major engine problem?

[busa13R]

after a 140.3 horsepower dyno pull, I performed a compression test on my busa and found one cylinder with low compression. I poured a capfull of oil into that cylinder and did the test again to see what the results would be but noticed the oil dripping onto the garage floor. There is a small "weep hole" of some sort located just under the exhaust ports on the cylinder head. This is wear the oil was coming out of so I am 100% sure the air in the combustion chamber also is leaking out here causing a drop in compression. Does anyone know what the purpose of those holes are and what type of repairs will be necessary? the other cylinders were reading 140-150, I am attempting to find a service manual to download to find out what the normal should be. PLEASE HELP ASAP I AM ALSO ATTEMPTING TO REMOVE THE HEAD MYSELF.http://www.busanation.com/forum/titanium/misc/progress.gif

[Quasar]

after a 140.3 horsepower dyno pull, I performed a compression test on my busa and found one cylinder with low compression. I poured a capfull of oil into that cylinder and did the test again to see what the results would be but noticed the oil dripping onto the garage floor. There is a small "weep hole" of some sort located just under the exhaust ports on the cylinder head. This is wear the oil was coming out of so I am 100% sure the air in the combustion chamber also is leaking out here causing a drop in compression. Does anyone know what the purpose of those holes are and what type of repairs will be necessary? the other cylinders were reading 140-150, I am attempting to find a service manual to download to find out what the normal should be. PLEASE HELP ASAP I AM ALSO ATTEMPTING TO REMOVE THE HEAD MYSELF.http://www.busanation.com/forum/titanium/misc/progress.gif

The small hole below the exhaust port that you are referring to is where the fresh air from the pair valve hose enters the headers to help complete the burn of the expelled A/F mixture. If you placed a cap full of oil in the cylinder, the oil MUST be expelled and when it is, it can leak through that small hole if the gasket is damaged or isn't tight enough HOWEVER, this WON'T cause a loss of compression in your cylinder, as this hole has no connection with the actual combustion chamber. If you've removed your pair valve, then you would have block-off plates covering each of the small holes.

What was the compression in the cylinder that you suspect has low compression?

[busa13R]

95psi - - - the pair valve holes are located above the exhaust ports. After pulling the head I was able to get a better idea of which direction the hole was going and found that it is actually a "weep hole" located in the spark plug hole. I am assuming that this is for any moisture that may accumulate or accidentally get spilled into the spark plug hole and will allow it escape outside of the cylinder head. Note that this will only prove useful if the spark plug is still installed. If the plug is removed, any liquids spilled will go directly into the combustion chamber. some of the oil I poured apparently ran into the weep hole. My problem is likely a blown head gasket/ warped head/warped cylinders. I'll have a machine shop inspect them soon. . . . . .overheated at the track once and i decided to buy a bunch of ice bags to help speed up the cooling process.

[Quasar]

95psi - - - the pair valve holes are located above the exhaust ports. After pulling the head I was able to get a better idea of which direction the hole was going and found that it is actually a "weep hole" located in the spark plug hole. I am assuming that this is for any moisture that may accumulate or accidentally get spilled into the spark plug hole and will allow it escape outside of the cylinder head. Note that this will only prove useful if the spark plug is still installed. If the plug is removed, any liquids spilled will go directly into the combustion chamber. some of the oil I poured apparently ran into the weep hole. My problem is likely a blown head gasket/ warped head/warped cylinders. I'll have a machine shop inspect them soon. . . . . .overheated at the track once and i decided to buy a bunch of ice bags to help speed up the cooling process.

I thought I recollected the holes for the pair valve as being under, but you are correct, they are above, but this changes nothing. Neither hole has anything to do with a "loss of combustion chamber pressure" and that was the point that I was making.

[PrimalBusa]

The holes you are referring to are there for water drainage only. When you were pouring oil down your spark plug holes some of it drained out. That is what those holes are for. Your compression loss is not because of these factory drain holes.