Water in Oil

[Peter Gutmann]

I recently had my 4.3L Mercruiser engine rebuilt and then I re-assembled the motor along with new risers and exhaust manifold. As well as giving the stern drive a full service. On my first test run we found water was getting into the sump.

Engine runs well with lots of power and no obvious problem when inspecting the plugs.

Could I have incorrectly fitted a gasket or run a hose incorrectly? The hydraulic steering fluid also appears a little milky?

 

[Scott Danforth]

was the block water jacket pressure tested or the block magnafluxed?

is this a 1996 and later motor? do you have the correct gasket on the intake?

are you using Mercruiser gaskets, or Sierra "green leaker" gaskets between the manifold and risers

Power steering is a separate system, so you have a separate issue there.

PS cooler could have been freeze damaged.

 

[Peter Gutmann]

Hi Scott
Thanks very much for your prompt reply. No pressure tests have been done on the water-cooling system. Is this hard to do?
I only had the boat for a year, when it needed a full engine rebuild, its a 2005 model. I can only assume that the correct gaskets were supplied with the new manifold & riser purchased from a Mercruiser dealer, how do I check?

I'm based in Sydney and we do not have any freeze issues, with cooling done by direct intake of sea water through the stern drive.

Peter

 

[alldodge]

First suspect would be the intake gasket

Next, was thread sealant used on head bolts?

 

[Peter Gutmann]

Could it be anything to do with the exhaust & riser assembly or the stern drive assembly, both of which were replaced or serviced by me.

 

[alldodge]

Not the drive, maybe on the exhaust but you said they are new. Pull plugs and see if any water is found on the plugs

 

[Peter Gutmann]

Did that, and the plugs look fine. I don't think there is any water in the combustion chamber. Engine sounds good when running with plenty of power.

 

[Scott Danforth]

if there is no water in the combustion chambers or inside the exhaust ports and only in the crank case. its either like AD suggested - a bad gasket (intake gasket is first suspect), lack of sealant on head bolts, or the block has a crack in it

to pressure test:

with water out of the block, take the hoses to the elbows and manifolds and combine them all together.

take the hose from the transom shield and install a pressure gauge and schroeder valve. you want to use a bicycle pump or other, pressurize to 15 psi (1 bar). it should hold pressure forever.

most likely you will hear hissing from escaping air.

if you hear air escaping, then you have a leak somewhere.

 

[Peter Gutmann]

Thank you both very much, I'll let you know how we go.

 

[ajcampbell31]

The milky hydraulic fluid suggests water is getting into the steering system too. Double-check all your gaskets and hose connections. It could also be worth inspecting the heat exchanger and cooling lines for any leaks.

 

[Scott06]

check the power steering cooler if PS fluid is milky. Does it by chance have a combination PS and engine oil cooler that may have cracked? Would answer both water in oil /PS fluid

 

[cyclops222]

Do you have more problems after the rebuild ? Then before the rebuild ?

 

[1985 Century Mustang]

I had a similar issue, it was the riser gasket. I replaced it, the oil filter and the oil, no more milky oil. As for your power steering, that could be a different issue

 

[alldodge]

Power steering cooler has no connection to block. If PS cooler was leaking oil would come out the exhaust

 

[Peter Gutmann]

I would like to thank you all again very much for the advice. I will check them all and revert back with the results.

Regards,
Peter

 

[Peter Gutmann]

By way of an update on my water in the sump issue. I removed the new exhaust manifolds and the risers and pressure tested them with no loss of pressure. We connected the motor up to a car radiator and pressure tested it 3 to 4 time at various engine temperatures and found no loss of pressure. We ran the engine up to around 90 deg, and oil pressures of up to around 50 psi and found no evidence of water going into the sump. I also drained and topped up the hydraulic steering fluid and after engine testing found that this had gone milky again. I can also confirm that a new inlet manifold was fitted.

Further to a discussion with the local Mercury dealer, he believes that the problem is likely to still exist and suggests that I run the boat for short stints undertaking regular inspections for ongoing water ingress in an effort to localize the problem.

Any other ideas would also be welcome.

 

[Scott Danforth]

if your power steering fluid has gone milky, then your power steering cooler has a thermal declination material breach....... the thing froze.

the only place where your power steering comes in contact with water is the cooler.

if the power steering cooler froze, that means there was one improper winterizing event in the boats life.

 

[Lou C]

Was the boat imported from the US as a used boat? Could it have been in a climate that gets freezes before your ownership?

 

[Scott06]

By way of an update on my water in the sump issue. I removed the new exhaust manifolds and the risers and pressure tested them with no loss of pressure. We connected the motor up to a car radiator and pressure tested it 3 to 4 time at various engine temperatures and found no loss of pressure. We ran the engine up to around 90 deg, and oil pressures of up to around 50 psi and found no evidence of water going into the sump. I also drained and topped up the hydraulic steering fluid and after engine testing found that this had gone milky again. I can also confirm that a new inlet manifold was fitted.

Further to a discussion with the local Mercury dealer, he believes that the problem is likely to still exist and suggests that I run the boat for short stints undertaking regular inspections for ongoing water ingress in an effort to localize the problem.

Any other ideas would also be welcome.

Does the engine get up to temp or run cool? If you dont get it good an hot regularly you can get milk in oil. People who let it idle at the slip to run it can get this...

SO looks like you check manifold for leaks, pressure tested the cooling system and verified water is getting into PS system?

Did you drain the water out of block and see if it holds pressure over night or just pressurize the system with coolant in it? I would agree that if PS getting milk would likely be caused by a freeze cracked ps cooler (could be rotted though), so unless it was missed in cooling system pressure test only way could be though bad riser gaskets leaking back into combustion chambers? Might be looking for water in them post shut down

 

[Grub54891]

Good point on running at the dock or easy putting around. my 140 mercruiser will get a bit cloudy when putting. My small lake at 140 acres doesn’t get a lot of room for a good run. Yes I can open it up and make abut five loops and it gets plenty warmed up to burn off the moisture. It runs the 140 thermostat and yes it gets to temp when putting. Needs a good hard run to burn it off.