Mercruiser 4 cyl water leaking from exhaust manifold

[LIbottomsup]

My boat will crank fine but will not start. I notice some water leaking from what is seem to be behind the exhaust manifold. It will kind of trickle and will leak more when I crank the engine. I check the oil and it is not milky. Could this be a bad gasket? I appreciate any information. Thanks!!!

 

[Don S]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

Since you probably can't see under there, get your digital camera and take a picture up under where the leak is. You would be surpised what you can see that way. Light the area with a trouble light so things how up.
Post the pictures here.

 

[LIbottomsup]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

Since you probably can't see under there, get your digital camera and take a picture up under where the leak is. You would be surpised what you can see that way. Light the area with a trouble light so things how up.
Post the pictures here.

I tried to get some pics but nothing really came out. I can't really see where the water is coming from but it is in the middle of the manifold and runs down the block. I have read some older posts but they said that the engine would run. Not sure if mine is the same issue.

 

[Don S]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

Pull the manifold and look. Those engine are noted for cracks about a half inch below the head gasket. Head gaskets never leak like that.

 

[Bondo]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

I tried to get some pics but nothing really came out. I can't really see where the water is coming from but it is in the middle of the manifold and runs down the block. I have read some older posts but they said that the engine would run. Not sure if mine is the same issue.

Ayuh,.... Welcome Aboard,.... Sorry to hear that,.....

Sounds Frozen, 'n cracked from poor or non-existent winterization...

 

[LIbottomsup]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

Guess I will get into that tomorrow. Any pointers to look out for? What is the best way to fix the crack?

 

[achris]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

... What is the best way to fix the crack?

Unfortunately that's a replacement block.... Anything else is just a bodge up and will not last...

 

[ENSIGN]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

Sounds like you neglected to winterize it!Probably time to bite the bullet and go engine shopping.

 

[Jmunk]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

If the block is cracked externally it maybe possible to fix it with JB weld, depending on it's location. If it's cracked internally then you need a new block. Have to run it and see if it makes a milkshake.

 

[havoc_squad]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

That's what happened with me, the previous boat I had owned slowly dripped water onto the engine block from the manifold seal area.

They pulled the manifold off and found a nice long rusted up crack in the engine block, leaking water. This wasn't found until 3 years after I had initially bought the boat, and yes I inspected it previously for leaks and it didn't leak, or it did it slow enough for it to miss noticing.

From the corrosion rate of how badly it would chip, I say it probably was that way the entire time I owned it and before that. I believe if I paid attention to the rust marks on the freeze plugs, I would have caught this.

That's the first thing I looked for on the current boat that I own, no signs of freeze plugs being pushed out, replaced/tampered with or painted over, and no leaks.

Start shopping for an engine block replacement, that's the only solution to this type of damage. It's just about as damaging as throwing a piston rod in the engine.

 

[1979 Quartermasters]

Re: Mercruiser 4 cyl water leaking from exhaust manifold

I don't know if thats totally true

I had a crack on my 1979 140 horse Merc in the typical place, just under the head. I ground out the crack, cleaned really well the applied 3 layers of JB weld, each one wider than the last. Don't let it totally cure between coats.

It held for three years. I don't know how the next owner delt with it. He said he would call and I would help him fix it again. That was two years ago.

The previos owner drove the boat like that for years and didn't know it was even cracked. He said he just ran the billage pump every so often and thought that was normal. He told me this when I called him to tell him he sold me a boat with a cracked block and didn't tell me. He said he didn't know, sorry.

I didn't totally trust it and didn't go far from shore. It never did leak. There are quite a few people who have who done this repair with positve results. But there are no guarrenties.



Good luck.....

Ken