Milky oil

[bwrag]

I have milky oil. I have changed it five times still milky and volume increases on dip stick. How do I know whether it's the head gasket vs the block. The engine runs fine. I really need help. Also will it be worth fixing or just replace engine. 98 22i

[hoopykat]

Milky oil most likely is water leaking into oil system. Culprit is probably the head gasket. What engine do you have?

-Mike

[AdaminMN]

When did this start? This spring, or in the middle of the summer? Did the engine overheat ever?

A head gasket is the cheapest fix. Hope for that.

That being said, nothing is cheap when it comes to boats. Except for the air in the trailer tires.

[bwrag]

It's a 350 black scorpion. I noticed it last week. Also when the thermostat kicks on at 160 it drops it to120 in about 3seconds is that normal?

[hoopykat]

Thermostat issue sounds normal. Stays closed until temp reaches 160, then as it opens, cooler water is allowed in and temp drops. I'd be more concerned with the water getting into the oil system. I have a Black Scorpion engine too...will be watching mine carefully.

-Mike

[bwrag]

So is there anyway I can determine whether it's the head gasket vs the block beforei yet into the cost whether to scrap the engine or not

[TeamAllen]

I don't think your temp. should ever drop like that. I don't think it's normal?

Your temp should reach whatever your t-stat is set for (160?) and stay there. 120 would be way to low IMO. I'm no expert, by any means, but I thought EFI engines needed a certain temp for proper burn efficiency? Maybe some one else has more knowledge about the subject?

[hoopykat]

I believe you can have the engine pressure checked to see if it's the head gasket. Each cylinder is tested to see if there's a pressure drop as the piston compresses...a drop in pressure means a possible head gasket leak at or near the cylinder. Been a while since I had Auto 101
-Mike

[laserfish]

First thing I would do is a compression test on all cylinders. Should be within 10% of each other. Your blown head gasket should show up with one or two cylinders really low. Could also be a cracked head if frozen or overheated. Can also be an intake gasket leaking into the crank case. These are the two cheapest fixes, especially if you do them yourself. Cracked block, big bucks.

[bwrag]

Is changing the headgasket hard or is it pretty straight forward? If its the block I have a new GM 350 to put in its place.

[lohe]

do a cylinder leak down test as well

[laserfish]

Just like working on a car. Larger exhaust manifolds but they should move out of the way easily.

[chpthril]

Head gaskets can rot/rust out between the oil and water passages and not effect compression at all. Take a compression test and leak-down results with a grain of salt. If the test come back with good numbers, dont assume it's a cracked block.

The ideal test, and one that would yield more accurate results, would be a pressure test on the cooling system. Not as easy to do on a raw water cooled boat engine though.

[bwrag]

IS what happened common? If the head gasket is bad would the boat still be running good?

[chpthril]

IS what happened common? If the head gasket is bad would the boat still be running good?

For a 12 year old marine engine, I'd say this is not out of the ordenary.

And yes, a leaking headgasket may not result in loss of cylinder compression. The head gasket does many things: It allows the block and head to expand and cotract at differnt rates as they heat and cool at different rates. It sepperates the coolent passeges from the oil passeges and combustion chamber, it seals the oil passeges from the coolant passeges and combustion chamber, and prevent combustion from leaking over to the oil and coolant passeges. So yes, a head gasket can leak between the water passeges and oil passeges and not effect combustion. That's why I caution against putting too much stock in a compression and leak down test.

Good compression does not mean the head gasket is NOT leaking between the oil and water passeges and does NOT mean the block is cracked. If the test come back with acceptable resutls, further tests are needed.