Back with another boat. Milky oil

[wnaplay]

I bought another boat and I did know it had issues. The PO stated although he didnt winterize it properly(only stabil the gas and fogged engine with it running or not I could not tell you), temps didnt go below the freezing point which makes me question what the real cause is. Dont get me wrong I am not necessarily taking him at his word on the freezing part. The boat is a 1984 sea ray. The boat has always been maintained and winterized professionaly until last winter. The PO opens the boat up this year(starts right up) and after running for 15 mins on the water ears he notices water is spraying from a crack on the top of one of the exhaust manifolds. Knowing nothing about boats and with his family no longer interested he just decides to sell. I pick it up and immediately notice the oil is very milky(chocolate milk as described). I buy it assuming it may be a cracked block. I have yet to start it myself or hear it run and see this cracked manifold myself. I do want to try and diagnose the cause before just diving into a new motor.

I read that the best way to initially check for a cracked block is to pressurize the block with 15psi however I could not find a write up on the proper technique or the tools needed to do so. I read that you need to disconnect some hoses and block them off but unsure the proper technique for blocking, which hoses and how to go about pressurizing and accurately maintaining 15psi. Can anyone shed some light on how I should tackle this or if in fact this is not where I should start?

Thanks so much.

I do have access to a used set of exhaust manifolds I was going to attempt at using before I read about the block pressurizing. Sorry I do not fully comprehend the way a boat cools and how it differs from a car.

 

[Don S]

Re: Back with another boat. Milky oil

I read that the best way to initially check for a cracked block is to pressurize the block with 15psi however I could not find a write up on the proper technique or the tools needed to do so. I read that you need to disconnect some hoses and block them off but unsure the proper technique for blocking, which hoses and how to go about pressurizing and accurately maintaining 15psi. Can anyone shed some light on how I should tackle this or if in fact this is not where I should start?

There is no specific procedure, or writeup on it, and it all depends on what engine you have, and what cooling system you have and type of exhaust.

You just block off all the hoses going to the exhaust and pressurize the engine with a hand air pump of some kind.
You also have to drain the cooling system. You may be able to hear the leak.
If the engine has been run and the oil is milky and the oil level went way up, then you know it's cracked and not worth the effort to pressure test.

 

[wnaplay]

Re: Back with another boat. Milky oil

Thanks Don. The oil level is way up. I know it has been started this year on land and I am in agreeance that the block is more than likely cracked. I would still like to try and see where the crack is and will attempt to pressurize it so the next time I know how. You say to drain the cooling system, is this a matter of just disconnecting a hose or a valve of some sort? I assume I can stuff some cloth and tape off the ends of the hoses going to the exhaust. I am still curious at what access point do you pressurize the block? Sorry, I am a little better at car motors. The motor is a mercruiser 288 5.0 305 I believe.

 

[Don S]

Re: Back with another boat. Milky oil

You won't be able to see the leak with a pressure test, only determine the cooling system is leaking into the oil. Since it's filled up with water, you know it's cracked. Just pull the intake off and look. It will be either the intake cracked under the water passage, or you will find cracks on the block behind the push rods.

 

[Don S]

Re: Back with another boat. Milky oil

I am still curious at what access point do you pressurize the block?

Doesn't really matter where, be creative.

Had you blown the core plugs out and wanted to find out if the block had cracks before you pulled the engine to replace the core plugs, then you could put some expansion plugs in where the core plugs were and then pressure test it to see if it was cracked internally or not. But since it's been run, the oil is milky, and the level is way over. It's obvious you have internal leaks.

 

[wnaplay]

Re: Back with another boat. Milky oil

I wasnt sure if there was any other way water could have mixed with the oil other than a cracked block. I read possible causes of this could be a cracked block, head gasket or exhaust manifold and since I knew I already had issue with the manifold being cracked I was hoping that would be the whole cause. I will take your word that the block is in fact done. I guess my next question is would it be possible for me to take one of my old chevy 305 motors from old car projects, rebuild it, buy some new exhaust manifolds and bolt everything back onto it from the old motor? Are these interchangeable?

 

[wnaplay]

Re: Back with another boat. Milky oil

Don my apologies for the Pm. I did not notice your signature. You didnt happen to go by a different name on here a few years back did you?

 

[Don S]

Re: Back with another boat. Milky oil

head gasket or exhaust manifold

Those two items will get you a little bit of water in the oil, but not a lot.
If the exhaust was the problem, it wouldn't happen with the engine running because the exhaust would blow the water out. With the engine off, the water has to leak past the piston rings. Usually you end up with a hydrolock first.
Head gasket is what every auto mechanic thinks, but it just NEVER happens on a marine engine with a raw water cooling system.
When the level is way over full, it's usually the block. Seldom is it even the intake.
Pulling the intake and looking is the easiest thing to do.

 

[wnaplay]

Re: Back with another boat. Milky oil

Will I visibly be able to see cracks you think, if I pull the intake? I guess at this point I need to see what my least expensive repair will be. Its difficult to find good marine blocks used where I live so its either try my luck with an automotive block or find a more readily available smaller motor and swap. Again I dont know if its just that easy and any boat motor will bolt up to bothe the mounts and outdrive I have, probably not.

 

[Don S]

Re: Back with another boat. Milky oil

The cracks will be really obvious.

Get a 5.7 truck long block, put brass core plugs in it, and all the marine accessories and go boating.

 

[wnaplay]

Re: Back with another boat. Milky oil

That sounds awesome don. Does it have to be a 5.7 for any reason? I assume they make a 5.0 truck motor, would that work? I dont care about going fast I am more concerned with the boat moving and not costing me a small fortune in full to run out and anchor just to swim. I was able to find a 302 motor which I assume is fords 5.0l, would my parts bolt to that including outdrive and motor mounts? If not what should I do while I have the engine out? Anything easier to replace with the engine out of the way?

 

[Don S]

Re: Back with another boat. Milky oil

Doesn't have to be a 5.7, but all the accessories are identical, including the drive ratio, and the 5.7's are usually a lot easier to find than a 5.0.
Just an easy bolt on 40 hp.

 

[wnaplay]

Re: Back with another boat. Milky oil

Any particular years? I assume 4 bolt main or does that even matter? What about a 1 or 2 piece rear main?

So your telling me I can find any 5.0/5.7 motor no matter the manuf., any year and these parts will bolt up from the old motor. All I should have to do is replace the freeze plugs with brass. And it will bolt to my boat? Is there anything to be cautious with when it comes to using a car motor or is a motor a motor? Soory if I am being anal, I just want to make sure I am getting my facts straight.

 

[Don S]

Re: Back with another boat. Milky oil

Marine engines don't use 4 bolt mains. Just get one of the same vintage, two piece rear main seal. Then your oil pan and all will. Your basic 5.7L aka 350 Chevy engine.

 

[wnaplay]

Re: Back with another boat. Milky oil

So I have been on the hunt for a new motor today. Not necessarily finding anything I trust but I did get to talking with a guy who swore a car motor would never work, He further went on to say if I were to even try it better be a 4 bolt main motor from a truck. I dont know what to think now.

 

[Don S]

Re: Back with another boat. Milky oil

So I have been on the hunt for a new motor today. Not necessarily finding anything I trust but I did get to talking with a guy who swore a car motor would never work, He further went on to say if I were to even try it better be a 4 bolt main motor from a truck. I dont know what to think now.

Neither Mercruiser, Volvo, OMC (when they existed) ever used 4 bolt mains except for the 60's. Obviously your friend isn't up on what a marine engine is.
The basic long block uses the same parts as a truck, except for the core plugs (marine are brass to prevent corrosion) and a marine cam. A truck cam is close but not exactly the same so.

PS: I'm a marine tech for 25+ years that retired a little over a year ago. So I have been around them for a little while.

 

[wnaplay]

Re: Back with another boat. Milky oil

I assume since thats the case either one should get the job done? In trying to further my education whats the difference in using a 2 piece rear main vs a one piece? Also have you ever heard of this stuff, I ran into a guy who swears by it but I dont know how you would introduce it into an open cooling system. I know its wishful thinking on my part but it is guaranteed, lol.

K-Seal Car Leak Repair: Coolant, Head Gasket & Radiator Sealant

 

[Don S]

Re: Back with another boat. Milky oil

I know its wishful thinking on my part but it is guaranteed, lol.

K-Seal Car Leak Repair: Coolant, Head Gasket & Radiator Sealant

Let us know when you want to join the real world.

You don't have a radiator to dump that sh*t into, so it can slowly seal off a small leak that will be temporary at best on a car as it circulates through the system.
Not a snow balls chance in hell it could work in a raw water cooled marine engine with a freeze cracked block.

 

[wnaplay]

Re: Back with another boat. Milky oil

I assume since thats the case either one should get the job done? In trying to further my education whats the difference in using a 2 piece rear main vs a one piece?

They state on their website it works on marine. I sent an email to them this morning asking how it could possibly work in an open system. I am curious the answer they reply with. The "guarantee" its a permanent fix but even in a car I dont see how it could work, it would be huge in the boating world if it could.

 

[thumpar]

Re: Back with another boat. Milky oil

My buddy tried something like that crap in his jeep many years ago. It didn't work. Read Don S' entire sig. I would look for a 5.7 truck motor at a junk yard. Find one from a truck or van that has been wrecked. Usually if they are wrecked the motor was good at the time and only ended up at a junk yard because of the wreck. Change the core plugs and mount the externals. The reason for not using a car motor is the cam. A truck and boat cam are very close.