OMC 5.7 Questions

[Sir_LR]

So Im New to buying a boat I just got my license and I am looking at boats I prefer owning an outboard but then I came across and inboard OMC 5.7 with (no hours he states) I don't know what that means and also what are common issues with inboards in general and what are specific issues with the OMC 5.7

 

[Keyboardman]

So Im New to buying a boat I just got my license and I am looking at boats I prefer owning an outboard but then I came across and inboard OMC 5.7 with (no hours he states) I don't know what that means and also what are common issues with inboards in general and what are specific issues with the OMC 5.7

The main issues with the OMC 5.7 is it's an OMC and also it's sterndrive not a true "Inboard" There's a lot of maintenance work needed with a sterndrive and it's best if you're an old mechanic so you can fix it when no other Marine service center will look at it. OMC has been out of business for 20 years and a lot of parts are listed as NLA. There's some still out there but I had to dig deep a few times looking for some. My OMC sterndrive was my first and last.

 

[MRS]

The main issues with the OMC 5.7 is it's an OMC and also it's sterndrive not a true "Inboard" There's a lot of maintenance work needed with a sterndrive and it's best if you're an old mechanic so you can fix it when no other Marine service center will look at it. OMC has been out of business for 20 years and a lot of parts are listed as NLA. There's some still out there but I had to dig deep a few times looking for some. My OMC sterndrive was my first and last.

Find one with a 4 stroke outboard you will be glad you did.
I just went from a I/O omc 4.3 to a 4 stroke outboard and will never go back to a I/O motor again.

 

[southkogs]

I don't mind the I/O setup comparative to outboards. Each has it's advantages, though outboards have regained some ground in the last several years - so they are becoming more popular.

Depending on the year of the OMC, there are still parts available and support. But OMC has been gone for a long time, as stated. So, you're up against an "antique" drive without a lot of marine techs who know them or like them. For me to buy an OMC (and I'm experienced with them), the boat would have to be in pretty amazing condition, something special and not very expensive.

If they're saying the engine has no hours on it ... I'd say that's your first red flag. If the boat hasn't run since it was purchased: it will have been sitting for over two decades.

 

[Scott Danforth]

So Im New to buying a boat I just got my license and I am looking at boats I prefer owning an outboard

then buy a boat with an outboard

but then I came across and inboard OMC 5.7

OMC means Obsolete Marine Company - OMC went out of business many decades ago

with (no hours he states) I don't know what that means and also what are common issues with inboards in general and what are specific issues with the OMC 5.7

the buyer is lying. no way the motor has 0 hours being that old.

typical use of a boat motor is about 20-50 hours a year. however OMC was in many low end boats that did not have hour meters on them from the factory. Since OMC made I/O's from the early 60's to the joint venture years in the early 90's you are guaranteed to have some hours on the boat.

boats do not do well if they are not used. sitting is absolutely worse than putting 8 hours a day on a boat.

the base motor itself is just a GM 350. nothing special

however the drive on the other hand may not have parts available, depending on the year

the other issues will be the boat itself. being that old, guarantee you will most likely find some structural issues with the boat. rotted transom and stringers would be almost guaranteed.

I would not recommend ever buying an OMC powered anything unless the boat has deep sentimental value. because as a boat, it is worthless

 

[Lou C]

I would tell you to avoid ANY old boat with a I/O power train they are very high maintenance regardless of whether it’s Merc, Volvo or OMC. You’re best off buying newer and 4 stroke outboard powered.
For the record I have had beyond excellent service from my 1988 OMC 4.3 Cobra. The first couple years I had it I had a few seals replaced and the bearing retainer replaced in the lower unit (it was then 17 years old). Since then no mechanical repairs to the outdrive and transom assembly. No leaks thru the transom mount no rotted steering arm like on Merc drives in salt water. Shifts with 2 fingers on the control. And used (moored) in salt water 15 seasons.
OMC parts are a bargain compared to Volvo I was able to buy a nice used Cobra drive for 1/3 the price of a Volvo SX. The Volvo is a popular conversion for the Cobra. I thought of converting but for now there is no need. I have the spare drive sitting on a stand in my garage if I need it. I also have a complete spare transom mount looks new for 1/3 the price of a comparable Volvo SX mount.
But would I tell someone to buy one who is not their own mechanic and not able to find parts? No way.
Buy a 5 year old boat at most and definitely 4 stroke outboard powered.
I/Os once they went to EFI and cat converter exhaust became something I would not ever buy due to the very high cost of exhaust replacement which is a regular maintenance item here in the salt pond. Parts cost $4500 for V6 Merc. No thanks!