Salt water in the engine oil

[Absolution 7]

We had an oil pressure alarm on the engine on saturday so I shut it down and had a look and found the engine oil had turned grey which appeared to be due to water contamination. I assumed that we had done a headgasket but when the engine cooled down I checked the fresh water level in the heat exchanger and found it still full and uncontaminated. It looks like it must have been salt water in the oil.

 

So assuming the engine isn't completely rooted I have given it 3 oil changes and the oil got a bit cleaner every time and now it looks like brand new oil on the dipstick. The engine is starting and running fine, not sure if the salt water would have done any damage, I hope not. The main concern is that I haven't fixed the root cause.

 

The only place that salt water could be getting into the engine is the injection into the exhaust. There is no siphon break between the heat exchanger and the exhaust which may be part of the problem. Also it looks like on a big angle of heal (i.e a broach) the heat exchanger could actually empty most of its contents straight into the exhaust which if it is already full may be enough to reach the exhaust manifold.

 

The other possibility is that with long spells at 12kts+ like we had on saturday we may have been forcing water into the saildrive, past the impeller and filled the exhaust that way. I have heard about multihulls filling there engines with water this way.

 

So the question is what do you have to do to ensure that you don't fill the engine with salt water in a) a knock-down or when sailing at 15kts+?

[shanson 0]

I had the same issue with my engine last year.

 

After removing the head and everything to do with the cooling system I found it was a sealed bearing between the cam cover and the raw water pump had failed.

 

We put 4-5 oil changes through the engine and the last two had Wynns oil treatment in (didn;t think it could hurt) and the engines been running like a dream ever since.

 

SHANE

[Absolution 7]

Thanks Shane, good to hear your engine is still going strong. I checked out the raw water pump but it is belt driven and there's no way it could leak into the oil which is why I figure it must be coming from the exhaust.

[wheels 543]

Do you have an engine Oil cooler???

 

Water would not get into the Sump via Exhaust without other real big problems showing up first. First off, it will corrode Valves real quick. Second, it will corrode rings and Bore and it will lock up Ally Piston to Steel Bore very fast and seize the engine. Thirdly, you would never start the engine. If you managed to turn it over, you would most likely hydraulic the engine and break or Bend Crank, Rods and Pistons.

[Absolution 7]

Do you have an engine Oil cooler???

 

Water would not get into the Sump via Exhaust without other real big problems showing up first. First off, it will corrode Valves real quick. Second, it will corrode rings and Bore and it will lock up Ally Piston to Steel Bore very fast and seize the engine. Thirdly, you would never start the engine. If you managed to turn it over, you would most likely hydraulic the engine and break or Bend Crank, Rods and Pistons.

 

Don't have an engine oil cooler. The engine was difficult to start at first and I thought the saildrive wasn't quite in neutral so moved the lever back and forth and then tried again, it started but took a lot of cranking. The engine is pretty tired and I noticed a fair amount of blow by so I am assuming the rings are well worn. Maybe the compression is down so much that the water could actually run past the rings?. We were racing for 9hrs or so, there would have been plenty of time for the water to trickle down. Plausible?

[Marshy 30]

Not sure if its the same problem but its another one to watch out for Hamish, On Ran-Tan going to Vila a few years back we took a few good waves up the back and water actually managed to go up the exhaust outlet and back fill that way causing all sorts of strife... Just one to watch for if you have a seaway running behind you.

[Farrari 4]

A mate of mine in a Chico355 had the same thing happen. The spring on the exhaust flap failed and he was out in some reasonable sized following seas. When he came to start the motor it wouldn't go (it had Hydrauliced). He got a tow back from Coastguard. That was another eventful story.

 

He ended up getting the oil changed several times and got away with it. The motor is still going fine. I guess he was lucky that nothing bent and that the oil was replaced quick smart before too much corrosion could set in.

[Deep Purple 511]

Do you have an engine Oil cooler???

 

Water would not get into the Sump via Exhaust without other real big problems showing up first. First off, it will corrode Valves real quick. Second, it will corrode rings and Bore and it will lock up Ally Piston to Steel Bore very fast and seize the engine. Thirdly, you would never start the engine. If you managed to turn it over, you would most likely hydraulic the engine and break or Bend Crank, Rods and Pistons.

 

I'll go along with that. Water through the exhaust can only get to the sump via the cylinders. Water in the cylinders won't let a strong healthy engine turn over at all (been there done that) Water in the sump via the cylinders without damage means the water has drained down past the rings or been lucky to hit an exhausting pot first with a little drainage past the rings thrown in.

[wheels 543]

Hmmm, yeah OK, I didn't quite understand the fact that the engine had not been running for 9hrs. It is possible then and you were really really lucky you didn't do some real big time damage. Very fortunate that the Engine was worn enough in this case.

You need to look at the exhaust set up sometime then. You don't want this happening too often. It can really wreck the engine. Mostly the Valves corrode up and the Pistons simply corrode and lock to the Bore. The ole Electrolysy issue of two dissimilar metals and an electrolyte. If they don't seize, they are at least eating into the sides of the bore and pitying them. Nasty and the engine won't last long that way.

A good gollop of water and the starter can provide enough force to actually break Engine components. I have even seen a Head physicaly broken. Although the Motor was runnign at the time and the driver dropped the nose of the 4WD into some deep water and she was all over. Brand spanking new Hilux and $15K of motor later and that was 25yrs ago.

[Guest]

I find it really hard to believe that water could find it's way into the sump via the cylinders. The rings would have to be virtually non existent. In fact if they were that bad, you'd have had huge starting problems way before now. Has to be something like a porous block.

[Grinna 2]

But hang on, if its salt water then it can't be a porous block can it? The block only has coolant (fresh water + antifreeze) charging around its galleries and the coolant is in turn cooled by saltwater in a heat exchanger (a water to water radiator) isn't it?

[wheels 543]

Correct Grinna.

I know what you mean Zen, it's hard to believe, but I can't think of any other way Saltwater could get there. Presuming it is Salt water. But then as Finline said, the Fresh water Coolant has not changed level.

Finline, if the engine is a Yanmar, check the Exhaust Elbow.They are notorious at being eaten away or blocked up completely and water could get back into the inlet at that point if there is a blockage below the point the Saltwater is introduced.

[Absolution 7]

The rings are pretty stuffed. Lots of vapor coming out of the oil filler although its probably a bit worse at the moment because its still evaporating a bit of water out of the system.

 

The engine is a crappy Daihatsu engine that I wouldn't waste money on rebuilding so I might just suck it up and replace it anyway. Its the worst part of the boat so it would be nice to have a new one.... but that will empty the sail budget for next year

 

It looks like both Beta Marine and Nanni have adapter kits that will bolt up directly to the existing Volvo saildrive. Hopefully not a major to swap them over.

[markm 30]

I think I need a sail budget like that Fineline, you wouldn't consider swapping it for us letting you win more often would you?

[Absolution 7]

I think I need a sail budget like that Fineline, you wouldn't consider swapping it for us letting you win more often would you?

 

We could probably figure something out... especially if I get to have your engine!

[shanson 0]

The rings are pretty stuffed. Lots of vapor coming out of the oil filler although its probably a bit worse at the moment because its still evaporating a bit of water out of the system.

 

Fineline

 

That exactly what we had, quite a bit of pressure in the sump and masses of steam comming out, we didn't have any problem with our rings, the issue was (I think) water evaporating out of the oil due to the tempreture.

 

We originally didn't know where the issue was an ended up spending about 6 months strippping different parts of the engine to find it, it turned out to be the RAW wather pump which we originally passed as ok.

 

There was a air gap between the RAW water and fresh water however an extra bearing had been installed which blocked this gap and the drain hole. It was this bearing (along with the one on the RAW side and the one on the Fresh side) which failed one by one causing the problem.

 

Cheers

 

SHANE

[ScarecrowR31 8]

Had a similar problem on a Nova 28. After broad reaching in about 25 knots with full rig (drying the genoa) for about 10 mins the genoa was dropped and I attempted to start the motor. No go, injector out, motor turned over and water blown out from top of cylinder. Motor started fine once injector in and system bled. Phoned around and several "older" mechanics all said to fill engine with diesel leave overnight and the flush before several oil changes. Motor (sole) actually ran much better after this and 9 years latter was still running well.

The theory being the diesel helps move all the salt down into the sump. In this case I suspect that the rings on Finelines stern cylinder may be damaged possibly be a previous incident but there is still compression on the other cylinder(s) so that there is still the ability to start the motor.

My question would be how high is the exhaust prior to exit?

[Absolution 7]

My question would be how high is the exhaust prior to exit?

 

Not very high at all. The engine is on top of the keel so the exhaust runs under the floor to a water lock under the companion way and up from there under the cockpit and then out the transom. There isn't much room for a loop under the cockpit but I'm looking at increasing the size of the water lock and putting in a loop under the companion way.

[rigger 47]

Did come across one boat that someone had fitted a valve at the thru hull for the exhaust - who ever did it was pretty switched on as they had also fitted a relay to avoid the engine being started when said valve was shut. nice little sign posted "check valve if engine does not start" - or words to that effect.

[Deep Purple 511]

Make sure the exhaust runs as close to the centreline as you can, i've seen some that arc out to the gunwhales. Picture the exhaust heeled.