1992 3.0L water in oil

[1970Mach1]

Hey you guys! Looking for some advice here. I have been getting water in my oil on my 1992 3.0 Mercruiser. Here's where it gets tough, the oil was milky so I changed it the beginning of the year and keep a eye on it. It was fine the first couple times I've taken it out. Then I noticed it again this weekend. I changed the oil again and took it out for a couple hours and it didn't have a drop of water in it. So its intermediate. I'm kinda thinking the water gets in it when i run it with earmuffs on but can't say for sure, or when it gets hot but can't say for sure why it didn't get water in it all day on the 4th of July. I have a crappy idle after the boat warms up, she will buck and chuck until you crack the throttle like three times to clear it out. It's been like that for 2 years now, haven't figure that out yet, unless it's getting water in the intake...

So I've pressurized the coolant system, took off the hose that goes to the outdrive and plugged it, took off the hose to the exhaust manifold and pressurize that. It has had about 15psi in it for about 24 hours now.

What would you do next? Tear into the exhaust manifold and riser to look at it? With it not getting water in it all the time makes it tough to track down.

Thanks!

 

[1970Mach1]

I forgot to mention that it always runs at about 135°. Although when you idle around the temp drops a fair amount. I was going to put a thermostat in it, I'm sure the temp should stay around 135 the whole time and not drop right?

 

[tank1949]

Hey you guys! Looking for some advice here. I have been getting water in my oil on my 1992 3.0 Mercruiser. Here's where it gets tough, the oil was milky so I changed it the beginning of the year and keep a eye on it. It was fine the first couple times I've taken it out. Then I noticed it again this weekend. I changed the oil again and took it out for a couple hours and it didn't have a drop of water in it. So its intermediate. I'm kinda thinking the water gets in it when i run it with earmuffs on but can't say for sure, or when it gets hot but can't say for sure why it didn't get water in it all day on the 4th of July. I have a crappy idle after the boat warms up, she will buck and chuck until you crack the throttle like three times to clear it out. It's been like that for 2 years now, haven't figure that out yet, unless it's getting water in the intake...

So I've pressurized the coolant system, took off the hose that goes to the outdrive and plugged it, took off the hose to the exhaust manifold and pressurize that. It has had about 15psi in it for about 24 hours now.

What would you do next? Tear into the exhaust manifold and riser to look at it? With it not getting water in it all the time makes it tough to track down.

Thanks!

Do compression test on each cylinder using reliable tester. If ok, time to pull exhaust/risers and test with acetone, even though you pressure tested. If you have any leak, acetone will slip through. I had to design and make an aluminum cap to cover where riser and exhaust connect. Sounds like, from my personal experience and your boat's age, it is time for riser/exhaust replacement. I hope that it is not a cancered head. I had one of them fail too. I also purchased a defective head years ago that destroyed a 350 Chevy. Water leaked into combustion chamber. Good luck!

 

[Rick Stephens]

Probably an exhaust/intake manifold problem. Could be a exhaust shutter no longer in good enough shape to prevent water intrusion.

 

[1970Mach1]

How do you quote someone on here?

#1 155psi
#2 157psi
#3 152psi
#4 160psi

 

[1970Mach1]

[No message]

 

[1970Mach1]

[No message]

 

[Rick Stephens]

Manifold time.

 

[1970Mach1]

Ok guys thanks so far! I didn't see anything jump out at me at first, but looking at the manifold the center exhaust ports have a couple cracks. Cracked in-between the 2 center exhaust ports. Plus cracked down in the exhaust port into the water jacket of the manifold. I imagine the riser is pretty rusted too. The exhaust shutter seems fine unless it should be sealed just sitting there. They flap i imagine they are ok.

Soooo can I assume that's how the water is getting in the exhaust ports or would it be hard for it to get in? What's your thoughts guys?

 

[tank1949]

Ok guys thanks so far! I didn't see anything jump out at me at first, but looking at the manifold the center exhaust ports have a couple cracks. Cracked in-between the 2 center exhaust ports. Plus cracked down in the exhaust port into the water jacket of the manifold. I imagine the riser is pretty rusted too. The exhaust shutter seems fine unless it should be sealed just sitting there. They flap i imagine they are ok.

Soooo can I assume that's how the water is getting in the exhaust ports or would it be hard for it to get in? What's your thoughts guys?

Use acetone to test exhaust and riser. If enough meat left on head and exhaust, I have used coarse flat file to re-surface. By chance is drip or spray water coming in via motor hatch? It has happened to me.

 

[Rick Stephens]

No need for acetone. Your manifold is cracked between water jacket and exhaust. That's where your water is coming from. Shutter looks fine. No idea on riser. With new mani, I'd probably replace it if I could afford to. Not have to worry about it for a while.

Rick

 

[1970Mach1]

Thanks, I'll see what I can dig up for a reasonable priced manifold and riser.

 

[1970Mach1]

I ended up getting a new Sierra manifold. Definitely runs better than it has in a couple years at a idle! Thanks guys.

Now to try and get some better warm starts out of it!

 

[Rick Stephens]

I ended up getting a new Sierra manifold. Definitely runs better than it has in a couple years at a idle! Thanks guys.

Now to try and get some better warm starts out of it!

Hey, that's great. Might consider a carb rebuild next. Take your time, but they are easy to do. Just get it really clean and replace the needle valve and seat then pay particular attention to float height. That should help the hot starts.