oil leak

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treeborn

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OK guys, help! 1970 Commando oil leak dripping from the left side of the cylinder head from the 3rd fin up from the barrels about an inch in from the exhaust pipe where the fin makes a slight angle in toward the center. The oil is dripping off this point on the fin where it makes this turn in. What is back in there that could be leaking? If it was the head gasket I would think it would be leaking between the head and barrel but no, it's three fins up from there. The cover over the valve adjusting cap is not leaking. This cover and the five fins above the leak are all dry. The three fins below the leak are wet and dripping. What do you all say? Ron
 
OK, I looked at another head I have. It's the push rod hole for the exhaust push rod for the left cylinder in the head that is "back in there" but why is it leaking three fins up from the barrel? Please don't tell me the head is cracked. Ron again.
 
treeborn said:
OK, I looked at another head I have. It's the push rod hole for the exhaust push rod for the left cylinder in the head that is "back in there" but why is it leaking three fins up from the barrel? Please don't tell me the head is cracked. Ron again.
Click to expand...

I had the same problem with a 850 that I have. When the hole for the stud was drilled it broke into the push rod tunnel allowing oil to leak out between the fins. If you look at where the leak is I think you will find the it is right where the inner nut holding the head is. Pull the head and look down the push rod tunnel and see if there is a hole. To fix my problem I used some 2 part epoxy putty that I picked up at a local auto parts store, kneaded it to a uniform color and rolled a small amount into a pea size ball and dropped it into the stud hole. Reinstalled the stud making sure none of the epoxy got into the push rod tunnel. Let it set up for a day or two and then reinstall the head.
Hope this helps.
John in Texas
 
Thank you John. I don't like the "pull the head" part! I was suspicious of that after looking closely at this other head I have and yes, I've used that epoxy for years to get out of trouble and it works. That stuff is a spin off of the space race. It has got me home many times and sometimes was a permanent fix. Thanks again. Ron in California (Pull the head...mumble, grumble, harumph)
 
Get a small LED torch and check the top of the cylinder stud by looking in between the fins, there is a good chance the oil is coming up the stud. You will see oil sitting on the top face of the nut.
Easily overcome if using a composite gasket, by using a small smear of sealant in a figure if eight around the pushrod tunnel and the stud hole on both sides of the gasket before fitting.
 
Hi.
Could be no oil leak from the head gasket but only oil leak from the rocker cover plate or valve cover.
If you loose oil from those parts the oil go down trough the internal finnes and arrives to the top of the barrells.
Piero
 
Last edited:
pierodn said:
Hi.
Could be no oil leak from the head gasket but only oil leak from the rocker cover plate or valve cover.
If you loose oil from those parts the oil go down trough the internal finnes and arrive to the top of the barrells.
Piero
Click to expand...
Yes, that was happening on my 850... poorly sealing rocker covers lead to seepage running down to emerge at lower head fins. I glassed the sealing edges of the covers. They were bad because previous own had them chromed and that left bad convex curves all along the edges. Glassing them took a few hours but essentially halted nearly all the seepage. I eliminated the final amounts by installing a PCV check valve on the breather hose to reduce crankcase pressure pulses.
No more leaks!
 
I recently walked into a conversation regarding a leaky Kawasaki, I was dragged into this by the comment "hes a Norton man ,he'll know all about oil leaks"; apparently the kawasaki man had been chasing this annoying leak for months.
" Easy" I said "blow down the breather and pressurise the crankcase and look for bubbles"! 5 mins later the guy comes over shaking my hand , my new best mate found a hairline crack in the cam case cover, application of Araldite fixed the problem, no more leak. Ive succesfully used this trick before on my norton and a plug oiling Suzuki RG500 with a cracked crankcase. Its simple, it doesnt involve stripping the motor to find ,worth a try. Dont forget to disconnect the reed valve breather if you have one. An application of soapy water can sometimes help. Good Hunting.
 
If the intake rocker cover leaks, the oil runs forward on the head and appears on the front of the fins.
 
Tornado said:
Yes, that was happening on my 850... poorly sealing rocker covers lead to seepage running down to emerge at lower head fins. I glassed the sealing edges of the covers. They were bad because previous own had them chromed and that left bad convex curves all along the edges. Glassing them took a few hours but essentially halted nearly all the seepage. I eliminated the final amounts by installing a PCV check valve on the breather hose to reduce crankcase pressure pulses.
No more leaks!
Click to expand...

Hi.
About how you say "I eliminated the final amounts by installing a PCV check valve on the breather hose to reduce crankcase pressure pulses." please, what valve you have installed?-
Thamks.
Piero
 
The one I installed was actually a brake booster vacuum check valve found at my local automotive parts store for under $10.
oil leak


I placed it at the top of the oil tank where the breather tube enters the tank. 5/8" hose from timing case to valve, then 3/8" hose to tank fitting.
With engine idling, putting my finger at the breather opening inside the tank neck, I could feel the air pressure pulses quickly diminishing after a 10-30 second of idling.

This valve is plastic with a rubber seal...so likely will not last too long...but a good first attempt and next time will try a proper PCV valve which are usually all metal. One popular one is from XS650 Yamaha bikes...search forum here for sources.
 
Tornado said:
The one I installed was actually a brake booster vacuum check valve found at my local automotive parts store for under $10.
oil leak


I placed it at the top of the oil tank where the breather tube enters the tank. 5/8" hose from timing case to valve, then 3/8" hose to tank fitting.
With engine idling, putting my finger at the breather opening inside the tank neck, I could feel the air pressure pulses quickly diminishing after a 10-30 second of idling.

This valve is plastic with a rubber seal...so likely will not last too long...but a good first attempt and next time will try a proper PCV valve which are usually all metal. One popular one is from XS650 Yamaha bikes...search forum here for sources.
Click to expand...

Thank you.
Piero
 
treeborn said:
Thank you John. I don't like the "pull the head" part! I was suspicious of that after looking closely at this other head I have and yes, I've used that epoxy for years to get out of trouble and it works. That stuff is a spin off of the space race. It has got me home many times and sometimes was a permanent fix. Thanks again. Ron in California (Pull the head...mumble, grumble, harumph)
Click to expand...

When I went looking for the oil leak on mine I pulled the head 3 times. Yes it is a pain and yes replacing the head gasket can be expensive. But there is a certain amount of satisfaction once you get it sorted out.
John in Texas
 
I experienced this that oil came out of the third rib on the left side (bolt no.9)
This was after a total renovation. I lifted it head 3 times. The same thing happened every time.
Then I called Matt in CNW. He told me about two things he had experienced.
One was oil from the banjo to the oil hose on the right side of the head and the other was from the valve cover to the intake valves.
If it leaks from one of these, the oil comes out above the 3rd rib on the left side.
I had an invisible leak from the banjo that ran into the head and out on the left.
So the tip from Matt solved my problem, and make me happy:)

Vidar
 
FIXED IT!! First of all I'd like to thank everyone who responded to my request for help. You're a good group! Vidar through Matt at CNW nailed it. It was the right hand head oil feed banjo leaking. When I removed it there were no washers of any kind on the banjo. The stream of oil out the fitting was indeed difficult to see and copper washers on both sides fixed it. Yeah!! Thank you Vidar.

Ron
 
Good the hear you've nailed.
FYI, sprinkling Talcum/baby powder around joints can help detect faint leaks.
 
And if the location is tpp awkward to sprinkle talcum powder (access from below only for example) you can buy a spray can of foot powder such as Desenex. Sprays on and drys like talcum powder. Best results if you can spray a degreaser on first and get the suspect area clean.
 
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