4.3 LX Water in oil

jb57 · 03-28-2011, 04:33 AM

The last repair I did to the engine was replacing the head gaskets, intake gaskets, exhaust manifold and riser gaskets. I also replaced the thermostat too. I put the muffs on and ran the engine for about 45 minutes. I had the oil filler cap off to observe any water mixing with the oil. After 45 minutes of running the engine at 1500-1700 rpm the oil did not turn milky color. I then took it to the lake ran it for about 20 minutes at 4000rpms. I then stopped the boat and let it idle while I opened the oil filler cap. The oil in the valve cover was extremely milky white. Again the engine ran smooth.

Thanks again

***300sflyer*** · 03-28-2011, 11:51 AM

Was the oil level on the dipstick higher after running the engine on muffs or out on the lake? If so, when, and by how much? Sometimes it can take 2-3 oil changes to remove all of the water.

Given everything you have stated, I would say there is a very good chance your block is cracked. However untill you do a pressure test, there is no way to know for sure short of tearing the engine down completely, and having the block itself magnifluxed.

jb57 · 03-28-2011, 02:20 PM

Running the engine with the muffs on did not change the color of the oil. Running the engine on the lake at a high power setting for 20 minutes turned the oil a milky color and added about a quart or better of water to the oil pan. It appears I may have a crack in the water jacket not visible from the exterior.

***300sflyer*** · 03-28-2011, 02:30 PM

Agreed... Do the pressure test, or pull the engine and tear it down completely to comfirm.

If it was me, I would find a new short block, and transfer everything over from the old engine. DO NOT reuse the existing exhaust manifolds and risers.... Buy new ones.

jb57 · 03-28-2011, 04:23 PM

I'll post what I found with the engine when I get it apart. How difficult is removing the engine?

Thanks again for the additional info.

***300sflyer*** · 03-28-2011, 04:53 PM

It can be quite difficult, depending on the amount of space available to get at the engine itself. I would highly recommend you consult an OEM service manual for both your engine and drive.

mercruiser service manual - 4shared.com download free

You will need some kind of engine crane to lift it out once everything is disconnected. An automotive engine crane does not usually have the ability to lift it high enough to clear the back of the boat. Here is how I solved that problem, if you do not have access to a fork lift or some other means of lifting it.

jb57 · 03-31-2011, 02:01 AM

One last piece of information before I remove the engine. I have had the intake mainifold of three times since I started trouble shooting the water in my oil. As I stated before each time I ran the engine on the lake the oil as seen through the oil filler cap was almost foamy white. The two times I removed the intake manifold and the valve cover with the oil filler cap the oil in these areas were milk shake white. I took the other valve cover off ,it had only a trace of water not enough to be milky white. Can anyone explain. See attached link this is what my engine looked like.

YouTube - Mercruiser 4.3, Blown Head Gasket

***300sflyer*** · 03-31-2011, 02:49 AM

Can't say for sure, but I'm betting once it is taken apart, you will have your answer.

Pjonline80 · 09-23-2013, 12:17 AM

I have a 93 mercruiser 4.3 and i have same problem with water in my oil.
Was it a cracked block? Or something else please let me know.

Thanks PJ

***ColoradoDiablo*** · 09-23-2013, 12:35 AM

First ..... Welcome to MOC!

Second , it would probably be better to contact the poster via email or PM him.
This thread is over 2 yrs old.
You might want to start a new thread with all , and any info you can think of on "your" problem.
It could be cracked block , heads , exhaust manifolds , intake gaskets , exhaust flappers , the list goes on and on.

Once again welcome , and sorry to hear of your problem.

4.3 LX Water in oil

Mercury MerCruiser