4.3 liter, the DC-10 of I/Os...

[jimmbo]

I know that some will not agree with me, but reading the Threads, I have come to the Conclusion that this engine is a Lemon

 

[Lou C]

I don't think so, at all. They can take a beating like any other Chevy small block, and are perfect for small boats. Mine suffered a bad overheat (2013) blown head gaskets and water in a couple cyls (2016) got a pair of reman cyl heads and new gaskets (2017) and is still running on the original 34 year old short block. So, I don't think I'd call that a lemon.
The only drawbacks to these are that in the Pre-balance shaft versions (94 and earlier) they don't run as smooth as the later balance shaft models and the split journal crankshaft is not as durable at high revs as the standard crank in the V8s. But that's only an issue for people who abuse their engines by over-reving them.
They are perfect in 17-19 foot boats due to the shorter size and 100 lbs less weight than the V8.
In fact, anyone who thinks its a lousy design, look up Merc's "all new" 4.5 liter V6. What you will see, is a LOT of old GM engineering, as in:
same all cast iron construction
same 90* cylinder angle
same split journal crank
same balance shaft
some minor changes to the cyl heads
the only thing that's "all new" is the induction/exhaust system.
these run great and are more refined than the old 4.3s but really go take a good look at a Merc catalog and you'll see what I mean. And these, have replaced V8s in most smaller boats getting Merc I/Os.

 

[Bondo]

Ayuh,.... I put over 2200 hrs. on my '94 in my ole fishin' barge,.....

Junkin' the boat now,.... pulled the motor, 'n ran a comp. test on it 'n was surprised with the results,....
Gonna drop it into another barge this fall, for another run,.... as is,.....

Btw,..... Boat motors don't die,.... they're killed by their owners,....

 

[Scott Danforth]

I know that some will not agree with me, but reading the Threads, I have come to the Conclusion that this engine is a Lemon

It definitely is a compromise

 

[H20Rat]

A 4.3l is probably one of the most reliable, if not the most reliable, I/O engines you can find in a boat.

Threads tell you nothing, because the 4.3l is also probably the most common.

 

[Lou C]

Cylinder Block, Camshaft, Crankshaft, and Balanceshaft

Cylinder Block, Camshaft, Crankshaft, and Balanceshaft

www.mercruiserparts.com

Cylinder Head and Rocker Cover

Cylinder Head and Rocker Cover

www.mercruiserparts.com

look familiar?
I guess Merc thought it was good enough, to update and refine it further....as I said, a lot of old school GM engineering appears to live on here...

 

[Lou C]

A 4.3l is probably one of the most reliable, if not the most reliable, I/O engines you can find in a boat.

Threads tell you nothing, because the 4.3l is also probably the most common.

and they came in a lot of bargain priced entry level boats that don't get maintained.
the only thing I can throw out there beyond what I said is that Merc made a big mistake with those one piece V6 manifolds that caused a lot of engine problems, (cracking & water intrusion) but that was Merc saving money not GM's engineering. That lasted 3 years and they went back to the 2 piece design, that cost a bit more but was much better.
OMC did the same thing though I never had trouble with the 3 sets of bat wings I had on mine.

 

[jimmbo]

I think the Chevy Small Block is a well engineered engine(I have a 5.7 in my 18 1/2 footer), I just don't think the same of the Chopped 3/4 length version.

 

[Lou C]

I think the Chevy Small Block is a well engineered engine(I have a 5.7 in my 18 1/2 footer), I just don't think the same of the Chopped 3/4 length version.

Some will agree but even Hot Rod magazine did a nice build up with the result being somewhere north of 300 hp. As a practical matter though, as long as the owner observes a 5000 rpm redline, well if you blow that 4.3 up, you might blow up a 5.0 or a 5.7 just the same.
Back when GM still supplied taxis to NYC, in the form of the old B-body Impala/Caprice, all the GM supplied NYC taxis were 4.3s, and these routinley rolled up a half a million miles on the mean streets of NYC. As good or better than, the competing Ford 4.6 OHC V8s.

 

[jimmbo]

I doubt that 300hp can come out a 4.3 unless is spun well past 5000, or has a Turbo/supercharger, or has NOx .
Those 4.3s in the Impala/Caprices may have been the smaller version of the Gen II LT1, a V8

 

[Scott Danforth]

90 degree V8s are bulletproof. The stock crank is stout, vibration is minimal

90 degree V6s are prone to vibration issues and have weak cranks

60 degree V6s are a better engine architecture (however not as good as an inline)

For the amount of money and work it takes to make big power from a V6, you can get double the power from a V8 for the same cost and you get 2 more cylinders

As I said, the 90 degree V6 (3.8 and 4.3) is a compromise

 

[Lou C]

Chevy 4.3L 262ci V-6 - Engine Build - Overview - Tech - Hot Rod Magazine

We build a Chevy 4.3L 262ci V-6 using V8 parts and technologies. Find all the details inside Hot Rod Magazine.

www.motortrend.com

The result was 301 hp at 5,500 rpm and 312 lb-ft at 4,700. Puny, but let us remind you that it's still 50 hp per cylinder (a similar 350 V-8 would make 400 hp), which is pretty good for the very mild parts we used. Besides, at 0.060-over, it's just 270ci.

 

[jimmbo]

Hot Rod Magazine... ROTFLMAO!!!! That is nothing but a Marketing Parrot for Accessory Manufacturers. I used to read that Rag in the late 70s, and never, ever saw anything but Praise for any piece of Hardware they installed. In 1970, they were claiming that a bone stock 350 in a Camaro with regular gearing could do wonders with a Single Plane Intake called a Torker.
Besides what works in a Car/Truck more times than not, doesn't work well in Boat.

 

[jimmbo]

90 degree V6s are prone to vibration issues and have weak cranks

60 degree V6s are a better engine architecture (however not as good as an inline)

For the amount of money and work it takes to make big power from a V6, you can get double the power from a V8 for the same cost and you get 2 more cylinders

As I said, the 90 degree V6 (3.8 and 4.3) is a compromise

Every 90 Degree V6 has serious rocking issues, even firing cranks actually made it worse on some of them.
The 60 Degree V6s usually suffered from not enough Space between the Heads for decent Manifolds, especially the early ones. More than once, you would hear someone saying "That's not an intake, that's a carb adapter". It got a tiny bit better when the Deck Heights were increased, but then the engine became as tall as an Inline.
To me, calling it a Compromise, is just being very, I mean, extremely Polite

 

[Lou C]

However….
The main point of difference…the crankshaft…in the almost 20 years I’ve been on this site & others I’ve never heard of a 4.3 breaking a crank. Not once.
Also one thing no one else mentioned:
Unlike the SBC V8 none of the cyl head exhaust ports on the V6 are right next to each other. The Siamesed design of the V8 center exhaust ports can cause overheating of that part of the cyl heads in high load apps like marine use. Over time this can lead to cracking. The exhaust ports of the V6 are spread out more & run cooler….
And just what do you think the fabled Buick 231 V8 Turbo in the GN Regals or the 80s was? Same design except a Buick!

 

[Scott06]

90 degree V8s are bulletproof. The stock crank is stout, vibration is minimal

90 degree V6s are prone to vibration issues and have weak cranks

60 degree V6s are a better engine architecture (however not as good as an inline)

For the amount of money and work it takes to make big power from a V6, you can get double the power from a V8 for the same cost and you get 2 more cylinders

As I said, the 90 degree V6 (3.8 and 4.3) is a compromise

And yet this compromise has performed very well for many folks in the typical <21 ft bowrider application for years. Works well for its intended purpose but certainly not a performance engine

 

[achris]

As you can see by my forum signature I'm familiar with these engines.

90 degree V6s are prone to vibration issues and have weak cranks

I did see broken big block crankshafts, but never a V6...

And yet this compromise has performed very well for many folks in the typical <21 ft bowrider application for years. Works well for its intended purpose but certainly not a performance engine

When I had my shop, I sold dozens of them. Installed in anything from about 19 foot to 23 foot, and while not a 'leap out of the water' fire-breathing dragon, they performed really well for what they are. I also maintained quite a few boats in the 25 to 32 foot range with twin v6s. Never seen a straight six produce the same power with the same reliability. The old 165, THAT is a hateful engine! Under-powered, thirsty, and bloody unreliable! Put me right off straight sixes.

@jimmbo I'm wondering if you've reached your conclusion on personal experience or just reading forums? If it's from reading forums, bear in mind that the size range of boats with V6s installed is the sort of size range who's owner would frequent forums. Bigger boats with bigger engines (V8s) are generally owned by people with bigger pockets, who are less likely to come to forums for help, they just pay for their help. And given the shear numbers of V6's sold, yes you're more likely to see them pop up with problems, because there are SO many of them out there. In my shop, we sold twice as many 4.3s as all the other engines combined!

So, let's all just agree to have differing opinions on this subject, and let this thread die a quiet death (before someone gets a holiday ...)

Chris.......
iboats mod team.

 

[jimmbo]

My experience with 90 degree V6s has made me look at them with Suspicion, and not to trust them in any Application. That Opinion was formed in the late 70s, early 80s, long before there was a World Wide Web.

 

[achris]

My experience with 90 degree V6s has made me look at them with Suspicion, and not to trust them in any Application. That Opinion was formed in the late 70s, early 80s, long before there was a World Wide Web.

So, no experience with the GM 262 then....

As a moderator I see this thread as antagonistic.

Thread closed.

Chris.
iboats mod team