How many hours will a marine engine run?

[KD4UPL]

So how many hours is considered "a lot" for a marine sterndrive engine? Specifically I'm looking at a 2002 boat with a VP 5.7 GXI that has 900 hours. That's certainly more hours than a lot of similar used boats seem to have. Thinking of cars (which I know is totally different) an engine with 200,000 miles might have well over 4,000 hours on it. I know farm and construction equipment often runs thousands of hours, how about boats.
I realize maintenance plays a big roll but surely there must be a design life for an engine. Let's assume a VP V8 is properly maintained "by the book" for it's whole life, who many hours does VP expect it's engine to run?

 

[Baylinerchuck]

One thing to keep in mind on hours is RPM. Cars spend most of their life under 2500 rpm and rarely run for long periods of time over 3000 rpm. Boats don't have variable gear transmissions and are run from idle to Wide open throttle fairly often. Boats are more apt to be used more consistently in the upper rpm range. I think the longevity of the engine is a direct reflection of HOW it was used, as well as how well it was maintained.

 

[SeaDooSam]

As Baylinerchuck said It is not really about the hours. It is more about the maintenance and how the engine was run. Something that was going WOT it's whole life will likely croak at lower hours. I have heard anything from 1,000 to engines going to 2,500 hours. It all depends on upkeep and preventative maintenance. What kind of person owned this boat? Was it an older couple, a family, or younger people? Do they have service records?

Keep in mind a boat with 900 well cared for hours could theoretically be much better than a boat with 100 hours because that means the boat has sat. When engines sit, the seals and baskets go bad. Check the overall condition of the boat? If it is clean, that is one sign of a well cared for boat.

 

[four winns 214]

I'm getting ready to buy a boat with 950 hours from a meticulous boater who maintained it well. The number of hours reflects that was run regularly for the life of the boat. There was a boat of the same type and year for sale that had 29 hours on it. I didn't even look at it.

 

[fhhuber]

how many years/miles will a car last?

Depends on maintenance. Keep it up and it can last a very long time.

 

[jimmbo]

Part of an Engines key to longevity is maintenance, another part is operating parameters(load, rpm and for how long). Continuous running at max throttle will definitely shorten its life, especially in the valve train. Same goes for full throttle before engine has been at operating temp long enough to warm up the oil. Overloading an engine (too much pitch for the load) will place enormous stress on the engine leading to, but not limited to: Carbon buildup behind rings, stuck rings, failure of oil cushion on Connecting Rod bearings. Frequent Oil Changes and careful selection of the Oil and Oil Filter used will be a factor too. Not all Oils and/or Filters are up to snuff for marine engine use.

Just shy of 1000 hrs is a long time if the engine was at WOT. If it lived most of its life at 1/2 to 3/4 throttle, it should have many more hours left in it. Have you done a compression test? A vacuum gauge, in the right persons hand, can tell a lot about an engines condition. When listening to the engine run, pay close attention to any noises(knocking, very loud ticking) that point to worn bearings

 

[Scott Danforth]

first, for the 2002 model year whether its volvo penta or mercruiser, the big old lump of iron in between the exhaust manifolds and under the intake is a GM truck motor

with normal maintenance I/O motors will go well over 3000 hours. 1000 hours is just broken-in in most cases as there are many hours of idling, light cruising, etc

even if the motor was at 4000 RPM its whole life, that would be like a car doing 80 mph for 72000 miles

Maintenance is the key.

Since your looking at a GXI, the I is fuel injected. get the engine RPM history. it will tell you number of hours a which RPM, including total run time.

my daily driver has over 205k miles on it and I routinely hit 5500 RPM every shift zipping thru traffic and drive for extended periods of time at 4500 RPM - yeah I flog it like I stole it. however every 5000 miles it gets an oil change (every 2-3 months), new plugs every 50,000, timing belt every 75.

 

[dingbat]

Hours are irrelevant. Kind of like asking how old do beef cattle live.....lol
Boat motors don't die of old age. Most die from overheating, corrison and neglect/ lack of use.

 

[Bondo]

Let's assume a VP V8 is properly maintained "by the book" for it's whole life, who many hours does VP expect it's engine to run?

Ayuh,.... I agree with dingbat,... My 4.3l is pushin' 2,000 hours, 'n still has nearly new compression numbers,...

I'd expect to see 'tween 3,000, 'n 4,000 hours outa it, if I keep it that long,...

 

[alldodge]

I consider high hours for a gas engine 1000 hours unless I knew who took care of it personally. At 1500 even with great care I would be looking at an over haul.

 

[KD4UPL]

Thanks for the responses guys. I was planning on taking my mechanic friend with me to look at the boat to do a compression test. I'll add vacuum test to that list.
I assume I would need a professional marine mechanic type scan tool to look at the engine hours or will any regular auto scan tool do it? Is it a regular OBDII port or something marine specific?
It sounds like 1,000 hours might be a lot for a boat run fast a lot or I could get another 1,000 out of it. I probably only put about 60 hours a year on a boat so 1,000 more hours would last me a long time.

 

[89retta]

When I bought my boat it was showing 280 hours. Took it in to have an inspection on it before I bought it. In reality the motor only had around 100 hours and most of those at idle. The guy I got it from had the key turned on to listen to music so he was racking up hours. Don't just go what the hours say

 

[ondarvr]

As mentioned, boat motors rarely wear out, they die for many other reasons long before their useful time is up.

 

[Lou C]

The things to do to make it last:
Maintain the cooling system (impeller, thermostat) and exhaust system (manifolds, risers, gaskets). Failures in these 2 systems are responsible for most premature engine failures. Cooling sys problems cause overheating which is obvious but the damage caused by leaky exhaust is not obvious, but causes corrosion of the exhaust valves, and low compression and rough running. Salt water boats especially need to have the exhaust inspected and probably replaced every 5-7 seasons.
Make sure the engine is properly propped so that it reaches its specified wide open throttle rpm. If your WOT rpm is too low it causes the engine to labor and will overheat exhaust valves and cause low compression and rough running.

My personal opinion is that inboards even in fresh water should be closed cooled because even fresh water will corrode cast iron and if you look inside the cooling passages you will see it, a layer of rust that impairs heat transfer. So if you buy a new boat, or re-power with a new engine, add at least a half system to protect the engine from internal corrosion. GM intended these engines to run with a pressurized cooling system with antifreeze with corrosion inhibitors. Outboards are designed to have open cooling, inboards were not really.

 

[H20Rat]

even if the motor was at 4000 RPM its whole life, that would be like a car doing 80 mph for 72000 miles

Not really apples to apples though. My car has a little 2.0l 4 cylinder in it and runs 3000+ rpm at highway. That is nowhere close to the load a marine engine is under, because I'm also around 10-15% throttle at highway speed. (yeah my car gives you throttle percentage readout also) 10-15% throttle on a marine engine would be a decent trolling speed. 50% throttle in my car is somewhere in the neighborhood of 110-120, so running around at that speed for 72,000 is a much more accurate comparison.

 

[jimmbo]

My First 5.7 Litre VP lasted 128 hrs. Near the end of its second, it sounded a little noisy, like it had mechanical lifters. I happened to lean against the remote oil filter and noticed it was cold. When I bought the boat I didn't want the hassle of trying reach the filter in the stock location. I had the dealer install the Volvo remote kit. Oil lines were cool too, the engine had been running for a couple hours and they should have been hot. I knew that the oil filter has a drainback valve aka check valve.
I suspected the oil lines were installed reversed and the check valve was preventing the oil from going thru the filter. Oil pressure had been fine, but a bit lower than when brand new. It had pressure to the sender because the bypass valve in the block had opened due to the blocked filter lines. So for its short life the engine never had filtered oil
I took the boat to my dealer, told them what the engine was doing. They looked at it and admitted they did hook the lines up wrong. Main Bearings shot, Con Rod Bearings shot, Cam Bearing worn, Camshaft pitted, Crankshaft worn out of round and grooved, Lifters plugged. Pistons were worn, but the rings were still within tolerance. A new longblock from VP arrived and I was back on the water.

 

[Maclin]

FWIW, a Marine engine's duty cycle in a boat with a planing hull is kinda like a reverse tractor pull. Starts out heavy then lightens up. Some.

 

[Scott Danforth]

Not really apples to apples though. My car has a little 2.0l 4 cylinder in it and runs 3000+ rpm at highway. That is nowhere close to the load a marine engine is under, because I'm also around 10-15% throttle at highway speed. (yeah my car gives you throttle percentage readout also) 10-15% throttle on a marine engine would be a decent trolling speed. 50% throttle in my car is somewhere in the neighborhood of 110-120, so running around at that speed for 72,000 is a much more accurate comparison.

my little daily driver is a 2.4 liter 150hp 4-banger that has 3 throttle positions. standing on the brakes, mashed to the floor or about 3/4 throttle cruising at 80mph (just under 4000 RPM). depending on traffic, I may not lift when I shift. however driving in the 11th worst metro area in the US for traffic, its safe to say, I do not baby it like most people would their cars or boats. However I maintain the heck out of it to get longevity

percentage of throttle is less important than IMEP (cylinder loading)

we all know marine motors are under stress for the hole shot and WOT cruising. similar to a loaded truck pulling a trailer up grade while in sand. however, not everyone is in a perpetual holeshot or at WOT.

my point was engine wear is a function of maintenance as well as loading.

 

[Scott Danforth]

FWIW, a Marine engine's duty cycle in a boat with a planing hull is kinda like a reverse tractor pull. Starts out heavy then lightens up. Some.

nice way to put it

 

[Peter Eikenberry]

Lets do apples to apples. My 1972 Sea Ray 190 has a Merc 165 (essentially a GM 250) it's 44 years old. Most of the stuff hanging on the block has been replaced, but the block has never been opened up. It still has good compression. Doesn't burn oil. It has gotten routine maintenance. (I'm a fanatic about oil changes) every spring and fall, and in between if necessary. Hours? I haven't any idea. I run it about the average most people do, about 100 hrs a year with some years less, some more. I only run it hard occasionally (my wife doesn't like speed) but usually keep the throttle about 1/2 to 3/4. Runs fine.

Point is, if you take care of it and don't abuse it it will last. Not forever, but a good long time.

Years ago I ran a Coast Guard facility that overhauled diesels and outboards. The outboards were used and abused, run hard and put away wet. We rebuilt them consistently with less than 1000 hours. Most of the diesels were 6v-53 Detroit diesels. The ones that came out of boats had the same problem as the outboards. Used and abused, and had to be overhauled at about 2000 hours or so. However the ones that were used on generators lasted many years. Some over 20 years before overhauls. Hours were irrelevant because these engines were maintained and taken care of. Plus, they ran at pretty constant speed. So it all comes back to use and maintenance.