LouisJamesNYC
Cadet
- Joined
- Jul 16, 2008
- Messages
- 17
I have a MCM 3.0L s/n # L311511. Boat mechanic says I need a new head gasket. Here are the symptoms:
1. The fore-most cylinder (the one closest to the thermostat and furthest from the drive) rates about 60 psi on the compression gauge. All other cylinders rate 170 psi (+/- 5 psi).
2. Engine makes a loud puff or pow like a motorcycle with a loud (or broken) exhaust.
3. A puff of air is felt coming out of the engine opposite this low compression cylinder at the bottom of the manifold where the manifold and head meet. And no, it is not a bad manifold as it's nearly new, and yes I've changed the manifold gasket (and riser gasket too.)
4. Engine runs fine otherwise. Temperature & oil pressure are good. Plugs are new, oil is new.
5. Runs fine except at 3000 rpm and greater then the engine starts to make an even louder metallic clanking and "pinging". Could this be related to low compression in the cylinder and the air leak?
My thinking & my mechanic's is that the combo of low compression and the puff or air indicates a blown head gasket.
What's YOUR thinking?
People have said it's worth pulling the head anyway to replace the gasket since if it's not a blown head gasket, any other problem that would be creating the two symptoms described above would show in the head (lifters, valves, etc.)
Watcha think??? The local mechanics here have steered me wrong on many occasions (like saying it was the manifold gasket for the above problem). ANY info & input will be GREATLY appreciated!!!
Thanks,
Lou
1. The fore-most cylinder (the one closest to the thermostat and furthest from the drive) rates about 60 psi on the compression gauge. All other cylinders rate 170 psi (+/- 5 psi).
2. Engine makes a loud puff or pow like a motorcycle with a loud (or broken) exhaust.
3. A puff of air is felt coming out of the engine opposite this low compression cylinder at the bottom of the manifold where the manifold and head meet. And no, it is not a bad manifold as it's nearly new, and yes I've changed the manifold gasket (and riser gasket too.)
4. Engine runs fine otherwise. Temperature & oil pressure are good. Plugs are new, oil is new.
5. Runs fine except at 3000 rpm and greater then the engine starts to make an even louder metallic clanking and "pinging". Could this be related to low compression in the cylinder and the air leak?
My thinking & my mechanic's is that the combo of low compression and the puff or air indicates a blown head gasket.
What's YOUR thinking?
People have said it's worth pulling the head anyway to replace the gasket since if it's not a blown head gasket, any other problem that would be creating the two symptoms described above would show in the head (lifters, valves, etc.)
Watcha think??? The local mechanics here have steered me wrong on many occasions (like saying it was the manifold gasket for the above problem). ANY info & input will be GREATLY appreciated!!!
Thanks,
Lou
