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Oil Leak From Left Front Side Of Valve Cover

14K views 18 replies 12 participants last post by  Mach VIII  
#1 ·
Hi all.


Forgive me if this post is redundant.

I did not ride for about 7.5 years. Then, in 2006, I picked up a used 2000 ZX12-R (lime green) with a Two Brothers slip-on exhaust and a Power Commander.

Not having ridden in so long, I thought everything was fine until I became more aware of a "burning" smell coming from my bike when it is at operating temperature. Having investigated the problem, I discovered a coat of oil coming from the valve cover. If sitting on the bike, it would be coming from the front side of the valve cover, from the left corner area.

I described this problem to a co-worker, and he said that his friend with a ZX-12R was experiencing the exact same problem.

I was wondering if an oil leak from this area is a common occurance on ZX-12Rs. I'm sure I can fix the problem myself by either checking the torque on the valve cover bolts or getting a new valve cover gasket.

Thoughts?


Thanks in advance.

-Z
 
#2 ·
yep.replace valve cover gasket with a new one each time you take cover off.use gasket maker on both sides of gasket and on o-rings on cover bolts.
 
#3 ·
Definitely replace the valve cover gasket and the little rubber washers for the valve cover bolts each and every time you crack open the cover. I went round-and-round on a previous bike using gasket sealant and reusing the old rubber gasket--THIS IS THE CAUSE OF VALVE COVER LEAKS. The rubber gaskets are not reusable. Once I replaced the gasket, all was well again.
 
#4 ·
Hi all.


Thank you for your replies.

The strange thing is that I bought the bike from a dealership that "supposedly" went through the bike. They did put on new tires, so I assume they actually went through the bike. Perhaps they went under the valve cover for something, and simply re-used the old gasket.

So, from what you are both saying, in addition to new valve cover bolt rubber gaskets and a new valve cover rubber gasket, use RTV (room temperature vulcanizing) gasket sealant on both sides of these gaskets?

If they are brand new, they won't suffice by themselves? If I put sealant on the underside of the gaskets, won't RTV get into the valve train and oil supply?


Thanks.

-Z
 
#5 ·
Yeah, I've never had to use RTV when using new rubber gaskets. I just use a little brake klean or something similar in the groove of the cover (where the gasket fits) to make sure there isn't any oil film in there and have never had a leak since.
 
#6 ·
i use the gasket maker cause i hate to redo my work over something i should no better not to follow thru on.
zx12r`s just have a problem with valve covers.oh well.nothig that 40 bucks and some labor can`t fix........it still pisses me off though.
 
#7 ·
Mine started to leak from BOTH sides at the end of last years riding season so it was a good time to check the valves and replace plugs too. Replaced all gaskets on valve cover and the book DOES tell you to use sealant around the "arcs" on the cover gasket, the "arcs" being the clearance cutouts for the cams ...the half rounds on the sides of the head ...Followed instructions and am now leak free (insert knock on wood emoticon) and valves are good !! I tried to over torque them last year but that really didnt seem to "stop" the leak. The valve cover bolts have a head just above the threads on them that prevents over torquing so that wont work !!
 
#8 ·
Avenger said:
...the book DOES tell you to use sealant around the "arcs" on the cover gasket...The valve cover bolts have a head just above the threads on them that prevents over torquing so that wont work !!
Good to know, now I (and others) won't go and make the same mistake.
 
#12 ·
I consider mine more seepage than leakage :wink:
 
#14 ·
Kawasabi said:
The cam sensor leaked on mine and its in that same area. New o-ring fixed it.
I know this is an older thread, but I found it while researching this same issue on mine. I've got a slight oil leak that appears to be on the front left of the motor. I suspect it may be coming from the cam sensor, but I can't really tell for sure. I replaced the seal with a new one, but that didn't fix it. I did not, however, put any sealant on the new one. Should I? Can I? Can I pull the cam sensor out and just put a little sealant on the rubber seal and stick it back together?

It's not a huge leak, but it is noticeable, and I can smell oil burning on the engine at stops sometimes, which is a bit annoying and disheartening (and embarassing too).

Thanks.
 
#15 ·
Valve cover leaks

Wow, I've never seen so many replies for such a simple subject. I've had my valve cover off three times and am still using the original gasket without any leaks anywhere. The secret is to take good care of the gasket when its off. Clean it with spray silcone and then lightly grease it with silcone grease which can be had at any Corvette/ Chevrolet dealer for about $2.50 for three small tubes. Clean the mating surfaces with silcone spray. Thats it. No gasket maker or anything else. Torque the valve cover correctly and in the correct sequence and unless the gasket is damaged or there is residual gunk on the mating surfaces, no leaks. Simple and cheap. When I checked the dealer wanted $60.00 for a new gasket. That's alot of beer to waste.
 
#16 ·
Well, I picked up my 12 a few months back from a dealer, so I don't really know the history as to whether the valve cover has ever been off. Since none of my other/prior bikes have had such a leak, I did a search here to see if this was a known issue on the 12's, and apparently it is.

While I can see some slight dampness around the valve cover gasket, I see more around the cam position sensor. I've had the fairing off and let it run after wiping things down to see where the oil is coming from, but it didn't really ever appear after 5-10 minutes. Since that gasket is a helluva lot easier to get at, I'd like to tackle it first and see if that's the cure. When I installed the replacement seal I didn't use any sealant. Now I'm wondering if I was supposed to, or if others have done so and resolved their leaking issues.
 
#18 ·
Valve cover gasket

You'll notice that the valve cover gasket has a raised area in the center of the gasket which fits into the grove of the valve cover. Its important to clean the gasket with silcone as it makes the gasket slippery and then to coat it with silcone grease which also allows the groves to match up and complete the seal. As long as the mating surfaces are clean and coated with silcone nothing should leak. As far as the cam position sensor, same thing hold true for the o-ring. Spray it with silcone, wipe gently and then coat it with silcone grease. Torque correctly and presto, No leaks!!