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For Average use and Good maint-what is the average hours of use before a marine engine-like a 500 needs an overhaul. Most of us think in miles-not hours. Time for our experienced mechs to step up with some opinions.

What percentage of life left in 450 hour engines?
 

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It's depends in the engine. If it's not a Hi-performance engine - like a cruiser engine; typical times for 600 to 700 hours.

For a high-performance engine (like the ones we like) I think you're looking at a rebuild at about 400 hours.

For instance I turned down a beautiful 35 Fountain last summer because it had pro-charged engines with 200 hours and all of my buddies told me that I'd only get about 2 seasons out of them before I'd have to have them rebuilt... new rings, bearings, etc...

- jeff
 

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It really depends on the care,,, when I pulled the 454 to install the 502. I did all the tests on it ,,, you would swear I was testing a brand new engine and it had like 540 on it.

Stick your finger over the hole for the breather and it draws a vaccum on your finger ,,, instaed of blowing it out !!!!
 

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gilla,I really don't think there is a magic number on how long a engine will last.I know people with 1000 hours on their motors,and no work done expect normal maintenence.

I pulled my upper half of the engine apart a week ago,and I was amazed at how clean it was. I have (as far as I know)a little over 550 hours on the motor.

I disagree about the difference in time between a cruiser and a performance boat. I think most performance boat owners pay much more attention to maintence,and most I know(me)are very anal about keeping everything extra perfect. Where most cruisers are just that,pure pleasure and not so much detail to their motors maintenence is given.Just because we run our motors a little hard,doesn't necessarily mean their life span will be cut any shorter. It's all in the care given,boat motors are designed to run at high RPM's.That's their purpose in life.Thank God!!!

Not saying thats 100% true,just my observation.

This should be a very opinionated thread.
 

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High RPMS's

I know guys who continually run their engines at 4,000 to 4,500 rpm's and in my personal estimation... I don't care if you change the oil every hour.....any engine run like that is not going to last as long as one that's run at 3,500 with equivalent maintenance.

Yes, marine engines were built to be run at higher rpms than conventional engines. but who's kidding who. If you only ran your car engine for 400 to 500 hours you'd have to park it after a few months.....therfore I'm not sure if I really BUY into the old bromide that marine engines are built to be run at high rpms. Whose to dispute that you can run a car engine at these rpms's for these number of hours and not wind up with two engines in the exact same shape. Perhaps it's all just a consirpacy spearheaded by Mercury Marine and promulgated by everyone else in the marine industry to keep sales up and profits fat! It seems to me that marine engines are looking more and more like automobile engines everyday.... closed cooling, efi.....etc...

'IT'S ALL A BIG CONSPIRACY!!!!!"

I'M MAD AS HELL AND I'M NOT GOING TO TAKE IT ANYMORE!!!!!!!!

:)



:)

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Where every post counts.....
 

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Like I said,this will be a very opinionated topic.

I wish I took pictures of the inside of my motor when I had it apart.All motors should look that good after running the way I do. To be truthful,my boat normally knows 2 speeds. On the trailer and WFOT..........I do cruise occasionally,but I use my boat for MY pleasure.
To me(and again just my .o2)whats the sense of the power if I'm gonna drive in the slow lane!

I guess if I drive my car at 35 mph and never go 70mph,it could laster longer too!!:confused:
 

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I agree with Jeff. I run a hp500, and I run it hard. I believe Merc tells us 300 hours for a rebuild. What ever they say is what I am going to do. They know more about there engines than anyone. By next fall if I have 275 hours I'm pulling the engine. To me its not worth the down time the next season. We only have about 4 good months and yet we pay for them all year. So if Merc says 300 hours, thats what I am doing. With this engine I am taking no chances!
 

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Canada Jeff,I don't totally disagree......
It's YOUR dime,spend it any way you like.

But I'm sticking to my ORIGINAL statement.I DON'T believe there is a MAGIC number.

Does Merc give you different options for overhaul ?
One if you run it hard,and another if you do more cruising??????:confused: :confused:
If so,please post .......I would like to see it!!

Hey,another ORIGINAL statement in my 1st thread,this will be a very opinionated subject.

I'll trust my 15 years experience as a line technician.......But again,another opinion

:D
 

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Engine life = ?????
Way too many varibles to consider. Like most have said already, maintenance and care are priorities. RPM's play a role, as do type of boat, how it was used or driven.
The hardest time on an engine is during crankup, after that long idle periods. Engine's will run their best and last their longest when run at their optimum rpm, which varies on setups, cam, timing, fuel, etc. Most hi-performance engine's breathe their best usually 500 to 1500 rpm below their max.
Unless you personally know the boat, take compression readings and check the plugs when buying used. This will tell most of the story ! :)
 

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Obnoxus tells it like it is.


Canada Jeff,
What year HP500 are you running. I know from past posts that they eat valve springs. 300 hours seems very quick for a re-build. I agree that you don't want the boat to be down over the summer. I wonder what parts Merc thinks are going to wear out so soon.
Dan
 

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Actually there may be more wear on a cruiser engine than a performance boat.
A cruiser is heavy and in many cases-underpowered. It's engine or engines are constantly under an uphill load. Most performance boats are well or overpowered meaning that unless they are getting on plane or WFOT they are spinning much more easily -higher RPMS but lower torque. The torque that a motor has to produce is what causes more wear on the internals. Of course a marine motor always has to produce more torque than a car motor thus the lower life span.

It is likely that the reason merc has a 300 hour rebuild on an HP500 is to check for stress type failures due to the repeated high RPM operation.

A good rule of thumb is that the closer an engine gets to 1 HP per cubic inch (or higher) the shorter it's overall life will be.
 

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Discussion Starter · #17 ·
On my dirt cars, we ran 454 and 427's .100 over. They never did blow-didn't go over 6,000 but worked em hard coming off the corner at 4000 rpm. Because of the torque of the big blocks, I geared with a QC so I could come off the corner w/o spinning-just hooked up-regardless of the size of the track. They easy went a 1000 to 1200 laps-they just got a little tired and you new it was time to freshen them up. Unless you have a part failure- I would think you could run them until you noticed a difference in performance and/or a problem with a regular comp check as you guys stated. Crank em up-put a broomstick to your ear and listen to the health of 500 ponies.
 

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I asked this question to a hi po mechanic that does work with Sunsation and he told me that there is a good chance I could go 1500-2000 hours on my 502 without having to crack it open. And no he doesn't work for Sunsation so he wasn't trying to sell me anything. Rob was the mechanic working on the boat from St Louis that had a coil puke on the HP 500 s at the Sunsation Rally.
 

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Discussion Starter · #19 ·
2000 hours at 45 mph is 90,000 road miles on a car engine. Sounds about right-most gas engines start using oil and get tired at 90,000 miles. At 100 hours of boating a year-drive on for the next twenty years, then worry.
 

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Aggressor Tom, I agree that a stock unblown big block used by the average boater, should easily go 1500-2000 hours.
But performance boats that are constantly run on the edge are going to cut those hours in half or much less.
Gilla, its like comparing your tow truck to your race car.
I'm betting your Crownline would go 2000+ hours, where Boatnut or OB would only get 400-500 hours. (no offense guys)
Unless you know the boat, do the compression test. If they refuse, find another boat, or be prepared for engine work or replacement down the line.
If I'm ever able to get back to boating, we've decided on ordering a new Checkmate just to avoid the headaches. Much simpler ! (actually I just think she agreed just to calm me down for now)
:smile1:
 
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