Milky Oil Coming From Valve Vents (Pictures)

[brsox88]

I ran my 4.3l Mercruiser today for the first time in actual water (not the garden hose) and after 3-5 minutes of running milky oil started coming out of the valve/header vent hoses that connect to the flame arrestor/intake filter. When I got the boat a month ago I found the free plugs on both sides popped out. Should I automatically assume the block is cracked? Where should I go from here?

If it is cracked, where do people go to get new engines or blocks?

 

[Bt Doctur]

what does the oil look like on the dipstick and the core plugs not freeze out plugs are a bad sign

 

[Scott Danforth]

They are core plugs for removing core sand during the casting process. So if the were pushed out. Most likely the block, heads and manifolds arw cracked from improper winterizing.

Pressure test the block and heads, however plan on buying a new long block

 

[tpenfield]

It is a pretty good assumption that the block is cracked. You can pressure test it to be sure. From here, I would go to the new engine store with checkbook in hand. (sorry to say)

 

[achris]

Who winterized the engine? I'd be tapping them on the shoulder for a new one.

Chris.......

 

[brsox88]

The engine runs great though, so I am hoping its just the block that is cracked. Where can I buy a cheapish replacement and how can I determine what engine I need, the numbers on my intake have rubbed off.

 

[Scott Danforth]

The engine runs great though, so I am hoping its just the block that is cracked. Where can I buy a cheapish replacement and how can I determine what engine I need, the numbers on my intake have rubbed off.

you cant just replace the block, you would need to re-bore and hone to match pistons. would be cheaper to buy a brand new motor.

if the block is cracked, most likely the heads and exhaust manifolds are too.

you determine the engine you need by the casting numbers of the block and heads.

FWIW, most cracked blocks run just fine. they dont last as water mixes with oil and they eat themselves from lack of lubrication, however they run just fine for about 10 minutes

begs the question that Chris asked. who did your winterization?

 

[tpenfield]

My concern about running a cracked engine block is when it goes boom.

Best to buy a short block, if the heads are good, or a long block which you most likely will need.

I'm thinking $2-3k all said and done.

 

[brsox88]

I bought the boat from someone and didn't know they had not winterized it properly. Engine looked fine and ran fine on the hose when testing, oil also looked fine after the 5 minute test.

I was thinking maybe the engine below would work if I just used marine head gaskets and freeze plugs: http://www.ebay.com/itm/Reman-GM-Ch...m3a6e650a1c:m:mfQIoMIFabL2Cs5jcLOJ5HQ&vxp=mtr

Also, do I have to pull the engine to find the casting number to know if its a #090 or not?

 

[brsox88]

Can anyone tell me how I can tell if my exhaust manifolds are no good? I never saw any leaks from them, the Y pipe exhaust I am replacing though since I think that is cracked somewhere. as water was pouring in when I put the boat in the water.

 

[Bondo]

I was thinking maybe the engine below would work if I just used marine head gaskets and freeze plugs: http://www.ebay.com/itm/Reman-GM-Che...LOJ5HQ&vxp=mtr

Also, do I have to pull the engine to find the casting number to know if its a #090 or not?

Ayuh,..... The castin' number is on the top aft block flange, right behind the port head, probably buried under the wirin' harness,....

That link is for a rebuild Kit, not another motor,.... No block, no machine work done, just a box of parts,....

To inspect the manifolds, pull the risers off 'em, clean the gasket surfaces, 'n they oughta be 'bout 1/4" wide,....
The y-pipe you can pull, 'n inspect after the motor is out,....

 

[brsox88]

Ayuh,..... The castin' number is on the top aft block flange, right behind the port head, probably buried under the wirin' harness,....

That link is for a rebuild Kit, not another motor,.... No block, no machine work done, just a box of parts,....

To inspect the manifolds, pull the risers off 'em, clean the gasket surfaces, 'n they oughta be 'bout 1/4" wide,....
The y-pipe you can pull, 'n inspect after the motor is out,....

So manifolds usually crack at the matting surface where the gasket sits, otherwise I am confused why the thickness of the manifold is important? I never saw any water leaks so I assumed they were fine. The Y pipe however I think was leaking, there was water coming in from the back somewhere by the transom so I think it may be cracked. Engine is out already but we haven't had nice weather to check it all over.

 

[achris]

Thickness of the manifold/elbow mating surface is important in stopping that gasket leaking and allowing water into the cylinders.

The water leak at the back could also be the engine rear CORE PLUG (please stop calling them 'freeze plugs') has also been forced out.

As for a replacement engine, you have 4 options.
1) go to your local Mercruiser dealer, hand over a squillion dollars and get everything all new.
2) Get a new marine long block from a marine engine supplier.
3) Get a remanufactured marine long block from an engine supplier
4) (this is my preferred) Got to a car junkyard, get an engine from a car of similar age and, using the cam and a lot of other gear from your broken block, rebuild a very nice tidy engine.

Chris. ....

 

[brsox88]

I got the Y exhaust off today and all cleaned up, and there doesn't appear to be any cracks anywhere and looks in very good condition. Does anyone have an idea why the back side of the engine/transom would be leaking? I couldn't see where it was leaking from but it was a decent amount. There's no holes in the bellows, so I am lost as to where to check.

 

[Rick Stephens]

As stated, there are core plugs on rear of engine behind the flywheel. Most likely cause.

 

[muc]

If you want to be sure where the water is coming from.
Put the Y-pipe and drive back on. Back the boat down the ramp into the water with the trailer tie-downs still on (the weight of the trailer will simulate the missing engine) you will now be able to see where the water leak is ---- with no engine, you can get a good look.