Replacing engine with bigger engine

[pensacola]

I am about to buy a 1984 23' Sea Ox. It has a 3.8 liter V-6 I/O in it currently. If I want to put a larger motor in what would I have to do and what size motor could I put in it?

 

[QC]

Re: Replacing engine with bigger engine

Which I/O?

 

[bomar76]

Re: Replacing engine with bigger engine

In today's market I can't see why anyone would want to buy a boat that they plan to repower.....buy something w/ the power you want.

 

[pensacola]

Re: Replacing engine with bigger engine

Not totally sure if it is under powered. The seller says it will go 40 mph. But I have been hearing that Sea Ox boats are heavy boats. I am going to test drive it tomorrow and see how it feels.

 

[Don S]

Re: Replacing engine with bigger engine

If it's OMC, it's a Stringer drive. They are old, no longer in production, OMC went out of buisness about 10 years ago (no new parts or techs being trained for repair) .
Fix your Mercruiser 5.0L. You will be $$$$$ ahead in the long run.

 

[pensacola]

Re: Replacing engine with bigger engine

Well heres the update. I plan on keeping the 5.0 for fun and this will be my fishing boat. We took it out today. It was running good but it started sputtering. We couldn't get it over 3000 rpm's. So we took it back in and he replaced the fuel filters. Took it back out and it was running a lot better but it still misses every now and then. He said its probably just a fouled plug or something. It will get up to 4000 rpm's then drop to 3500. Then every so often it would speed up to 4000 then drop back to 3000. What could this be. I am about to buy it, but I need to know if this is something minor or a major problem. By the way it is a OMC stringer drive. There is a guy locally here that said he can get parts for it.

 

[chiefalen]

Re: Replacing engine with bigger engine

run don't walk away from that stringer.

 

[bomar76]

Re: Replacing engine with bigger engine

somehow I get the feeling that the OP is gonna buy this boat even if it had flames shooting out the cupholders on the sea trial.

Sad thing is, I just left that area (was in Panama City Beach for 3 months) and there are so many GOOD non OMC Stringer drive boats for sale down there you can't swing a dead cat around your head w/o hitting one.

 

[Bondo]

Re: Replacing engine with bigger engine

or a major problem. By the way it is a OMC stringer drive.

Ayuh,...... That it Is..............

 

[pensacola]

Re: Replacing engine with bigger engine

somehow I get the feeling that the OP is gonna buy this boat even if it had flames shooting out the cupholders on the sea trial.

What is a OP?

Anyways I just went and did a compression test on the motor.
It had 90 psi on all cylinders but one. That cylinder only had 30
So it looks like I have been saved from buying this boat. From the sound of it must be a very good idea to shy away from stringer drives.

 

[bomar76]

Re: Replacing engine with bigger engine

OP=Original Poster

 

[Fishermark]

Re: Replacing engine with bigger engine

From the sound of it must be a very good idea to shy away from stringer drives.

 

[pensacola]

Re: Replacing engine with bigger engine

Thank god I dodged that bullet.

 

[Don S]

Re: Replacing engine with bigger engine

Next time you want to do a compression test on an engine, take this with you.
http://www.boatfix.com/merc/Bullet/97/97_25.pdf

 

[brunolund]

Re: Replacing engine with bigger engine

that's an excellent list don. i've seen so many people that have no clue what a compression test can tell them, or how to do them properly.

case in point. co-worker bought boat, took it for a ride after he got it home. ran a little rough, did compression check with finger, removed head. asked for help. went there, inspected everything, told him he needed new sparkplug. fixed problem.

 

[pensacola]

Re: Replacing engine with bigger engine

Thanks for the advice. I beleive before I buy any motor now I need to do a compression test first. It will tell you a lot more than I thought. Plus I was being told 90 psi or above was good. Basically if its below 100 psi on any cylinder I don't want it.
Very good information to know.