Milky Oil
 

I have been reading and troubleshooting. Here is what I have done so far:
1. Changed the oil 5x. It now looks clear.
2. Pressure tested the manifold. It passed.
3. Pressure tested the block. It passed.
4. Removed the manifold and valve cover. Everything looks good. The valve cover gasket came apart on removal, so it's possible that was a source of infiltration.
5. Examined externally the water pump. I don't see any evidence of leaking seals.

Upon reflection, I wonder if an episode this summer where I sprayed water around the engine compartment (it was not intentional, but I don't want to talk about it :D) caused this problem. I had milky oil 2 years ago, but that cleared up after changing the oil 3x. Any ideas?

Side note: should I use gasket sealant when putting the new gasket on the valve cover?

Yes use a good Permatex Aviation Grade or Number 2 grade.

The water pump can leak into the oil via the rear seal. If the water getting in has been consistent it's a likely suspect. Intermittent could be from the hush hush spraying.

Dave Neptune :cool:

Are you raw water cooled?

Yes, I am.

Water in the oil does not have to be from an engine issue. The only time I had water in the oil was a result of large wakes hitting my stern when I was stuck on a sandbar. If you do not have a plate over your exhaust through hull, then a wave or wake could have pushed water up through the exhaust and into your engine. Also extended cranking with the cooling water through hull open can fill your water lift muffler (if you have one) and also push water into the crankcase through an open valve.

Lots of info regarding this topic on the forum. I'm sure others will chime in and help figure out what's causing it. What about the possibility of over cranking with the sea cock open? Any restrictions in the exhaust?

I have been reading the various threads on this issue. I'm hoping that this was the result of an event, such as the water spray in the engine compartment or infiltration through the exhaust (no plate over my tail pipe). I was able to rule out cracks in the manifold or the block, plus engine compression test shows great on all 4 cylinders, so that's good. The boat's on the hard now, so it will have to wait until next year to know for sure. It was definitely not extended cranking. The one bummer is that, while putting the valve cover plate back on, I broke a bolt by overtightening. Now I have another problem to solve.

Have you checked the head?

Once you get the broken bolt extracted, this is a great time to convert to studs! :cool:

Yes, I did a compression test and all 4 cylinders were around 115.

That's a good point. I hadn't thought of that.

Back to work
 

Boat launched, and still have milky oil issue after changing oil again. My understanding is I should next go with the water pump seals. BTW, thanks for the convert to studs idea. It was definitely the way to go.

First: make sure the water seals "wheep hole" is not blocked. This hole can be seen at 0:37 of the video
https://www.youtube.com/watch?v=lKKJc02PAQE
It is located after the seals, at the bottom side of the pump casing. Its duty is to let drain any water that would go past the seals (seals located around the shaft). If seal leak become simportant, it will potentially overflow that hole an go into the oil. But if you have 0 water draining out AND this hole is clear, I would scratch my head a little more around potential other culprits...

+1 on it being the seals in the pump. This happened to me. Once water got past the first seal into the bearing, the shaft wore in the seized bearing and created a wobble in the shaft that destroyed the next seal, which sent water shooting right past the open 'weep' hole into the crankcase. The weep hole was definitely weeping, more like pouring, and cooling water was diverted from engine cooling to the bilge and the crankcase. The engine overheating was what clued me into the problem. The pump was completely failed, but the impeller was fine.
So, you may need a new shaft in addition to new seals. Having a working pump as a backup is a good idea.

Weep hole
 

How can I tell that the weep hole is clear?

stick a screw driver trhough it. If you can hit the water pump shaft, it is not blocked

If the weep hole leaks when engine is running, it is clear, and you need to work on the pump. If you have the problem I had, there will be no doubt the weep hole is clear. I don't know what could clog the weep hole, which is pretty big, unless you have the old-style pump with the grease cup and have been forcing grease past the seals. And even if the weep hole is open, the pump could still be the source of water in the crankcase oil, if the seals are completely shot.

Continuing the trouble shooting
 

No water exiting the weep hole on water pump. It doesn't make sense to me that the pump would be the source without seeing water leaking. I don't want to rebuild the water pump if I don't have to. Water is exiting the exhaust and the engine is not overheating.

Continuing to have milky oil. Could there be back pressure on exhaust from muffler? No problem with engine running. Very smooth.

You could have a tiny leak in a number of places dumping water into the oil that would not make the engine run poorly.

Are you definitely getting more water? Getting the water out can be a bit frustrating as it takes a few changes to do so. Take a careful look via the dip stick to see if the level is actually going up. Since you did a pressure check and it passed the block and manifold are good. That leaves the water pump or the exhaust back filling.

Another note, did you run the engine up to temp when you did oil changes? If the oil level is not rising (the careful check above) it may be you are not getting all of the "oil" out. Just a tiny bit of water will turn the oil milky. I usually add a table spoon of liquid dish detergent as it helps to emulsify the water into the oil and helps in getting it out. I do this twice then add just the oil and run. The oil will often look a bit milky still and you will see condensation at the oil fill. I just run her for a couple hours at cruise speed and cook the rest of the water out and when it clears change and your good to go.

Dave Neptune :cool: