AD41A Water in Oil

[Tim777]

After many years of good service my starboard AD41 failed yesterday. I was on the plane and smelt oil. The oil pressure had dropped to 30psi. No problem with temperature, no alarms went off. Boat speed did not suddenly fall off. Pulled into the anchorage at Osbourne Bay and raised the hatch. There was about 2 to 3 litres of oil in the bilge and it had been ejected through the crackcase breather filter. The oil level was v.high and the oil was a gloopy grey. Came home on other engine.
Now I have to find the cause. Presumably head gasket, turbo or oil cooler failure? Any one experienced this?

 

[Jonmendez]

Hi Tim almost certainly the head gasket - been there! at least it is relatively easy on your boat! Jon

 

[dragoon]

Jon's probably right, although before stripping the head off (unfortunately, been there), it might be worth double-checking. Is the coolant water obviously low? If not, it's possible it's not the closed circuit cooling providing the water, which doesn't indicate the head gasket. At that point, it could be sea water in the oil - which points elsewhere - oil cooler maybe, or even exhaust manifold spring to mind?

The only confusing thing there is that I thought the oil cooler had higher oil pressure than water, so I would expect leaks to go out the exhaust with the cooling water.

Just some thoughts. Hope you get it sorted.

Cheers,
Paul

 

[Tim777]

Just been to boat. No loss of fresh water coolant so --- oil cooler ? Problem is oil/water mix is so thick it won't extract using my Pela oil change extractor. Have had suggestion of putting diesel fuel in to stop corrosion, it might also thin the gloop? Any thoughts to prevent further damage?

 

[dragoon]

Just been to boat. No loss of fresh water coolant so --- oil cooler ? Problem is oil/water mix is so thick it won't extract using my Pela oil change extractor. Have had suggestion of putting diesel fuel in to stop corrosion, it might also thin the gloop? Any thoughts to prevent further damage?

Hi Tim,
I think the diesel seems a reasonable idea to break it down, and stop corrosion. I would then add a new fill of oil as soon as possible.

Before running the engine though, you need to be quite sure that much of it is gone. Ideally, you'd want the engine out, and the sump off, but I appreciate it's not a preferred thing to do in a boat.

You may consider removing the turbo feed and returns to make sure they're clear. Also, the oil cooler and filter housing to make sure everything is clear.

There are engine flushes available which can assist - typically I don't like them as they tend to put years of accumulated dirt into circulation. However, they can help to remove sludge.

As to the causes, it sounds like the closed loop cooling isn't to blame. On the raw water side, possible causes are the oil cooler, exhaust manifold, exhaust bend, raw water pump and possibly others. Is the engine on a gearbox or outdrive?

Cheers,
Paul

 

[Tim777]

Hi Paul

Thanks for all the input. Will concentrate on shifting the mess first, or at least getting it to move. Boat is on outdrives so no gearbox in this problem.

 

[volvopaul]

Before you go ripping parts off your engine you need to diagnose the faults, you have sea water in the engine asyou say no coolant loss, it may be the oil cooler as your pressure has dropped, you need a proper suck out pump a piela will not do the job, you may have piston problem as oil spitting out the breather, id get the oil out, new in and test engine again, if you can pressure test the oil cooler then that would be good, thats where id start.

 

[omega2]

Got agree with Paul, no loss of fresh water=got to be raw water, and the only place those two meet is in the oil cooler, the stack needs pressure testing.

 

[Tim777]

Progress now

Ok getting there now. Oil was so gloopy and thick the only device which would pump it was a yachtsmans small brass handpump. Even a Volvo mechanics electric oil pump could not move the oil. It took 5 hours of tedious work to extract oil. Annoyingly the engine does have a sump plug but it can't be reached in the boat, the floor of the hull getting in the way on one side and the tall engine bearer on the other.
So oil cooler off and to Serck who tested and rebuilt it for £48. Reassembled I started multi oil changes. I did not get the improvement in oil I was expecting.

Fortunately I was running the engine with the rockers off to check that oil was coming up the oilways when I had a dull screech from what I thought were the belts. Sprayed WD40 on belts but noise did not go away. Decided to take raw water pump apart. Found it! Bearings in pump were obviously ruined by ingress of sea water which was passing through to engine. The seals must have moved because normally I would expect a stream of seawater from the housing as a warning. Nothing was! (well not at idle anyway) The state of the bearings was awful and shaft in pump scored so off for a repair kit today.

Hopefully this is it; I don't think I have had such a tedious problem before. I am keen to get good oil through the engine a.s.a.p. to limit damage. Keep you posted!!

 

[dragoon]

Hi Tim, glad you're getting there.

Is your pump missing a 'flinger' from the shaft? Normally (at least on my 40s and with many other industrial pumps I've rebuilt) there's a rubber ring that fits around the exposed area of shaft to make sure that water leaking along the shaft will be sent elsewhere and not into the second bearing set. It's this flinging of the water that then helps make the leak obvious.

Good luck with the pump rebuild. I would check your other engine pump also. For the pump rebuild kit, I suggest to try KeyPart.

Cheers, Paul