Water in oil and on Spark plugs

I posted this under Marine Power as well, I believe Mercruiser and Marine power engines are basically the same and see that this forum subsection gets more views and responses.

Hi everyone - I need some help and advice on some used Marine Power Engines that I recently purchased. They are 2004 4.3 V6 EFI VORTEC fresh water/Closed cooling with 600 hrs.

I'm know a bit about engines but mostly do simple maintenance and not sure how to proceed with this issue. I bought these engines about a month ago and was told they were in good working order by the owner and also the shop that took them out of the boat. The prior owner was upgrading to higher HP engines.

Once in possession of the engines I wanted to run them and change the oil since the last change was January 2013. I checked the oil level and that is when I noticed the oil was milky looking and much different than old oil I have seen before in my other engines. This is when I started to get worried and found thru research it was a sign of water getting I the system. I was hoping it could have been condensation from sitting or not being run up to full temperature or pressure washer cleaning or something. Here is where I am at now and symptoms.

1. Oil is milky colored
2. Under the oil cap was ice cream like gunk
3. When I hooked everything up to test run the engine they wouldn't start.
4. spark plugs are fouled looking and had some condensation on them.
5. Changed spark plugs restarted giving a little throttle and the engine started and needed throttle to keep going but shortly after would idle fine with no need to throttle. My understanding is no throttle should be needed with EFI engines. To start the engine now it needs a little throttle but once started idles fine.
6. After warming up a bit I drained the oil which is all milky brown.
7. New oil and filters
8. Pulled plugs on the starboard side of motor one was black, one was perfectly clean but had water on it and in it. The last was less black than the first.
9. Was hoping the condensation was just from them sitting or getting pressure washed changes in temperature but I am fearing that is not the case.

From what I have researched it could be the head gasket, exhaust manifold, cracked block, etc.

from theses symptoms is there any way to narrow down what the repair is? Definitely head gaskets? Definitely the exhaust manifold? Both or something else?

I am not really sure where to go from here and feel like I have been totally ripped off but also I should have known better and checked them out more thoroughly.

Tomorrow I plan to check the compression in all cylinders and see what that tells me.

If anyone has had a similar experience or has suggestions for narrowing down the problem that would be appreciated. If it is just the exhaust manifolds would change those myself, as i have done that on other engines in the past. Head Gasket is foreign to me so might have a shop make that repair.

Thanks

Are you using these as closed cooling or raw water cooled?

Did they come with exaust manifolds?

Raw water manifolds use a different gasket between the elbow and manifold then closed cooling systems.

for other answer read other post you chimed in on.........

Hi kghost - They are closed cooling, yes they came with exaust mainfolds. I just contacted the Seller to see if they had any service records for when the manifolds were last replaced.

The boat came from California, it is a 26' Bertram so I would assume it was used in salt water and manifolds and risers would need to be replaced every 4 years or so based on what I have read. There are no external signs that the manifolds were failing and the motor is very clean with little to no rust.

Both engines have the same milky colored oil. Here are some pictures:

First thing to find out is, Is that antifreeze or water mixed with the oil???

Closed cooling should be ONLY antifreeze....... Raw water only exits the elbows and heat exchanger........should not be in the motor.


That will determine the next step

I was thinking that too but not sure how to determine if it is the raw water or antifreeze from the coolant. It looked clear and had no green tint to it, also tasted it and it tasted like fresh hose water, spit it out immediately after of course.

if it is water then you need to follow the fresh/raw water path and see if maybe a hose is connected to the wrong location.

If you are not loosing antifreeze from system????????? then the cooling system is leak free. DO you know if this is true?

In a closed system like yours the only place raw water should be present is at the elbows (to keep exhaust cool all the time) and passing thru the heat exchanger and the power steering and or transmission cooler.

So raw water should not be able to get into the motor at all.

My only thought would be the elbows have an issue allowing water to get into the exhaust manifold. If the raw water is leaking into the exhaust manifold (s) the it could be leaking into one of the cylinders.


That's all I have.

Squirt oil in the cylinders and see if compression is higher with oil then without. If no change then problem is heads only. Put new exhaust manifolds also. You should put new at least every 5 years.

Thanks rl65028 and Kghost for your replies.

I did the oil in the cylinder test and there was no change so it looks like my compression issue is with the head. Yesterday I pulled the risers and manifolds and it looks like the risers definitely needed to be changed. When I pulled the riser off the side with the low compression the gasket came apart so it is hard to know now if there was a leak in it although the fact that it came apart probably tells me something. The exhaust outlet on the head had rust in it so would assume this means the riser has been leaking into the manifold and then into the cylinder. The valve probably got some rust and corrosion on it causing it to not fully close causing the low compression. There is a marine mechanic in my boat club that is going to come analyze the situation with me and confirm my findings and help me with the next step. Here are a few photos of what i found when taking off the riser and manifold: