Somethings cracked...

[ElCameeeno]

Ok, I have a 2000 4.3l Mercruiser. Took it too the lake this morning and all was well until about a half hour into the run I opened up the throttle. I noticed a loss of power and a knocking noise. So I shut it off, pulled the motor cover and observed steam coming out of the pcv hoses from both sides where they are vented up at the breather assembly.

So, I limp back, load up the boat and go home. Inspection reveals a white creamy slime in the oil fill cap and milky oil on the dipstick. Something cracked or a blown head gasket right? Given the symptoms that would be my deduction EXCEPT that it was coming through BOTH sides of the engine. The steam has to mean its introduced into the combustion chamber I would think. ...maybe I am trying to convince myself that the block isn't damaged. I think the knocking noise was the engine ingesting steam.

Thoughts?

 

[lowkee]

Re: Somethings cracked...

I'm a little new at the marine engine thing, but it sounds like your exhaust manifold or its gasket is down for the count. Although you didn't mention if this is the first run for the season or the 30th. First run in a winter area may also indicate cracked block, depending on how it was winterized (and if properly done).

 

[ElCameeeno]

Re: Somethings cracked...

I am a car guy, boats not so much... so this manifold gasket. Is it gasket that seals the manifold to the exhaust ports or some other gasket? How hard are those things to get off? They are massive.

A little background, I am in Central Texas, it does freeze here, but not too hard. This was the first outing for the season. Last time the boat was on the water it was spring '07.

Its a 2000 Crowline 180BR with a 4.3l Mercruiser Alpha One.

I can use all the advice I can get....

 

[lowkee]

Re: Somethings cracked...

The manifold gasket is what seals the manifold to the engine block. Although with a 4.3 you may have two, one on each side. I've never worked on a 4.3, only a 3.0L. Since it was your first run, things aren't looking good, and I'll let more experienced people take it from here. Either way your car engine background will come in handy, unfortunately

 

[ElCameeeno]

Re: Somethings cracked...

Can someone explain how these manifolds work as far as the water routing/sealing?

 

[carcraze]

Re: Somethings cracked...

Good day

You should go to the adult section and find the manual for your motor and outdrive. It should have in it the water routing. Milky oil is generally a bad sign. Could be cracked manifolds, riser, block, maybe head gasket. After engine cooling the wer generally passes through the exhaust manifolds and then out through the risers or some redition of that per your manifold. There is also info here to pressure test most of the system, manifolds with possibly installing riser block plates as well a pressure testing the block.

It does not take much of a freeze to damage a not winterized motor.

Good luck and keep us posted.

 

[bruceb58]

Re: Somethings cracked...

I think the knocking noise was the engine ingesting steam.

The knocking noise was the engine trying to run on milky oil.

What is the level of your oil? Was the engine properly winterized?

If the oil level has risen significantly, you have a cracked block. Its not going to be your manifolds in that case. Time to do a pressure test on your block's cooling passages.

 

[Bondo]

Re: Somethings cracked...

...maybe I am trying to convince myself that the block isn't damaged.

Ayuh,... Good Luck with That,.... From what you've stated, I think it Froze,+ Cracked...

 

[ElCameeeno]

Re: Somethings cracked...

The boat ran fine in the driveway with the water muffs on, I took it too the lake and it ran fine for an hour or so. It was when I put the throttle down that the problem occured.

I took it back home and ran it and it sounds fine, with the exception of the steam out the pcv lines, which to me means water is getting into the combustion chamber. Now that Bruceb58 mentions it the oil level may indeed look a little high, I need to check that.

If I take it to the dealer and ask them to pressure test it, I am sure it will point to a crack, but can they isolate the area of the crack?

I am newbie when it comes to boats.

Also, do I need to remove the manifolds to get at the sparkplugs, I can't see them at all under those behemoths.

TIA!

Jon

 

[John_S]

Re: Somethings cracked...

I took it back home and ran it and it sounds fine, with the exception of the steam out the pcv lines, which to me means water is getting into the combustion chamber.
Jon

If it was water in the combustion chambers, the steam would be going out the exhaust. Allot of blow by, is either rings/valve guides shot or if it is steam, water in the oil.

 

[ElCameeeno]

Re: Somethings cracked...

It was definatley steam coming out of the pcv. The inside of the breather assembly was saturated with water condensation from the pcv. I see what you mean about it should be going out the exhaust though. What would cause super hot steam under the valve covers and routing out the pcv? The motor probably doesn't have 50 hours runtime since new and it was never abused so I doubt if the cylinders/rings/guides are worm significantly.

worst case scenario..... how hard is it to swap a new 4.3 in one of these boats?

Again, I appreciate all the help from you guys.

 

[carcraze]

Re: Somethings cracked...

The block can and should be pressure tested by itself, is if fails that would indicate a block crack. Would have to tear it down to isolate, there are probably instructions here to pressure test yourself (info on just about everything here).

By what you are saying it sounds like a cracked block, you should drain the oil and check it but the steam is probably coming from water in the oil. Sounds like it is not cracked into the combustion area hence why it runs well, well until it runs on milky oil for too long.

The engine exchange is not too difficult relatively speaking.

 

[wire2]

Re: Somethings cracked...

....

Also, do I need to remove the manifolds to get at the sparkplugs, I can't see them at all under those behemoths.

TIA!

Jon

No, get a light and a small mirror, follow the ign wires, you will see the plugs.

 

[OldNBold51]

Re: Somethings cracked...

I am a car guy, boats not so much... so this manifold gasket. Is it gasket that seals the manifold to the exhaust ports or some other gasket? How hard are those things to get off? They are massive.

A little background, I am in Central Texas, it does freeze here, but not too hard. This was the first outing for the season. Last time the boat was on the water it was spring '07.

Its a 2000 Crowline 180BR with a 4.3l Mercruiser Alpha One.

I can use all the advice I can get....

I too am in Cntrl Tex. My 7.4L cracked the block in Jan when we had that weekend overnite temps of 10degF.

Read up on cracked blocks and how to test. Basically you pressurize the cooling system. If it holds pressure you're golden. If not, you're SOL.

 

[system-f]

Re: Somethings cracked...

I didn't see anywhere in the post where you said you had or had not winterized the block. Did you drain the water from block when you put the boat up? If not I would just go ahead and pull the engine to make inspection easier because according to my Austin sources you guys had more than enough cold to crack this block. If you did drain the water from the block as the manual specifies then please disregard.

If you are at all mechanically inclined pull a boat engine is easy.