Mercruiser 3.0 Head Gasket

[sthibeau]

I have a 1998 3.0 Alpha 1. I pushed air through the cylinders and found air coming out one of the #2 intake so I am guessing it is my head gasket as I have oil in the water. Compression was around 120 for all 4 cylinders. My question is when I am pulling my head the manual that i down loaded only talks about having the #1 cylinder in the top dead center position. Do I need to roll the flywheel to have every cylinder in TDC before I remove all the rockers arms and rods. See SelocMarine Manual steps below that I copied from the online version. I'm guessing they all need to be. If that is the case, any suggestions on how to ensure i do it correctly so I don't mess up the timing. Or is is something I worry about when I put it all back together. Which will be the same question on adjusting the heads

1. Open or remove the engine hatch cover and disconnect the negative battery cable. Remove the cylinder head cover as detailed previously.
2. Bring the piston in the No. 1 cylinder to TDC. If servicing only one arm, bring the piston in that cylinder to TDC. The No. 1 cylinder on 3.0L engines is the first cylinder at the front of the engine.
3. Loosen and remove the rocker arm nuts and lift out the balls. Lift the arm itself off of the mounting stud and pull out the pushrod. It is very important to keep each cylinders component parts together as an assembly. We suggest drilling a set of holes in a 2 X 4 and positioning the pieces in the holes.

 

[tlewis1]

I have done a few of those..never have worried about having each cylinder at TDC when taking apart. Just have to make sure after everything is put back together that you time it properly. If it has Elec ignition you will need a timing shunt to put the engine into base timing mode and time from there. I would also run a straight edge across the head and be sure it hasn't warped any. May need to have head shop resurface it for you.

 

[sthibeau]

Thanks for the reply, yeah I know the head may have to go to the machine shop depending on if I warped it or not.

 

[fishrdan]

Before you do anything, pressurize the water jacket of the block to see if you can find out where the water in the oil is coming from, once the head is off you can't do this.

If you pressurize #2 cylinder and have air hissing out the intake (that's the way I take what you said), it's a poorly sealing valve, not the head gasket. You would still need to remove the head to have a valve job done, but it's not an easy head gasket swap.

While a leaking head gasket could leak water in the oil, I would suspect a cracked block. You will find out once the head is removed, but pressure test the block first, before removing the head. Pressurize the block and listen for hissing in the valve cover oil fill and externally.

How much water is in the oil (IE: drained 9 quarts of milkshake) and have you replaced oil/filter to have to water contamination return again?

 

[bruceb58]

Did you have #2 cylinder at the top when you tested it?

Having air leak through the intake does not mean it's a head gasket at all. Means you have a bad intake valve.
EDIT: Just saw Dan said the same thing.