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Dreaded Milkshake

Old 04-30-2008, 10:04 PM
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Default Dreaded Milkshake

Hello everyone. This is my first post, but I have been visiting the site for quite a while and have found a lot of useful information within the forums.

I am having a problem with water in my oil. I develop a milkshake within approximately 30 minutes of being on the water. Inside of valve covers develop a thick white scum. This does not SEEM to happen when out of the water and attached to a hose. Although I have never really ran the motor for an appreciable amount of time (more than 10 minutes) out of the water while on the hose. I prefer to run the motor under a load. I have performed four oil changes with less than 2 hours on the new motor. One of which was performed after a 15 minute breakin. I don't know what psi the coolant system produces at when at higher rpm's and in the water.

My build-up consists of the following;
Boat: 1994 22'-3" Wellcraft Scarab
short block: 383 cu in. stroker motor, w/ 6" rods, steel crank
Heads: Dart Pro - Cast Iron
Valvetrain: hydraulic roller camshaft,lifters and roller rockers
Intake: Dart Cool Can - dual plane
Exhaust: Eddie Marine HP Thunder system
Carb: Holley 750 double pumper mechanical secondaries
C/R: Static - 11.1:1
redline: 7,000+ although I have not exceeded 5,000 yet due to an out drive pump that wont trim up due to high power or leaky rams. Still figuring that one out.

The cam has a significant amount of duration and overlap which might result in a small amount of reversion. I have actuall confirmed SMALL amounts of salt crystals within the manifiolds indicating same. There are also some water tracks, again minute, from the riser into the manifold. All plugs indicate the engine is running rich, black and sooty. The number 8 cylinder plug seemed a slight amount lighter than the others which may have been from steam cleaning due to reversion. The manifold on the #8 side actually showed less traces than the opposite side where all plugs were sooty. I simply don't understand how reversion can reult in a 1/2 a quart increase in oil within thirty minutes! If only five minutes of that time is spent idling, where reversion is most likey going to occur, and the other half is at 2,000rpm or above, how can a 1/2 of a quart of water get by the rings in such a short amount of time? This does not seem likely. Should I remove the internal exhaust flappers located between the end of the risers and the thru hull tips?

I have a 140 degree thermostat that results in a water temp of close to 200 prior to exiting the thermostat. I believe that location gives me a better indication of the engine temp than the temp sender being located in the distribution block where raw water mixes with the hot water from the engine. Could condensation be the issue? Is it possible in such a short amount of time? I have performed several oil changes in a short amount of time, all but the first due to a milkshake, it is not like the condensation has had much time to build up. What gives?

My next step would be to take an infrared thermometer to determine the oil temp at the oil pan. I have read that it needs to exceed the boiling point of water to remove condensation. Before I do this and take a risk at damaging the motor I want to exhaust all other possibilties of the cause.

Compression test confirms all cylinders are at 200 psi, with very minimal variation. I don't think there is a problem with a blown head gasket.

I have pressurized the coolant system by removing the risers and plugging off the jumper from the manifold and pressurized the coolant system through the raw water line servicing the distribution block. I pump up to 40psi and the pressure loss is about 10psi in 20 minutes. I suspect some of the air is being lost around the hoses at the clamped connections. I have removed the valve covers to insert a motor stethoscope down into the lifter valley at the front and rear on both sides to listen for a leak of air at the coolant crossover connections at the intake manifold. The sound is akin to putting your ear up to a conch shell and hearing the ocean. I don't care where you put the darn thing the same sound occurs everytime. With that being said, it does sound a little louder at the rear crossover. It just doesn't seem as loud as it should considering how sensitive the instrument is.

My initial suspicion lied within the intake manifold-cylinder head connection (especially since I milled the heads and decked the block for proper quench , yes I checked the alignment/clearance of both when installing). I perfomed one last check before tearing into the intake manifold. I reinstalled the valve covers and plugged off the breathers so that all pressure leaking through a coolant passage into the crankcase would be ejected from the dip stick tube. I didn't think that the possiblity of air leaking by the oil soaked oil control rings, and all piston rings would eliminate the possibility that air would also blow out the dipstick tube. I placed a small amount of soapy water at the end of the dipstick to confirm leaking air with the coolant passages pressurized at 40 psi, and nothing. I am also sure that residual oil in the pan or dip stick tube did not interfere with the passage of air through the tube. I then tried to blow through the dipstick tube while the coolant passages were still under pressure and I hear a whistling sound coming from the starboard exhaust manifold. The sound has to be coming from leakage by the rings. If there was a crack in the cylinder wall I am sure it would result in a dead miss, or an excessively clean spark plug. There are no indications of a cracked cylinder wall.

Through all of this testing I have come full circle and still have no idea where to start. There is not a single item that I can point out that eliminates the possibility of another. I am hoping you all can give me insight as to where to start without haphazardly tearing into my brand new motor. I like to make educated decisions.

Please help.

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Old 04-30-2008, 11:15 PM
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Pressure check your exhaust first and if it is good then pull your intake manifold and re-seal it good with the proper amount of silicone.
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Old 04-30-2008, 11:44 PM
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Check your oil heat exchanger.

Marine motors don't like large overlapping cams.
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Old 05-01-2008, 06:52 AM
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When I got my tasty extra large milkshake, it was from the headers leaking. When we pressure tested them they were leaking like niagara falls. Good luck and hopefully it will be easy to find for you.
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Old 05-01-2008, 10:20 AM
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The only oil heat exchanger I have is for the power steering fluid.

JC & Driven ,

I will go ahead and pressure test the risers as the manifolds already checked out with the initial pressure test.

I f only 5 minutes of time is spent idling and the rest is at higher RPM, what is the chance of a leaking riser contibuting to the water in oil? It would seem to me that at high enough rpm all of the momentum would be pointing out of the boat.

Even still, all of that water (1/2 quart) has to get by the rings in that short amount of time. Is my logic flawed?
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Old 05-01-2008, 12:28 PM
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when i got my $7000 milkshake it was due to a cracked blocked. looked good when ran on muffs. took it to the lake, not good.
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Old 05-01-2008, 07:15 PM
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I pressure checked the risers with a plumbers test ball and compressed air. The risers seem to be fine. I think I will move on to the intake manifold next.

BTW, I will scuttle the boat if it is a cracked block!
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Old 05-01-2008, 09:50 PM
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Are you sure you have the correct head gaskets? A well respected engine builder in our area made this mistake. Symptoms were the same as yours.
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Old 05-01-2008, 10:06 PM
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Originally Posted by GO4BROKE View Post
Are you sure you have the correct head gaskets? A well respected engine builder in our area made this mistake. Symptoms were the same as yours.
It has been over a year since I assembled the engine with a buddy of mine who owns an automotive machine shop. I don't recall exactly what gasket I used. I believe I ended up using a 400 head gasket due to the firing ring coming very close to hanging out in the combustion chamber, where the valves were unshrouded. I do remember it was a marine gasket ,and besides the diameter of the firing ring, it should be exactly the same as a typical 350.

I only remember the smaller details like the compressed thickness of the gasket at .039 and the pistons coming out of the hole .007 - .008! Man I hope I can get this worked out without completely tearing down the motor. In hindsight, I probably should have wrote everything down.
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Old 05-01-2008, 11:07 PM
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This may be really stupid but here goes.......I have heard stories where in some instances oil temp doesn't get hot enough to burn off any condensastion that may have developed from big temp flucuations between air temp (hot) and water temp (cold).
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