3.8 OMC replacement motors?

[Rockybuysjunk]

Happy Holidays everyone!! I have a 1983 concord with the 3.8 OMC v6 and I guess the stringer out drive ? I want to replace the motor because of a cracked block. Can anyone tell me if I can replace it with another motor? Merc v6 or?? Any help would be greatly appreciated!! Thanx in advance!! Rocky

 

[Scott Danforth]

Your motor is a 1981-1984 GM 229 V6 (found in GM G-bodies). Your choices are the same motor, or a 1985 (only) 4.3. Or you can go with a newer 4.3 and have a custom splines coupler made

 

[kenny nunez]

The cheapest easiest thing for you would be to find a 3.8 from a junk vehicle and rebuild it with a new set of manifolds.
Finding a complete running 4.3 from a Mercruiser/ Volvo package is possible, it just depends on what part of the country you are at.
Just like SD said about the drive coupler, that can be done.

 

[Rockybuysjunk]

Happy Holidays everyone!! I have a 1983 concord with the 3.8 OMC v6 and I guess the stringer out drive ? I want to replace the motor because of a cracked block. Can anyone tell me if I can replace it with another motor? Merc v6 or?? Any help would be greatly appreciated!! Thanx in advance!! Rocky

 

[Rockybuysjunk]

The cheapest easiest thing for you would be to find a 3.8 from a junk vehicle and rebuild it with a new set of manifolds.
Finding a complete running 4.3 from a Mercruiser/ Volvo package is possible, it just depends on what part of the country you are at.
Just like SD said about the drive coupler, that can be done.

I always heard that the “marine “ motor or block is not the same as a car motor? They’re built different because of the load they’re always under? Always wondered about that , if not the case would be great!! So basically find a good block and all the marine parts will work?

 

[Rockybuysjunk]

Your motor is a 1981-1984 GM 229 V6 (found in GM G-bodies). Your choices are the same motor, or a 1985 (only) 4.3. Or you can go with a newer 4.3 and have a custom splines coupler made

So the 85 4.3 is the only one that will work with my lower unit?

 

[Rockybuysjunk]

Your motor is a 1981-1984 GM 229 V6 (found in GM G-bodies). Your choices are the same motor, or a 1985 (only) 4.3. Or you can go with a newer 4.3 and have a custom splines coupler made

 

[Rockybuysjunk]

Your motor is a 1981-1984 GM 229 V6 (found in GM G-bodies). Your choices are the same motor, or a 1985 (only) 4.3. Or you can go with a newer 4.3 and have a custom splines coupler made

1985 only because of the line up with the lower unit?

 

[Scott06]

I always heard that the “marine “ motor or block is not the same as a car motor? They’re built different because of the load they’re always under? Always wondered about that , if not the case would be great!! So basically find a good block and all the marine parts will work?

Gm marine engines are essentially truck engines. Typical differences between auto and marine are camshafts, head gaskets, core plugs.
the real differences are in electrical, ignition and fuel systems those are very different

if you really like the boat and its in decent shape get a complete tear out of a 4.3 with an alpha one. While this would be a bigger project and require transom work to fill in the hole yiu wouldnt be messing around with replacing an engine on an obsolete drivetrain .

 

[Scott06]

1985 only because of the line up with the lower unit?

The existing coupler wont bolt up to the 86 & up crank shaft

 

[Scott Danforth]

1985 only because of the line up with the lower unit?

Because 1985 was the last year of a 2-piece Rear Main seal crank on GM motors (except the 3.0)

There are no OMC couplers for the 1-piece RMS cranks as OMC stringer ended in 1984

So your only choices are have a custom made coupler and use a newer motor, have your coupler welded up and re-machined and use a newer motor or find a 1985 and older motor and rebuild, or rebuild your transom and install a Mercruiser or Volvo motor&drive

Being your drive is a stringer 800, you could also get a 1981-1985 305 V8 to replace the V6. However you would have to get appropriate OMC style exhaust manifolds and redo your mounts

 

[Rockybuysjunk]

Because 1985 was the last year of a 2-piece Rear Main seal crank on GM motors (except the 3.0)

There are no OMC couplers for the 1-piece RMS cranks as OMC stringer ended in 1984

So your only choices are have a custom made coupler and use a newer motor, have your coupler welded up and re-machined and use a newer motor or find a 1985 and older motor and rebuild, or rebuild your transom and install a Mercruiser or Volvo motor&drive

Being your drive is a stringer 800, you could also get a 1981-1985 305 V8 to replace the V6. However you would have to get appropriate OMC style exhaust manifolds and redo your mounts

I really appreciate your help and obviously you’re knowledgeable on this subject and hopefully let me pick your brain.? This boat is a83 concord which I’ve always loved the style of, everything works great on the boat and has just been sitting in a garage. I’ve always been a bit sketchy about the way the trim/ motor hydraulics work, seems a bit odd for all that. But I would actually like to replace it all with something updated without all the hydraulic motor trim stuff going on. So if I was and want to,, after filling in the transom and modifying for a different setup my question is ,, is that transom made strong enough for the modification? Not the hole I’m filling in but is the transom designed for the stress of the new setup? Thank you so much for your knowledgeable help

 

[Scott Danforth]

I'd you want to replace the whole motor/drive with something like a Mercruiser or Volvo

You have to rebuild your whole stringer and transom properly.

The stringer drive is mounted to the stringers at 4 points. The other motor/drives are mounted to the transom shield at 2 points and the stringers at 2 points.

Nothing wrong with how a stringer drive works with respect to the trim (it's really quite simple and bulletproof). It's just that they are obsolete and the vertical driveshaft in the drive is a known failure point

 

[Lou C]

The decision of what to do all depends on how long you intend to keep the boat. If just a few years start searching for the older style GM V6 that used a 2 piece main seal that will work with your drive system. However if keeping it indefinitely rebuilding the transom to take a late model Merc drivetrain makes a ton of sense that way you get away from the obsolete stringer system & NLA parts.

 

[Rockybuysjunk]

The decision of what to do all depends on how long you intend to keep the boat. If just a few years start searching for the older style GM V6 that used a 2 piece main seal that will work with your drive system. However if keeping it indefinitely rebuilding the transom to take a late model Merc drivetrain makes a ton of sense that way you get away from the obsolete stringer system & NLA parts.

Thank you for your knowledge and help

 

[Rockybuysjunk]

I'd you want to replace the whole motor/drive with something like a Mercruiser or Volvo

You have to rebuild your whole stringer and transom properly.

The stringer drive is mounted to the stringers at 4 points. The other motor/drives are mounted to the transom shield at 2 points and the stringers at 2 points.

Nothing wrong with how a stringer drive works with respect to the trim (it's really quite simple and bulletproof). It's just that they are obsolete and the vertical driveshaft in the drive is a known failure point

Thank you for your help and knowledge on my mess !!

 

[Rockybuysjunk]

Thank you for your help and knowledge on my mess !!

Hi Dan ! Rockybuysjunk here asking to pick your brain again!! I found a OMC 3.8 v6 in a 85 rinker, would this work for a drop in ? I have a 83 concord with the 3.8V6 stringer drive , thank you in advance!!

 

[Scott Danforth]

Hi Dan ! Rockybuysjunk here asking to pick your brain again!! I found a OMC 3.8 v6 in a 85 rinker, would this work for a drop in ? I have a 83 concord with the 3.8V6 stringer drive , thank you in advance!!

exact same motor, exact same drive (there were no 3.8's in 1985, only left over 1984's registered as 1985's)

I would buy the whole thing for spare parts as the shift cable alone is $950.