Sport Jet 120 wont turn over with 4 plugs

[SportJet]

Bought this boat without hearing it run. I Hooked up my hose to the cooling hookup and according to the forum filled my bottom cylinder up with water. Once I cleared and cleaned the water out I brought it down to the lake and it started right up, I ran it a little above idle for about 5 minutes then shut it down. When I tried to start it again it would not turn over, similar to when the cylinder was filled with water. I brought it home and pulled the bottom cylinder plug again and just a little thick brown oily water came out but not a lot. If I leave the bottom spark plug out it turns over no problem, with it in it wont turn over. What is going on?

Thanks for any suggestions.

 

[kend301]

Re: Sport Jet 120 wont turn over with 4 plugs

his one is gonna be hard to do without being there but I would start by pulling all 4 plugs and let it sit for 2 days , then spray some WD40 in each plug hole leave the plugs out , rotate by hand a few times and then do a compression test , You may have internal engine damage.
Also on the bottom plug are there and marks on the plug end that looks like something may be hitting it /

 

[SportJet]

Re: Sport Jet 120 wont turn over with 4 plugs

Thanks for getting back to me. The plug looks fine, not being hit as far as I can tell, no marks, they are the flat top type plugs though. I am leaving town until next Tuesday so I will pull the plugs as you say and get a compression meter, then check it when I get back and post my findings.

(Suppose I should WD 40 the manifold bolts just to get a jump start)

Thanks again,

 

[SportJet]

Re: Sport Jet 120 wont turn over with 4 plugs

Sorry for the delay, I had to order a pressure guage. The readings are as follows from top to bottom

Cyl 1 = 178lbs
Cyl 2 = 190lbs
Cyl 3 = 170lbs
Cyl 4 = 300+ Off the scale.
l
Put a cloth in front of Cyl 4 again and very little water comes out. The plug totally is covered with wet brownish sludge as was the guage when I pulled it out.

Any help is appreciated.

 

[SportJet]

Re: Sport Jet 120 wont turn over with 4 plugs

Follow up, I found this post from 2006 http://forums.iboats.com/showthread.php?t=177177&highlight=SportJet+120+newbie

(cut and paste it in a new window)

The guy has pics and a very similar situation I have. So I pulled the head and shot a pic, below. I believe the cylinder had a large amount of sludge in it but not enough to push out of the spark plug whole, I would say 4 or 5 tablespoons came out.

I took off the exahust manifold and it was full of the gunk too. Pics are all attached. Maybe the same amount or more came out.

I think the culprit was the exahust manifold gasket, it was in really bad shape espicially around the center. I can see rust around some of the bolt holes and it looked like water may have been seeping in. I think once I put pressure on the intake the gasket failed once and for all.

The question is, . . . do I need to pull the intake and clean / oil anything or put it back together and fire it up?

 

[kend301]

Re: Sport Jet 120 wont turn over with 4 plugs

It does look like you found your problem , Here is what I would do next
1. check piston deck height at TDC for each cylinder to be sure you did not bend the #4 rod. Also check the head to be sure it is not warped.
2 . As far as you are into this I would pull the intake and take a look just to be safe .
3. Clean the engine as best as you can including making an adapter out of pvc pipes so you can attach a 1/2" plastic hose to a shop vac and clean inside the crankcase as best as you can .
4 . Clean her up , soak inside crankcase with WD40 , reassemble , Offer a beer to the boating Gods and start her up !

 

[SportJet]

Re: Sport Jet 120 wont turn over with 4 plugs

Thanks for reviewing my progress. Ill do as you say and let you know, maybe a few days.

 

[jerryjerry05]

Re: Sport Jet 120 wont turn over with 4 plugs

Fill out your profile.What part of the country can tell us other clues.Maybe frozen?? Cracked water passage etc.J

 

[kend301]

Re: Sport Jet 120 wont turn over with 4 plugs

Just took a better look at the pics you posted , Jerry may be right here in cyl 3 it looks like you could have a crack on the bottom of the bore about 1 inch down , Could you clean up all the muck and post some pics of the bores cleaned ?

 

[SportJet]

Re: Sport Jet 120 wont turn over with 4 plugs

Just a follow up. I put everything back together and backed it into the pond. It started up and idled very well. I finally got it out to the lake a week later and it started and ran just fine. After some mid range runs I throttled it full and got about 35 mph on the odometer with 2 peeps and a half a tank of gas. I think I will do a ring job next winter. What you saw in the 3rd cyclinder is some bad scoring. The final compression numbers had 3 about 30lbs off from the 2 and 4 which were at around 195. 1 was also lower but only about 15 off.

Thanks for all your help. The boat is kept in Massachusetts, so freezing could have been an issue but I have no records, I just bought it.

 

[kend301]

Re: Sport Jet 120 wont turn over with 4 plugs

Gotta know , did you follow all of my advice and offer a beer to the boating Gods ??? VERY important step when you own a boat

 

[SportJet]

Re: Sport Jet 120 wont turn over with 4 plugs

Lol, yes I did offer up a Beer, Samuel Adams no less. Im a bit superstious too and thought that was a great idea. Lots of whoops when it started.

 

[kend301]

Re: Sport Jet 120 wont turn over with 4 plugs

Well as long as you have been a good sport about that , offer a shot of Crown just to be sure