Cam Case Cover oil leak
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  1. #1
    Senior Member Kerosene's Avatar
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    Cam Case Cover oil leak

    I have a freshly rebuilt 72 CL350 and after my first 50 miles a leak has developed along the cam case cover. Not a drop from the head gasket or base gasket. All new gaskets were used and all the old material was removed from the engine prior to reassembly. Isn't this area kinda "low pressure" as far as oil goes? I've never had a leak happen from this area. It's mostly from the front left side. The right side is dry. I'm going to try and retorque the engine to 13.5 lbs. If that doesn't help, what should I be looking for when I pull the engine and to see what might cause this?

    This is been a bit disappointing since the bike was almost 100% complete. But it's all a part of the learning experience and I'm okay with that.

    Cam Case Cover oil leak-20190910_092704.jpg
    74 CB350F
    72 CL350

  2. #2
    Senior Member ancientdad's Avatar
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    First, make sure the oil isn't coming from the inside of the points cover, from the seal on the camshaft behind the points plate. If it isn't, then it's likely you put the gasket on the cam bearing cap backwards... though they look like they will fit the same no matter which side is facing outward, they have to be put on correctly or the gasket will pinch one of the rocker shaft o-rings IIRC
    Tom

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  3. #3
    Senior Member Kerosene's Avatar
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    Thanks for the reply. First thing i did check was inside the points housing. I thought that too, but it's dry in there.

    I know the orientation is critical for the gasket alignment because it looks like it symetrical, but im pretty sure i put it on correctly.
    74 CB350F
    72 CL350

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  5. #4
    Senior Member Kerosene's Avatar
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    I went out and purchased a digital torque wrench to get a precise reading on the head bolts. I wasn't too far off. I know I went to the lighter side rather than over-tightening and most of the nuts were torqued around the 12 lbs range. So I retorqued all of them to 13.5 lbs. And unfortunately, the problem persisted. Looks like I'll be pulling the engine. A bit bummed, but what can you do.

    I do have a question since the engine runs perfect. Can I pull the cam case cover off without disturbing the head gasket? I think this could be accomplished by leaving in the two bolts under the spark plugs? The engine was assembled probably about a month ago. If I have to redo all the gaskets, I'll do that rather than pulling the engine twice.

    Thanks!
    74 CB350F
    72 CL350

  6. #5
    Senior Member Boomer343's Avatar
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    My experience with rebuilding these engines has me going to a higher torque spec than the FSM uses. Originally the spec I use came from reading about building race engines.

    The spec I use is first to oil the threads and washer then torque in stages to 16.5 foot pounds. Obviously a higher torque value plus adding the oil increases the actual torque reading.

    If you pull the cam box and replace the gasket then torque to a higher spec you should be OK but as you state it would be a pain to pull it again if your gamble doesn't pay off.

  7. #6
    Sensei 66Sprint's Avatar
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    Find the EXACT source of the leak FIRST...... Clean and baby powder will show it....
    .Then fix that, whatever it takes....You will NOT be happy if you shear a screw......
    "I have a mind like a steel trap.....Old and rusty, of antiquated design, and hard to get stuff back out of...."
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  8. #7
    Senior Member Kerosene's Avatar
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    Quote Originally Posted by 66Sprint View Post
    Find the EXACT source of the leak FIRST...... Clean and baby powder will show it....
    .Then fix that, whatever it takes....You will NOT be happy if you shear a screw......
    No, I agree. Planning on tearing down slowly to find the issue.
    74 CB350F
    72 CL350

  9. #8
    Supporting Member Yendor's Avatar
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    Over Torqueing the bolts will NOT be the solution to your problem.
    It WILL in fact create problems.
    It will begin a cascade of failures from metal fatigue. Resulting in broken fasteners etc.
    DON'T DO TI ! !

    Not only is the idea of overtorquing fasteners bad but the concept of oiling the threads and then over torquieing them is worse.
    Torque Values are ALWAY given for DRY fasteners.

    ANY Type of lubrication INCLUDING - Anti-Seize throws off the actual effective Torque.
    A bolt that has been oiled then torqued to 10 Ft Lbs. has an effective Torque of approx 12-14 Ft Lbs.
    The bolts will stretch then add heat and cooling the end result will be a metal fatigue failure.

    **Right Click on the Pic below and OPEN in a NEW TAB to see full size.**

    Cam Case Cover oil leak-torque-effect-oil.jpg

    Sourec: https://www.engineeringtoolbox.com/t...ts-d_1693.html
    1970 CB 350 CAFE - Current Project on the bench,
    1972 CB 350 K4 Red - Now a Happy Rider ! !
    1972 CB 350 K4 Green (My Sons) DONE - YES !,
    1st Bike 1970 SL 350 (Brought home in Parts - Trailer/Trunk/Back Seat - I miss that bike),
    2nd - Bike Kawasaki 750
    3rd - '73 XLCH 1000

  10. #9
    Senior Member Boomer343's Avatar
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    Quote Originally Posted by Yendor View Post
    Over Torqueing the bolts will NOT be the solution to your problem.
    It WILL in fact create problems.
    It will begin a cascade of failures from metal fatigue. Resulting in broken fasteners etc.
    DON'T DO TI ! !

    Not only is the idea of overtorquing fasteners bad but the concept of oiling the threads and then over torquieing them is worse.
    Torque Values are ALWAY given for DRY fasteners.

    ANY Type of lubrication INCLUDING - Anti-Seize throws off the actual effective Torque.
    A bolt that has been oiled then torqued to 10 Ft Lbs. has an effective Torque of approx 12-14 Ft Lbs.
    The bolts will stretch then add heat and cooling the end result will be a metal fatigue failure.

    **Right Click on the Pic below and OPEN in a NEW TAB to see full size.**

    Click image for larger version. 

Name:	Torque Effect-Oil.JPG 
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ID:	290316

    Sourec: https://www.engineeringtoolbox.com/t...ts-d_1693.html
    I don't disagree with your comments except that in my experience the method and torque settings I use on the head bolts has not resulted in any issues on the 8 engines I have rebuilt using it. No broken studs, no striped nuts and no leaks at any of the joints over a period of 10 years for the first one and nothing on the more more recent ones either.

    Of course your experience may vary.

  11. #10
    Senior Member Kerosene's Avatar
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    I spent some time researching oil leaks and came across some posts about blocked breather hoses. My breather hose is definitely not blocked nor pinched but i do have a small filter attached to the end. This wouldn't cause enough pressure to force oil out of the cam case gasket? The leak happens more at higher rpms, for what it's worth. Just thought I'd ask before the motor is pulled tomorrow.
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    74 CB350F
    72 CL350

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