Oil in water intake hose

[rjamaro]

Hi all,

I just bought a bot one of these days and after some engine issues while taking her to her new home, I engage in a extensive overhaul.

Today while unplugging all hoses and cables to take the engine out, I noted something that is very odd (at least for me).

Let me describe first what were the issues that I faced while bring the boat home. After some hours of a very low regime of RPM, the engine stoped and when I checked the reason the filter of the water intake was empty. After some minutes of rest the engine would start again.

Today when I was unplugging the hoses, I noted that there was oil in the hoses that connect the fiilter to the water pump">raw water pump. The more strange is that there is no oil residues on the through hull.

Can this be an issue on the water pump seals? Eventually to much oil pressure building up and then escaping from the water pump seals?

Any clue?

The engine is a Volvo Penta MD 17D.

Thanks in advance,
Ricardo

[redbeard1]

Hello,


Just to confirm, you found oil in the hose (marked A in yellow in the attached picture) between the raw water pump and the sea water filter. Correct?

If the water and oil seals on your raw water pump were failing, oil could make it into the raw water pump. But if it were to happen the oil would more easily move downstream not upstream. Maybe after the pump stops, the oil left in the pump is gravity fed to the hose but that is just a guess. On some of the raw water pumps, there is a weep hole between the oil and water parts of the pump. If you have a weep hole, check if you see oil in that area.

I’m not sure that a leaking raw water pump could cause your engine stop troubles. A leaky raw water pump could break and cause an overheating issue but you did not mention any overheating. Failing seals on the pump could let raw water into your oil. That might cause problems but I don’t know if those problems include stopping the engine for only a while. Have you checked for signs of water in your oil?

[rjamaro]

Thanks Redbeard1,

yes, the oil is appearing were you highlighted in yellow and I am facing overheating issues in my engine. The strange is that it only happens after some hours of having the engine working.

So far I didn't notice water in the oil, the oil seems to be ok without any water presence.

What happend when I was bring her home was the following:
1 - Smoke in the cabin
2 - To much eat in the engine compartiment
3 - Engine warning buzz starts sounding
4 - Engine shutdown by himself
5 - No water in the strainer...

When I disassembled the hoses then I saw the existance of oil both in the hoses and in the strainer. This saturday I'll take the engine off and I'll start a major maintenance work in the engine. I just hoppe for the required parts to be available...

Fair winds,
Ricardo

[Sailmonkey]

Are you sure it's oil? What you're describing sounds like old hose gunk made slimy by heat.

If your engine overheated to shutdown it may be badly damaged....also if the impeller ran dry its shot.

You should replace the impeller, then try to find the air leak into the strainer. Maybe as simple as the gasket on the lid of the strainer. Then run the engine and monitor the water flow from the exhaust.

[rjamaro]

well,

I beliave that is oil, yet it is grey and the engine oil is black but eventually it can be caused by the water...

when you say badly damaged, can you specify what or how do you think it is damage? It will be something that don't have any possible repair?

Fair winds,
Ricardo

[Captsteve53]

The over heat sounds pretty serious, but at least this is a simple engine to work on and the repair manual can be found here: https://www.maritimepropulsion.com/files/pdf/1001252

I would be not only changing the raw water impeller but replacing the thermo stat and checking the exhaust riser, hopefully the oil is coming from a cylinder head gasket and not cracked head, again at least these are separate heads on this model,

Marine Parts Express has a very good on line schematics and parts listings as follows: Volvo Penta, Mercruiser and more - Marine Parts Express - engines, outdrives, propellers

Cheers Steve

[rjamaro]

Thanks for you support.

I hope that due to the simplicity of this model I can be able to solve the issue. I never attempt to do such repairs, but I am a guy interested in mechanics, so I belive I'll be able to do it with the support of the workshop manual for the engine... my affraid is that if I'll require any part that it is out of stoc...

Well fingers crossed and let's expect the best.

Fair winds,
Ricardo

[redbeard1]

Hello,


To isolate the problem, it would be helpful to confirm that you are finding oil in the strainer and not hose residue. Unfortunately, if your engine has the original raw water pump, I don’t think it will have a weep hole. If it does, it will be on the bottom of the pump, in the area marked A in the picture. If you find oil next to the weep hole, you at least have a raw water pump seal problem. If you don’t find the weep hole, remove the impeller cover (close sea cock if your pump is below waterline). If you find oil in the impeller area, again you know you at least have a raw water pump seal problem. If you caught the problem early, you will only need to replace the seals. The seals are relatively inexpensive. If the metal shaft has marks, you may need to replace the shaft and the bearings. Not inexpensive.

If you find no oil in the impeller area, then you may not have a seal problem. If the impeller is destroyed (you mention no water in the strainer, if the impeller ran for a few seconds without water, it will be destroyed), then you can replace the impeller but before running the engine you need to find out why you have no water in the strainer or you will destroy another impeller.

You wrote your strainer had no water. How did you check for water? In looking at your engine diagram, the original equipment strainer is all metal.

[rjamaro]

Thanks for your feedback,

the privous owner replace the strainer by a plastic one, the ones with a crystal cover where you can see the water flowing. When the engine stopped, I saw the strainer and it was empty. When I was disassembling the hoses to remove the engine, I look to the strainer and it was all black from the inside (together with the hoses), it was such a thick stuff that only come out when I clean it with diesel.

On regards the weep hole, I don't know if it have it. I'll search for it to confirm.

Thanks for your support and for the tips.

Fair winds,
Ricardo

[redbeard1]

Looking at the diagram of your engine, it seems the strainer is below the water line. If you have the sea cock open, if your strainer is below the water line, you should have water in the strainer.

You may want to see if anything is clogging your raw water intake on the hull (watch out for stray electric current if you are diving and take all precautions). If that looks clear, close the sea cock, remove and examine the hose between the seacock and the strainer. Hopefully you will find something blocking the hose.

Were you able to check the impeller area for oil?

[rjamaro]

Hi redbeard,

I saw the oil in the hoses and in the strainer with the boat dry on land in the shipyard. Since I am doing a major refit, I am pulling all out, so I checked the water intake and it was fully open without any thing that could prevent water from flow. Even in the water in one of my attempts, I let the water run free trough the sea cock and it was ok, a good flow of water was comming out.

It is in fact a mistery, but I believe like you said before that something is wrong, or the water pump, or the thermo stat, or even both.

My biggest fear is if the problem is cause by some major mechanical issue... at this moment and after buying the boat I don't have to much money to spend on a newer engine, so let's open the pandora box and see what comes out...

Many thanks for your suppport.

Fair winds,
Ricardo

[redbeard1]

That does sound like a mystery. How many times did your engine stop? If it just stopped once, maybe something (large plastic bag for example) blocked the raw water intake but only until the engine stopped. Once the engine stopped, the suction disappeared and the bag floated away (just a guess). If the engine stopped many times on the way home, that explanation is not likely.

Once you start working on the engine this week-end let us know what you find.

[rjamaro]

It stopped once on every attempt... Today I removed the water pump and no signs of oil...

What a big misery I have here...

[redbeard1]

Does your engine have fresh water cooling or just the raw water?

If you have fresh water cooling, and the impeller area had no oil, then the oily paste you found in the strainer might be the hose residue mentioned by sailmonkey which makes me wonder if a collapsed hose is causing your water intake problems? What is the condition of the hose between the intake and the strainer? Is it firm?

If you only have raw water cooling, then I imagine it might be the same collapsed hose or maybe oil from a leak in the coolant galleries although I can't imagine how the oil would travel upstream to the strainer without leaving a mess in the impeller area which you say you found to be clean.

[Stu Jackson]

Originally Posted by rjamaro

1. >>>>>>>>>>>> Today I removed the water pump and no signs of oil...

2. What a big misery I have here...

1. Good news.

2. Mysteries are for books and TV shows. Anything mechanical has a REASON. With all the good advice you have received here, you should be able to work out a SYSTEMATIC approach to the problem. Step-by-step.

Good luck.