4.3 milky oil

[marada98]

Hi all,

So I recently acquired a boat from a close family friend since he no longer had time for it (health reasons). However, it has been sitting high and dry for approximately five years. The boat was always winterized, covered, and maintained properly. Even after sitting for so long, the motor( 1998 4.3L mercruiser) started up right away and it sounded and ran very smooth. I actually couldn't believe it. After that I probably ran the motor about several other times and not once overheating.

When it came to giving it an oil change, I checked the oil which was perfect and then ran it for about 10-15 minutes to get it to operation temp. Once i reached that temp, I shut down the motor, checked the oil once again, which was still perfect, and proceeded to drain the oil out from the dipstick. This is where I ran into in trouble. As soon as I began to suck up the oil from the bottom of the pan, it began looking like a milkshake. Heartbreaking!. Now I've flushed the engine with new oil, but still milky.

I am wondering if anyone has ever experienced this before? Thought it was strange that I never saw any milkiness each time I checked the dipstick before I ran it. I am obviously leaning towards head gasket repair, but also wanted to know if I would get this problem from my manifolds? I have the original 1998 manifolds on the motor (One-piece bat-wing style) that are certainly due for a change since the boat ran in saltwater for many years. I'd appreciate the help and answers. Thanks!

 

[kmarine]

I would not get so excited about a head gasket yet. You may have some moisture from long term storage. You may want to provide more information on how the boat was stored , was it winterized I RECOMEND REPEATING some oil changes first check for a cracked exhaust manifold. Were you running the engine on a hose or in a launching ramp. Were you attaching flush muffs or aseawater pump flush kit. If you had lots of milk I would be worried. I would to do a lot more investigating first.There are lots of people in this forum happy to assist you. we need more info thank you

 

[wrench 3]

The 4.3l Vortec engines also had a bit of a habit of cracking the water passage in the intake manifold.

 

[marada98]

I would not get so excited about a head gasket yet. You may have some moisture from long term storage. You may want to provide more information on how the boat was stored , was it winterized I RECOMEND REPEATING some oil changes first check for a cracked exhaust manifold. Were you running the engine on a hose or in a launching ramp. Were you attaching flush muffs or aseawater pump flush kit. If you had lots of milk I would be worried. I would to do a lot more investigating first.There are lots of people in this forum happy to assist you. we need more info thank you

The person I got it from is a gear head and former coast guard mechanic so he knows a lot about marine motors. He winterized with antifreeze, fogging oil and then would drain and blow out the hoses for any trapped water. He was very meticulous with the bait when he owned that's why I don't think it could have froze over the winter. He knew his stuff. I ran it on the hose with muffs on the outdrive. Not my favorite method but it was how I did it. As for the milky oil, it seemed like a lot to me. The more I drained out the milky it was. I plan on doing a few more oil changes and a pressure test to see if I can track down the problem. Thank you for all the responses!

 

[kmarine]

Don't forget to check the engine oil cooler, many people who use antifreeze sometimes forget to backflush the cooler with antifreze. just a suggestion. The dealership where I used to work did not allow us to use antifreeze.I have stored hundreds of boats dry over my 25 years of winterizing.

 

[tpenfield]

Agree with the others . . . it may take a bit of experimentation to find the source of the water that is getting into the oil. Also, if you are judging the quality of the oil via what shows on the dip stick, it is often too thin a film of oil to show the consistency.

Some possibilities are . . .

- Manifold gasket leaking, causing water to get into the exhaust side of the manifold and into the cylinders during idling (aka reversion) and while the engine is off.

- Internal crack in the manifold due to insufficient winterization, causing similar issue to the gasket issue.

- Crack-in-the-block (or heads) due to insufficient winterization.

- Head gasket failure (you can test for that with a test kit)

- Oil cooler failure allowing water and oil to mix

The high probability causes are the first few that I listed.

It is best to try to isolate the problem before you pick up the wrenches, as once you open up the engine, things may not be so obvious and you may be into some guesswork.

 

[flipbro]

Take manifolds off and cheak them using the acetone test. If you find nothing there pressure test the block.

 

[mikeincolo]

Adding to existing thread with same topic/issues...

Preface: I have winterized 25+ boats, never a problem. I pulled my 2008 Sea Ray 185 Sport with 4.3L V6 MerCruiser our of storage (Colorado), inspected, hooked up hose, started right up, ran to temp, all good with oil pressure, temp, sounded great. Then performed lake test. Let it warm up, then ran at 3000rpm for about a mile or 2... milkshake coming out of breather, starboard valve cover.

Shut it down, got it home, did compression test: all spark plugs looked good and not wet, compression was 130psi except cylinder #4 was 100psi. Drained oil, let it drain for a couple of days, and got about 3 gallons of milkshake out. Note: thick milkshake drained very slowly, tried manual vacuum pump with qt least 500 pumps - and it was just too thick to get pulled up and out

Removed exhaust manifolds, looked good, removed valve covers, lotsa milkshake but looked good otherwise, removed intake manifold, gaskets looked fine and... it was cracked on the underside, starboard side. I figured I was this deep so I might as well pull the heads to have them magnafluxed and reman'd (but not planed). Cylinder head on starboard side had a leaky valve which explains the lower compression on cylinder #4.

Waiting on new intake manifold, will reassemble and post again.
Contemplating how I will clean out the milkshake from motor. Spec is 20w-40 NMMA FC-W rated oils, synthetic preferred. But to rebuild, add oil, run at temp for 20-30 mins and then drain/add, maybe I could use non-synthetic with Marvelous Mystery Oil for the cleaning / relubricating process.

Big takeaway - when winterizing remove plug from intake manifold to drain water, in addition to all the blue plugs, etc.

Question: Does anyone have experience and advice for the first run of the motor after reassembling - with the objective of cleaning up the milkshake WITHOUT seizing/breaking anything. That said, any other sage advice?

Thanks in advance, Mike

 

[Bondo]

Feb 5, 2017

Ayuh,..... Welcome Aboard Mike,...... Start a thread of yer own,....

'n Please read our forum postin' rules,......

Thank you,.....