Lost without a clue: Saltwater in oil

[pbmaise]

I think I am confusing things.

The elbow to me looks like an elbow and point water is injected into exhaust. It is not the big riser loop that is at peak 3 ft above waterline.

My outlet on side of boat is one foot above waterline.

I am now back on vessel and now concluded 100% it is seawater from exhaust. We are reducing riser height to reduce amount of water that can flow back to engine. I don't want-trust commercial to flush line before shutting off engine.

Exhaust is used to heat coolant and it is this coolant exchanger that may be source of slow long term leak of coolant.

Since we have engine down we are going to install new head gasket and other seals.

Head gasket kit has 12 small metal parts that look like shives obviously two per cylinder. What are these?

[pbmaise]

BELAY

I see something counter intuitive. A slow coolant leak can result in saltwater inside the oil pan.

The coolant leak first fills the pipe to the muffler and at that point salt water mixes with coolant. This combined fluid then continues to rise until it enters engine.

This would be especially true if attached to radiator is a gravity fed reservoir which is exactly what the crew did.

The overheating event damaged the seal between the radiator and exhaust gas pipe.

Sorry radiator is the large chambered exchanger on side of engine with radiator cap.

[mvweebles]

Attached below is an article on exhaust system design from Steve D'Antonio that might give you some tips.

I'm having a hard time picturing your engine and issues with regard to filling exhaust muffler. Sounds like you have two issues - coolant loss/mix with oil; and saltwater intrusion. And you've had an overheating event due to a blown hose. If the blown hose was a raw water hose, would definitely explain both events - head gasket and exhaust elbow would get much hotter than design.

I'm not sure about the 12 small metal parts. Maybe shims for the valves? At the risk of sounding simplistic, make sure you reset the valve clearances after you torque the head. Was on a recent thread about a Yanmar that had lost compression and it became apparent the head gasket had been changed 18-months prior but the valves were not reset. Head should be retorqued and valves readjusted again around the 50 hours mark after install.

As long as you have the head off, you may want to have it checked for warp and valves done.




http://www.oceannavigator.com/May-Ju...system-design/

[Martkimwat]

Can't speak for the Isuzu as I am unfamiliar with it but on Yanmar GM series engines, a common problem is the if the raw water cooling to the exhaust, corrodes the exhaust mix manifold and goes undetected for a while, the salt water then corrodes the exhaust port(s) in the cylinder head, eventually corroding right through and allowing saltwater to enter the oil gallery. If caught quickly it can be remedied either by head replacement (expensive) or having the exhaust port sleeved, which I had done on a 1GM10 I had on a previous boat. cost about £65 per port in UK. From what I understand, it does not take long for the corrosion to take place due to the thiness of the exhaust port/ oil gallery interface. Sleeving with a 5mm wall stainless steel insert, reduces the exhaust port slightly, but fixes the problem and did not seem to noticeably affect the performance of the unit. This could happen with either freshwater or raw water cooled units, as the head is the same.

[Sardean]

It would be easy to put an interlock limit switch on the intake valve in series with the startemotor coil so motor can’t be started until valve is open. Even as a temporary test to see if it stops water problem

[sailah]

Comment specifically to head gasket replacement:

If you are pulling the head off to replace gasket, you should check the head for flatness, especially since you may have experienced an overheat at one point.

I had this same thing happen, but the overheat was from a previous owner and I did not know it. I did not check head for flatness and promptly blew out the new head gasket along with a fit of other coolant related issues. I finally pulled the head and had the machine shop check (was def warped). They surfaced it and I reinstalled with a new HG and all has been well.

It's pretty cheap to check and resurface a head compared to the time and cost of pulling it again.

[Bill O]

Originally Posted by sailah

Comment specifically to head gasket replacement:

If you are pulling the head off to replace gasket, you should check the head for flatness, especially since you may have experienced an overheat at one point.

I had this same thing happen, but the overheat was from a previous owner and I did not know it. I did not check head for flatness and promptly blew out the new head gasket along with a fit of other coolant related issues. I finally pulled the head and had the machine shop check (was def warped). They surfaced it and I reinstalled with a new HG and all has been well.

It's pretty cheap to check and resurface a head compared to the time and cost of pulling it again.

Also if in the machine shop, check worn valves/bent stems and reseat valves.

[Bill O]

Originally Posted by pbmaise

I think I am confusing things.

The elbow to me looks like an elbow and point water is injected into exhaust. It is not the big riser loop that is at peak 3 ft above waterline.

My outlet on side of boat is one foot above waterline.

I am now back on vessel and now concluded 100% it is seawater from exhaust. We are reducing riser height to reduce amount of water that can flow back to engine. I don't want-trust commercial to flush line before shutting off engine.

Exhaust is used to heat coolant and it is this coolant exchanger that may be source of slow long term leak of coolant.

Since we have engine down we are going to install new head gasket and other seals.

Head gasket kit has 12 small metal parts that look like shives obviously two per cylinder. What are these?

If you don't have an anti-siphon valve well above the waterline, would put one in as high as possible. Very cheap insurance ($30 and some hose) to make certain it doesn't back up through the exhaust.

Originally Posted by pbmaise

Thank you for your diagnostic help everyone.

"I assume you have a water lock muffler. Have you looked to see if it is full?"

Can someone explain this question to me. Are you suggesting I take it apart and look inside. It is a large stainless steel anode protected round tank. Is it possible that after 20 years this tank is full of junk?

From one of your previous posts, I believe they were asking if you have a water lift muffler in your exhaust system after the elbow.

Your SS tank is probably ok, but after 20 yrs it may be time to take it out and see if there is any junk in it causing restrictions and reducing the out flow.

A PO of our boat had an issue w/water in the newly replaced motor (1 time) and had the very solid SS water lift muffler ripped out of the boat. The mechanic told him a bad muffler was why he had water coming back into the engine. Nothing was wrong w/the muffler, but did notice he didn't have an anti-siphon in place. Purchased the boat, installed the anti-siphon and never had an issue. This is why I also know it was a $30 fix!

[Wulf]

Originally Posted by Bill O

Also if in the machine shop, check worn valves/bent stems and reseat valves.

And have them check the head for cracks. While not really suspect in this case it should be done anytime an engine is apart due to overheating. Takes one more item off the post repair “gee, I wonder” list. And not expensive to do.

[Nico Domino]

Did you check the breather pipe/conector and dipstick connection.
Depending on conditions, high humidity and windy weather can induce water, in particular if engine is run frequently for short periods. It can cause corrosion in the engine as well. Just a possibility.

[mokkerse]

Do you have a "vented Loop" in the raw/ sea water system? If that valve gets stuck or there is a blockage, you can get a reverse suction. Happened to me on my 50hp Yanmar and took some investigation before we discovered it was the cause.

[feudalkaos]

Originally Posted by pbmaise

We have been trying to figure out how saltwater is getting into our engine and run out of ideas.

Isuzu 6BD1 engine.

We removed the coolant/saltwater exchanger and took it to a shop for testing. No leaks. Excellent condition.

We removed the coolant/oil exchanger and it was fine too.

A taste test of water in the oil pan = saltwater
A taste test of engine coolant = no salt
Transmission fluid fine.

One possible clue we thought was the slow loss of coolant before this occurred. The boat is run commercially now which mean I am not their to oversee it all the time. The mechanic installed a gravity fed reservoir to the radiator. One strange guess I have is someone refilled that reservoir with saltwater instead of fresh.

However, I insisted on removing the reservoir and salt water got into the engine oil yet again.

I just purchased a complete head gasket kit since I thought the problem was coolant mixing into the oil. I am now concerned installing it would be wasted effort. We have no smoke issues with the engine and it sounds fine.

I had saltwater in the engine before, however, that was almost 12 years ago while crossing the Pacific in rough weather. I am still not sure if that saltwater came up the exhaust or through saltwater supply line to the engine which was open. I was paranoid after that and would close the saltwater supply line even at the dock. That was fine while it was only myself starting the engine since I could be certain to open the supply line before starting the engine.

I never had saltwater in the engine since I began closing the supply line, however, I also have not been crossing the Pacific either.

The engine is mostly above the waterline. The saltwater mixing elbow is above the waterline too. This said, the oil pan is below it.

Given the commercial crew, I really worry about telling them to begin closing that supply line each time they shut the engine off. They could do a lot of damage if they forgot to open it if they were in a hurry.

The vessel has not been in any rough water for over 2 years.

I hope this is enough information for someone to give me a clue as to what to do. My only thought is to review the current procedure of opening and closing that saltwater supply line despite the fact I doubt it is the problem.

I had a similar issue of getting salt water in the engine. I have a PSS Shaft Seal on my boat and the vent/cooling line on the shaft seal we piped into the raw water line of the engine. I understand this is a fairly normal install for any boat that can do more than 12knots.

I found that where this connection was made was just above the water line. What was happening was the boat would rock or tilt just enough to put this connect below the water line causing small amounts of sea water to come up through he vent/cooling line on the shaft seal into the raw water line which was at the top of the mixing elbow for the exhaust. This slow drip caused the water muffler to fill with water slowly and eventually start back filling the engine.

Not sure if this applies to you but thought it was worth mentioning in case it gives you some clues.

[tomtriad]

For what it's worth, as I have little experience with inboards, but here goes. My 4 stroke outboard oil got contaminated with saltwater, discovered when changing the oil. Replaced with fresh oil, ran motor a few minutes, checked oil and contaminated again - cloudy and muddy looking, and oil level rising on dipstick. Consulted with factory mechanic, who advised it was due to either a bad head gasket or a cracked head. Could this not be your problem as well?

[gulfislandfred]

In my (limited) experience, oil in water is usually a head gasket or head/block corrosion problem.



Quick and dirty head gasket check: Check the freshwater expansion tank for bubbles when the engine is running. Check under load at higher RPM if possible.


As others have said: look at places where cooling water is next to oil passages: Head gasket, Manifold gasket, oil passages with covers or in the block. Until you get real data, be suspect of fresh water side, as well as salt water side.

[LooseGoose]

Not many places where raw water and oil get close in a closed cooling system engine. Trace the raw water circuit. The oil cooler warrants very close attention.