How do I diagnose a cracked engine block?

[Compass790]

You can check for cracks yourself on the head if you want. A welding supply store should have spray cans of crack testing spray.It's better if you have a little experience using the stuff but there are probably videos on youtube. Instructions are usually on the cans but if you are not confident any cylinder head reconditioner will do it

[Symphony]

subscribed!

[Sailorbob8599]

Originally Posted by Cheechako

Yes, most non marine shops don't care and should be able to test it. I've had a marine diesel head rebuilt by a auto head shop before.

Engines do not know if they're installed in a Boat, car or whatever. An engine is an engine is an engine. An engine don't even know what make it is, it's just an ENGINE. Period. The only reason to go to a dealer shop is because they probably 'know' youe engine better than a general repair shop. Also, they will know about recalls & updates etc. but it's still just an engine or, if it's really broke, we call it an anchor.

[Dave22q]

You are looking at potentially large expenditures to solve what may be a non problem. Rather than tear things apart to start why not install your new gaskets, change the oil and possibly install an exhaust temperature monitor. If she does not run hot or show any other symptoms when warm, put away your tool box and relax.

[Siberian Sea]

It could be a possible cracked cylinder liner. Water is drawn into the cylinder on intake stroke and on compression stroke some passes the rings into crankcase and the rest is seen as white smoke out the exhaust

[farmall.dude]

Originally Posted by Sailorbob8599

Engines do not know if they're installed in a Boat, car or whatever. An engine is an engine is an engine. An engine don't even know what make it is, it's just an ENGINE. Period. The only reason to go to a dealer shop is because they probably 'know' youe engine better than a general repair shop. Also, they will know about recalls & updates etc. but it's still just an engine or, if it's really broke, we call it an anchor.

Actually, I don't think that's true. I know some NASCAR (amateur division) folks that are always looking for marine engines. They're built to tighter tolerances because they run at high RPM constantly. Or so I'm told...

[flyingfin]

Have you drained the oil and re-filled yet?? Did hull have water inside over the winter, or do you pull the plug and ensure full drainage??
Remember this is an inboard engine, not an outboard. The main seal on the engine is to keep the oil in, not to keep water out. I have seen smaller trailer boats fill with water because the owners failed to pull the plug. Once the standing water gets above the level of the main seal water gets into the oil pan.
Easy fix is to drain oil, refill, run for 10 hours, then drain and re-fill again.
If you still see milky oil, time to check for cracked head or block.

[dgz3]

The castings on those engines are so robustly built that it is extremely unlikely you have a cracked block. And I doubt you neglected to drain the water jacket before freezing weather...
The most likely culprit is still the water pump shaft seal. As i recollect, there are two. one faces one way to keep oil in the engine, and one faces the opposite direction to keep water in the pump. Don't just inspect them. Change them. Don't forget to inspect the shaft carefully. They can become pitted from corrosion.
Those pumps can be finicky and hard to reach, so be meticulous with your cleaning.

[KimSails]

I have an update for anyone that might interested...

First, I very much appreciate all of the comments and suggestions. It is very helpful and one of the reasons that this is a great forum/site.

Based upon the input here regarding the water pump seals, and what I could tell from looking at my seals (intact but clearly very old), I figured that the water pump really is the likely source of the water in my oil. I debated about whether or not to pull the cylinders off to have them checked (since the heads were already off) -- or -- just presume that the water pump is the culprit, replace those seals, and reassemble with a new head gasket.

In the end I pulled the cylinders and took them, and the heads, to a local diesel shop for inspections. They said that the cylinders are *not* the source of the water intrusion, but that one of the liners was cracked. They also said that a vacuum test of the valves indicated that they were not sealing well. I am having the shop machine the valves/seats, and hone the good liner. I am looking for a new liner to replace the cracked one.

From what I can see, the liners are sold as kits with a matching piston and rings. I assume then that buying a used liner and using the existing piston is not recommended? ASAP Supplies has the piston / liner kits for about $400 each, but they are backordered. Marine parts Europe has them for about twice that. I have asked ASAP for a backlog time estimate. If it is reasonable then I will wait for that.

Thanks,
Kim

[model 10]

A liner should be available from your local machine shop guy. Same with the rings. The piston could be cleaned up, maybe even knurled or whatever.

[Symphony]

Originally Posted by KimSails

In the end I pulled the cylinders and took them, and the heads, to a local diesel shop for inspections. They said that the cylinders are *not* the source of the water intrusion, but that one of the liners was cracked. They also said that a vacuum test of the valves indicated that they were not sealing well. I am having the shop machine the valves/seats, and hone the good liner. I am looking for a new liner to replace the cracked one.

Kim

wow, Kim.
this is the condition of your reman'd engine after how many hours? did it ever run correctly?

[KimSails]

Guy – Thanks. I will ask the shop about that.

Symphony – The engine is original – about 37 years old. I have only owned the boat for four years. In that time my only complaints are:
-- Takes a lot of cranking to start when fully cold. But it always started, and it started easily if at all warm.
-- Some white smoke under load

This spring was the first I saw of water in the oil. And my first trip out this year I saw a *lot* of white smoke once the engine was fully warmed up. I presume that the cracked cylinder and the valve seating are likely the cause of the hard starting. And (hopefully) the water pump seals will take care of the water in the oil.

[mark maulden]

Marine Parts Express has the kit in stock for $701. The MD11 uses the same p/n as the MD17. Being that you are planning on a Beta in the near future, you might entertain a used liner with current piston. Maybe even keep the rings. Measure the gaps. I have several liners with ~2400 hrs on them. Pm or email me if interested. Email preferred. BTW, that engine will always be hard starting when cold. Your fixes will surely help that but still....just the nature of the beast...

[KimSails]

Thanks Mark, I will send you a PM. I don't see how to get an email address for you.

Regarding the Beta, if I can get the Volvo running reasonably well, and very reliably, for a fraction of a re-power investment, then I would put off the re-power as long as possible. If I *have* to re-power, then it will at least a year, likely two, before I can do that.

Given that, the question is how much of a difference is there between using the existing piston with a used liner from a different engine vs. a new matched liner/piston? I presume that there is something to the matching since they sell them as a pair, but perhaps not.

Thanks,
Kim

[Compass790]

Dont sweat too much about the matching, it's more about the tolerances. A used liner can be fine as long as it isnt worn over spec. You should check a workshop manual for the maximum bore diameter for your liner. The reco shop will be able to measure it for you as they will have a bore gauge or internal micrometer. Same goes for the piston, it needs to be a minimum diameter & preferably not too scored. I'm glad you updated us as it adds to the store of knowledge when trouble shooting. I'll probably forget it but you live & hope :-)