1996 120xr. Sport Jet. leaking water from #4 (fixed)

[4shore]

My sj 120xr has done the same thing as another members post but mine is slightly different.

I first noticed a damp plug on the lower cylinder #4 as I was timing the motor. (I had it in the lake 4 days prior.) It had a slow to start on the lake but then bumped motor 2-3x it and she was ready for the lake. I did not know what to think of it. It seemed at the time minor but unknown. I finished timing the engine (per manual) and I wanted to run it to hear how it sounded.

So I hooked it up to a hose connected to the black hose near pump base. Let the water run slowly through the system for 5min. Water was coming out of the lower pump area as normal. I went to crank it and I noticed a slow to crank issue. I bumped over several times and then it would crank. The longer it ran the smoother it became without any engine shake. After a moment or so the over heat alarm came on and I shut it down. I thought that was strange as I did not run it but for 60-90 seconds before alarm and I have not heard this noise before. (I had to look up the sound).

An hour later I decided to let the water flow though the engine for a flush as I thought there maybe a clog. ( Did not know that top was for cooling bottom port is to flush the pick up) I came back to check for water in #4 and water poured out. I then checked all plugs and it was only #4. I then purged the water out by cranking with no plug then squirted a table spoon of 2 stroke oil into the chamber to help against the water.
I know that I had some water at the lake and the hose was for sure. It may have been like that the entire time but this time I checked it with out clearing the cylinder. Any advice??

 

[4shore]

Re: 1996 120xr. Sport Jet. leaking water from #4 (need diagnosis please)

Re: 1996 120xr. Sport Jet. leaking water from #4 (need diagnosis please)

Exhaust gasket...

 

[downeastrob]

Re: 1996 120xr. Sport Jet. leaking water from #4 (need diagnosis please)

Re: 1996 120xr. Sport Jet. leaking water from #4 (need diagnosis please)

Was it obvious on the gasket once you removed it?

 

[4shore]

Re: 1996 120xr. Sport Jet. leaking water from #4 (need diagnosis please)

Re: 1996 120xr. Sport Jet. leaking water from #4 (need diagnosis please)

Was it obvious on the gasket once you removed it?

I thought long and hard about it once I pulled it off. I noticed there was a burnt rusty discoloration near the exit port of the manifold. I figured that the only reason why it would be discolored was from water seeping past the gasket. The overall condition was good but old and becoming brittle with no other signs of distress. (Free the old gasket with a thin putty knife from the block/manifold) Keep the old gasket unscathed to examine any week links. The new Gasket was slightly tacky and when compressed to the walls of the manifold and block it will stick and not release once compressed. No on and off once installed. So don't bust a thread on the block once installed ( you will need an additional gasket if you bust a thread). Use anti seize on the bolts and make sure you clean the block/manifold with carb cleaner and steel wool or like product then blow out the bolt holes before attachment. I also used Xylene (home depot) to help clean areas. Very aggressive solvent with no sticky residue. Not necessary though if you have enough carb cleaner...

 

[MWMike]

Re: 1996 120xr. Sport Jet. Cant See if leaking water from #4

Re: 1996 120xr. Sport Jet. Cant See if leaking water from #4

I have a 1995 sport jet and it was not starting this year at all. so after replacing number 1 and number 4 pistons and then replacing a stator due to weak spark. it runs out of water and not in. when i back it in to the river it will start and run for 20 maybe 30 seconds and then die . when i pull it out and let it all drain for a bit it will start right up. I pulled the spark plugs and did not find any water. we did pull the exhaust manifold and found oily sludge in the bottom of the exhaust ports . so we cleaned this all up . cleaned the surfaces well and installed a new gasket. tried the same tests again and same results. the boat still dies in the water after 30 seconds or so. still cant see water in the spark plug. any other ideas or do i still have some kind of exhaust leak and just have not sealed it yet. and would the exhaust leak cause the number 1 and 4 pistons to go bad.. as broken rings and small parts of piston breaking off ?

 

[4shore]

Re: 1996 120xr. Sport Jet. Cant See if leaking water from #4

Re: 1996 120xr. Sport Jet. Cant See if leaking water from #4

I have a 1995 sport jet and it was not starting this year at all. so after replacing number 1 and number 4 pistons and then replacing a stator due to weak spark. it runs out of water and not in. when i back it in to the river it will start and run for 20 maybe 30 seconds and then die . when i pull it out and let it all drain for a bit it will start right up. I pulled the spark plugs and did not find any water. we did pull the exhaust manifold and found oily sludge in the bottom of the exhaust ports . so we cleaned this all up . cleaned the surfaces well and installed a new gasket. tried the same tests again and same results. the boat still dies in the water after 30 seconds or so. still cant see water in the spark plug. any other ideas or do i still have some kind of exhaust leak and just have not sealed it yet. and would the exhaust leak cause the number 1 and 4 pistons to go bad.. as broken rings and small parts of piston breaking off ?

If you had a water issue last season and put it up for the winter with water in the cylinder....
Could be from:
Engine sits and rings rust to cylinder walls.
Overheated and rings gall on wall.

Any type of mystery sludge. (Cappuccino color) is water induced..

If you had to re-build #1.... That sounds more power head gasket or block. (but could also be
Check compression. If bottom cylinder reads higher than normal... water could be in it....

Unfortunately # 4 cylinder can be a victim of any of the top 3 cylinder as the water goes to the bottom of the block and enters through the exhaust ports.

cold engine only.

bump # 4 piston to the down stroke position... remove #4 plug.... hook water up to exhaust manifold (slow flow) (keep water flowing while checking) watch for water... No water then check all plugs for water... bump motor as you check other plugs. Still no water.

Check fuel screen filter then replace with 3-4' of 3/8 hose and fuel lines from pick up tub in tank. Tank tubes clog easily. Remove shut off valve permanently (too small for force spec) . add primer valve to system (glass fuel filter ok too). (no fuel water separator!) Clean out oil t fitting with carb spray cleaner... If dirty. Then check carbs for blockage. Start with lower bowl then locate pilot jet. Run paper clip wire into jet . No easy pass threw... Carb flooding motor.