Milky water exhaust question??

[blhickson]

Hi All,
I cleaned out my Groco ARG 500 raw water filter recently. The PO had it plumbed backwards, the "in" side was closer to the pump and "out" was closer to the incoming thruhull valve. According to MaineSail's directions, I reversed that, replaced washers and cleaned the viewing container and basket. The filter had some grass in it but was not clogged as I expected it to be. As MaineSail had told me how the filter functions, the bits of grass were in between the filter basket and the viewing container. I've had the boat 5 yrs and have not cleaned this filter til a week ago.
NOW, immediately after this change and cleaning, the exhaust water is looking like very watery milk. It was almost clear before. Prior to this change , the exhaust water would have a couple of spurts of watery milk immediately upon startup but then would go clear. Now it's watery milk the entire time the engine is running. ALSO, prior to this change there would be a small amount of oil smoke upon startup but it would clear within a minute or so. Now there is some oil smoke the entire engine run time.
The volume of water exhaust is the same about 2 1/2 gals. What is going on??

[hanleyclifford]

If the only change you made was reversing those connections, then the change must be related. Is your engine raw water cooled?

[hanleyclifford]

If the engine is raw water cooled, you may have changed both available pressure and flow to the castings. This could cause a "cleaning" of salty deposits which could then be seen downstream in the exhaust. If this made the engine run colder, tolerances could change and let more oil past rings and guides.

[lat 64]

Hi Barbara,

Is there an oil sheen on the water?

If not, this "milkiness" is maybe some thing else. What?

Does it dissolve in the water after it drops in?

One idea in my little head was; maybe it's air entrained in the water. Perhaps from a small leak in the hose or seals in the strainer. Grasping at straws here.

Collect the discharge in a bucket and get empirical evidence— just what the heck is it anyway?

[Dave Neptune]

Like Russ stated save a bucket of the discharged water and let it sit. What you were noticing was probably just tiny bubbles being forced into (airieated) the water from the exhaust gasses and water being mixed a bit better or different. If not the oil in the water will rise to the top of the bucket!!

Good luck!

Dave Neptune

[JOHN COOKSON]

If you are feeding the manifold from the high end with water comming out the low end reverse this so water goes in the low end of the manifold and comes out the high end. I think you will be happier.
Search the forum by the word "THATCH" to read all about it.

TRUE GRIT

Any chance there is a crack in the manifold and exhaust is mixing with water in the manifold? There may be a manifold pressure test in your near future.
I don't like this idea too much because water usually ends up in the engine if there is a crack in the manifold.

[blhickson]

HanleyClifford: yes, it is raw water cooled. What are "castings?"
The ambient water temp is such that I am not sure if the operating temp gets to normal after 30 mins of run time at dock.
Lat64: No oil sheen; water collected in bucket appears to be clear EXCEPT for what appears to be a slight gasoline sheen on top, very greasy but its not oil.
JohnCookson: I have searched "Thatch" and many posts appears, primarily regarding converting to fresh water cooling. I do not know the "high end" of manifold from the "low end". I do know that my A4 is a v-drive and, from talking to Ken at MM, the usual bow end of engine is the aft end.
I will attempt to post a picture. Thanks for the help you guys! I compression tested the engine about 4 years ago and got great marks on all 4, in the 100-114 range for each of the cylinders. Don't know if that is "wet" or "dry" readings.
The picture uploaded and the Groco filter is to the left of the engine. Is this the high end or low end of the manifold? I'm afraid of what this foretells.

[JOHN COOKSON]

Unless your engine is dead level in the boat one end of the manifold is higher than the other end.
Here's the concept:
If you introduce water into the high end of the manifold it will run down through manifold and leave air pockets. This happens because the internal diameter of the manifold water passage is more than the diameter of the inlet.
If you introduce water at the low end of the manifold it will push air up and out as it rises up through and out of the manifold high end.
Result: Better cooling of the manifold.

TRUE GRIT

[lat 64]

I'll focus on the water pollution and let others help with the plumbing.
So,..
The way I understand it, the white-ish water goes into a sampling bucket and then clears up, but has a bit of exhaust "crappy slime" floating in it.

Is that correct?

[tenders]

The castings are just the internal passageways through which the cooling water flows. With the old flow, an equilibrium was established between the flow and the crud that built up in those passageways over the years. Change the flow, upset the equilibrium for a while, cause some crud to be displaced for a while until a new equilibrium is established.

I have a v-drive too and have not done the simple "thatch" modification to the manifold hoses...but for what it's worth I suspect the side of your engine with the v-drive on it is lower than the flywheel end - ie, the engine is pitched forward a few degrees. The flow through the rubber cooling water hose enters the manifold from the flywheel end of the engine and flows "downhill" through the manifold, then out the lower manifold cooling hose and to the standpipe or muffler. This has the potential to introduce bubbles in the flow and leave hotspots in the manifold but, I think, tends to leave less water hanging around in the manifold when the engine is shut off which is why I haven't done the thatch mod.

Like lat64, I think the cloudiness is caused by an air leak in your strainer that is letting bubbles get into your raw water. I would take it apart and make sure all the gaskets are smooth, all the threaded fittings are taped or gooped and fastened tightly, and all the hose clamps are tight on the barbs.

If you've ruled that out, you're positive you don't have water leaking OUT of any plumbing, and the engine is starting and running smoothly, frankly I would not be too worried about the cloudiness or the sheen. The sheen might be caused by a carb set a bit rich or an engine that isn't fully warmed up yet. What you're giving up in efficiency you might be getting back in ease of starting.

[blhickson]

Thanks for the help. I took the boat out yesterday since the plumbing "fix." There was good propulsion in lower rpms but decidedly not as rpms increased (barely making 3.25 knots with no current). The oprating temp was a good bit higher than usual as well.
The cooling water enters the pocket at the gear end of the engine, flows underneath thru a casting to another hose entering the water pump which pushes it into the manifolds. The gear end faces forward and sits lower in the boat than the flywheel end.
I think at this point I should just put the raw water filter back the way it was. Gas may be leaking past the rings and I don't want to blow one. Gas never came out of the exhaust before and the temp never rose above 145 on the hottest days in Aug. I'm guessing the air pockets may be causing the lack of good cooling but why would fuel be getting past worn rings now when it never did before?
Thanks.

[blhickson]

And she does start very easily!

[blhickson]

Yes Lat64 that is correct.

[blind navigator]

Besides collecting some discharge and seeing what settles out, have you checked the dipstick for milkiness in the crankcase oil? If there is any trace of white in there, it's caused by water in the oil, possibly from either a crack in the head gasket (which can sometimes close up as engine temps increase) or a leak in the water jacket of the wet exhaust which allows water back into the crankcase oil. Have experience with both. Both are curable, but at some aggravation and expense. Send me a PM if you need more.

[Mo]

Try taking one plug wire off at a time. If you pull one that doesn't change the engine rpm change out the plug. Restart and see what you have. Test same thing again and see if it make a change now....if so, dead plug was the culprit.

Sometimes a dead plug will leave a whitish residue and sheen on the water. If the boat is moving you may not notice the sheen so much.

See if that does anything for ya.