Spark plug leaking

[Robert Mayrand]

Ok got.a strange problem. While doing my valve adjustment and TB balancing i realise when i replace one spark plug  puff of air coming from the spark plug hole with the spark plug in place. I thought it was just not screwed right, so i rescrewed it ......same thing. Put a new one in place......same thing! Was starting to worry. Did a compression test and both cylinder are the same at about 155psi, so not a crack head or blown gasket. The plug wer perfect, not oily or anything. The thread look nice and can get a lot of torque. Seat seam ok. Any idea!

 

robert

[szurszewski]

Are you saying you think air is leaking out past the spark plug when it is in place, but NOT past the fitting for the pressure gauge when you're doing a pressure test?

 

 

[dirtrider]

35 minutes ago, Robert Mayrand said:

Ok got.a strange problem. While doing my valve adjustment and TB balancing i realise when i replace one spark plug  puff of air coming from the spark plug hole with the spark plug in place. I thought it was just not screwed right, so i rescrewed it ......same thing. Put a new one in place......same thing! Was starting to worry. Did a compression test and both cylinder are the same at about 155psi, so not a crack head or blown gasket. The plug wer perfect, not oily or anything. The thread look nice and can get a lot of torque. Seat seam ok. Any idea!

 

Robert

 

Evening Robert

 

Are you SURE that the puff of air is coming from the spark plug????

 

If you didn't get the valve cover donut (the rubber ring around the spark plug well) back in properly then you might be hearing air escaping from the crankcase as the pistons go down the cylinder & pressurize the crankcase.   

 

Take the oil filler cap off then see if the air leak decreases.

[Robert Mayrand]

The pressure gauge come with a big rubber o ring at the end so it seal ok and i don’t feel any puff of air when it’s in place, but i definitely feel a big puff when it’s a spark plug. I doubt its due to the donut around the spark plug hole, or i would also feel it when the pressure gauge is in place. And i don’t just hear it, it’s a big air puff blown at each stroke.

[dirtrider]

12 minutes ago, Robert Mayrand said:

The pressure gauge come with a big rubber o ring at the end so it seal ok and i don’t feel any puff of air when it’s in place, but i definitely feel a big puff when it’s a spark plug. I doubt its due to the donut around the spark plug hole, or i would also feel it when the pressure gauge is in place. And i don’t just hear it, it’s a big air puff blown at each stroke.

Evening Robert

 

I'm not sure what you have going on there. Does your spark plug socket fit into the plug well & not binding therefore keeping the spark plug from getting tight?

 

If it isn't the spark plug being broken (doubtful), & the cylinder head isn't cracked then it almost has to be leaking at the plug threads.

 

 

[Robert Mayrand]

The problem was the donut as pointed by you guys!, it felt while i reposition the cover! thank you so much! She’s now breathing like a young stallion!!!!!!

 

thanks again!

this forum is always amazing!

[ron c]

.............another incredible solve by the Oracle........

 

Ron C.

[Jim Moore]

To keep that from happening again look into the spark plug hole after you install the valve cover. You can see if the donut isn't installed correctly.