Volvo MD11C water in the oil

[brett6913]

I am working on an old raw water cooled MD11C that is causing me some grief. My problem right now is that I am getting water in oil and I don't know where it is coming from.

Before I take the engine apart, are there any tests I can do to determine where it might be leaking, and how serious the problem might be? I am hoping it is just the head gasket...

-Brett

[jackdale]

A compression test may reveal a head gasket problem, assuming the rings are OK.

[erps]

The injectors sit in little copper cups that are surrounded by coolant. That seems like another weak spot. Another possibility is that the raw water pump is leaking coolant past the seal. If the weep hole is plugged with something it might drop water into the crankcase. That might explain a coolant leak on a motor that is running okay. I guess I would start there first.

[Omatako]

Check if you have an oil-cooling heat exchanger. They sometimes let the oil and water mix.

[klem]

As stated above, the interfaces between water and oil are the head gasket, oil cooler (if you have one), water pump, and injectors.

Do you get a big puff of blue/white smoke when you first start up? That is often a sign of a headgasket.

A good place to start would be a leakdown test. If your head gasket is compromised, then there is a good chance that the combustion gases will leak down into your cooling system or oil system. When a head gasket fails, it is usually because of the pressure from combustion gases so you will be forcing combustion gases into both other systems since the pressure is higher. This results in a pressurized crankcase and lots of air bubbles in your cooling system. If the head gasket failed, you should be able to reason through what the cause and effect are based on knowing what the pressures are.

The last head gasket I diagnosed, we didn't even have to do a leakdown because the cooling system was getting combustion gases in it when cranking with compression and was not without compression. Hopefully you will get this lucky.

[mccormick201]

hi i have water leak just at top of head on one cil any one got a works manual on pdf i could buy or get for free need it yesterday
john

[Rockter]

Brett....

In 1998 I had a similar problem with the three cylinder version of you motor.
Mine is the MD17C.

It turned out to be the liner base O-ring on one of the barrels.

If that is the case, then you will have to take off the exhaust manifold, then both cylinder heads. You will at that moment, probably see that one of the cooling chambers is not holding water. One will be full, and one will probably be empty.

The Volvo dealer in Aberdeen Scotland had the necessary equipment for the pressure testing, but the leak was apparent simply by pouring water into the gap between liner and barrell. He confirmed that.

I doubt if it is either of the cylinder head gaskets, but it might be.

With time, the cooling jacket O-rings get tired and can lose seal, particularly if the motor has been overheated at any time.

The cooling jacket O-rings are expensive when sourced from Volvo... they are about $70 for 4 of them, if I remember.

On re-assembly, you will need a top end gasket set and exhaust gaskets. They are still available as a pattern set.

Don't do what I did and put one of the exhaust gaskets on the wrong way round. The motor will start OK, but on shut-down, seawater drips out of the air filters.

I nearly wrecked the motor with that mistake, but still it runs perfectly, 12 years on.

You can do all of the remedial work with the motor still in the boat. You do not have to lift the motor out. When you lift the barrels, don't lose the "bumping clearance" shims, and don't mix them up. Don't mix up the barrels either. You shouldn't have to touch your pistons, unless they are scored, and it is not difficult (with help) to get the barrels on again. It is just fiddly. If you have to take the pistons off (and you should not need to), then get back in touch, because that really is a fiddle to get them on again (blowtorch and freezer stuff for me, at least).

It is a good motor, and very well built. The price of spare parts is outrageous, however.

Don't run the motor with water-laden oil, of course. the engine will not tolerate that for long.

You will probably have a lot of water in the sump, and if the motor is still in the boat, it will need to be sucked out. If the motor is out of the boat, it is a lot easier. It can take a wee while to get it all out. We managed by repeated oil changes with cheap oil, with the motor run hot, until it cleared.

Let us know how you get on.

[mccormick201]

hi thanks for all your help ya no sure what problem is till get view bits of so will let you know how i get on thanks john

[mccormick201]

hi rockter do you know wer i get manual for the gear box on this engine need to take it of try if i can swap the gear box of the other engine md5b 7hp
thanks