[jb57]

Have a 1993 4.3 LX. Removed and replaced head gaskets, exaust manufold gaskets, intake mainifold gaskets, had the heads and intake manifold magnifluxed for cracks. reassembled and still getting water in the oil. Other than an internal crack with the engine block, what else could it be and is cast iron weldable?

[300sflyer]

Did you have the exhaust manifolds checked for cracks? Chances are very good they are cracked internally if the entire engine was not winterized properly.

If they were checked, then your block is cracked internally and must be replaced.

[jb57]

Would a cracked exhaust manifold put water in my cylinders too?

[jb57]

The left exhaust manifold has a slight fracture on the outside and bleeds water over a period of time.

[300sflyer]

Yes... Every time the engine is turned off, water will flow into any open exhaust valve, and into the cylinder. If it is cracked on the outside, 100% it is cracked inside as well.

Install new manifolds and risers, and you should be ok.

[jb57]

I have no water contamination in the cylinders they are all dry. I did have a frost plug leaking on the left side of the block a couple of years ago. The Water in the oil started some time after that. The engine runs smooth that tells me there is no water getting to the cylinders. Is there an easy way to pressure check the intake manifold?

Thanks

[300sflyer]

With cracked manifolds, the engine will run just like normal. The escaping hot exhaust blows out any water that may be present. It's only after the engine is shut down, does the water flow into the cylinders through the exhaust valves. Once there, it will seep by the rings and drain into the oil pan.

To check for internal cracks, you need to pressurize the cooling system with air, just like on a car radiator. Not easy to do on a marine engine, but it can be done. Drain the entire cooling system of any water, then plug/ clamp off every hose, including the ones going to the exhaust manifolds. Pump it up to 15 PSI and see if it holds.

[jb57]

Thanks for the info 300sflyer. The last time I changed my oil I ran the boat on the lake for about 20 minutes. I opened the oil filler cap and found the oil was extremely milky white. The engine ran fine could this still be an exhaust manifold?

Thanks

[300sflyer]

Before you spend any money on new manifolds and risers, test the block with air. If you think it is holding, then change out both manifolds and both risers, and do an oil change. Let it run with your garden hose and muffs for 15 to 20 minutes, at full operating temperature. [Just at idle] Stop the engine, and check the oil for color and to see if it is any higher on the dipstick.

If all looks good, then head out on the lake and run the boat at crusing speed for15 minutes or so, and check the oil again. Don't stray too far from the launch ramp though... Sometimes internal block cracks do not leak, until the engine is fully heated up, and run under load.

Good luck!

[300sflyer]

Originally Posted by jb57

Thanks for the info 300sflyer. The last time I changed my oil I ran the boat on the lake for about 20 minutes. I opened the oil filler cap and found the oil was extremely milky white. The engine ran fine could this still be an exhaust manifold?

Thanks

If I understand you, you changed the oil, then headed out to lake without running it on the muffs? Did you stop the engine at all during those 20 minutes? How much higher was the oil level after the 20 minute run?