Mercruiser 3. 0 water in spark plug cylinders 3 and 4

[Seanb600]

Good evening all, this my first post. I recently acquired a 2006 Bayliner 185 with the Mercruiser 3. 0 and Alpha Drive. Boat has been running really well. I've had it on the water approximately 10 times after purchase and all is running really well. A few cosmetic things here and there the idol was a little rough. so I decided I was going to do a compression check and a tune-up.
The the tune up consist of new plugs wires distributor cap rotor. Rotor button I also went ahead and put in a new ignition module. Along with a new coil. So the whole ignition system is practically new still has a little bit of a rough idle but not a big deal it keeps running. but what I was changing the plugs I found that cylinder 3 & 4 had a small amount of water on the plugs. So that prompted me to do a compression check. so I got the engine up to running temperature after the tune up hooked up my compression gauge and I basically have between 160psi and 165psi on All 4 cylinders, so it's telling me it's not quite a blown head gasket. What else could be causing water to get in those back two cylinders.
Thank you for your time and your help in advance I do appreciate it.

 

[Scott Danforth]

Welcome aboard

Look at the elbow and manifold. Leaking elbow gasket will leak water into 3 and 4

 

[Seanb600]

Awesome Scott
thank you for your help,
One more quick question.
Can I wait till September to do this or does it have to be done immediately?

 

[Bt Doctur]

Not unless you want to put a new motor in. I would not risk a motor for a $6 gasket

 

[Scott06]

I wouldn't wait on checking this. I assume this is a salt water boat?

 

[Seanb600]

No fresh water only

 

[Seanb600]

I suppose that could make it idle a little rough ?

 

[achris]

Leaking gasket, or rusted through elbow, will destroy the engine in very short order. Getting onto it as quickly as possible will reduce the amount of damage done...

Chris........

 

[Seanb600]

Enough said looks like I will be getting on it after work tomorrow. Thank you everybody for their input and their help

 

[Scott06]

When you get it apart check the sealing surfaces for flatness and corrosion. It would be unusual for fresh water to rot the manifold but stranger things happen. There's only like a 1/4" of surface area between the water and the exhaust passages. If leaking would think you'd see rust streaks in manifold vs carbon soot

 

[Seanb600]

The first picture you see is the exhaust manifold after removal the second picture is the riser I could not see anywhere where water or rust was going through the gasket itself. However I did go ahead and replace this and the intake / exhaust manifold gasket I was able to Source them locally for about 28 bucks. I have not had a chance to test it yet as it started raining on me. I will keep you guys up to date

 

[Seanb600]

Okay y'all. I got a chance to run it under the water hose today. I let it idle warm up for about 15 minutes. Then let it run in neutral for about 30 minutes at 1500 RPM I'm not taking it any higher than that under a garden hose. Shut it down let it cool off for about 2 hours hold the cylinder number 4 spark plug which was the worst with water there was a little bit in cylinder 3. Fingers crossed it was bone dry. I'm going out on the lake on Saturday so that will be the real test and then I'll check it Sunday morning after it cools off I will keep you guys up to date. Again thank you for everybody that chimed in with their assistance.

 

[Seanb600]

Okay guys I wanted to say thank you for all your help. I spent a good 8 hours on the water yesterday let the engine cool check and check the spark plug this morning and it was dry as a bone. So it appears that that solved my issue again thank you guys for all your help

 

[Scott06]

Great good to hear