner (or atmosphere in my case).
Last edited by hattitude; Jul 2, 2021 at 09:22 PM.
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From: Montreal
Please remember to report what they find...
The breather assemblies in the rockers, control the crankcase venting. They are pretty simple and I've not heard of them failing before.. Most breather assembly problems come from being assembled wrong with the rubber butterfly valve put on wrong, and actually then blocking the crankcase pressure form escaping through the head/breather bolts, etc... I'm very curious now, what they will find. whether it's these breather assemblies themselves, or some of the hoses/passages after the breather assemblies they think are blocked...
FYI......
Forgive me if you already know this, but here are a couple of pics of the breather assembly in the rocker boxes. It's located between the rocker arms. The first pic is the breather assembly unit. It was just before I removed it, so the two bolts that hold it in place are missing. The second pic is with the top of the breather removed, exposing the rubber umbrella valve. That valve directs the pressure through the entire breather system.. from crankcase to air cleaner (or atmosphere in my case).
The breather assemblies in the rockers, control the crankcase venting. They are pretty simple and I've not heard of them failing before.. Most breather assembly problems come from being assembled wrong with the rubber butterfly valve put on wrong, and actually then blocking the crankcase pressure form escaping through the head/breather bolts, etc... I'm very curious now, what they will find. whether it's these breather assemblies themselves, or some of the hoses/passages after the breather assemblies they think are blocked...
FYI......
Forgive me if you already know this, but here are a couple of pics of the breather assembly in the rocker boxes. It's located between the rocker arms. The first pic is the breather assembly unit. It was just before I removed it, so the two bolts that hold it in place are missing. The second pic is with the top of the breather removed, exposing the rubber umbrella valve. That valve directs the pressure through the entire breather system.. from crankcase to air cleaner (or atmosphere in my case).
I bought the 2 umbrella breathers you posted earlier. I was going to change them out but when i tested them using a straw i was able to confirm there functionality. Maybe they do need to be replaced, well see, i will definitely report back.
Thxs again 🙏
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From: Montreal
So just got the bike back from Harley and the problem was one of the umbrella valves that was not working anymore, they changed both of them and so far no more oil dip stick blowing off!!! So happy it wasn't the piston rings.
Good to know if anyone encounters the same issue, you can add the 2 umbrella valve replacement to the list of possible causes to crank case pressure.
Thank you everyone for there help!!🙏
Good to know if anyone encounters the same issue, you can add the 2 umbrella valve replacement to the list of possible causes to crank case pressure.
Thank you everyone for there help!!🙏
Seasoned HDF Member
Joined: Sep 2008
Posts: 14,061
Likes: 11,080
From: San Diego, CA
So just got the bike back from Harley and the problem was one of the umbrella valves that was not working anymore, they changed both of them and so far no more oil dip stick blowing off!!! So happy it wasn't the piston rings.
Good to know if anyone encounters the same issue, you can add the 2 umbrella valve replacement to the list of possible causes to crank case pressure.
Thank you everyone for there help!!🙏
Good to know if anyone encounters the same issue, you can add the 2 umbrella valve replacement to the list of possible causes to crank case pressure.
Thank you everyone for there help!!🙏
Thanks for the update...
I would have loved to see how it failed... must have "stuck closed" to the metal frame.. or maybe the fiber filter got clogged up real bad with old oil...
This is the first time I recall hearing about them failing in a blocked position... good info to know..
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Joined: Mar 2019
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From: Montreal
Thanks for the update...
I would have loved to see how it failed... must have "stuck closed" to the metal frame.. or maybe the fiber filter got clogged up real bad with old oil...
This is the first time I recall hearing about them failing in a blocked position... good info to know..
I would have loved to see how it failed... must have "stuck closed" to the metal frame.. or maybe the fiber filter got clogged up real bad with old oil...
This is the first time I recall hearing about them failing in a blocked position... good info to know..
Thxs for all you help Hattitude!🙂💪
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justgliding99
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Aug 15, 2018 07:24 PM