Sport Jet 120

ranman57

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1995 120 Hp Sport Jet

I'm getting water coming out of #4 cylinder, I am about to pull the engine and just wanted to know what your thoughts are.
I'm thinking its a blown exhaust gasket, or head gasket, anything else should I look for??

Thanks for any helpful advice.
 
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ranman57

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Since I wrote this post I haven't had much response, so I have pulled the exhaust manifold.
Here is a pic but I can't tell if the gasket is blown or not, it does look kind of bad on the left side anybody have any answer?
Before I put any more money into gasket just need to know if it could be any thing else?
Thanks for any input.
 

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GA_Boater

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SportJets are kind of rare here. Not too many owners in the forum.

Since the motor is an outboard motor, a worn lower crankshaft seal can allow water in the bottom cylinder. That's often accompanied with what we call steam cleaning and a clean spark plug - No carbon on the plug or piston. I can't tell by the picture.
 

ranman57

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Thanks for the input, I do have a clean spark plug and like I said water in #4 cylinder. So I'll look into the crankshaft seal, I know the boat is older but I have been running it for the last 4 or 5 years that way but want to try to get it running better,
Thanks again.
 

ranman57

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I pulled the motor and looked at the crankshaft seal but doesn't look like nothing wrong.
Besides those things is there anywhere else that anybody knows where water can get into the #4 cylinder?
 

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danhobal

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Hey Ranman, from what I found on youtube towards that is the exhaust manifold gasket (jetdrive) be replaced every 5 yrs, or yes water may be sucked into the cylinders because of the water jacket proximity to the exhaust ports.
But what I dont know for sure about it could probably fill a warehouse.
 

ranman57

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Hey Ranman, from what I found on youtube towards that is the exhaust manifold gasket (jetdrive) be replaced every 5 yrs, or yes water may be sucked into the cylinders because of the water jacket proximity to the exhaust ports.
But what I dont know for sure about it could probably fill a warehouse.
Hey thanks for the info, I just don't know anywhere else except for the exhaust that would bring water into the cylinder.
 

The Force power

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Hey thanks for the info, I just don't know anywhere else except for the exhaust that would bring water into the cylinder.
Inspect the gasket between the block and adapter-plate as these most likely the blow
For more engine info; post your question(s) in the force engine section as the blocks are identical
 

GA_Boater

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Hey thanks for the info, I just don't know anywhere else except for the exhaust that would bring water into the cylinder.
Don't start another thread. This one has been moved to the Force/Chrysler section.
 

Redbarron%%

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I had a 90 that is basically the same with one less cylinder.
My problem with water getting into the bottom cylinder was the wrong gasket installed when the motor was changed.
The correct gasket has a definite block from the old water entrance in the bottom front of the water log.
The cooling water for the sport jet comes in the hose in the back of the exhaust cover.
If the wrong gasket is installed water will leak under the block and into the bottom of the exhaust chamber, filling the lower cylinder with water.
What I did before I pulled the engine was to fill the 3/4" hole in the front corner in the front water jacket with JB weld. Water goes through this hole and into the space under the block and from there up into the exhaust.
The first gasket shown is the wrong one that is open from that 3/4" hole to the bottom of the exhaust.
The base plate does not have a passage for cooling water like the outboard.
The correct gasket has that hole completely surrounded and should stop that water flow, unless it has been damaged or has failed from age and heat.
As I said I filled that 3/4 hole with JB weld and put in the correct gasket.
Some people say that you have to start the engine before starting cooling water, but this only puts exhaust pressure on the manifold. I can start water and run a pretty high flow and have not had problems with water in the cylinder since changing the gasket and filling that hole.
 

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Redbarron%%

Chief Petty Officer
Joined
Dec 7, 2017
Messages
433
I had a 90 that is basically the same with one less cylinder.
My problem with water getting into the bottom cylinder was the wrong gasket installed when the motor was changed.
The correct gasket has a definite block from the old water entrance in the bottom front of the water log.
The cooling water for the sport jet comes in the hose in the back of the exhaust cover.
If the wrong gasket is installed water will leak under the block and into the bottom of the exhaust chamber, filling the lower cylinder with water.
What I did before I pulled the engine was to fill the 3/4" hole in the front corner in the front water jacket with JB weld. Water goes through this hole and into the space under the block and from there up into the exhaust.
The first gasket shown is the wrong one that is open from that 3/4" hole to the bottom of the exhaust.
The base plate does not have a passage for cooling water like the outboard.
The correct gasket has that hole completely surrounded and should stop that water flow, unless it has been damaged or has failed from age and heat.
As I said I filled that 3/4 hole with JB weld and put in the correct gasket.
Some people say that you have to start the engine before starting cooling water, but this only puts exhaust pressure on the manifold. I can start water and run a pretty high flow and have not had problems with water in the cylinder since changing the gasket and filling that hole.
Also the shallow pan seen on the adapter plate is where the water carries over to the exhaust. There is a filler block in the jet that sits there as well. In the outboards this is where the exhaust exits the engine any water here just runs down with the exhaust and causes no problems.
 
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