Four Stroke Mercury's how long before rebuilding?

**Brad Zastrow** · 01-18-2022, 10:56 AM

Wondering how many hours before rebuilding on the new 300R, 400R or 450R? Having been disgusted in the past with the 2.5 racing series blowing up and rebuilds at 100 hours. I am really happy with my 300X engines as they appear to run about 1000 hours from what I can find out. What does everyone expect or witnessed with the new Mercury four strokes? Any idea on cost to rebuild?

**Lake rat Skater** · 01-18-2022, 12:41 PM

Inline 6 verados seem to be able to go 2000 hrs with proper maintenance, many go way over that. I would expect the 300R to easily go 2000 Hrs. I also love and respect the 300X but I think all three new four strokes you mentioned will last at least twice as long before rebuilds. Now once it is time to rebuild the four stoke I don't know exact cost but it would have to cost a lot more than a 2 stroke rebuild.

**XstreamVking** · 01-18-2022, 01:00 PM

Rebuild? You just buy another one and keep on boating.....

**Noah Burns** · 01-19-2022, 08:11 AM

I have a cousin that retired a couple years ago and bought a center console with a 250 four stroke on it, he fishes literally every day unless they're on vacation. He's well over 1000 hours and not a problem one.

**22VelocityProMax300** · 01-19-2022, 08:31 AM

Originally Posted by Brad Zastrow

Wondering how many hours before rebuilding on the new 300R, 400R or 450R? Having been disgusted in the past with the 2.5 racing series blowing up and rebuilds at 100 hours. I am really happy with my 300X engines as they appear to run about 1000 hours from what I can find out. What does everyone expect or witnessed with the new Mercury four strokes? Any idea on cost to rebuild?

Brad, I have a nephew over in New Jersey that has a 150 mercury 4 stroke on a Boston whaler, he has been putting on a lot of hours on his motor, rather than a re-build it’s electrical demons that he has to work through. He loves the motor otherwise. Frank

**Z06man** · 01-19-2022, 08:50 AM

I have put a set of 300 L-6 WITH 2000 hours from marine patrol serviced every 100 hours . He is now over 3000 with them.Just mait.

**Chaz** · 01-19-2022, 09:44 AM

They can't even deliver new motors to dealers. You really don't expect them to have any parts available to a guy who walks in and tries to order parts over the counter ..

But lats say for a moment that they did have a genuine interest in selling parts to their consumers.

So if they command $398.00 for a small hand full of O-rings for a Pro/Max intake. (BTW- I forgive you for not getting back to me on how you .. well you know)

What do you think the leaches would want for a simple set of piston rings ...

Maybe a gasket set ..

New rod bolts ...

Valve springs ...

That's if it ain't hurt ... just weak ..

**JBS** · 01-19-2022, 11:32 AM

Originally Posted by XstreamVking

Rebuild? You just buy another one and keep on boating.....

Yep,do this.
I heard that some law enforcement boats in South Florida have several thousand hours on their V rods without any issues.

**Speed Jr.** · 01-19-2022, 01:46 PM

Get your order in now Brad. Do the rigging next winter when they come in. They are at halt right now due to prop shaft supply issues.

Jr.

**mikesufka** · 01-19-2022, 01:50 PM

Brad -

You gonna hang a pair of 450's on the Talon ?

MDS

**FUJIMO** · 01-19-2022, 03:25 PM

...highr any mota spins, more often it gitz rebilt. 2.5 race vs diesel...

**Brad Zastrow** · 01-19-2022, 03:52 PM

There are cars that spin 8000 rpm that do not need rebuilding every 100 hours. Motorcycles that spin 12k plus that run for a long time. I have blown at least eight 2.5 racing motors that were not drags, just 260's and 280's. I love the 300x but might be tempted to go with the new engines.

**Brad Zastrow** · 01-19-2022, 03:56 PM

[QUOTE=Chaz;3326908]
So if they command $398.00 for a small hand full of O-rings for a Pro/Max intake. (BTW- I forgive you for not getting back to me on how you .. well you know)

I have no clue as to what you are saying here. You forgive me for what?

**FUJIMO** · 01-19-2022, 04:03 PM

Originally Posted by Brad Zastrow

There are cars that spin 8000 rpm that do not need rebuilding every 100 hours. Motorcycles that spin 12k plus that run for a long time. I have blown at least eight 2.5 racing motors that were not drags, just 260's and 280's. I love the 300x but might be tempted to go with the new engines.

...brad, all these years later, i still see & hear what a 2.4/2.5 center engine on an offshore race cat goes through @ wot...lol. most people would not believe it. its amazing that they even last an hour...

...

**Speed Jr.** · 01-19-2022, 04:11 PM

With what some people are willing to pay for used 300x and 300xs motors, why not upgrade to new stuff....There's a reason why there is an uptick of people who are upgrading. Lock it in now cause they aren't getting any cheaper and the value of the dollar isn't getting stronger. Twin 450s or Triple 300Rs would be slick Brad.