Twin 250 efi mercury 1996

[Tipitina]

Thoughts on rebuilding one of these guys? I have twin '96 efi mercury 250's on a scarab sport of same year. One of the motors recently froze up. I thought it was an overheat as I hit a sand dredge and tried to reverse off when the motor stopped. I assumed it just needed to cool and would be fine. I replaced all cooling components (water pump/impeller, stats, poppet) however when I took it to the mechanic to help with lining up the lower unit and realign new throttle/shift cables (no help to lift :( ) he informed the motor had a cylinder seized. I'm wondering all of your thoughts on rebuilding? I just had the boat 40-50 miles offshore the day before and ran it all day the day it seized with no issues.

What do I look for? What should I ask the mechanic? I wouldn't mind repowering for efficiency but it isn't cost effective at the moment.

Help??

awesome forum by the way!

[CptAJ]

I'm really not the person to be responding to this so I'll leave the gritty details to some of our real mechanics in the forum.

But some basic stuff, are you planning on rebuilding yourself or do you just want to make sure the mechanic is right before you hand over the work to him? A rebuild like this is not amateur stuff (Unless you're ready for quite a learning experience!)

[Tipitina]

Mechanic threw out a number like 5k and I'm not super impressed with him to this point anyway. I was going to give it a shot myself. I've never torn that deep into outboards. Always done my own maintenance though to include the basics. Have more experience on truck motors. I do have a PDF of the manual I've been through about cover to cover and think I can muster up the patience to do a good job. I originally was leaning towards repowering with some newer used optis or verados, and now am thinking of trying the rebuild myself. Mainly for the experience as I love to tinker, but also for the financial reason. Worst case as I see it is I end up out a few hundred and go from a frozen motor to a disassembled motor I part out. Best case is I learn a lot about what many say is a bulletproof engine and I'm back on the water via my own two hands.

[kingsbiship]

I also have been an auto mechanic all my life, and started learning/repairing outboards years ago!
The two have no similarities other than both reciprocate! Measurements and specifications are
more important on O/Bs and patience is a large advantage! As my first piece of advice....
double check EVERYTHING!

[Go Time]

You also need to make sure you have a competent machinst that can support outboard work nearby, otherwise you'll shipping the block off. There are not that many around with the right type of boring machine and understand sleeving & porting.

[Tipitina]

I'm working on that piece now. I understand its a blind bore?

anyone have links to some picture heavy threads/blogs regarding v6 rebuilds? I'm not having much luck with the search function here :(

thanks for all the help thus far!

[CptAJ]

Yeah, the search function is a pain. Try using google advanced search and limit the search to screamandfly.com only.

It seems like you have the mechanic experience to tackle this. Hell, I'm fixing my own 250hp twins with absolutely no mechanic experience on anything. Just an insane need to tinker. You'll be fine.

Go ahead and open that bad boy up and have a look at those holes. It may not be that bad. Also, 5000 seems insane. You could get a running motor for that much!

[kingsbiship]

Hell, I'm fixing my own 250hp twins with absolutely no mechanic experience on anything.

You have GOT to let me know how things work out for you!

[CptAJ]

You have GOT to let me know how things work out for you!

Already got one up and running, check out the other 250 efi thread I started (the one about fuel pumps). Manuals are a big help and I do have engineering background so its not like motors are a magic black box to me :p

Like you said. Patience. Lots of patience. (And reading screamandfly threads)

PS: I also have little to no access to spare parts being middle class in a third world country with rampant inflation and widespread shortages. How's THAT for a challenge? :D

[kingsbiship]

I didn't read your location... My hat is off to you sir!