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Discussion Starter #1
My Kawaaki zx750 after some days on vacations i turn it on and suddenly all the oil came out form the engine..

why it happende so suddenly? what could be the reason?..

my mechanic sid could be the gasoline was licking inside by tears until it had a lot of presure..
but hes not sure about it also..

any idea why this things happens i mean so suddenly?

Thanks!
 

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Vintage bike addict
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Smell the oil. If it smells of gasoline I'd say your mechanic is right. More often a fuel leak will go out the overflow tubes to the floor. How many miles on the bike?
 

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Discussion Starter #3
Smell the oil. If it smells of gasoline I'd say your mechanic is right. More often a fuel leak will go out the overflow tubes to the floor. How many miles on the bike?
im not sure about miles but on Km might be like 47 .000 km, (might be 30000 miles)
 

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Navy Vet Search & Rescue
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Smell the oil. If it smells of gasoline I'd say your mechanic is right. More often a fuel leak will go out the overflow tubes to the floor. How many miles on the bike?
+1 Sounds like the fuel tank has emptied it's self into the crankcase.
 

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Discussion Starter #5
+1 Sounds like the fuel tank has emptied it's self into the crankcase.
yes, well the Tank was tearing some fuel in.. i forgot to close the fuel petcock.. but ive never heard that reason.. so that why i asked.. but seems a good reason.. any other?
 

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Vintage bike addict
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Could be floats aren't seating the needle valves properly. I'd run a few tanks of fuel with a good carb /injector cleaner. Just the tiniest bit of foriegn matter stuck in there will allow fuel to pass. Change the oil first and get your leaks fixed. Did you in fact smell gas in the oil?
 

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Discussion Starter #7
Could be floats aren't seating the needle valves properly. I'd run a few tanks of fuel with a good carb /injector cleaner. Just the tiniest bit of foriegn matter stuck in there will allow fuel to pass. Change the oil first and get your leaks fixed. Did you in fact smell gas in the oil?
Yes it actually smelled like gas on the oil.. a lot, and one thing caught my attention, when i oppenbde the CAP of the oil, it blew a lot of air!. like there was a lot of presure inside..

and it continued sendign air when the engine was on of course , is it normal?
 

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Vintage bike addict
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Running a motor with gasoline in the oil is asking for huge trouble! The oil cannot lubricate properly and gas vapor are building pressure inside and venting everywhere. Add hot exhaust and possible sparks you sir are standing next to a bomb!
 

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Yes it actually smelled like gas on the oil.. a lot, and one thing caught my attention, when i oppenbde the CAP of the oil, it blew a lot of air!. like there was a lot of presure inside..

and it continued sendign air when the engine was on of course , is it normal?
Heated gas expands creating pressure if it is in a confined space. Thats one of the reasons your fuel tank has a vent. It doesn't take much heat for this to happen. Just the normal air temp rise in the course of a day can cause it especially if the sun is beating down on the container. Take a sealed plastic gas container about half full and set it out in the sun and watch it swell if you want to see just how much this happens. As Antiq said, you are next to a potential bomb running your engine like that. Not to mention the wear it's causing. Change the oil immediately. I would also check the crankcase vent.


It is normal to have a little air comming out of the oil cap while the engine is running.
 

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Discussion Starter #10
Heated gas expands creating pressure if it is in a confined space. Thats one of the reasons your fuel tank has a vent. It doesn't take much heat for this to happen. Just the normal air temp rise in the course of a day can cause it especially if the sun is beating down on the container. Take a sealed plastic gas container about half full and set it out in the sun and watch it swell if you want to see just how much this happens. As Antiq said, you are next to a potential bomb running your engine like that. Not to mention the wear it's causing. Change the oil immediately. I would also check the crankcase vent.


It is normal to have a little air comming out of the oil cap while the engine is running.
yes im more clear now, a lot more clear. i t actually happened on very sunny days.

but .. how it happens i mean How exaclty the fuel leaks In to the crankase?.. and yes im gonna check the ventilation first.. thats my first tought when it happened..

so how where is the leaking?
 

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Sounds like the float needle/seats are not sealing off properly and leaving the petcock "ON" put them to the test. I think it was already mentioned earlier in this thread by someone.
 

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Discussion Starter #12
Sounds like the float needle/seats are not sealing off properly and leaving the petcock "ON" put them to the test. I think it was already mentioned earlier in this thread by someone.
o yes, thanks a lot man.. i have the picture clear now.


well thats My case, but is there any other reason why kaskets blow?..

Now im having a very small leaking of oil from another bike a (katana) but seems too smal to put the engine down.. any advice??
 

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The Cruising Gunsmith
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well thats My case, but is there any other reason why kaskets blow?..
Gasket material is not able to withstand strong solvents such as gasoline, acetone, kerosene. The gaskets are designed to handle oil, but not solvents.

I tested a cork gasket once with acetone and it disnitegrated. Most newer gaskets are just pressed fiber (paper) with some rubber added. Solvents can make those fall apart easily. If you got gas in the oil, it ate the gasket.
 

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Vintage bike addict
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Gaskets will blow for all the reasons stated above and #1 improper torque. #2 uneven torque. #3 Dissimilar metals ( expanding/contracting with heat at different rates) #4 warped mating surfaces. #5 Incorrect gasket material or incorrect thickness. #6 Pressurization of components not normally pressurized.
 

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Discussion Starter #16
CAN THEY JUST BLOW BEACUSE OF OLD?.. or not a really reason?
 

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CAN THEY JUST BLOW BEACUSE OF OLD?.. or not a really reason?
Age really has very little to do with a gasket blowing. Age and vibration can loosen bolts which would then allow gaskets to leak.
 

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Discussion Starter #18
Thanks guyz i learned a lot . Here MAny bikes run with one of the vent tank tubes closed, just because they dont know whats it really for and want to avoid leakings..
but seems pretty dangerous!
 
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