Volvo MD5A water in crank

[Mattm]

Hi all. Have an issue with my diesel engine where I keep getting water in the crank. I've seen weeping at the head gasket so I am assuming there is something wrong there. So pre-spring launch I am going to be replacing the head gasket as well as rebuilding the water pump">raw water pump. Can anyone think of any areas where water could be getting to and mixing with the oil so I can take the pre-emptive measure of replacement. This is not a little bit of water it is filling the crankcase with 10-20 minutes of run time.
Thanks in advance

Matt

[Mattm]

I know there are typos, I cant figure out how to edit. My apologies

Sorted, Pete7

[billknny]

That's a LOT of water to be getting into the crankcase!

First question, are you sure it is coolant and not raw water? If it is raw water then the head gasket is not the problem. If it is raw water, letting it sit in the crankcase over winter before getting things cleaned and dried will be a disaster. Even properly diluted coolant is a corrosion issue with bearings and such just letting it sit there.

If it is coolant, you would obviously see a big drop in the coolant level, and probably oil in the coolant as well.

Before you rip off the head be sure you have eliminated all the other possibilities for a leak. It would really be better to FIND the leak than to fix all leak sources you can think of.

[Mattm]

Originally Posted by billknny

That's a LOT of water to be getting into the crankcase!

First question, are you sure it is coolant and not raw water? If it is raw water then the head gasket is not the problem. If it is raw water, letting it sit in the crankcase over winter before getting things cleaned and dried will be a disaster. Even properly diluted coolant is a corrosion issue with bearings and such just letting it sit there.

If it is coolant, you would obviously see a big drop in the coolant level, and probably oil in the coolant as well.

Before you rip off the head be sure you have eliminated all the other possibilities for a leak. It would really be better to FIND the leak than to fix all leak sources you can think of.

Its definately raw water. I don't have a closed loop on this engine. The boat is on fresh water. So no salt and I check the oil often so I caught the water intrusion almost immediately and have flushed the engine by isolating the sea cock and running with new oil for a minute and then pulling the oil out.
I haven't fixed it yet because I was looking into replacement. But $12k for engine and leg is a lot of money for a boat I don't plan on keeping for much longer than another 2-3 years
My reasoning for the replacements is if there are only a few possible failure points why not just replace them all.
Raw water pump bearing seal should be done as a PM anyways, the head gasket is weeping so there's already a reason to replace it. After that water could be feeding back up through the elbow but I don't suspect that. Or I could have a cracked block which would mean there's no way around a replacement

[gmakhs]

We have the same engine , Volvo replacement of 10 hp cost around 4000, at least in canaries so 12:000looks overpriced .

You are probably have a hole in your cooling system .
Remove the head and inspect , change the casket.

The raw pump if it leaks it leaks outside of the motor . It has special holes for this , my pump have leak twice Very easy fix cost 20 euro of spare parts .

If a.mechanic told you that this pump can leak in the motor change the mechanic .

Even if you have a leak in the lines or the head all the parts of this motor are replaceable or repairable .
I have been rebuilding this kind of one cylinder motors for years on other machinery

[Mattm]

Originally Posted by gmakhs

We have the same engine , Volvo replacement of 10 hp cost around 4000, at least in canaries so 12:000looks overpriced .

You are probably have a hole in your cooling system .
Remove the head and inspect , change the casket.

The raw pump if it leaks it leaks outside of the motor . It has special holes for this , my pump have leak twice Very easy fix cost 20 euro of spare parts .

If a.mechanic told you that this pump can leak in the motor change the mechanic .

Even if you have a leak in the lines or the head all the parts of this motor are replaceable or repairable .
I have been rebuilding this kind of one cylinder motors for years on other machinery

Thank you. I do all my own engine work so it was me who suspected that perhaps the seal could leak into the block. Long story but I will never trust anyone to work on my boat but myself.
The quote I got for replacement was in canadian$. The cost for engine only was 8k.
I also looked into electric propulsion since my primary engine is actually a 2012 8hp mercury outboard that was installed by the previous owner when his mechanic told him the injection pump needed to be replaced (once I took possession of the boat i teared the pump down and found the piston was installed backwards)

Once the head is off is it easy to see the water passages?

[gmakhs]

I wouldn't do a eye inspection , you can block the exit of the water system and fill it up with water or coolant to see if you have a leak once the head is out .

The water pump has 2 seals , one on the engine side blocks oil coming out and one on the water side blocks water coming out between the 2 seals there is small space with little holes all around to make sure that a leak can be spotted without running in the motor , so if your pump was leaking and both seals where broken you would have water on your engine room bilges as well .

I don't know about electric ... I dream about it all the time .
But an outboard or just electric outboard seems more suited solution.(if the outboard can generate power as well ) .

The main problem.with electric is power generation you can't get enouph solar or wind on a small boat like yours and mine .
That's my opinion but if you come.out with a solution let me know .

Now if you have a hole in your cooling system and you can't repair it on a workshop and can't find a replacement what I did on a Kubota engine with this issue was to use plastic steel putty , it worked well and since there are no big pressures there it keeps going strong .
I am not telling you this is the perfect solution but that's how I temporary repaired and small tractor back home

You might need to remove the cylinder block as well .

Ps.
If I had the same as you and end up dismantling the engine I would do an overhaul as well so the engine is like new

[DougR]

As already mentioned, there is the possibility of water working past the water pump seals, but it seems to be a lot of water for that. It could also be a head gasket leaking water into the pushrod cavity or a cracked head.

There is another possibility, and that is a cracked cylinder liner or bad O rings at the bottom of the cylinder liner, where the cylinder liner sits in the block. This should be checked as well.

I think the way I would check this is to pull the engine from the boat, drop the oil pan and remove the valve cover. Then pressurize the coolant system with low pressure air and see where the leak appears.

If the head is cracked you will see and hear air escaping from the top of the head or into the pushrod cavity. Should be the same with a head gasket leak.

If it's a liner crack or liner O ring you should see or hear something into the crankcase. You might have to put water into the cooling system and then pressurize it if you can't find an air leak.

DougR

[roverhi]

Do you have anti-syphon valve on the raw water dump into the exhaust?? If that's failed you could be syphoning water into the muffler and then into the engine through an open intake/exhaust valve. Had that happen with our MD2. Took the valve out of the anti-syphon fitting, replaced it with a 1/4" hose barb and ran a 1/4" loop high up on the interior of the boat and out to a through hull on rub rail. That effectively broke the syphon without that pesky valve to stick and flood the engine. Almost never got any outflow from the hose and no longer had an issue with engine flooding.

[Farmr Mike]

Been there... I had that same problem. I had two problems...#1 bad head gasket- Planned head and changed gasket-($518). #2 Bad seal on water pump- cost $7.55 to fix. There is a rubber seal on water pump shaft. Got out-of-round from inactivity. I had trouble finding one from Volvo, got it from an industrial supply. SKF #504260. Been working fine for two years. I now found reasonably priced parts for my old Volvos at "Albin Motor and Fashion" in Sweden. Got my parts in a week. Cost about $35 in shipping. A good company.
Not a fully happy ending.... #3 Got water in my crankcase again, but only when not running/sitting, and only about a 2 pints... and it is suspected to be the manifold gasket. Got a new upper engine gasket set for about $135... Forget how many Kronors.

[DaveSIM]

Originally Posted by Mattm

Hi all. Have an issue with my diesel engine where I keep getting water in the crank. I've seen weeping at the head gasket so I am assuming there is something wrong there. So pre-spring launch I am going to be replacing the head gasket as well as rebuilding the raw water pump. Can anyone think of any areas where water could be getting to and mixing with the oil so I can take the pre-emptive measure of replacement. This is not a little bit of water it is filling the crankcase with 10-20 minutes of run time.
Thanks in advance

Matt

you should check your exhaust system to verify you are not getting water back thru the exhaust system. Is you exhaust pipe high enough above the water line so you don’t get back flow into the engine. I would start there . Most water leaks like this are from bad head gaskets or block cracks. The next step is to connect a garden hose to the raw water system with the engine off and see if the crankcase fills up with water thru the dipstick reading. If this shows inflow then check the gasket and block cracks. Good luck. Dave Spiers

[Mattm]

I have gotten glycol in the crank the first winterization by making the mistake of using a hand pump to pump glycol through the engine but as long as my starting battery is full I get enough compression to not allow the water to build up to the elbow. Right now I'm just getting my gameplan together. I usually have a week or 2 at best to prep for launch which takes a lot of preplanning and preordering of parts. Canadian winters make good maintenance very difficult especially when the launch schedule is aimed more at appeasing the racers who basically want to launch the second the ice is off the water.

[DaveSIM]

Matt, There are only a few ways for water to get into the oil pan. Backflow through the exhaust elbow, a bad head gasket or a cracked block. The raw water pump itself wont put water in the oil. Connect a water hose to the raw water system and turn the water on without the engine running with the exhaust elbow disconnected( no backflow). See if water gets in the oil (check with dipstick). That will leave as problems the gasket and cracked block. Pull the head off and look at gasket and block and head for cracks. Welders purple dye will help seeing cracks. Let me know what you find! Davsim

[Bay_Sailing]

The head might be corroded through. I can't see how a leaky head gasket would let that much water in.

[DaveSIM]

Matt, Does the exhaust pipe system get above the waterline between the engine and the exit from the boat? Does it have a vacuum breaker installed? I assume it has a belt driven water pump. Do you have any signs of water leaks around it? i.e. seals gone. A bust head gasket or cracked block wont give any change in the exhaust just more water coming out. A bust gasket between a water channel and a cylinder will put some water in the crankcase but not much. A cracked block between water channel and crankcase will give you lots of water in the crankcase. Have you left water in the engine cooling side where it might freeze? Do you add antifreeze in the engine when prepping for winter or open pitcocks to drain it? How does the engine sound when running? Good or uneven? Do you have an oil pressure gage and what does it read? Many variables here, need answers.... DavesIM