Engine Advice OMC Stringer 4.3l v6 262

krustyCrab

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Jul 1, 2014
Messages
27
Hey Everyone,

Ill give you the specs first... I have an 1986 OMC stringer powered by a 4.3l v6 262 v6. 8 bolt manifold, rochester 2 barrel carb.

If you look at some of my older posts I talk about white smoke coming from one of the valve covers, I assumed at the time I could be dealing with a cracked block, head, or something like that.

Well I decided to pull the motor at the end of the season, ripped it all down, and generally inspected all of the components. Everything visually looks good, though I think we can agree that doesnt mean a whole lot. Reason for pulling it was to rebuild the engine, new seals gaskets the gamut.

As spring is hopefully nearly around the corner I need to make a decision to proceed with repowering or to procure either a new engine or get into a new boat.

I like the hull I have, i know dealing with a stringer is not necessarily the cheapest or best bet, but the outdrive is in good shape and works well, as much as I was able to test it last season anyway. The one thing that freaks me out, is the exceptionally large transom hole with a simple rubber belows between the engine and the ocean, im sure its fine but it freaks me out a bit LOL

So im looking for advice, should i rebuild the engine, im thinking i would have the cylinders bored out, new rings etc etc, I would likely still have to have the block checked for cracks, along with the heads... I estimate that cost to be somewhere in the neighborhood of 2k, I assume that process would start with getting the block cleaned up and magnafluxed for cracks, at which point proceeding with a rebuild is not an option and im out the 400 bucks to check the block. Option 2 would be to procure a new rebuilt engine, now some questions abound by that, could I go with a newer block, say like a 97 vortec or something like that with a 12 bolt manifold (obviously i would have to get a new manifold) still working within the same specs (4.3l v6). I could then use some of the parts known to be working off my old engine like the alternator, starter etc etc OR should I make an attempt to find a rebuilt engine made with the 8 bolt manifold and match motor for motor?

Lastly the third option is should I just scrap this boat altogether and use the money I have set aside for a new vessel. I could potentially recoup some of the money I have into the boat by salvaging as much as I can from the hull, parting out the outdrive, selling the trailer... Im thinking I could probably get about a grand for some if not all of that stuff.

Rough estimates on cost for what im trying to do, I think maybe 2-2500 for a rebuild. Probably 3kish for a new rebuilt engine, or a new ship altogether for maybe 5-6k.

If your of the opinion that a new rebuilt engine is the way to go, could you recommend some online shops that might carry what im looking for at a decent price, same with the new boat should i go that route, im thinking craigslist for that venture though.

I am mechanically inclined, but i would likely have a shop do all the work on the engine rebuild should i go that way.

Any advice would be greatly appreciated.

PS. A previous discussion in one of my threads discussed the possability of just finding an automotive 4.3l 262 and swapping out that motor on the cheap, a lot of research says this can be done however not recommended due to the marine cam, freeze plugs and things like that. Any thoughts there?
 

Bondo

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Staff member
Joined
Apr 17, 2002
Messages
71,099
Hey Everyone,

Ill give you the specs first... I have an 1986 OMC stringer powered by a 4.3l v6 262 v6. 8 bolt manifold, rochester 2 barrel carb.

If you look at some of my older posts I talk about white smoke coming from one of the valve covers, I assumed at the time I could be dealing with a cracked block, head, or something like that.

Well I decided to pull the motor at the end of the season, ripped it all down, and generally inspected all of the components. Everything visually looks good, though I think we can agree that doesnt mean a whole lot. Reason for pulling it was to rebuild the engine, new seals gaskets the gamut.

As spring is hopefully nearly around the corner I need to make a decision to proceed with repowering or to procure either a new engine or get into a new boat.

I like the hull I have, i know dealing with a stringer is not necessarily the cheapest or best bet, but the outdrive is in good shape and works well, as much as I was able to test it last season anyway. The one thing that freaks me out, is the exceptionally large transom hole with a simple rubber belows between the engine and the ocean, im sure its fine but it freaks me out a bit LOL

So im looking for advice, should i rebuild the engine, im thinking i would have the cylinders bored out, new rings etc etc, I would likely still have to have the block checked for cracks, along with the heads... I estimate that cost to be somewhere in the neighborhood of 2k, I assume that process would start with getting the block cleaned up and magnafluxed for cracks, at which point proceeding with a rebuild is not an option and im out the 400 bucks to check the block. Option 2 would be to procure a new rebuilt engine, now some questions abound by that, could I go with a newer block, say like a 97 vortec or something like that with a 12 bolt manifold (obviously i would have to get a new manifold) still working within the same specs (4.3l v6). I could then use some of the parts known to be working off my old engine like the alternator, starter etc etc OR should I make an attempt to find a rebuilt engine made with the 8 bolt manifold and match motor for motor?

Lastly the third option is should I just scrap this boat altogether and use the money I have set aside for a new vessel. I could potentially recoup some of the money I have into the boat by salvaging as much as I can from the hull, parting out the outdrive, selling the trailer... Im thinking I could probably get about a grand for some if not all of that stuff.

Rough estimates on cost for what im trying to do, I think maybe 2-2500 for a rebuild. Probably 3kish for a new rebuilt engine, or a new ship altogether for maybe 5-6k.

If your of the opinion that a new rebuilt engine is the way to go, could you recommend some online shops that might carry what im looking for at a decent price, same with the new boat should i go that route, im thinking craigslist for that venture though.

I am mechanically inclined, but i would likely have a shop do all the work on the engine rebuild should i go that way.

Any advice would be greatly appreciated.

PS. A previous discussion in one of my threads discussed the possability of just finding an automotive 4.3l 262 and swapping out that motor on the cheap, a lot of research says this can be done however not recommended due to the marine cam, freeze plugs and things like that. Any thoughts there?

Ayuh,.... If the motor ya got now, has 8 intake bolts, somebody has already installed Vortec heads, 'n intake,....
If original, yer motor would have a 12 bolt intake,....

The Problem yer gonna have is,....
Chevy dropped the 2 piece rear main seal in '86,....
There's darn few 2pc seal 4.3ls out there,...
Findin' a junkyard motor will be 'bout Impossible,...

Ya made yer 1st mistake pullin' the motor apart, Before ya pressure tested the block's coolin' jackets,...
Findin' cracks got alot more complicated, 'n expensive,....

If ya decide to junk it, the smaller ya make the pieces, the Bigger the pay-off,...
A Whole stringer ain't worth much, but stringer parts are Golden,......
 

krustyCrab

Cadet
Joined
Jul 1, 2014
Messages
27
thanks Bondo, I agree it was a rather dumb move pulling the engine, I have a tendency to get overzealous about projects. If I did get a new engine, would I have to worry about the rear main seal, forgive my ignorance but my initial thought was that wouldnt matter if it was a completely different engine. I could be mistaken about the bolt pattern on the intake, i thought I had the prevortec intake which I thought was 8 bolt but it very well could be 12, ill take a closer look tonight and update this thread.

When I did pull the engine apart, I noticed a few things that could be problematic, while im mechanically inclined, I dont know the finer details of things.... So the heads, if i peer into them and look at teh valve stems, they all seem rather corroded with rust, inside the block jacket around the cylinders if i peer in there with a flashlight i see the same surface rust with some decent rust flakes inside. The valleys, crank shaft and all associated internals look about normal, at least what i would expect to see on an engine this old.
 

Bondo

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Apr 17, 2002
Messages
71,099
thanks Bondo, I agree it was a rather dumb move pulling the engine, I have a tendency to get overzealous about projects. If I did get a new engine, would I have to worry about the rear main seal, forgive my ignorance but my initial thought was that wouldnt matter if it was a completely different engine. I could be mistaken about the bolt pattern on the intake, i thought I had the prevortec intake which I thought was 8 bolt but it very well could be 12, ill take a closer look tonight and update this thread.

When I did pull the engine apart, I noticed a few things that could be problematic, while im mechanically inclined, I dont know the finer details of things.... So the heads, if i peer into them and look at teh valve stems, they all seem rather corroded with rust, inside the block jacket around the cylinders if i peer in there with a flashlight i see the same surface rust with some decent rust flakes inside. The valleys, crank shaft and all associated internals look about normal, at least what i would expect to see on an engine this old.

Ayuh,.... Pullin' the motor outa the boat, Had to be done,...

Tearin' the motor apart, destroyed many diagnostic testin' possibilities,.....

My "Guess" for the rusty valves, is leakin' exhaust manifolds,..... could be cracked heads,...
It's a clue, 'n you gotta follow the rust tracks to See where the water came from,....

Rust in the coolin' jackets is quite normal, even in a car, run with antifreeze,...

Things ya need to find out,....
How many intake bolts,..??
2pc. or 1 pc seal,..??
Staggered, or straight across bolt pattern of the starter,..?? that'll tell ya the flywheel diameter,....
 

southkogs

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Messages
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Run with Bondo on the engine stuff: I'm gonna' toss in my 2? on the "what if" questions above ... Just went though this (sorta') myself with my Stringer.

If you can repair / rebuild and get back on the water for under $2k, and you like the hull and it's in good shape, then I think that's a good option. - My boat in good shape really isn't worth nuthin' to nobody except a goof-ball like me who likes it. So, anything over about $1,800 - $2,000 is too much to really spend on it. So far, I keep managing to put her back on the water for less than $500 per year in repairs.

If you can't repair or rebuild for less than $2k ... I'd say part her out and move on. It's probably not worth re-powering. For just a little more than you'll wind up spending getting it re-powered, you can get into a better rig that's easier to part and service. Lotsa' good boats out there.

I'm not too afraid of the Stringers - I kinda' like mine - but practically, you're dealing with a museum piece and that has it's price in practicality.

Good luck: hope you can fix it cheap and easy.
 

krustyCrab

Cadet
Joined
Jul 1, 2014
Messages
27
Sorry for the delay in getting the factual information, crazy weekend over here.

The intake is 12 bolt

I havent pulled the flywheel so I cant determine the 2pn/1pc rear main seal

As far as the starter is concerned, it has a straight across bolt pattern, though one bolt is about 3" while the other is 2", not sure if that matters.
 

Bondo

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Sorry for the delay in getting the factual information, crazy weekend over here.

The intake is 12 bolt

I havent pulled the flywheel so I cant determine the 2pn/1pc rear main seal

As far as the starter is concerned, it has a straight across bolt pattern, though one bolt is about 3" while the other is 2", not sure if that matters.

Ayuh,.... That says it's pre-Vortec,....

'n That says it's got a 12" flywheel,....
 

Howard Sterndrive

Rear Admiral
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Nov 5, 2008
Messages
4,603
I havent pulled the flywheel so I cant determine the 2pn/1pc rear main seal
It's 2 pc.
All stringer drives have 2 pc rear main. There's no stringer coupler for 1 pc rear main engines, so it can't be one pc.
Your engine is that rare 1985 4.3 one year thing from before the switch to the newer crank and seal. .
 
Last edited:

krustyCrab

Cadet
Joined
Jul 1, 2014
Messages
27
Thanks for all the tips and advice thus far gents! So we know that i have a pre vortec 4.3l v6 2pc rear main seal with a 12" flywheel... What do you think i should do, is it worth taking the engine to a shop to have it repowered, could i potentially get a newer updated engine(rebuilt) like maybe a 97 vortec 4.3l, if thats the case i imagine i would also have to procure a new flywheel, intake manifold, etc etc. Or would my best bet be to just scrap this project and get int something newer, theres a few vessels on craigslist that are in my price range.

To be completely up front, this stringer is the first boat i have owned myself, I grew up on the bay my dad had a quahog skiff. I think now that i know a bit more about boats, engines, and outdrives i could find something that works for me a little better.

Thanks for your time guys!
 

Bondo

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Apr 17, 2002
Messages
71,099
Thanks for all the tips and advice thus far gents! So we know that i have a pre vortec 4.3l v6 2pc rear main seal with a 12" flywheel... What do you think i should do, is it worth taking the engine to a shop to have it repowered, could i potentially get a newer updated engine(rebuilt) like maybe a 97 vortec 4.3l, if thats the case i imagine i would also have to procure a new flywheel, intake manifold, etc etc. Or would my best bet be to just scrap this project and get int something newer, theres a few vessels on craigslist that are in my price range.

To be completely up front, this stringer is the first boat i have owned myself, I grew up on the bay my dad had a quahog skiff. I think now that i know a bit more about boats, engines, and outdrives i could find something that works for me a little better.

Thanks for your time guys!

Ayuh,.... In all honesty, you've got 1 of the least desirable drives out there, 'n bein' the oddball '85 only 4.3l complicates it even more,....
I don't think you can update the block,... as Howard said, No coupler to couple the new motor's bolt pattern, to the stringer,...

If you part it out, in the smallest pieces possible, to others tryin' to get one more lap outa their Stringer drives,....
Ya might pocket enough cash to buy a decent Merc or Volvo, Chevy powered drivelines, in a hull that better fits yer needs,....
 

southkogs

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The minute you stare at a Stringer and ask yourself, "do I really wanna' deal with all of this?" You just answered your own question ... ;)
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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I would build a pre 1985 5.0 liter and drop it in. those you can find in the salvage yards for about $300. then you will need to buy new exhaust manifolds. you can use the same starter and alternator you have along with the circulating pump.
 
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