280 drop-on on 225PM??

[white03]

Guys,

I stuck a piston on my 96 225PM last night and am considering options. I could sure use some answers that you guys probably think of as basic info...but please bear with me as I try to learn so I can make an informed decision

I was looking at the possibily of buying a 280 "drop-on"...presuming it is a complete drop-on ...will I have to change anything else ...or will it really "drop-on" my mid???? Will my 225 pan and cowl fit?? Don't 280s have external fuel pumps...do you think a drop-on would come with the fuel pump or is this something I should be sure to ask???

Over on S&F I see 280 "drop-ons" advertised.

Any cautions I need to be aware of....???

Any questions I need to be sure to ask ...???

Any year models of 280s better than others...??

Any year models to avoid...???

I know these are a lot of questions but I would very much appreciate your help. If you can tell me anyhting , either what I've asked or what I do not know enough to ask, please take time to help me.

Thanx

Bill

 

[froggy]

White03,

A few things I can think of re:280

1. 280 uses an automotive style alternator which requires an "alien" style cowling and pan for clearance.
2. 280 is "tuned" for a 'drilled' mid-section (exhaust relieved).
3. 280 uses outboard fuel pump as you mentioned.
4. 280 uses a larger diameter water pump tube to the powerhead.

I may have missed a couple, but this is a start.

froggy

 

[BP]

Bill off the top of my head (froggy and I were typing at the same time, so some duplicates)

1.Your cowl will work, if Alien style

2. External fuel pump, fuel pump relay and fuel return line to tank will need to be added.Inquire of the seller if a fuel pump is included.

3. One piece exhaust adapter plate.

I don't know if any year is better than another, but at some point Mercury switched to top pin pistons (they all fail, if abused).

I think what would be more important than the year is...hours of usage and at what rpm ranges.
Ideally,scan with a DDT and perform a leakage check.
Additionaly, ask about prior failures, any welds, which ECU is it equipped with (offshore or std.),past maintenance/repair history and who pefromed the work.
They are not tolerant to overheating, so make sure your water pump is up to spec., when and if you make the switch.
A procedure that I think adds greatly to the lifespan, is to warm the motor up before hammering on it and let it cool down before shutting it off.

Get a good one,treat it right and you will love the upgrade!

 

[fishnfireman]

These guys have summed it up better than I can.
I would think if they are selling it as a drop on that it is re-built :?:

But this may not be the case.

I would not buy one if it had the side pinned pistons.

But that is only because I have had 2 promaxs and 1 280 that droped a piston because of a side pin ring failure The first one we put back together not knowing there was an issue with the pins....... It droped another shortley after we rebuilt. The other two mtrs we had the pistons top pinned and they are still running fine.

 

[John Richied]

Here is the engine serial number of the first Mercury top pinned 280’s

OT430856 vertically pinned 2002 and up

When you get the drop on see if you can get the following with it…

The complete cowling.

The one piece exhaust plate and tuner.

And the fuel pump, the 260/280 fuel system is completely different then the 225 Promax and you are also going to have to add a fuel return line… most of this is just time consuming and easy to do.

You are going to have to remove the top solid motor mounts, and drill those two holes out in the swivel to accommodate the top two bolts that go into the one-piece exhaust plate.
Also the back three holes where the exhaust plate mounts to your midsection are going to need tapped, but that also is easy.

 

[white03]

THANK YOU ALL VERY MUCH!! I sincerely appreciate it. Help such as you willingly gave me is the reason I have been reading and occasionally commenting on this site for 8 years or so. Again, thanx to my Ally family!!

 

[2fast4mom]

Despite the hassles you will love the 280 compared to the 225.

Even with the mods, mixing the oil, and generally poorer gas mileage, the motor makes the 03 hull scream and that made it all worthwhile to me!!