No compression - I can't see why
#1
No compression - I can't see why
As many of you know, this was a plug spitter I bought a few months back. After I did the timesert and a new coil, it still had a misfire on the same cylinder. A compression check revealed zero compression in #7. I did a borescope on the cylinder and there was liquid in the cylinder and signs that the previous owners helicoil had been chewed up and spit out, but no damage to cause zero compression.
I pulled the head and removed the cam to make sure the valves were sealing by putting liquid in the ports and looking for drainage. The intake valve weeps ever so slightly - just like the other cylinders. There is a chunk of the head missing where the spark plug threads in as pictured, but the plug seats and seals. I did a liquid test on it too.
The cylinder looks good to me and despite the obvious damage from the mastication of the helicoil, I can't see how this would cause zero compression.
The cam is good as well. I can only think it may be a blown head gasket. Here's a bunch of pics, what do you people think?
I pulled the head and removed the cam to make sure the valves were sealing by putting liquid in the ports and looking for drainage. The intake valve weeps ever so slightly - just like the other cylinders. There is a chunk of the head missing where the spark plug threads in as pictured, but the plug seats and seals. I did a liquid test on it too.
The cylinder looks good to me and despite the obvious damage from the mastication of the helicoil, I can't see how this would cause zero compression.
The cam is good as well. I can only think it may be a blown head gasket. Here's a bunch of pics, what do you people think?
#3
Can't be valve seats, they don't leak liquid when I filled the ports. I did the same thing for the spark plug hole. I didn't see anything obvious on the head gasket, but it wasn't stuck to the head or block.
#4
#6
The first pic looks like a crack in the head between the valve at the bottom at about 10 o'clock going toward the plug hole. Doesn't look like enough for zero compression though.
Did you do your liquid test in the cylinder to see if the piston and rings are holding?
When the damage happened the piston could have been hit hard enough to seize the ring and when it cooled down it may have contracted with the piston.
Just guessing though.
Did you do your liquid test in the cylinder to see if the piston and rings are holding?
When the damage happened the piston could have been hit hard enough to seize the ring and when it cooled down it may have contracted with the piston.
Just guessing though.
#7
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#10
The first pic looks like a crack in the head between the valve at the bottom at about 10 o'clock going toward the plug hole. Doesn't look like enough for zero compression though.
Did you do your liquid test in the cylinder to see if the piston and rings are holding?
When the damage happened the piston could have been hit hard enough to seize the ring and when it cooled down it may have contracted with the piston.
Just guessing though.
Did you do your liquid test in the cylinder to see if the piston and rings are holding?
When the damage happened the piston could have been hit hard enough to seize the ring and when it cooled down it may have contracted with the piston.
Just guessing though.
I think I'll TIG that part of the head and put it back together.
#14
#15
1. I would think for a ring failure bad enough to cause zero compression, there would be scoring on the cylinder.
2. A liquid test should reveal a substantial failure.
3. I really don't want to drop the pan!