Why do I/O's have short engine life?

[hibbert6]

I'm looking at 10-15 year old runabouts and I'm amazed at how many have new or rebuilt engines, usually a 4.3L v6.

Given that in a car, that same engine should last 100,000 miles, or 1500 hours, easily (with only minor maintenance) why do these engines typically last less than 500 hours in a boat? Is it the high rpms and rapid acceleration that ski boat engines are exposed to?

Dave

 

[ChrisCraftJohnny]

Re: Why do I/O's have short engine life?

When you are cruising on the Xway, what is your engine RPM?

1800? 2000? 2200?

Your transmission takes care of this for you.

In a boat when you are cruising what is your engine RPM?

3200? 3600? 4200?

Huge difference. Plus, it stays in these RPM's for a long while. Full load, high RPM's and let's not forget salt water, even fresh water for that matter, over time getting into places that it should not.

Don't forget raw water cooling. Your auto engine has it's own private Idaho when it comes to cooling. An I/O uses caustic sea water or pond/lake water to cool itself. With all that comes along with it.

The street environment, and the water environment are two extremes set apart.

Johnny

 

[wire2]

Re: Why do I/O's have short engine life?

It takes a lot of energy to keep a boat on plane. Just observe how fast it settles down into the water when you cut the throttle back to idle.
A car will coast ? mile if placed in neutral at 65 mph.

The point being; a boat engine is working hard ALL the time, not just from a stop. So it wears out much faster than a car engine.

 

[Lou C]

Re: Why do I/O's have short engine life?

I have not found that to be the case at all, mine is 22 years old (unknown hours but at an average of 50 a season, well that's a fair number)...if you do the maintenance and keep water out of the exhaust....run at about 3/4 max rpms (like 3500) as a normal cruise...don't let it overheat...1500 hrs plus should be easily attainable. Even here in salt water in fresh water its common to find IOs with up to 2000 hrs on them. You are most likely looking at beater boats that were not kept up...

 

[Bondo]

Re: Why do I/O's have short engine life?

You are most likely looking at beater boats that were not kept up...

Ayuh,.... Exactly,....Lack of Maintanance...

 

[airdvr1227]

Re: Why do I/O's have short engine life?

I agree. Alot of boat owners look at them just like they do cars. They don't understand how things work so they have no clue as to how it should be treated and maintained.

I hear people talk about warning buzzers and such. I have none of that on my '91 so I imagine a whole bunch of people never bothered to check the gauges until they smelled something burning or the engine just quit.

 

[Bifflefan]

Re: Why do I/O's have short engine life?

In a boat when you are cruising what is your engine RPM?

3200? 3600? 4200?

Johnny

You must be pretty young. It was not so long ago that the normal cruse RPM in a auto was 3000 to 3200.
And those motors lasted as long or longer than they do now.


To the OP, my boat is 26 years old and running strong as ever, and per the hype I have the worst one in history. A 470.
It sonds as if you need to keep looking, as the ones your looking at right now are on poor side of maintance.

 

[Philster]

Re: Why do I/O's have short engine life?

RPM? ::shrug:: Not so much of an issue at all.

Got everything to do with:

Load on the engine (a boat engine has the stress of pulling a full load uphill almost all the time)
Wet exhaust
Not 100% closed cooling, and most have raw water cooling
Lack of maintenance
Lack of regular use
Difficulty in getting maintenance done
MONEY

You gotta spend money on the car that gets you to work or the boat that sits 80% of the time.... and you choose the car... although some don't! Still, the family car gets the 1,000 dollar repair and tires. The boat? She doesn't take you to work (for most) or get the kids to soccer practice... so she rots....

 

[guyaverage]

Re: Why do I/O's have short engine life?

It was not so long ago that the normal cruse RPM in a auto was 3000 to 3200. And those motors lasted as long or longer than they do now.

No doubt, I learned how to drive on a 1980 Honda Accord. At 70mph, it was just a tick below 4000 rpm. The old man was religious about changing the oil at 7500 mile intervals, and the engine went well over 200,000 before they traded it in.

Most boats dont last because the owners dont maintain them, and if most prospective owners were honestly told how much maintenance the boat would require over its life, they probably wouldnt have bought it in the first place. Boating isnt cheap.

 

[Howard Sterndrive]

Re: Why do I/O's have short engine life?

a couple weeks ago, I talked to charter guy with a single 454/Bravo
He runs 1500 hours per year.
he has had the boat 5 years and changed the drive once, but not the engine
that's 7500 hours, and it was a used boat when he got it

 

[Howard Sterndrive]

Re: Why do I/O's have short engine life?

to propel a compact car down the road at highway speeds takes about 25HP.
regardless of the gearing and the rpm, the engine is not working hard in a car

 

[Doernuth]

Re: Why do I/O's have short engine life?

Lack of use is as hard if not harder on an engine as regular use. As an engine sits oil settles back into the pan. When you turn the key some of the moving parts are un lubricated.

Use a car engine like that and you have problems too."

 

[Lou C]

Re: Why do I/O's have short engine life?

And as long as you have proof that the engine in the boat is really NEW if the price is right and the rest of the drive system and boat structure is good then it can be a good deal. Honestly your biggest problem in 10-15 year old boats is not replacing an engine...it's WOOD ROT.....I might not shy away from an older boat with a new engine but one with wood rot...well run like crazy is all I can say. Replacing an engine is easy compared to ripping up and replacing a deck....

If I am evaluating an older boat...the first thing I"d look at is the structure...if it's bad...forget it...if it's good...then we move on to the mechanicals....

and looking at the money end of it...I built a new version of my old boat on the Four Winns website while I was doing my rebuild...$420000 list for a nicely equipped Horizon 200 but the new model is almost a foot shorter than my old one and the engine access is not good like on my old one...so I'm not sorry I fixed it....

 

[security6]

Re: Why do I/O's have short engine life?

Many have mentioned lack of maintenance as the cause, but to be even more specific: Many perfectly good boat engines are ruined every year due to lack of winterization. Look at the threads in this forum from March to May, and you'll see lot of questions about cracked blocks.

You see a lot of 4.3's being replaced because they are found on many boats geared towards the first-time boat owner. First-time boat owners often need to attend the school of hard knocks to learn about winterization. Not that larger engines are immune to lack of winterization, but first-time boat owners tend to buy smaller boats with smaller engines (like the 4.3), and experienced boaters tend to want a bigger boat then their first boat, and bigger boats have bigger engines.

 

[jkust]

Re: Why do I/O's have short engine life?

Yep here in MN, lack of winterzation is common. Or people try to do it them selves and don't get all the standing water out of the pasages only to realize the next season. The 3.0's and the 4.3's are great for first time owners though when I see 4.3's I believe it's because people didn't buy the optional v8 due to the expense not necessarily because of first time statue. Due to our extremely short boating season, lot's of boats don't see the use they should and they just sit. There are plenty of original, ancient I/O's out there. I have several outboards and an I/O and hands down the outboards require less maintenance.

 

[IES99]

Re: Why do I/O's have short engine life?

Mostly from lack of proper maintenance.

 

[sethjon]

Re: Why do I/O's have short engine life?

I'm looking at 10-15 year old runabouts and I'm amazed at how many have new or rebuilt engines, usually a 4.3L v6.

Given that in a car, that same engine should last 100,000 miles, or 1500 hours, easily (with only minor maintenance) why do these engines typically last less than 500 hours in a boat? Is it the high rpms and rapid acceleration that ski boat engines are exposed to?

Dave

High RPMs is part of it. Many people that get a 4.3 are underpowered. That means for the most part they are hauling *** when cruising or are pulling tubes and skiers a lot. I think the biggest reason is simply lack of maintenance. They take a lot of abuse and need to be tended to, particularly changing fluids.

 

[6meter]

Re: Why do I/O's have short engine life?

If you read this forum, you are reading about all the problems people are having with there boat. How many other people aren't on here because they are not having problems? Most of the problems are caused by ignorance or laziness. Don't winterize it, I'll fix it later. Channel markers mean nothing. What do you mean, I'm supposed to check the outdrive oil level? Generally just the lack of maintenace.

 

[109jb]

Re: Why do I/O's have short engine life?

I don't think the number of rebuilt motors in I/O's has anything to do with the RPM's, load on the engine, etc. I think you are seeing a lot of engines that had to be replaced because the boat wasn't winterized properly or at all and something froze and busted. Outboards don't have this problem because the water naturally drains out of them. If it didn't drain out of outboards I would bet you would se a lot of ads saying "new powerhead" or something to that effect.

 

[zip34788]

Re: Why do I/O's have short engine life?

Oil change and maintenance is the make it or bust it factor.

I once had a 26' SeaRay with twin 4.3 V-6's. When I sold the boat it had almost 1100 hours on the Starboard engine and 950 on the post side. Neither engine was ever overhauled. They were both running strong and smooth when the new owner took the helm.

I think my success came from religiously changing oil and filters every 25 hours. Most boat owners will on rare occasions check the oil level, but never think about changing it.