1989 3 ltr rebuild advice

[shimano]

So I have a 89 21 ft renken fishing boat with the 3 ltr cobra.I have owned it for 18 ish years.Although they aren't well rated ,it's been a great boat.yhe original 3 ltr engine seem to be getting tired,yesterday after a hour of 3500 rpm something went bad,now stumbles after 2500 rpm.idles great, doesn't run hot.oil pressure is a little low,plugs look fine this motor has a ton of trolling hours on it,is it worth rebuilding?

 

[Bondo]

now stumbles after 2500 rpm.idles great, doesn't run hot.

Ayuh,..... Change the fuel filter, 'n see if it clears up,....

 

[bruceb58]

Have you done a compression check on the motor?

 

[shimano]

Just got it home went for 40 miles yesterday had to go get it with the trailer.it ran best in years for the first hour.filters are clean.also new fuel water separator.yes I did just put in gas (150$) before ride.but not a hiccup for a hour.I will be doing a compression test first.it does sound louder than normal and when you rev it in neutral there is a sound from( seems) front half of oil pan.around 3 k.

 

[shimano]

Sorry more like 2400 rpm not 3

 

[shimano]

So just did a compression check#1,130 psi #2and#3 were 150 #4 was 135. Did a quick calculation and in the 20 years I've owned the boat I have approx + -1200 hrs .(lots of it trolling) when I roll the engine by hand and listen it seems smooth but harder to roll at points.

 

[Scott Danforth]

cylinders 1 and 4 are low, however not terrible.

put a mechanical gauge on the motor to verify oil pressure. do not rely on a 33 year old $3 gauge and $5 sender

1200 hours on the boat is about like 50,000 on your car with maintenance your motor could last well over 4000 hours

look at your fuel system for the running issue.

 

[shimano]

I will check that next,fuel pressure too.when it started acting up it also seemed to get louder,not sure why.

 

[shimano]

So I decided to disassemble the carb to check and found the seat( needle,seat) had unscrewed( again) I just fixed this last fall,I know there is alot of vibration but it was tight.can I use locktite on this?.

 

[Bondo]

So I decided to disassemble the carb to check and found the seat( needle,seat) had unscrewed( again) I just fixed this last fall,I know there is alot of vibration but it was tight.can I use locktite on this?.

Ayuh,.... How are the threads that it screws into,..??

Loc-tite oughta work Ok,....

 

[shimano]

Threads are fine.I did use a dab of loctite.hope it stays in.