Md7a water in oil

[Xawdisney]

I have an MD7A with an aftermarket freshwatrr cooling system. Bought the boat last year... lots of overheating system problems. I think I fixed, changed oil last fall and ran engin for about an hour. Temp gauge read barely up to temp.

Long Story. but checked oil, and more than 2 qt more than I put in. Milky... antifreeze in oil..

Engine was running ok. Dont think it would be head gasket to pump that much water into oil that fast.
Heard about possibility in water getting into oil sump through a water pump. Hiw's that work and how can I fix?
Diesel mechanics here are tied up; and would probably insist on checking head gasket first.

[Engine man]

Obviously, you have a major leak. These old raw water cooled engines eventually rot from the inside out, allowing water / coolant to mix with the oil. If the water is salt, the engine will need replacement. We have also found several MD7A engines that eventually accumulate copious amounts of rust flakes inside the water jacket, leading to restrictions and overheating. When that occurs, engine replacement makes the most financial sense, as the old engine has reached the end of it's service life. Putting more time, $ and effort into that engine will be a very frustrating and expensive endeavor. We suggest that you consider putting your resources into a new or rebuilt, more modern engine. Joe

[neilpride]

Oil cooler maybe.

[hpeer]

I have an MD 7A, salt water cooled.

2 quarts is lot. One year the engine sat outside under a tarp. I reinstalled it and took off on a long trip, had frothy oil. But I was a long way from a mechanic so I ran it. The froth simply disappeared and has never returned. Incan only believe it was condensation which burned off.

The water pump is driven by a shaft that extends into the engine block. One end of the shaft is divide the engine bathed in engine oil. The other end holds the water pump impler. There are a couple of seals on that shaft. If they leak water can be forced into the engine.

Taking the pump out is not technically difficult but a real PITA because of the location and the type of tubing seals.

My suggestion is to buy a brand new pump which is expensive (Johnson). But also take the old pump to a place that that sells seals and get a few, they cost pennies. Install the new pump, rebuild the old pump and carry it as a spare.

[svhydra]

maybe a cracked mixing elbow from possible heat/overloading. all the best!

[boatpoker]

Originally Posted by svhydra

maybe a cracked mixing elbow from possible heat/overloading. all the best!

How would oil get into the mixing elbow and back into the oil pan ?

[svhydra]

i'm not a mechanic and i have been wrong before (alot) but i'm thinking it may be possible water can get into the oil. something like this happened to me a few years ago. all the best.

[skipperpete]

Is it definitely coolant? If so, the path in to the cylinders and downward to the sump could be via the injector sleeves/tubes. This is very common after overheats. If however this is seawater in the oil it could be that the mixer elbow or siphon break has allowed water entry. Incidentally, the entire contents of the fresh water side of the cooling system is probably about what you have (2 qts) but only a small amount is able to enter via a leaking injector sleeve... half a quart perhaps but a cracked cylinder could drop 2 Qts

[Xawdisney]

Pretty sure it is coolant, especially since there is no coolant except at the very bottom of the engine. And I had filled both the coolant and oil at about the same time. It was on the hard, and I was running the system with hose for raw water.

I bought the boat last year, without a survey, and was a few miles down the river before I discovered it was overheating. Hardly used the engine after that, just sailing.

I had thought this was a normal MD7A raw-water cooled until I looked into it more closely. I knew there was a coolant leak, but thought it was through a hose. It never pulled any coolant from the reservoir, which was suspicious. And I did notice the raw water was cold when it exited the exhaust.
I knew there was a clog in the exhaust, and got that repaired. When I told the mechanic it was a fresh-water-cooled engine, he was surprised, because there was no coolant in the exhaust manifold. I later discovered the coolant was in the oil.

When i changed the oil last fall, what I took out seemed to be ok. This can only mean that there was no coolant in there when I bought the boat. The previous owners were novices, and the MD7A is normally raw-water cooled, so they probably never thought of it. They saw water coming out the stern and did not worry, and probably did not look at the temp gauge.

One question I have is whether the leak is likely to come from the head gasket, other water pumk seal, or somewhere else, and whether is may not be worth repairing anyway,because the engine has clearly been run for some time with NO colant. Any thoughts? I know the MD7A engine is pretty robust, but no coolant? I assume it is worst to have coolant in the oil than to have no coolant at all. Thoughts?

[boatpoker]

We check all fluids in our surveys, the following four photos are from engines that required rebuilds

[Xawdisney]

Didn't look much like any of those. Oil looks milky grey on a the dipstick. Muddy grey when drained.
I started to open the head, but stopped when the heat did not lift off easily. There was a black oily residue around the valves... Looked like just oily residue of the end of the season of an old engine.

Most scary to me is having run with no coolant. Problem with buying a modified engine which is usually raw-water cooled, since you think it is ok if water is coming out the exhaust.

[hpeer]

Your above post did jot make a lot of sense to me. Perhaps because I have a salt water version.

BUT, first all YOU NEED A BETTER MECHANIC.

This is not something you want to dick around with if you have any hope of keeping this engine.

These are very simple engines any half decent diesel mech should be able to help you out.

Someone may disagree but here is my suggestion, given the problem is not obvious and you are struggling with the diagnosis…..

1. Get the contaminated oil out of the engine.
2. Put in clean oil and turn the engine over by hand. This is EASY as you have a compression release on the valve cover. Flop it one way and the engine will tirn with one hand on the flywheel. The other way it will not.
3. If you still have water in the oil repeat until you don’t.
4. Pull the injectors and squirt some WD40 or something down there.

This should clean any water out and stabilize the engine in a benign environment and buy you time to sort it out at leisure.

[MicHughV]

I had a MD7B years back and discovered water in the engine one time. Mine was raw water cooled, and for reasons I never quite understood, sea water had siphoned back into the engine. Not exactly sure how this happened, but it did. Seized completely up.

Interestingly, this occurred miles from anywhere, and with no other choice available to me, I removed the cylinder head, siphoned all the water out, banged on the one piston with a big hammer till it reached bottom, put new oil in, and put everything back together using all the original gaskets, etc. Hit the starter button, and son of a gun, it fired right up. A few more oil flushes, and that engine ran like nothing had happened. Smoked a little, but ran for years after.

While the cylinder was off, also took the time to ream out the cooling passages around the cylinders, which were horribly clogged up. Never touched the injectors.

Lucky ?? Maybe...

[skipperpete]

Since you’ve had a history of overheats with that engine YES the head gasket could be the problem, you need to get serious about finding out what’s going on here. Start with hpeers excellent advice and once the first part is completed do a pressure test on the coolant circuit and see if the coolant disappears.... do this with the injectors still in and tight and be prepared for a sump full of water.
To find out WHERE the water entered the crankcase my next move would be to do a cylinder leakage test, nothing too fancy, just 50-100 psi into the injector cup then listen and look for the hissing or bubbling sound.
Bubbling in the expansion tank..... head gasket, cracked head (or cracked cylinder)
Hissing in the intake ... leaking valves
Bubbling in the exhaust.... leaking exh valve
Hissing from oil filler cap... buggered rings or worn cylinders.
This is a bare bones outline of how to find out where the cooling system is dropping out the coolant....(but not the seawater). You mentioned that you ran the engine with a hose and freshwater for the seawater side of the system so there’s a chance you flooded the engine depending on how you actually did that.... the safe way is from a bucket via the jabsco suction hose.

[Bill O]

Since everything appeared "normal" when you laid it up last year, will ask if you or someone properly winterized the motor before it was too cold?
From your description it may have frozen, cracking something or blew the head gasket.