Wonder if I should go IO again or go OB?

[tpenfield]

@hostage now that you’ve gotten a fire hose of info and opinion- what do you think you’ll do?

 

[cptbill]

One more opinion from me. I just bout a regal and got rid of the wellcraft for me I/O is the only way to go outboards are over priced for one thing and way to complicated. Give me a VP that's GM based and I'll be happy and the maintenance and repairs are easy

 

[QBhoy]

Must admit. I unexpectedly love my new merc 115 2.1 litre outboard. It’s just the pinnacle of mid range outboards right now and light years ahead of any other brand in the game. No doubt about it.
But it doesn’t excite me the way my old GM V8 Mpi does, when I hear her start up through the side exit Corsa Marine exhausts .
But pound for pound…these new mercs are mostly just incredible things, I think. For a 2.1 litre engine badged at 115hp…to be as light as the old 2 stroke 115 that was I think only a 1.5 or 1.8 litre…and be miles more powerful than it…even more powerful than the wonderful 125 optimax in recent tests…just speaks volumes about how good these things are. I’m at a 1000 hours on this machine as of this weekend…it’s still as new, runs like a clock and been faultless to date. I learned recently that there are two of these on an aluminium small car ferry just near me. This ferry can take about 3 cars and a few passengers. It runs across a narrow river here and hard worked. These things clocked past 4000 odd hours a wee while ago, without issue of any sort apparently. Still going strong I hear. Amazing.
Sorry to ramble on…but finally, the fuel consumption is unreal. 1.5-1.7 miles per litre at about 22/23 mph cruising speed and from memory around 3500ish rpm. Think she uses early teens litres per hour at that. Even flat out at 43-45 mph gps (on a 19ft deep v cuddy) and 6050-6100 rpm…she maxed out at about 41 litres per hour at that.
Using this boat and engine…has literally changed the way I use a boat. Just so cheap to run.

 

[jimmbo]

If I were buying again, I prefer to get an Outboard, unfortunately there are no more 2 strokes being Built, and while the 4 Strokes are getting better on Acceleration, they are still a bit slower then what the Old 2 Strokes can do. My current 18 1/2 ft I/O has 5.7 in it, and it can accelerate quite Quickly and has a good Top Speed, I just like the look of an Outboard, it gets the Engine out of the way, and the boat responded to Engine Trim better, and they used to be much cheaper and Easier to Winterize, than the I/O

 

[QBhoy]

If I were buying again, I prefer to get an Outboard, unfortunately there are no more 2 strokes being Built, and while the 4 Strokes are getting better on Acceleration, they are still a bit slower then what the Old 2 Strokes can do. My current 18 1/2 ft I/O has 5.7 in it, and it can accelerate quite Quickly and has a good Top Speed, I just like the look of an Outboard, it gets the Engine out of the way, and the boat responded to Engine Trim better, and they used to be much cheaper and Easier to Winterize, than the I/O

The new merc 115 CT will out accelerate a 125 optimax, like for like. And see it off on top speed. Amazing

 

[Dubed]

Seal behind gimbal bearing is not to keep water from coming in, it's there to keep grease and dirt out.

Yes it's not a packing gland

 

[Chris1956]

I had an '88 Alpha I 4.3LX. I liked it, but lots of stuff broke or wore out. 1 set manifolds and risers: several thermostats, circulating pump and belts: 1 set power steering hoses:2 alternators and starters: 1 set of bellows, u-joints and yoke seal plus the normal maintenance items found on the outdrive, plus carb rebuild, spark plugs, wires, rotor cap etc. I did all my one maintenance and took good care of it. Saltwater is real hard on them. My oil filter rusted thru twice, and my oil pan once. Each spring the bilge had unknown black rusted metal pieces. All in 14 years.

Winterizing took 1/2 day, which was from noon to sundown late in the year, when I did it. On one spring start-ups, my riser gasket failed and hydro locked the motor. No damage but needed to lap risers and manifolds. On another spring startup, the alternator shorted and started smoking. Never had that happen, Luckily I was there to see the smoke and pulled the battery cable.

Let's see on outboards. I only had 2 cycle carb ones, but have had them for 4+ decades. Waterpumps every 3-4 years, an occasional carb rebuild, an occasional set of thermostats, a voltage regulator, PTT motor, spark plugs when they rust externally. Winterizing takes 10 minutes. Once I did need to paint them and get new decals.

OB all the way........especially now with all the high HP ones.

 

[Lou C]

Agreed I’d have a hard time ever buying another I/O. In my saltwater environment they are just too much work. OBs cost more initially but the benefits are worth it.
Longer season, due to self draining design
Better performance due to less weight for same HP
Safer:
less concern with fuel vapors in the bilge no bellows to fail
no cooling hoses in the engine compartment to leak & flood the bilge with sea water
Transom mount & exhaust system design on I/Os has many places that can leak water into the bilge; difficult & expensive to repair, most require an engine pull
Poor access in many modern boats make replacing starters and steering actuators very difficult. In some cases an engine pull is necessary
The boat companies don’t help either they have created designs that look good but make engine access horrible. Example: sunpad walk thru makes engine compartment narrower many have these on the same side where the starter is on every Merc or Volvo V6 or V8 I/O set up. Total lack of planning and disregard for owners and mechanics. No thanks!

 

[muc]

my two cents from 30 some years as a tech.
I like both, but what's right for you depends on how and where you will use the boat.
Just remember that new O/B's are a gift that keeps giving. Mercury Marine sets the price on extended warranties. They feel that outboards will cost double in repairs vs I/O's over the first 5 years.
People seem to bad mouth the catalyst engines. I'm guessing none of them are well trained techs. The cats had some problems the first few years, most of this was due to uneducated techs. At this point in time the cat engines are better then the non cat engines. A good tech can diagnose them faster.
The boat manufacture makes more profit when they sell a O/B powered boat then when they sell a I/O boat.

 

[alldodge]

my two cents from 30 some years as a tech.
I like both, but what's right for you depends on how and where you will use the boat.
Just remember that new O/B's are a gift that keeps giving. Mercury Marine sets the price on extended warranties. They feel that outboards will cost double in repairs vs I/O's over the first 5 years.
People seem to bad mouth the catalyst engines. I'm guessing none of them are well trained techs. The cats had some problems the first few years, most of this was due to uneducated techs. At this point in time the cat engines are better then the non cat engines. A good tech can diagnose them faster.
The boat manufacture makes more profit when they sell a O/B powered boat then when they sell a I/O boat.

Not disagreeing but love to talk or hear more about cost of the two. Your the expert but just not seeing it. Popet valves, water pressure sensors, cat temp sensors, so many problems seen at the forum

 

[Chris1956]

I/Os are obsolete, IMO. I do not see new ones of those at all. All the new motors are 4 cycle OBs. Someone should check the I/O units sold over the past few years.

OBs now have 400HP 4 cycle engines, which outclass the 7.4L BBC I/O. A 150HP OB will outperform a 205HP 4.3V6 I/O, and a 115HP OB will outperform a 3.0L I/O. I think their niche is gone, due to weight and maintenance. At least in my opinion.

My personal experience shows that I/Os are twice the maintenance of OBs. OBs never need exhaust manifolds or risers. Their starters last their life, they for the most part, do not have alternators. They do not have circulating pumps or hoses or for the most part, belts.

 

[Lou C]

Ahh I don’t know it’s hard for me to wrap my head around OBs costing that much more than I/Os especially here in salt water. Most people here do not trailer their boats due to the traffic and roads, so the majority of pleasure boats are kept in marinas or on rotating moorings. In that environment the I/O requires much more maintenance (yearly drive pull drive painting with anti fouling exhaust replacement every 5 years). However due to more complex engine designs on the 4 stroke outboards, & higher parts prices when engine repairs are required yes they are more expensive to repair. I’ve got 20 years of self taught I/O maintenance experience in salt water and it would be REALLY hard for me to buy another here….

 

[QBhoy]

Not disagreeing but love to talk or hear more about cost of the two. Your the expert but just not seeing it. Popet valves, water pressure sensors, cat temp sensors, so many problems seen at the forum

AD. I totally get what you are saying here. Despite me now (unbelievably) being a huge fan of the current 115 Mercury CT 4 stroke I have on one of my boats. The one I use 99% of the time…I honestly can’t sing it’s praises enough…but the huge and overwhelming fact of the matter, with my situation, is that….I wasn’t the one that had to pay for the engine in the first place. I was incredibly lucky enough to have been offered this particular boat from 2002…but having had a 2016 Mercury 115 CT fitted to her in 2017. She then lay unused until I bought her from her elderly owner in 2019. I won’t publicly say what I bought the package for…but I will say that the whole thing cost me less than receipts show the last owner paid for just the engine that was fitted to her just before I bought her.
I bought her with 18 hours on her (10 of which were clocked by the dealer to run her in). She now has around 1100 faultless hours since.
Point being. Great engine…but jeez…would I have been the one to pay 14k for the engine in the first place…to replace her original engine ?? Almost certainly not.
If I was needing to replace the original 2002 Yamaha engine…would I pay the above stated money ??? Again…certainly not…I’d have found an old 135/150 v6 merc 2 stroke and thrown her on it.
Extremely fortunate to have the engine that’s on her now. And what an engine….but I didn’t have to shell out the serious money that it cost.

 

[muc]

Not disagreeing but love to talk or hear more about cost of the two. Your the expert but just not seeing it. Popet valves, water pressure sensors, cat temp sensors, so many problems seen at the forum

I’ll use Mercury Marine because they make both I/O’s and O/B’s. So based on what they charge for their different products I can form an opinion on long term cost.

Pretty big difference when you buy one new.

250 hp I/O msrp $15-16,000

250 hp O/B msrp $25-28,000

Merc sells what they call Mercury Product Protection. This is kind of like an extended warranty. So we can use the price they charge for this as a good indicator for what failures are going to cost over the life of plan.

250hp I/O 5 year extension $1,420

250hp O/B 5 tear extension $5,560

So Mercury Marine feels that the cost for failures in the five years after the original warranty ends will be more than 3 times higher for O/B’s. Another thing we can learn from this is that they offer up to 5 years extensions for O/B’s but offer up to 7 years extensions for I/O’s . Kind of makes me wonder if they figured out how much they would have to charge for years 6 and 7, that they decided people would realize just how short the average life of an O/B is vs. an I/O?

These numbers are pretty consistent where the two product lines overlap.

350 hp I/O msrp $24-25,000 -- 5 year extension $2,700

350 hp O/B msrp $33-36,000 -- 5 years extension $8,460



430 hp I/O msrp 40,000 -- 5 years extension $5,140

400 hp O/B msrp $38-40,000 -- 5 years $13,220



520 hp I/O msrp $39-41,000 -- 5 years $6,770

450 hp O/B msrp $61-65,000 -- 5 years $17,910



Merc sells service interval kits for the 100 hr/yearly and 300 hr/ 3 years recommended maintenance.

V8 I/O 100hr kit $72 -- 300hr kit $378

6 cylinder verado 100hr kit $86 -- 300hr $451

Note that the I/O kit doesn’t include bellows so there will be a slight savings for the O/B by year 6 when it might be time to service the transom assembly.



I’m guessing that what we see on this forum might be due that a lot of people here are do-it yourselfers.

Keep in mind that there are people here looking for advice because they hooked up the battery backwards. People that talk bad about the single point drain system even though they either don’t use anti-freeze for storage or if they do it’s the pink stuff. People who think buying parts off of ebay or amazon to swap out is a substitute for actual diagnosis.



Is it possible that some on this forum look at an I/O and think, hey that’s just like the motor in my car. I can fix that? And people who take the cowl off of a newer high horse power high dollar O/B and seeing all the hoses and wires crammed in there think, wow I better take this to a shop before I screw something up and make it worse?



While I talk to techs around the country, I don’t talk to many who work in salt water. And almost all of my personal experience is here in MN, and that’s about as far away from salt water as you can get. But I do know there aren’t too many 15 year old O/B’s running around in salt water. Part of the beauty of O/B’s is you can cut the bolts off and hang a new one in just a few hours.



My purpose with writing this isn’t to talk someone out of buying an O/B. I think they’re great for some boaters. Part of the reason no one makes a 4 cylinder 140hp I/O is because an O/B is much better on a small boat. I just want people making this decision to have facts, not internet hearsay.



In case anyone is interested,

600hp O/B msrp $80-85,000 – 5 year extended protection plan $21,480 wow

 

[muc]

I/Os are obsolete, IMO. I do not see new ones of those at all. All the new motors are 4 cycle OBs. Someone should check the I/O units sold over the past few years.

OBs now have 400HP 4 cycle engines, which outclass the 7.4L BBC I/O. A 150HP OB will outperform a 205HP 4.3V6 I/O, and a 115HP OB will outperform a 3.0L I/O. I think their niche is gone, due to weight and maintenance. At least in my opinion.

My personal experience shows that I/Os are twice the maintenance of OBs. OBs never need exhaust manifolds or risers. Their starters last their life, they for the most part, do not have alternators. They do not have circulating pumps or hoses or for the most part, belts.

Very few I/O's are sold lately compared to O/B's but I'm guessing that when catalytic converters start being required on O/B's (and that day will come) we will see the pendulum swing back to I/O's. I’m guessing that’s why Merc and Volvo are still in the game.

That 400hp O/B has a very expensive alternator. Starters pretty much last until they get wet in both apps. I think you might be using 2 stroke engines in your 150hp and 115hp comparisons because the performance advantage of an O/B is due to its weight and the new 4 strokes don't have as great a advantage as they once did. Almost all O/B’s over 200hp have belts and most need the valve adjust checked and sometimes adjusted. Anyone who has adjusted “bucket shim” valves knows how much fun that is.

I honestly believe your personal experience. But does that experience include 200-300 motors a year?

 

[alldodge]

Thanks Muc, as before your the go to guy. Never saw those kind of cost

Was thinking about OB myself because I'm getting really tired of hanging upside down to change a bravo raw water pump impeller. Then just paying more then $1000 for a outdrive jack because I'm getting to old to man handel it

CATS give me the Willie's just thinking about what was not thought about prior and during development

Merc cool fuel is crap IMO and raw water pumps are more complex then need be. INDMAR has return to tank so no need for cooling fuel and has fir years. Why does Merc have special cooler for V8 yet V6 uses old style.

The cost to warrant appears to me that they don't trust their own designs much less want to actually warrant them. Do appreciate the cost comparison, does show OB may not be the way to go.

Many thanks, all the best. Look forward to more insights

 

[tpenfield]

I am on my 3rd I/O boat in salt water.

The first one was raw water cooled and the engine was basically worthless after about 20 years of use. Surprisingly, the outdrive was fine.

The second boat, and now my 3rd boat, are/were both full closed cooling. It makes a big difference for longevity.

As @muc pointed out, OB's are expensive, and right now hard to come by, if you are considering a conversion. The cost comparisons are interesting and probably still show that not much has changed.

Merc has gone mostly to in-house production of their I/O engines, with the 4.5 and 6.2 designs, leaving the 8.2 (and 3.0 ?) as the old-school GM engines. Along with fuel injection and smartcraft stuff, the I/O engines are more pricey to fix than their ancestor GM engines of 20 years ago. (probably goes for everything in general though)

To me the real advantage of an OB is the lower unit vs. the outdrive . . . IF (if) you keep the boat in the water. Tilting the engine up out of the water (OB) makes a big difference as far as outdrive/lower unit maintenance. Plus having to paint outdrives and props with AF paint really kills performance.

If you trailer your boat, then it is really not much of a difference I/O to OB . . . IMO.

Then it all comes down to how you use the boat. Stern access for sandbar activity . . . I/O boats still shine. Designs are improving for the OB optioned boats, but you may not have the funds to buy new.

There is no right answer, and it is a matter of what works for you.

Although it looks like I/O's (Merc) are getting more expensive to maintain, OB's are still far more expensive. I would not be too surprised if 'the pendulum' swung back a bit and I/O's maintained a decent (albeit small) portion of the market, particularly in fresh water.

 

[Scott06]

my two cents from 30 some years as a tech.
I like both, but what's right for you depends on how and where you will use the boat.
Just remember that new O/B's are a gift that keeps giving. Mercury Marine sets the price on extended warranties. They feel that outboards will cost double in repairs vs I/O's over the first 5 years.
People seem to bad mouth the catalyst engines. I'm guessing none of them are well trained techs. The cats had some problems the first few years, most of this was due to uneducated techs. At this point in time the cat engines are better then the non cat engines. A good tech can diagnose them faster.
The boat manufacture makes more profit when they sell a O/B powered boat then when they sell a I/O boat.

Muc thanks for the responses here- I think your response for how and where you will use the boat is 100% accurate and biggest factor.

I do larger inland lake boating aka skiing and swimming, so having the swim platform an sun pad uncluttered is important to me. My brother has a fishing CC so the outboard works well there.

I assumed there was no free lunch in terms of maintenance and regardless of it you have an IO or OB you need diagnostic software ( I had to buy if for my seadoo to reset TPS...).

One question on the warranties - regardless of cost diff between them is it worth it for a reasonably handy person to buy them? I have always declined them on my cars as I figured if the manufacturer didn't make money as a whole on them they wouldn't offer it.

Bucket shim - I always paid to have that done on my older VW's , the old ('95) Volvo I had never had to lash in 200k... odd they would make a come back on such high tech engines...

Thanks

 

[Nickm86]

I went from an outboard to an IO and wouldnt go back. For the kids tubing and the look of the boat, the outboard just doesnt work. It is true however that they are generally better in every other way.

 

[Lou C]

The only way I see the pendulum swinging back to I/Os is if the EPA forces the abomination of the cat converter on OBs which will make them even bigger and heavier. Even then, there are still some very significant advantages of outboards:
No bellows that can leak and let water in the boat and ruin the gimble bearing and ujoints
lower unit tilts all the way out of the water
cooling system is all self contained outside the boat, a failed cooling hose
can't fill the bilge with seawater
same applies to the exhaust system, an overheat does not melt exhaust hoses which risks water flooding into the boat
no concern with fuel vapors in the bilge
much easier and quicker winterizing, can use boat later and earlier in the season

I/Os made sense when OBs were crude, thirsty and smokey and I/Os were powered by simple to maintain & repair GM marine engines. When they went high tech, both because of regulation and Merc adding so many features, the complexity and repair cost became big issues. Yes OB parts are very expensive but check what Merc charges for engine parts on the new 4.5 which to me, looks like they bought the old GM 4.3 tooling and just updated it a bit and refined it with modern integrated ignition, engine controls and EFI. Why? because it has the same included angle of 90*, same balance shaft, same even fire crankshaft (split journal crankshaft) everything looks VERY similar except for some modifications to the cyl heads. If you were designing an "all new" V-6 why would you use a design that GM used to save money, many years ago (making a V6 by cutting down a V8, they did this with the Buick 231 V6 and later with the Chevy 3.8 and 4.3 liter V6s), then adding an even fire crank and balance shaft. You'd design a modern 60* V6 with DOHC and variable valve timing. They have given us an update GM pick up truck engine, yet they charge like 3x the price of standard GM parts. And how about making closed cooling standard Merc, instead of that rats nest of plastic parts and feet and feet of cooling hoses? Closed cooling is the main technical advantage of an inboard vs outboards! So exploit it then, instead of these silly easy drain systems that clog up with cast iron rust flakes in salt water (yes that happens here), with plastic parts that can break and cause leaks.
Why then would people put up with the designed in drawbacks of I/Os?
I love Chevrolet small blocks but I'd like my next one better in a '69 Camaro, !

For me, I will repower this old boat with its ancient ignition and fuel system, and add closed cooling to the new engine. That's about 1/10 the price of any new boat I'd like to have.
I'm nearly totally independent of mechanics this way and have a bunch of OMC Cobra spares in my garage!