Used Boat "Hours"
 

To frame up this question, Im talking about Mercruiser BBC Black motors. (454, 496, 502)

STOCK, never opened up. But well maintained. (As that is all I would consider)

What do all you consider "A lot" of hours on a used boat engine?

300, 400, 500, 600?

400 is a lot, but I have seen boats for sale with 600!!!

Depends on the age, 300 hours on a 10 year old motor isn't bad. 30 hours a year for example however 300 hours on a 2 year old motor is bad

black engines will last quite a while if properly maintained and they weren't ragged on.

before rebuilds 1000 hours isn't uncommon. Performance boats maybe 800.

How is it bad? Regular use is better than letting it sit and use it every so often.

With proper maintenance those engines should go 1000hrs.

Depends on how those hrs were spent..........wot -redlined or crusin' i'd think.

I looked up the lifespan of stock power on other forums. From what I have found is most stock motors die an early death from overheating or water ingestion, both usually from bad manifolds. There are claims on iboats.com of black motors making it to 3000hrs over there. My motor has 560hrs on it and runs like a watch.

If you want a 2 year old motor that has 300 hours than more power to you! I don't. A diesel powered truck may last a million miles if properly maintained but who would buy a 2 year old truck with 300,000 miles?

My truck monitors how many gallons of fuel it has consumed. If you could get that on a boat, then you would be able to determine if 300 hours in 2 years was bad. IMO... hour meters are useless by themselves. Since you don't have "gallons of fuel consumed" you have to use other indicators, such as the condition of the hull. How clean is the boat inside and out. Do all the accessories work. How clean is the bilge? etc. Hour meters alone... no indication of how much torture the motors have seen.

I think this is the biggest criteria.

I've got a bud with nearly 2000 on a carbed 454 at 17 years old. I'd bet no more than 50 were at redline, the rest cruising.
His last compression and leakdown were still spectacular.
I completely agree with the usage staying regular and not lots of downtime between taking it out on the water.
His thoughts are like its comparable to a truck with 100k miles and he feels that he should make 3-4000.
My 525 SC's have 550 and still have great comp and leakdown. One member posted years ago that Merc racing benched tested this package for 1000hrs with rpm's between 3500 and 5000 during testing!!!
I however am as nervous as a schoolgirl on prom night.
I wouldn't sweat the right boat with 1000, just make sure and survey the engines with a comp and leakdown test.

Happy new years eve, remember to keep it safe!!!

See ya,
Kelly

Those with 500+ hrs on stock black motors. Have you replaced or going to replace valve springs as "regular" maintaince?

So answer the question. How is a 2 year old engine with 300hrs worse than a 10 year old engine with 300hrs?

More info:
The boat is immaculate. (I wouldn't be interested otherwise)

Its a 1999 Sunsation Aggressor. With a little 600 something hours on a 7.4 MPI.

I like the looks. But I think I could find a nicer one for about the same $$

If you like the boat and the price I wouldn't sweat it.
Just write an "offer to purchase" contract with a reasonable
(10-25% refundable) deposit and state that results from a survey on the boat plus powertrain and a seatrial are dealbreakers if they come back with results as to what you feel are such.
I, and a few others here, saw MAJOR price reduction below the contracted purchase price after the survey.
I got 25% of my price dropped due to non-disclosed baby pencilhead blisters below the freeboard for the price of repairs to sand them out and apply new gel coat.
I never saw my boat in person, only in pic's from the seller over 2000 miles away.
I had a TEAM MERC marina perform the powertrains first and the survey/seatrial afterwords
Most folks here will tell you that a survey by an accredited marine surveyor is your best money spent.
I'm sure you wouldn't purchase a home without a home inspection by a licensed inspector.
BTW, the only times my bud has pulled his valve covers were at each several hundred hours to look for sludge beneath.
The valvetrain is still stock.

See ya,
Kelly

I have 800 on 92 502 carb engines and they run perfect . I would say most of it is at 4000-5000 rpm! I have 2 friends with Formula cruisers that run pretty hard with well over 1000 and never opened up.

Think about this. 1000 hours on a stock 454 or 502 run at 30 mph for the lifetime is 30,000 miles.
ed

These miles are uphill pulling an overloaded trailer, in a boat. When you are cruising down the road at highway speeds your engine is turning around 2000 RPM's. I don't know too many people that cruise at less than 3000 in a boat. Also look at the MPG, that is a good indicator on engine load. A boat, depending on hull design, with a BBC will get 1-5 MPG. A truck with a BBC will get in the teens. Fuel consumption is related to load. 1000 hours is more like 200,000 plus miles.

I don't know when they started it but on later model Merc's the computer stores how many hours the engine has spent it each RPM range. I think it is broke down into every 500 RPM's. Ex. 1000-1500, 1500-2000...etc... I'm sure someone on here knows if your rig has this in memory.

That would be engines with a PCM 555 meaning 496 mag, 496 HO, 525 EFI......etc.

600hrs wouldn't scare me.friend of mine has a '98 38 PQ w/ T-502 with just over 1200 original hrs.Starting to burn some oil now but otherwise no issues

Keeping the golden rule of salt water in mind (if it ain't running it's rotting) I would prefer the 2yr old motor with 300 hours.

One of the local PD's had 502 powered Scarabs that would run anywhere from 3,000 to 5,000 on a set of engines.

Happy New Years,
RB

Remember, stock bbc 454/502 require a top end rebuild at every 250-350hrs, that's approx. $2500. 500-600hrs require bottom end, that's not cheap, so consider the hours and ask if top and bottom rebuilds where done timely. 496 is different, and a lot more stout, I think it's 800hrs for the first rebuild.

Good Luck

Who said it was worse? I said that 300 hours in 2 years is bad compared to 300 hours over 10 years and by bad I didn't mean that the motor is "bad" just referring to it having a lot of use in a shorter period of time. I've taken my boat out almost every weekend since I bought it in June and I still haven't put 30 hours on it yet so to me someone that puts 100+ hours in a year is a lot. That's just my opinion but opinions are like azzholes, everybody has one!

Not everyone is running in saltwater though.

That is a requirement for a box stock Mercruiser 454 or 502 ? Probably the most overlooked maintenance requirement in the marine industry.
ed

You did. Post #3 in this thread.

I put 150+ hrs a year on my boat, as anyone who has owned boats know the more you use them the better everything stays working. The worst thing for a boat is to sit unused. In south florida we boat year round. Any stock engine outboard, I/O ect that isn't a HP model will easily run for 2000 hours if it is maintained properly. As somebody else said the hours are nearly meaningless on a used boat condition is what is important, that is especially true of an older boat running a 454MPI or 502 ect. A survey and engine inspection are the best options.

And your comment about the diesel truck is wrong also, a two year old truck with 300k miles means the thing was driven on the highway almost exclusively and will have very little wear and tear compared to a 10 year old truck with 300k miles. Like you said just my opinion.

At 600 hours my main concerns would be how hard the engines were normally run and if regular maintenance was performed. If the previous owners ran the boat conservatively, and if the engines had regular maintenance performed (documented maintenance history), and the numbers on your engine survey look good, you should be fine. Otherwise, run Forest run! :whistle:

not on a black engine maybe blue

I could not agree with this more - boats were meant to be used. When they sit around collecting dust things begin to deteriorate. I would not be concerned with a well used, well maintained motor. As said several times above, get a survey!

Not even close to being true. 454/502mags have better internals than 496s and they don't need anything done to the top ends until maybe 700-1000hrs.

I think its common knowledge that the 502 is the best off the shelf platform.

Another Question.

After 1000 hours of meticulous care (high quality oil, changed at good intervals) And Normal performance boat use - How much HP is lost?

As in - is a 415HP 502 still 415HP?

I think someone earlier was pretty accurate in where the motors were ran, salt or fresh water, how hard it was ran, 525's that have 70 race hours on them vs 300 hrs of typical cruising rpm's 3800-4200 for 75% of its life, and obviously meticulous maintenance. I've argued with friends when they said over servicing an engine is a waist of money. Oil changes at 25-50 hours of normal weekend use, plugs and wires annually, impeller kits every 50-75 hrs etc. all these things give the motors optimal life. Unfortunately, things do happen and parts break so I always believed in controlling the condition of the parts that were easy to maintain. We have friends that had 600-1100 hrs on Merc motors and ran them religiously. Hours don't bother me, boat condition tells you just as much.

That varies, but if its still running good with no issues, then it probably has not lost much. A leak down test will tell you a lot.