Boat engine reliability

[Bpracing1127]

Ok so I have seen some talk about certain boat engines not lasting as long as others. So I wanted to get peoples opinion on what are too many hours for a boat and which engines last longer than others.

496 mag
496 mag ho
Older 502
Hp 500 efi
Hp525
600 sci

Will these go 1000+hours are the ticking time bombs past 500?

 

[Tooms22]

Ok so I have seen some talk about certain boat engines not lasting as long as others. So I wanted to get peoples opinion on what are too many hours for a boat and which engines last longer than others.

496 mag
496 mag ho
Older 502
Hp 500 efi
Hp525
600 sci

Will these go 1000+hours are the ticking time bombs past 500?

Solid thread... I've always wondered the same thing. Hopefully the RDP Brain Trust has some good info.

 

[HALLETT BOY]

So many variables : application of throttle , fuel , maintenance , integrity of parts from manufacture , initial person doing assembly , technical ability of person
doing annual maintenance , the moon and stars etc ....

 

[OldSchoolBoats]

Got a 1998 502 Mag MPI with 250 hours. Just getting broken in!

 

[YoPengo]

Got a 1998 502 Mag MPI with 250 hours. Just getting broken in!

My 2000 502 Mag MPI has about the same hours... Runs great. I know Bobby V has the same motor and double the hours with no issues.

 

[Andy B.]

Have about 600 hrs on it still pulls 26p to 4800 rpm 25' boat. All that with a exhaust manifold leak and the engine locking up, that was over 2 years ago!! I have an awesome mechanic!!!

 

[FreeBird236]

I would guess most engines don't see 1000 hrs. before a major rebuild. The guy that cruises at 3200 RPM most of the time vs. Balls to the wall has to make a major difference. Seems like some engines have exhaust problems as they age. Mercury Racing are better built than Mercruiser, but the higher horsepower may equal out the life expectancy. I think 5-6 hundred would probably be doable with proper care, maybe more.:blah:

 

[AzGeo]

Assuming you are talking about engines built for marine use, by marine knowledgeable companies . There are differences between street and marine motors, new and rebuilt .

I look at; 1) moister in the crankcase, it effects engine life .

2) over rich conditions, fuel dilution of motor oil, effects engine life .

3) weak valve spring pressures, water damages valve spring material, makes them soft or break .

4) raw water not drained from block, head gaskets, clogged passages, overheating .

5) water lying on the motor, rusts bolts, components, effects electrical .

6) operation conditions .


Every model marine engine has had it's share of 'teething problems', often parts failures, but they are most often worked out by the builder over time .

The only 'marine engine' that I would consider being 'problematic' would be the Mercruiser 470 . They have had their longevity tested over the years, and they are prone to fail . Merc no longer builds nor repairs them, for good reason .

To say that any small or big block GM motor "engine block or crankshaft", or even "a certain cylinder head has a problem", this may have happened in a few 'limited instances', but it was a 'part or machine finish problem', and not a 'design ready to fail' ...

Knowing a little about 'valve springs', I am surprised that so many people are getting 10 or more years out of factory valve springs, I never go longer than 5 years on a stock motor .

 

[Bob Bitchen]

Let me simplify:
It is directly related to the pressure on the loud pedal versus the care and maintenance performed.

 

[Bpracing1127]

I understand that full throttle everywhere you go has a major impact to the longevity of boat engines. But lets say normal use with regular maintence done. And factory mecruiser.mercury racing engins only. Can I expect a 496ho to break at 500 hours with normal use on them.

 

[Tooms22]

I understand that full throttle everywhere you go has a major impact to the longevity of boat engines. But lets say normal use with regular maintence done. And factory mecruiser.mercury racing engins only. Can I expect a 496ho to break at 500 hours with normal use on them.

I am looking for the same answer. On average... which motors last the longest and how long?

Obviously running WOT everywhere and lack of service/maintenance will reduce the life.

 

[Havaduner]

I understand that full throttle everywhere you go has a major impact to the longevity of boat engines. But lets say normal use with regular maintence done. And factory mecruiser.mercury racing engins only. Can I expect a 496ho to break at 500 hours with normal use on them.

I know Throttle has well over 500 hrs. on his 496HO. All routine maintenance has been handled by qualified individuals, and he runs his boat, but never abuses it. I'm sure with the hours on it valve springs at the minimum would be a help, but last I talked with him about it compression was good, no oil leaks or burning etc..

 

[AzGeo]

I understand that full throttle everywhere you go has a major impact to the longevity of boat engines. But lets say normal use with regular maintence done. And factory mecruiser.mercury racing engins only. Can I expect a 496ho to break at 500 hours with normal use on them.

A 5 year old one, or a 10 year old one ? When the motor sits in 'one position' for long periods of time, it may suffer more than being operated every day . The 496 is a 'closed cooling system' and that helps engine life considerably .

When the motor is not running for long periods of time; 'one valve is open and another is closed', and this can speed up the failure rate of some parts .

A damp engine compartment during storage could effect electrical, such as the IAC motor, and the fasteners on the motor .

500 run hours is not much at all for a roller cam motor, IF it is within a reasonable time frame (years) along with reasonable service and use .

Working with local Law Enforcement Agency's, I remember a couple of 454 motors in Mohave County Sheriff's boats that had over 2500 run hours on them . One was a 24' v-bottom patrol with a King Cobra drive, and the other was a 28' steel hulled utility, with a Castoldi jet drive . 12 hour patrol days put the hours on in less than 5 years, each boat . Neither engine FAILED, but I replaced the long blocks when "they used as much oil as they did fuel" .

 

[cnj]

Adding to this question....I had a '96 Ultra 21LX jet a while back. It had the Marine Power 454 in it. I wasn't too familiar with the brand, so I always wondered if it would have been as reliable as a Merc motor over the long haul.

So.....Mercury, or Marine Power???? Why?

 

[Englewood]

I had a 500efi in a previous boat with 300 hours and it ran excellent. It solely depends on how it is maintained and driven.

With routine maintenance and "normal" driving, I don't see how these engines won't go to 500-1000+ hours.

 

[guest hs]

You can't go wrong with the 454 or 502 mag much better engines longevity wise compared to the 496's the 500 hp engines are great too just got to keep an eye on the valve train on those

 

[GRADS]

I understand that full throttle everywhere you go has a major impact to the longevity of boat engines. But lets say normal use with regular maintence done. And factory mecruiser.mercury racing engins only. Can I expect a 496ho to break at 500 hours with normal use on them.

I'd be willing to bet that with normal maintenance the majority of 496HO's will make it to 500 hours no problem. I had one in one of my boats and the motor spent most of its time at 5000 rpm's, it had 300 hours and ran like it did the day I bought it.

 

[relaxalot]

My Howard Sportdeck with the mercury 600 sci with a couple whipple wonder upgrades ran for seven years and 405 hours without any problems mechanically. I just had it rebuilt but strictly out of caution. The last run before the rebuild was 94 mph with 2 guys and 3/4 tanks. There were absolutely no issues after teardown inspection, no oil usage at all, good oil pressure etc. I figured after the rebuild I should be good to go for 7-8 more years. I drive my boat at varying speeds and all conditions. I have been known to lean on it when it is called for. I have a friend with a 496 ho and he has about 400 hours on it and runs it wide open frequently for long periods with no problems. It is ten years old and runs perfect. Both of these motors are serviced by the best shop in Lake Havasu...Absolute Speed and Marine! I always want to acknowledge them for keeping me on the water with a big smile on my face and bugs in my teeth!

 

[77charger]

I dont have any of those engines listed but i have an older carbed 350 mag with 480 hours on it.Sounds like new to me still.

As for wear and tear i would think its how a boat is driven i have seen some boats multiple times at the river driven full throttle non stop i prefer to keep mine 3500-4k rpm most times.

 

[PVHCA]

Got a 1998 502 Mag MPI with 250 hours. Just getting broken in!

My 502 got to 510 hours before the alleged rebuild that never happened.

My buddy's 502 was at 750 when he sold his Howard and it's still going strong 2 years later.

Another buddy's 496HO is close to 500 hours and per Hallett, PERFECT compression on his last service just last summer.

IMO either one is quality.

 

[PVHCA]

I dont have any of those engines listed but i have an older carbed 350 mag with 480 hours on it.Sounds like new to me still.

As for wear and tear i would think its how a boat is driven i have seen some boats multiple times at the river driven full throttle non stop i prefer to keep mine 3500-4k rpm most times.

My other buddy has a 350 in his 210 Hallett, runs perfect and closing in on 700 hours, again no issues with proper maintenance. He runs that thing all over the RPM board.

 

[milkmoney]

I am a believer in the first 20 hours during break in is important to longevity and then followed by care and maintained properly.

Doesn't hurt to clean interior with q-tips. [emoji202][emoji41]

 

[GRADS]

I am a believer in the first 20 hours during break in is important to longevity and then followed by care and maintained properly.

Doesn't hurt to clean interior with q-tips. [emoji202][emoji41]

Are you talking cows or boats here?:headscratch:

 

[plaster dave]

A buddy just called me last night saying his buddy got a 496 with 900+ hours on it but it's getting tired.

 

[Deja_Vu]

subscribing....I am quickly approaching 500 hours on my carbed 454.

I need a new drive plate and was wondering if I should rebuild while the engine is out.

 

[Bradsrvrtoy.]

Ive seen mercury verados with 1500 hrs no issues...(gen IIs)..Ive seen many 454s and 496hos with over 1000 hrs with no issues! As far as a blue motor for hrs? It all depends...but people dont dish out the huge price difference over a black motor to idle it around and baby it..

I am blown away by the boats listed for sale stating 100 hrs on it and its 15 years old had the interior replaced twice and they are the fifth owner! who are these sellers trying to fool? Throw a scan tool to it and find out she has 650 hrs...still nothing maybe wrong with it.. And it may have years and years of life left!

 

[djhartley2003]

Great thread. I am going threw a divorce and going to be selling my boat so I'm already looking for a new one and have been wondering if there is anything that I should lean towards or stay away from. Thanks for asking this question.

 

[H2O]

Mercury OptiMax 300XS whackers, run on fresh premium fuel = 2000 hours on the powerheads....no problem:thumbsup

 

[pronstar]

I dont have any of those engines listed but i have an older carbed 350 mag with 480 hours on it.Sounds like new to me still.

As for wear and tear i would think its how a boat is driven i have seen some boats multiple times at the river driven full throttle non stop i prefer to keep mine 3500-4k rpm most times.

My old Tahiti's Volvo Penta SBC had over 900 hours showing on the meter, and my buddy who sold it to me said the meter broke well over a decade ago LOL

 

[mjc]

My first boat had a 454 mag with 850 hrs when i sold it. Last boat 500efi valve springs at 230 hrs and I had to replace the heads at 297 for failed leakdown on 3 cylinders.
I have been putting a small bucket of Damp-Rid in the bildge when I put the boat away to help keep the moisture down during storage.

 

[Meaney77]

I purchased my 2000 Eliminator with an HP500 that had 175 hours when I bought it. When the meter hit 300 hours I pulled the motor and had Jim Grub go through it for no other reason than piece of mind. The motor ran great with no issues but I knew at around 300 hours the heads and valve train on the HP needed some love. Jim pulled it apart and everything looked cherry- no issues. At 300 hours I had a full rebuild done along with dyno tune. Motor now has almost 600 hours according to the current gauge and it still runs well. I do the occasional hot lap at 5250 but for the most part cruises at 3k. I change the oil, fuel filter, and water pump every season and knock on wood fingers crosses no issues and hope for another season with no issues. However I wonder at what point do I need to go through the motor again. It runs great, but would rather be proactive and do preventive maintenance, rather than have to do something unexpected that would mess up my season.

 

[HST4ME]

On the base big block motors 1000 hrs will need the heads done at a minimum

Blue motors, if you made 500hrs you've done good and like above the heads will need to be done at a minimum.

I service many small blocks in fishing/charter boats that are well in to the 3000 hr range.

 

[guest hs]

Im going to throw this out there. Most of the big block engine will go 1000 + hours if you ever get there by NOT overheating the engine. Most failures I see at my shop are due to overheating the engine or lack of maintenance. The fact is most big block engines with bravo drives have been overheated at least once before the 300 hour mark due to not replacing the impeller in the sea water pump especially the earlier ones that are in the 1 piece plastic housing. This will due one of 2 things. #1 cook the valves in the cylinder heads. #2 the engine gets so hot it when it shuts down the engine will run backwards for a second and suck water up and put it on top of the pistons and there you have the begging of the end of your engine. IMPELLER IMPELLER IMPELLER guys once year on these engines regardless of use!

 

[Flying_Lavey]

Mercury OptiMax 300XS whackers, run on fresh premium fuel = 2000 hours on the powerheads....no problem:thumbsup

I kinda wish there was a way to figure out how many hours are on my 30 year old 200 blackmax. It's never had the block opened up (I had to change the head gaskets and surface the heads once due to an impeller issue). I should probably check my valve train........ [emoji12]

 

[throttle]

I know Throttle has well over 500 hrs. on his 496HO. All routine maintenance has been handled by qualified individuals, and he runs his boat, but never abuses it. I'm sure with the hours on it valve springs at the minimum would be a help, but last I talked with him about it compression was good, no oil leaks or burning etc..

About to turn 800 hours on stock 496HO [emoji106]

10 years old [emoji3]

 

[Singleton]

About to turn 800 hours on stock 496HO [emoji106]

10 years old [emoji3]

Time for a upgrade

 

[throttle]

Time for a upgrade

Ya think... Gonna hope another opportunity is avail when I am!

 

[FreeBird236]

About to turn 800 hours on stock 496HO [emoji106]

10 years old [emoji3]

I heard you drive real easy.

 

[LargeOrangeFont]

About to turn 800 hours on stock 496HO [emoji106]

10 years old [emoji3]

Nice..

We think my buddy has about that much on his 6.2.. no hour meter and 15 years old with lots and lots of trips over the years.

His boat runs about as strong as my 6.2 with 40 hours..

 

[throttle]

I heard you drive real easy.

I hope you didn't read that anyplace on the internet. I have a reputation to maintain. :grumble:

 

[Long Way Home]

It's been a while but back when I was going to ski school it was not uncommon to see ski boats with 2500+ hours on the meter.

 

[shueman]

At the shop, I've seen 454 / Bravo 1 installs from the late 80s - early 90s that are still going strong ... hundreds, if not, thousands of hours :thumbsup

The WORST damage is done when the boat DOES NOT get used ...