Author Topic: Cam cover oil leak  (Read 490 times)

Offline mo goldie

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Cam cover oil leak
« on: November 01, 2026, 05:00:53 PM »
Hi guy`s

I have just got a cb750 K4 for the first time and it`s got oil coming from the Cam cover at the front and running down the front fins of the Engine.....as I am not up much on them I wanted to know do any of you guy`s use a sealent on the gasket or just put it on Dry ? the thing I do know you can`t get the cam cover off without taken the engine out or doing things like the frame ralils cut and No way am I going to do that  :-X but you can get the old gasket off and the new one on while it is in the frame, as I just got the old one off......... I wonder if someone put the gasket on Wrong.....I have watched the YourTube video on one bloke saying about the little Nick in the gasket should be put on on the nearside of the bike...... but as said just wondered if anyone thinks it is a good Idea to put anything on it or Not......If so what would you use ? I use in most cases Wellseal so to use or Not to use ?

Cheers Mo
Currant BIKES:

1980 Triumph Bonneville 750 T140/D Special Black & Gold
1962 BSA 650 Rocket Gold Star ( silver ) 
1977 Norton Commando 850 MK3  Interstate ( silver )
1977 Kawasaki KH400 Triple ( Green )
1999 Harley Davidson 1200S Sport (Diamand Ice silver )
1975 Honda Monkey st70 Dax ( Candy Sapphire Blue)
1967 Honda CB450 KO  ( Black Bomber )
1973 Yamaha Fs1-E ( Popsicle Purple )
1974 Honda CB750 K4 (Flake Sunrise Orange )

Offline Skoti

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Re: Cam cover oil leak
« Reply #1 on: November 01, 2026, 06:06:08 PM »
Take the engine out and fit a new genuine Honda gasket, make sure the surfaces are clean and dry before fitting the new gasket.

Absolutely use no gasket sealer whatsoever.


BTW

Have you checked the oil leak is not coming from the tacho drive oil seal?

Good luck.
Skoti


Motorcycling is Life, anything B4 or after is just waiting...

1976 Honda CB750F1

Offline McCabe-Thiele (Ted)

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Re: Cam cover oil leak
« Reply #2 on: November 01, 2026, 06:09:20 PM »
Trouble with sealant is removing it if you have to do the task again.

I have always used a light smear of grease on both surfaces, pretty sure many fit it dry.
For rubber type gaskets I use red rubber grease.

I also check the vent is clear as crankcase pressure will pump oil out.
.
« Last Edit: November 01, 2026, 06:11:02 PM by McCabe-Thiele (Ted) »
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline Nurse Julie

  • 1977 CB550/4 Mongrel Brat. 1974 UK 500/4 K1. Honda CD250u.
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Re: Cam cover oil leak
« Reply #3 on: November 01, 2026, 06:13:43 PM »
The prime suspect for leaks in this area are the pucks, (cylinder head oil seals). Even if it is just the gasket, the proper way to replace is remove the engine.
LINK TO MY EBAY PAGE. As many of you know already, I give discount and do post at cost to forum members if you PM me direct.
https://www.ebay.co.uk/sch/julies9731/m.html?item=165142672569&rt=nc&_trksid=p2047675.m3561.l2562

LINK TO MY CB400/4 ENGINE STRIP / ASSESSMENT AND REBUILD...NOW COMPLETE
http://www.sohc.co.uk/index.php/topic,14049.msg112691/topicseen.html#new

Offline mo goldie

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Re: Cam cover oil leak
« Reply #4 on: November 01, 2026, 07:02:06 PM »
Thanks All.

Well I will try the engine Not out first and see if I can do that and put gasket on "DRY" oh it is a Genuine Honda gasket.
I have a new tacho oil seal coming as I thought I would do that at the same time there was a bit of oil from there but Not much
..is that easy to get out the old one do you think ?

I have lots of other job to do on it so it will take me a while to sort it all out but will get back on my hours.......... oh taken the easy way first LOL  ;D
« Last Edit: November 01, 2026, 07:30:17 PM by mo goldie »
Currant BIKES:

1980 Triumph Bonneville 750 T140/D Special Black & Gold
1962 BSA 650 Rocket Gold Star ( silver ) 
1977 Norton Commando 850 MK3  Interstate ( silver )
1977 Kawasaki KH400 Triple ( Green )
1999 Harley Davidson 1200S Sport (Diamand Ice silver )
1975 Honda Monkey st70 Dax ( Candy Sapphire Blue)
1967 Honda CB450 KO  ( Black Bomber )
1973 Yamaha Fs1-E ( Popsicle Purple )
1974 Honda CB750 K4 (Flake Sunrise Orange )

Offline Skoti

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Re: Cam cover oil leak
« Reply #5 on: November 01, 2026, 07:56:07 PM »
To renew the tacho drive oil seal, I recommend heating the cam cover with a hot gun or the wife's hair dryer.

Then use the appropriate item from a hook and pick set to extract the seal, but try to avoid damage to the oil seal seating area.


ATB.
Skoti


Motorcycling is Life, anything B4 or after is just waiting...

1976 Honda CB750F1

Offline mo goldie

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Re: Cam cover oil leak
« Reply #6 on: November 01, 2026, 11:29:44 PM »
ok thanks........... I got a heat gun.........mrs will heat me if I use her hair dyrer lol

and I got some pick tools too  ;D
Currant BIKES:

1980 Triumph Bonneville 750 T140/D Special Black & Gold
1962 BSA 650 Rocket Gold Star ( silver ) 
1977 Norton Commando 850 MK3  Interstate ( silver )
1977 Kawasaki KH400 Triple ( Green )
1999 Harley Davidson 1200S Sport (Diamand Ice silver )
1975 Honda Monkey st70 Dax ( Candy Sapphire Blue)
1967 Honda CB450 KO  ( Black Bomber )
1973 Yamaha Fs1-E ( Popsicle Purple )
1974 Honda CB750 K4 (Flake Sunrise Orange )

Offline Spitfire

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Re: Cam cover oil leak
« Reply #7 on: November 02, 2026, 08:51:01 AM »
This is how I removed the tacho seal on my 750F1.


Cheers

Dennis
1976 CB750F

1977 CB750F2 In bits

1964 BSA A65R In bits

Offline McCabe-Thiele (Ted)

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Re: Cam cover oil leak
« Reply #8 on: November 02, 2026, 11:22:05 AM »
I did the same.
Honda CB400NA Superdream (current money puddle)
Honda CB500 K1 (second money pit)
https://www.sohc.co.uk/index.php/topic,28541.0.html
Honda CB400 four super sport (first money pit)
Link to my full restoration http://www.sohc.co.uk/index.php/topic,23291.0.html
This is a neat 500 restoration in the USA.
http://forums.sohc4.net/index.php/topic,151576.msg1731556.html#msg1731556

Offline mo goldie

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Re: Cam cover oil leak
« Reply #9 on: November 02, 2026, 06:40:44 PM »
yes ok I will do that then makes sence rather than going in with picks..

cheers Guy`s
Currant BIKES:

1980 Triumph Bonneville 750 T140/D Special Black & Gold
1962 BSA 650 Rocket Gold Star ( silver ) 
1977 Norton Commando 850 MK3  Interstate ( silver )
1977 Kawasaki KH400 Triple ( Green )
1999 Harley Davidson 1200S Sport (Diamand Ice silver )
1975 Honda Monkey st70 Dax ( Candy Sapphire Blue)
1967 Honda CB450 KO  ( Black Bomber )
1973 Yamaha Fs1-E ( Popsicle Purple )
1974 Honda CB750 K4 (Flake Sunrise Orange )

Offline mo goldie

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Re: Cam cover oil leak
« Reply #10 on: November 03, 2026, 05:23:59 PM »
hi

went into the workshop today and used the screw to get the old oil seal out along with a bit of heat and yes all good as
it came out and new one fitted so thanks guy`s I am getting there .... mind you got till next year to finish it as for our weather as only a fair weather rider now lol Age ha  ;D
Currant BIKES:

1980 Triumph Bonneville 750 T140/D Special Black & Gold
1962 BSA 650 Rocket Gold Star ( silver ) 
1977 Norton Commando 850 MK3  Interstate ( silver )
1977 Kawasaki KH400 Triple ( Green )
1999 Harley Davidson 1200S Sport (Diamand Ice silver )
1975 Honda Monkey st70 Dax ( Candy Sapphire Blue)
1967 Honda CB450 KO  ( Black Bomber )
1973 Yamaha Fs1-E ( Popsicle Purple )
1974 Honda CB750 K4 (Flake Sunrise Orange )

Offline mo goldie

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Re: Cam cover oil leak
« Reply #11 on: November 08, 2026, 05:51:06 PM »
well it was workshop day. And got the gasket on so hope that do Not leak Now  ::)

as if Julie is right then it will be an engine out......but loads of other jobs to do before I can get to start it to find out if its ok.
when I get there I will let you all know who it go`s.
Currant BIKES:

1980 Triumph Bonneville 750 T140/D Special Black & Gold
1962 BSA 650 Rocket Gold Star ( silver ) 
1977 Norton Commando 850 MK3  Interstate ( silver )
1977 Kawasaki KH400 Triple ( Green )
1999 Harley Davidson 1200S Sport (Diamand Ice silver )
1975 Honda Monkey st70 Dax ( Candy Sapphire Blue)
1967 Honda CB450 KO  ( Black Bomber )
1973 Yamaha Fs1-E ( Popsicle Purple )
1974 Honda CB750 K4 (Flake Sunrise Orange )

Offline Skoti

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Re: Cam cover oil leak
« Reply #12 on: November 08, 2026, 06:47:41 PM »
Here's how I managed to remove and refit my CB750 engine myself.

https://photos.app.goo.gl/bT5X3iyGV89S47w26


But you need a smooth concrete garage floor to be able to slide the bike sideways on the main stand.


Good luck
Skoti


Motorcycling is Life, anything B4 or after is just waiting...

1976 Honda CB750F1

Offline mo goldie

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Re: Cam cover oil leak
« Reply #13 on: November 09, 2026, 05:30:55 PM »
Hi Skoti

I replaced the the gasket on the cam cover yesterday without taken the engine out and its all on now......... Just hope when I get round to starting it there is No Oil leaks...we shell see but Might take a bit of time as loads to do before I get to that stage  ;D

Cheers Maurice
Currant BIKES:

1980 Triumph Bonneville 750 T140/D Special Black & Gold
1962 BSA 650 Rocket Gold Star ( silver ) 
1977 Norton Commando 850 MK3  Interstate ( silver )
1977 Kawasaki KH400 Triple ( Green )
1999 Harley Davidson 1200S Sport (Diamand Ice silver )
1975 Honda Monkey st70 Dax ( Candy Sapphire Blue)
1967 Honda CB450 KO  ( Black Bomber )
1973 Yamaha Fs1-E ( Popsicle Purple )
1974 Honda CB750 K4 (Flake Sunrise Orange )