2008 Mercury 150XL Optimax Serial #: 1B705774 Cylinder #6 & water coming out exhaust?

[STLBassBuster]

Hello Don,

20008 150hp Optimax XL Serial #: 1B705774
30 hours all original powerhead & lower unit

After following your compression procedure I am getting 120 psi on cylinders 1-5.

Cylinder #6 (bottom left when facing the back of the engine) is getting 95 psi.

I noticed a decent amount of water coming out of the exhaust, is this normal? It has a strong stream coming out the pee hole.

Any thoughts or suggestions on what I can do myself?

Thanks.

[leonreno]

Water out the exhaust at idle is normal, not sure what to tell you about #6, that’s low. Was #6 the last cylinder checked? If so I would make sure battery wasn’t low when checking my that cylinder. Otherwise, not sure what to tell you but you need to get eyes on the cylinder through spark hole or pulling head off. Could be gasket, hopefully.

[STLBassBuster]

I have some Mercury power tune soaking in the #6 cylinder. All the spark plugs look the same. I will run it again in the tub and will check the compression again on #6. A local shop told me it could be the adapter plate gasket that could allow water to wash out the cylinder. I would think the spark plug would show signs of that.....

[.44mag]

I recently redid the exhaust diver plate gasket and seal on mine. If you look at my thread, rebuild or repower, you will see pictures of where I pulled one of the heads off of mine. the middle and bottom cylinders had maybe a drop of water each in them. When I took the plate off the seal almost fell into the exhaust holes to the mid section and was in two pieces. The plugs were just wet and black (carb gaskets and cleaning done) but couldn't tell if they had water on them. Not sure if that gives any idea but......

[lpugh]

Hello Don,

20008 150hp Optimax XL Serial #: 1B705774
30 hours all original powerhead & lower unit

After following your compression procedure I am getting 120 psi on cylinders 1-5.

Cylinder #6 (bottom left when facing the back of the engine) is getting 95 psi.

I noticed a decent amount of water coming out of the exhaust, is this normal? It has a strong stream coming out the pee hole.

Any thoughts or suggestions on what I can do myself?

Thanks.

Perform a cylinder leak down test to measure the percentage of leak and identify where the leak is.

[EuropeanAM]

Jeff- Try repeating the test. Charge battery FULLY, follow the instructions in the link below, and START AT THE BOTTOM, working UP (just a hunch that you might see something different):

Compression Testing

[STLBassBuster]

Thanks Don I will give it a try and will report back in the next few days.

[moetorola]

Hello Don,

20008 150hp Optimax XL Serial #: 1B705774
30 hours all original powerhead & lower unit

After following your compression procedure I am getting 120 psi on cylinders 1-5.

Cylinder #6 (bottom left when facing the back of the engine) is getting 95 psi.

I noticed a decent amount of water coming out of the exhaust, is this normal? It has a strong stream coming out the pee hole.

Any thoughts or suggestions on what I can do myself?

Thanks.

Was there problem that caused you to do a compression test?? down on power??

Is the engine running fine?

[STLBassBuster]

Same result after testing the compression again. I dropped it off at a certified merc shop to figure this thing out. One of the only boats I did not check the compression before buying based on condition and extremely low hours. I won’t make that mistake again.

[EuropeanAM]

Hopefully something simple like a cylinder head o-ring.

[STLBassBuster]

Shop said it could be an injector that is stuck. They are suppose to get back to me next week.

[EuropeanAM]

That's possible... Direct (Air) Injector, anyway.