Milky Engine Oil After Replacing Cylinder Head

Hi boaters,

I have a 1973 Tom Sawyer 180-v powered by a 1973 Chevrolet C-10 4.1 liter inline 6 engine. Bought the boat cheap with milky engine oil present. Boat would turn over when purchased. I took the engine apart and had to replace the cylinder head due to several cracks. New gasket for cylinder head and exhaust manifold, thread sealant on bolts and everything torqued to specs in correct pattern. The exhaust manifold was pressure tested to about 15 psi and held for 15 minutes before I called it good.

The engine has been running fine, but the white oil hasn't gone anywhere. I initially flushed the engine with diesel. Once I had everything back together I ran the engine on the river 4 separate times replacing the engine oil every time and the oil filter twice.

I did notice a crack in the block but checked the cylinder walls as carefully as possible to determine it was only on the outside. I used JB weld and it seems to be holding.

The white engine oil seems to only be getting slightly better, hard to tell. Any ideas?

Thank you

 

assuming the reassembly was done properly I would guess rings or water jacket

 

milky oil usually is sign of water in the oil, there are only a few places where that can happen, mostly the head gasket. Otherwise likely a crack or porosity between the water jacket and the oil sump. Usually any crack is a reason to reject the block, but in low stress area it should run for a while without issues (temp cycling usually will elongate the crack).

You might try putting some radiator sealant (stop-leak), it is inexpensive and will not harm the engine. Most car manufacturers install some sort of stop leak in the new cars with the antifreeze. There is no reason to fear the stop-leak will cause any issues, it will not plug the radiator, heater or water jacket; there are no passage ways small enough to be affected by it.

There are several types, the inexpensive ones that are temporary but work (usually about $3-4) and the permanent type that requires flushing, and overnight curing of the sealant, it usually costs about $10. I have used this type with good results to seal a head gasket.

Good luck.

 

I tested the compression across three cylinder heads and they read 150. I was assuming that meant the rings were okay. Would I be incorrect in assuming this?

What specifically do you mean by the water jacket? Where do you think that crack would be? This is my first boat, I'm 21.

What do you mean by the oil sump?

 

that checks the compression rings , but not the oil wiper ring

on second thought rings would be least likely to let water into the oil

 

I don't think water would be in the oil pan, or oil sump because of a bad gasket, their is not much, if any water in that area. I don't know how it could make a difference? It doesn't seem to drip oil at all.

Is the oil wiper a connection at the bottom of the piston that is in contact with the water jacket? I guess that would mean new block.

 

You really need a good mechanic to get to the bottom of your problem.

You did say you got a great price on this, right? I think it's now time to pay the rest of the bill...

Or, you could sell it as is and cut your losses.

-Tom

 

Bad oil rings would lead to the engine burning oil and a smoky exhaust, not related to water problems.

In most engines there are only 2 ways for water to get in the in the oil
1. a crack in the water jacket
2. the head gasket not seating properly.
Did you check the top of the cylinder block and the cylinder head with a straight edge?

 

The cylinder head was brand new so I didn't check for flatness. I didn't check for flatness of the block either. So that is a step I could go back to. It's feeling more and more like it needs a new block. I drained the oil and flushed the engine with diesel. I cranked the engine over a few times by hand and drained the diesel then flushed with some oil. I let it drain all night. I plan to put fresh oil and filter in and run the boat today. Anything I can look for? Recommendations?

 

Cracked block or improper head installation . Pull the head and replace the head gasket making sure that the torque sequence is correct. Are you are sure that the head installation was correct , pressure test the engine cooling system .
Could there have been water in the engine in the beginning ? Did you drop the oil pan and clean it ?

 

I replaced the cylinder head and gasket after finding out it was cracked and testing the pressure of the cooling system. It seemed okay.One test I did was filling the water jacket of the engine block up with water and observing the level the next day. It was the same.

As I said earlier the head was installed with a new gasket and torqued to specs in the correct sequence.

I did not clean the oil pan. Yes, the oil was milky when purchased.

 

Sounds like a faulty installation of the new head. Leak in gasket? Something between head and gasket?

The fact that the oil gets less milky, points towards the gasket. That may set and seal better and better.
But I would check it.

 

filling the water jacket and letting sit overnight will not tell you if you have a leak that only shows up under pressure. Typically the cooling system runs at 4 to 14 psi (depending on the design of the system), it may only leak under pressure. The compression test would not necessary show up a bad gasket (or a crack) either, I had a leaking head gasket in an old toyota that compression tested out fine, but it was using water that was leaking out the exhaust as steam, and making the oil milky. I drove it for a long time by just topping up the coolant every time I got gasoline.

The stop leak is your cheapest and fastest way to see if you can stop the seepage of coolant into your oil. Try it, if it works than you are good. If you have a more serious problem that stop-leak will not fix, than you have to pull the head and possibly replace the block, depending on where the leak is located (cracked block or leaky head gasket).

If you pull the head take a large polished granite tile with 400 grit wet and dry sand paper, glue it to the tile and use it as a sanding block. Sand the top of the block off until you get an even texture on the surface. That will tell you if it is smooth, you want an even matt finish on it (this is cheaper than pulling the block and having a machine shop resurface it, and it does a better job). Clean the block and head gasket surface good, use no sealant on the new head gasket. Clean all the bolts and the bolt holes good and use thread lube on the head bolts (light grease works, but an auto parts store can sell you thread lube). Than when you torque the head bolts in sequence you will get even compression of the head gasket. Most older engine designs also require you to retorque the head bolts after about 5-10 hours running time. During this run time you must not ever run it at full throttle.

Good luck.

 

Did every step you explained, but the last two. I may try to re-install.

Engine oil stop leak is being suggested. Any risk?

 

The Chevy is almost twice your age and was designed around 1940.
Do not spend much time and money on it, just use it until it falls apart.

Just a few drops of water will already result in milky oil. If the thermostat doesn't close or the previous owner threw it out, low engine temperature and high air humidity may already cause condensation in a perfectly sealed engine. Yours is bound to have hair cracks between cylinders 3 and 4: it was never designed to live 37 years!