Soot in coolant - need help!

[biroka]

Hi captains.
I have Westerbeke 44c Four in my boat and I found soot in my coolant tank when I opened the cap! I checked the oil and see no water in the oil, no reducing in oil level too. I also run the engine more than 20 min and the temperature didn’t go more than the normal level. I also removed the oil cooler on which the oil filter was attached and therefore was no failure on the oil cooler too.
I suspect exhaust elbow and manifolds also. Could you please share your opinions and experiences if you also faced this kind of problem before.
Thanks in advance.

[Rucksta]

exhaust gasket leak.

[Sailmonkey]

Have you ever changed the coolant and flushed the block?

Ever added an incompatible coolant to the engine?

I would pressure test the block as well.

Your mixing elbow isn’t the problem here.

The previous post doesn’t make any sense either.

[steamgoat]

I would suspect a defective exhaust manifold , the exhaust elbow only mixes exhaust and external cooling water. I think the only exhaust connection with the internal /antifreeze water is a head gasket leak or a exhaust maniifold leak. Fairly easy to remove and test, then flush system.

[MartinR]

As the soot is in your fresh water cooling system, it is possibly a cylinder head issue. Cylinder head gasket?

[Cheechako]

It looks gummy ? Is it oil or soot?
Otherwise, yeah...... head gasket.
Any bubbling in the water when you run it?

[George_SD]

I agree that it's most likely a gasket leak. It's possible for head to be warped if overheated.

[bcboomer]

Looks like great accessibility.
Pop the head off, clean up the surfaces and put in a new head gasket and thermostat.
Flush the cooling system, change the oil and you are good to go.
That's assuming you haven't overheated it.

[Scubaseas]

Has to be from where coolant is exposed to exhaust gas. mixing elbow is raw water not cooling water. It also has to be where there is a higher pressure of exhaust gas to coolant pressure, likely a head gasket issue. Possibly exhaust manifold but you would probably have other symptoms if exhaust manifold like coolant disappearing and smoke.

You could pressure test the cooling system overnight or for a day to two and see if you loose any pressure and coolant. If the coolant is low after being under pressure some time, pull out the injectors and crank engine over. If coolant comes out of a injector hole you then know what cylinder is involved. Probably a head gasket but possible a cracked or porous head.

Another method would be to put a tester on the coolant fill and run the engine. Watch and see if the gauge builds pressure when the engine is running. If so again look for head gasket or bad head. Note that during warm up the pressure will slowly increase as the engine warms but should level out. Vent pressure of as needed to keep it under about 15PSI. But if while running the engine you continually build up pressure you know exhaust or compression gasses are getting into the cooling system. This usually happens at or near the combustion chamber and typically a bad head gasket.

[BillKny]

Before you rip off the head, there are actually several places where exhaust gases are separated from coolant by a simple gasket, and most of these are WAY WAY easier to inspect and fix than taking the top of the engine off.

Before I pulled the head I would pull off the exhaust manifold and replace that gasket. On some Westerbeke's the exhaust elbow is bolted on the exhaust manifold, and THAT gasket can most certainly allow coolant and exhaust to mix.

Both of these gaskets are subject to leakage because of temperature cycling, or corrosion and not everybody is very rigorous about re-torquing the bolts as they should. These gaskets are quick, easy and cheap to replace. If leaks from these spots can't be otherwise ruled out it is irresponsible to just say "head gasket".

Only after doing these easy steps, would I condemn the head gasket. If a mechanic was charging you for the work, then he might be tempted just say "it's the head gasket" because these other parts come off and would be fixed as part of that expensive (but possibly unneeded) job

[Cadence]

Originally Posted by MartinR

As the soot is in your fresh water cooling system, it is possibly a cylinder head issue. Cylinder head gasket?

He seems to think water in the oil is the only head gasket failure mode. Compression into a water gallery might be the problem.

[Scubaseas]

Originally Posted by BillKny

Before you rip off the head, there are actually several places where exhaust gases are separated from coolant by a simple gasket, and most of these are WAY WAY easier to inspect and fix than taking the top of the engine off.

Before I pulled the head I would pull off the exhaust manifold and replace that gasket. On some Westerbeke's the exhaust elbow is bolted on the exhaust manifold, and THAT gasket can most certainly allow coolant and exhaust to mix.

Both of these gaskets are subject to leakage because of temperature cycling, or corrosion and not everybody is very rigorous about re-torquing the bolts as they should. These gaskets are quick, easy and cheap to replace. If leaks from these spots can't be otherwise ruled out it is irresponsible to just say "head gasket".

Only after doing these easy steps, would I condemn the head gasket. If a mechanic was charging you for the work, then he might be tempted just say "it's the head gasket" because these other parts come off and would be fixed as part of that expensive (but possibly unneeded) job

Very good advice but I would try and diagnose either before diving in and doing the lets replace stuff and see if that's the problem. A cooling system pressure tester could tell you a lot about how soot (if it is soot) is getting into a pressurized cooling system. Assuming the cap is working the pressure on the cooling system is somewhere between ambient air pressure and whatever limit the cap is (likely 10 to 15PSI). For soot to get into the cooling jacket it has to be at a higher pressure than the cooling jacket. It is possible for the gasket between the exhaust manifold and the head to be leaking but even if the elbow is clogged I doubt the exhaust pressure would be much over about 3 PSI. So while the engine is coldish I could see exhaust gas going into the cooling jacket bit not if the cooling system is over say 3PSI or whatever the running exhaust back pressure is. A simple test would be to eyeball the coolant when running and see if there are bubbles coming up from it. If you pressure test the system for a length of time and leave the exhaust hose off the elbow you should see coolant coming out the exhaust if the gasket is leaking. It's hard to imagine an exhaust manifold gasket only leaking exhaust gas into the cooling jacket and not also the other way around. But then I am presuming the OP is not loosing coolant.

If he's not loosing coolant, and it's soot the likelyhood that it's from a high pressure area of the exhaust into the relatively low pressure cooling system is the culprit. This area would be around the combustion chamber.

[Sailmonkey]

Originally Posted by BillKny

Before you rip off the head, there are actually several places where exhaust gases are separated from coolant by a simple gasket, and most of these are WAY WAY easier to inspect and fix than taking the top of the engine off.

Before I pulled the head I would pull off the exhaust manifold and replace that gasket. On some Westerbeke's the exhaust elbow is bolted on the exhaust manifold, and THAT gasket can most certainly allow coolant and exhaust to mix.

Both of these gaskets are subject to leakage because of temperature cycling, or corrosion and not everybody is very rigorous about re-torquing the bolts as they should. These gaskets are quick, easy and cheap to replace. If leaks from these spots can't be otherwise ruled out it is irresponsible to just say "head gasket".

Only after doing these easy steps, would I condemn the head gasket. If a mechanic was charging you for the work, then he might be tempted just say "it's the head gasket" because these other parts come off and would be fixed as part of that expensive (but possibly unneeded) job

The exhaust manifold gasket is dry (evidence is in the photos). As is the mixing elbow gasket. Changing those has nothing to do with the coolant.

[Searles]

On some of these engines the exhaust manifold and the heat exchanger top tank are open at the rear end and corrosion or a gasket failure will allow crossover,exhaust back pressure will do the rest ,back pressure at pull power must not excede 1.5 psi if greater chech exhaust system .⚓️����⛵️

[Sailmonkey]

Originally Posted by Searles

On some of these engines the exhaust manifold and the heat exchanger top tank are open at the rear end and corrosion or a gasket failure will allow crossover,exhaust back pressure will do the rest ,back pressure at pull power must not excede 1.5 psi if greater chech exhaust system .⚓️����⛵️

Arghghfh! Look at the photos!! The mixer on the engine in question is not one that is open to the coolant circuit!