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buying a factory sealed 496HO with almost 500 hours

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buying a factory sealed 496HO with almost 500 hours

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Old 11-08-2018, 07:07 PM
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Default buying a factory sealed 496HO with almost 500 hours

I've got an option to buy a '03 Nordic with an untouched 496HO and Bravo drive, showing about 500 hours on the clock. (can't access the boat for a accurate hour scan in its current winter storage location) By all accounts the boat was well cared for and well maintained. Professionally winterized and serviced regularly. No deferred mechanical maintenance....only significant repairs were a new heat exchanger and new drive bellows.

Question - Is a 100% factory sealed 496HO and drive a good thing at almost 500 hours? (Assuming the leakdown test is good and the engine runs strong with no codes)

Or you would you be more comfortable buying the same package showing recent repairs on some of the known trouble areas? I know the answer is "that depends" and I need to budget for repairs and maintenance on any 15 year boat...even ones with lots of receipts. I can see both sides of the argument...If you don't neglect or abuse a 496 it should be good for 1000+ hours right? Even spoke with a guy who had a parasailing business that went 2000+ hours. We've all had cars (or boats) that are just "runners" and go high miles with minimal repairs.

On the other hand, I've looked at a ton of boats over the last few months and most (mainly 502's) were advertising new motor, fresh top end, or fresh drive, etc. I'm sure some were from neglect (reversion in manifolds, frozen block, etc) but it was rare to see anything advertised with 500 hours and untouched. Personally I'd at least like to see a new gimble (pivot pin & U bolt), or maybe new gearset in the Bravo, but maybe thats just my bad Bravo karma from the past.

So how does the braintrust feel about "factory sealed" vs "recent repairs" on a 15 year old 496HO?

Last edited by motuman; 11-09-2018 at 12:40 AM.
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Old 11-08-2018, 08:20 PM
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The 496 is probably the most reliable engine out there but doesn’t respond well well to mods. If you’re comfortable leaving it alone then 1000+ hours isn’t unheard of. I would personally prefer that over a 502 if keeping stock power.
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Old 11-08-2018, 08:26 PM
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Agree with Baja Rooster, as long as engine is stock it will run for a long time. I would look into the fuel system and have the injectors flowed. Upgrade the impeller housing if it hasn't been done. More likely though the drive is going to need inspected and some maintenance.
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Old 11-08-2018, 10:14 PM
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At the 496 power levels you can probably change the drive oil and go.

Is it an X or an XR?
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Old 11-08-2018, 10:45 PM
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oem stock Merc 496 were bravo one for the 375 hp MAG and then used the Bravo X for the 425 hp HO MAG... STOCK apps

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Old 11-08-2018, 10:56 PM
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related common issues depends on engine serial number. First gen ign coils and first gen crank sensor failures not uncommon. Sensor issues not uncommon no matter of years. IAC poor design and needs constant PROPER maintenance if not expect to pay the price for those related failures and can lead to PCM failure.

Injectors suffer from contamination, The stock 496 fuel injectors are mostly reliable themselves, its just the contamination issues they suffer from.

Gen VII water impeller housings are complete junk

The water air actuators leak over time and can even leak at high rpms when water pressure increases.

500 hours will need a new water circ pump and complete coolant drain and flush.

I have repaired many many and do I MEAN many 496's from ( they are not out of the woods for failures & issues ) including PCM failure. I know cause I personally fixed those to

Actually tech speaking the stock OEM marine 350 carb and the 454 carb engines are the most reliable by far. Had to throw that in there.

forgot to add the 496 has good low range power and good mid range power --- BUT top end a complete dog.. Stock apps

The 502 with forged internals a better motor
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Last edited by BUP; 11-09-2018 at 12:20 AM.
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Old 11-08-2018, 11:22 PM
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I want to ask what is your meaning or whom is giving you the wording " FACTORY SEALED " do you mean totally factory stock OEM Mercruiser 496 engine ??

The term factory sealed came from the APBA factory classes as factory sealed meaning they really had tamper proof seals so that the engines persay were on the same equal level playing field with the seal unbroken upon tech inspection.

Surely your not talking about the true GM 496 that was used as a race engine back in the APBA days ?
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Old 11-08-2018, 11:57 PM
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Originally Posted by BUP View Post
I want to ask what is your meaning or whom is giving you the wording " FACTORY SEALED " do you mean totally factory stock OEM Mercruiser 496 engine ??

The term factory sealed came from the APBA factory classes as factory sealed meaning they really had tamper proof seals so that the engines persay were on the same equal level playing field with the seal unbroken upon tech inspection.

Surely your not talking about the true GM 496 that was used as a race engine back in the APBA days ?
Just picked up that expression from friends (& forums) who may have that phrase left over from race days, but this is definitely a run of the mill stock 496, not a race engine.
Maybe "unmolested" would be a more accurate description :-)

Last edited by motuman; 11-09-2018 at 12:02 AM.
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Old 11-09-2018, 12:14 AM
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Originally Posted by BUP View Post
related common issues depends on engine serial number. First gen ign coils and first gen crank sensor failures not uncommon. Sensor issues not uncommon no matter of years. IAC poor design and needs constant PROPER maintenance if not expect to pay the price for those related failures and can lead to PCM failure.

Injectors suffer from contamination, The stock 496 fuel injectors are mostly reliable themselves, its just the contamination issues they suffer from.

Gen VII water impeller housings are complete junk

The water air actuators leak over time and even can leak at high rpms when water pressure increases.

500 hours will need a new water circ pump and complete coolant drain and flush.

I have repaired many many and do I MEAN many 496's from ( they are not out of the woods for failures & issues ) including PCM failure. I know cause I personally fixed those to

Actually tech speaking the stock OEM marine 350 carb and the 454 carb engines are the most reliable by far. Had to throw that in there.

forgot to add the 496 has good low range power and good mid range power --- BUT top end a complete dog.. Stock apps

The 502 with forged internals a better motor
Do you suggest replacing the stock WP with the Hardin SS pump?
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Old 11-09-2018, 12:26 AM
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Originally Posted by motuman View Post
Do you suggest replacing the stock WP with the Hardin SS pump?
I do BUT MERC has a good repair kit for their stock unit UNTIL it completely fails. I even moded and added to the merc repair kit to offer a better kit on top of. It works perfectly bar none unless it has shaft / bearing issues or even internal side wall groves. The repair kits I have comes in 2 versions and not pricey at all. Whats helps with this kit it retains a true merc made impeller. And Yes Merc OEM impellers are the best to use for their apps. The OEM repair kit is fairly new to market even for dealers. Just saying

Last edited by BUP; 11-09-2018 at 01:39 AM.
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