3.0 LT Mercruiser exhaust manifold water leak

[brentjmorgan]

I have a water leak coming from between the block and the exhaust manifold. what would cause this and is it going to hurt it running? This motor is on a 1988 searay.The motor runs great doesnt over heating or anything. Also I ran it on a water hose for abot 30 min and I dont have water in the oil.

 

[chiefalen]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Welcome aboard ! Gasket went??

Did you try to tighten the bolts down?

 

[brentjmorgan]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Thank you Im not sure about the gasket. As for the bolts no I didnt try that. This is my first boat.

 

[chiefalen]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Try to tighten the bolts easy does it, hope thats what it is, if not got to replace the gasket, to do that the manifold got to come off with the riser in one piece hopefully.

Hope that the second thing is the problem cause the third problem could be a cracked manifold.

Or even worse the engine has a crack under there.

Did you try to see exactly where it was coming from with a mirror?

 

[brentjmorgan]

Re: 3.0 LT Mercruiser exhaust manifold water leak

No but I will get one out tomorrow and check. do you know where I can see a online service manual For replacing the gasket?

 

[chiefalen]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Go to the top of the forum " Adults only " And go to the manuals and d/l the one you need.

Thanks to Don s it's free.

 

[fishrdan]

Re: 3.0 LT Mercruiser exhaust manifold water leak

There's isn't any water passages between the head and manifold, so I doubt it's the manifold gasket. Maybe one of the small casting plugs in the head between the head and gasket, but I kind of doubt that one as it's sealed with the casting plug and then the gasket should seal it off too.

Where exactly is the water leaking? From the center of the manifold and dripping down the manifold, under the manifold and dripping down the block, end of the manifold, riser?

Did you winterize it last fall (drain block, etc,,) and was it cold enough to freeze in your area this winter? Seems that right behind the manifold is where 3.0's like to crack.

Have any pics?

 

[brentjmorgan]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Its leaking in the center of the manifold up underneth and running down the side of the block. I cant figure how to upload the pic of my motor.

 

[brentjmorgan]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Sorry I forgot to answer this. Im not sure about the winterize. I just bought the boat last weekend and I was told that had been.

 

[chiefalen]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Dan woke me up, my mind must be on vacation or something.

The manifold got to come off, maybe a water passage is cracked on the bottom a core plug is leaking.

Or it froze the motor and cracked behind the manifold.

Disregard the tightening of the bolts.

Thanks Dan too many wakes to go to tomorrow, no excuse i know, but 3 people went on yesterday, none really close to me but my wifes side.

Nice people was sudden.

I ain't posting any more tonight.

Again i'm sorry about the tightening of the bolts.

 

[Don S]

Re: 3.0 LT Mercruiser exhaust manifold water leak

http://forums.iboats.com/forumdisplay.php?f=32

Go to the above link and look at the first 3 stickies. If you can't post pictures after using them, you probably won't be able to fix your leak either.

 

[brentjmorgan]

Re: 3.0 LT Mercruiser exhaust manifold water leak

Thank you guys for all your help. I took the exhaust manifold off today and found that I had a cracked block. I went to a shop and they had me put marine tek on the crack. We let that set up and ran it so far so good.Once again thank you

 

[chiefalen]

Re: 3.0 LT Mercruiser exhaust manifold water leak

You do know thats not what your supposed to do. You need a new block.

 

[Bondo]

Re: 3.0 LT Mercruiser exhaust manifold water leak

I went to a shop and they had me put marine tek on the crack. We let that set up and ran it so far so good.Once again thank you

Ayuh,...

As I said at that Other forum,...

I've seen Marine-Tex'ed blocks provide years of service,....

Good Luck with your's......