Notes from the valve job on my 2007 3.0

[flyman219]

Here?s a heads up for those of you who may be planning a valve job on your Mercruiser 3.0. I was ready to reassemble mine when I noticed some holes in the engine block that looked to be closed up with carbon. At first I thought they were not being used and covered by the head gasket. Possibly some ports for casting purposes that had no value after. Then I placed the head gasket and noticed that there are holes over these ports. I checked the head and the ports were larger and square and also mostly blocked by rusty flakes and debris. I proceeded to clean out all four ports in the block and head. I also located one hole in the block right behind the water pump that was blocked. This looked to be the port that fed the water to these water jacket areas. I have circled these spots that became blocked to make others aware of the potential problem area.

I?m not sure if this was the only reason I had a valve tulip on my motor but I?m sure these blockages did not help matters at all. So words of the wise, if you see blocked out holes in the block make sure they are fully cleared before you start to reassemble the motor.

For those of you who are still reading my ramblings a question for you. Since my boat is raw water cooled and moored at a fresh water marina, is there anything I can do to keep this buildup from happening again? If it was a closed system a additive would be that answer.

By the way the motor runs better than new now.

Mike

 

[Bondo]

Since my boat is raw water cooled and moored at a fresh water marina, is there anything I can do to keep this buildup from happening again?

Ayuh,..... Generally speakin', drainin' the block in the fall gets most of the debris build up, which is Why, I'm always mentionin' pokin' out the drains with a screw or nail,...

 

[Grub54891]

^^ Agreed With Bondo,but poking out the block drains will get some of the flakes out,but not all of them. I don't think you can do much in preventing it from happening again.

 

[jhobbs26]

Awesome post....for me anyway. I'm getting ready to bolt my head back on tomorrow after sending it out for a freshen and having screw in studs installed. I'll be sure to check the block closely making sure the steam ports are open.

 

[flyman219]

Let me know what you find in your ports Jhobbs26, I'd like to know if my case was unique or something that is common on the 3.0 motor head and block.

Mike

 

[jhobbs26]

my steam ports were clean.

 

[jhobbs26]

i just looked closer at your pictures. The pic of the block you circled the steam holes, the hole on #2 cylinder has rust going from the hole to the cylinder. looks like the head gasket failed there. Is this what lead you to pulling the head?

 

[flyman219]

No Title

I think what you are seeing is the rust shadow of the larger square port in the head that is just above the smaller round port in the block. I did have a slightly blown head gasket between the #2 and #3 cylinders. The compression in #2 was 0 and #3 was 100 (1 and 4 were at 120). The loss of compression in #2 was due to a tulipped intake valve, it was so deformed it did not seat, even the valve seat had to be cut out and replaced. I'm not absolutely sure what started the failure but I'm guessing too much prop pitch (14.25X21), reduced circulation and possibly detonation caused by a piece of a spark plug that had broken off in the cylinder.

Here is a picture of the deposit on top of my #2 piston.


Mike