Salt Water in my Isuzu engine

[dsbentley]

I need some advice on a problem I discovered. I went to check my main engine oil and found water most of the way up the dipstick. I pumped out some of the oil and ended up pumping out 9 gallons of sea water from the oil pan before getting to the oil which never mixed because I never started the engine. I had my mechaninc come over and he preasure tested the fresh water system and found that to be good so I dont believe I have a craked head or block. He said he thinks the water might be coming from the exhaust. I have a 5" exhaust that goes over a loop after the main engine manifold. The sea water enters the loop on the other side and flows down the 5" exhaust to the aqualift then travels under the rear bed up the transome about 5' and back down to the waterline. The Aqualift has a drain plug and used to have a valve that opened when the engine was shut down to drain the water. This was supposed to help cut down on the tank rusting. I removed that switch over a year ago and have not had any issues until now. When we removed the plug, we got a lot of water to come out, seemed like over 40 gallons so I think the whole exhaust was filled with water. I dont know how that loop works and what keep the sea water from going into the engine which sits below the water line.

One more note, I occasionally hear a gurgling sound a few times a nights when all is quite and I am sleeping. I thought this was a bilge related issue and repaired the anti siphon and the check valve, but I still here the noise. I dont see how any water can ge coming in up the exhaust line and down into the engine.

We were able to get all the water out of the pistons today and flushed the pistons with oil. The engine ran fine and after shut down I drained the aqualift again and only got about 10 gallons of water. We took out the injectors and found no more water and will check them again tomorrow.

Any advise would be appricated.

[JimsCAL]

The loop is supposed to prevent water from siphoning back into the engine. This is apparently not working. The top of the the loop has to be above the waterline - the higher the better. I've never heard of a system where the waterlift muffler had to drained each time the engine was shut down. I have seen a vent installed in the loop at the top to admit air and prevent a vacuum from developing. A check valve in the vent line prevents exhaust from backing up when running.

[Omatako]

There is really no way that exhaust water can get from the exhaust system into the crank-case. There simply is no connection.

This is also not a coolant problem because 1st, the coolant is fresh and hopefully as some anti freeze in it and 2nd, the fresh water system probably does not have 9 gallons of coolant.

I reckon that you have an oil cooler on your set-up and there is a breach between the two sides of the heat exchanger. Have your mechanic check this out.

Hope this helps
Andre

[Valiente]

If there is a plunger and spring-type vent on the top of the anti-syphon loop, this can fail or otherwise stick. Then you can get the contents of the hose, from the top of the loop to the mixing elbow, potentially backing into the crankcase via the valve chamber.

I replaced the spring and loosened the vent housing. Now I get dripping when the engine is running, but no other issues with water backing into the engine. I intend to finish the job after my engine rebuild (unrelated) by running a hose from the top of the loop out to the deck or some other high point. The spring-loaded vent itself is a failure point...why bother?

[HoffaLives]

The waterlift is supposed to be filled with H2O so that's normal. People have already mentioned the antisiphon valve, so the other thing to check is the elbow - where the water enters the exhaust. Depending on the configuration, if this corrodes internally, water can be pumped into your engine.

If you found water on your pistons, it had to come in through the exhaust.

[Omatako]

Valiente - your note seems to imply that there is a connection between the exhaust system and the crank case via a "waterlift". Help me understand what that is please. I have not come across this before. In my experience any tendency for the exhaust system to siphon will result in the exhaust manifold filling with water and then running into the top of the engine via an open exhaust valve or two.

I find it reasonably difficult to imagine 9 gallons of water getting by the piston rings unless of course the engine hasn't been run for a longish time. But then again in my experience, if there is salt water lying on top of a piston for more than a few days, the engine is beyond redemption and will never be started again. This engine apparently started again quite easily.

Seems to me that unless there is a direct connection between the exhaust system and the crank case, 9 gallons of water will not filter down from the top past the rings (unless of course the engine is knackered).

Have I missed the point?

Andre

[sailingdog]

Omatako-

Any engine with a water-lift type muffler should not be cranked for longer than 15-20 seconds as a general rule. Cranking the engine for longer than that without it starting will cause water to fill the waterlift muffler, and enter the engine via the exhaust valves—causing the engine to hydrolock. Hydrolocking an engine is really bad.

The reason this happens is that the exhaust back pressure normally forces the water out of the waterlift muffler, but if the engine is cranking but not starting, there is no exhaust back pressure. If you do have to crank the engine for an extended period of time, it is highly recommended that you shut the raw water seacock that feeds the waterlift muffler, usually the same as the raw water cooling system seacock—just remember to open it once the engine is running.

I don't think your water source is the waterlift muffler, unless you've blown one of the rings... which I seriously doubt.

[christyleigh]

Last July I had a 'hydrolock' with the cylinders above the pistons filling with water. It was caused by 'mud dauber' wasps clogging the siphon break air line at the top of the exhaust loop. It sat like that for 2 weeks while I chased my tail looking for other problems as it seemed at first that my start battery had died as the engine wouldn't turn over. No water leaked past the rings into the oil pan and no damage was done. The mechanic I called simply pulled the 4 injectors and hit the starter spraying the dirty water all over himself and the pilothouse - but the mess was the extent of the damage......ahhhhh.....

[CapnHand]

If you check and there is no oil cooler or if there is but it checks out ok, there is one other possible, but unlikely, entry point for water into the crankcase oil.

There is a breather for crankcase ventilation, it's usually located on the valve cover with a hose running down from it to the area of the air intake. It's purpose is to vent off any blowback from the cylinders into the crankcase. Water can be pulled up this hose into the crankcase when the engine cools after being shut down.

[HoffaLives]

Originally Posted by christyleigh

Last July I had a 'hydrolock' with the cylinders above the pistons filling with water. It was caused by 'mud dauber' wasps clogging the siphon break air line at the top of the exhaust loop.

And I wouldn't be surprised to learn that a hummingbird could take out your rig.
Man, this kind of thing tells me only a knucklehead would have anything to do with boats. A wasp taking out your engine just about caps it.

I think the smart thing to do is sell the boat, buy a permanent seat at the bar overlooking the harbour, and have a good, good laugh while throwing peanuts at the poor bastards down there with their their boats.

If God had intended man to float he would have given them bigger asses.

Anyway, on with the thread...