I want to learn the Mercury 2.4/2.5 V6, where do I even start?

**ADDvanced** · 05-18-2021, 10:29 AM

I'm looking at picking up an outboard pretty soon here, and I'd like to know more than I do now. Apart from combing through random threads, is there a primer/faq/main page that shows the history/development/differences in High Perf Mercury V6s somewhere?

Help me figure out where to start.

**rgsauger** · 05-18-2021, 11:57 AM

Welcome to S&F! Well, for starters, the Merc V-6's are basically 2.0, 2.4, and 2.5. The 2.4's ended around 1990/91 and the 2.5's took over from there. They both run great but the 2.5's have more performance potential for a given amount of $$$. Not a 100% statement but more true than not.

What are you putting it on and what are your goals? A 2.4 or 2.5 200 HP is kind of the backbone of these motors. You can spend more and get 260's and 280's and such but there are a LOT of 200's out there to be had.

Tell us more about what you have in mind and we can try to steer you in the right direction. There are some SHARP people on here who have been there, done that. Read, read, read and then ask questions!

Rob

**ADDvanced** · 05-18-2021, 02:33 PM

I have a recently rebuilt 200 that I'm looking at that is local, but I'm just wondering if there is a main site that has all the main information on these, what midsections (some have built in trim, some require external trim pump, etc) so I can just read up on everything, know what issues to look for, etc.

**rgsauger** · 05-18-2021, 10:36 PM

Sorry but the answer is no. Just start here and read... watch rebuild videos, etc. What boat is it going on?

**ADDvanced** · 05-19-2021, 01:39 PM

Sleekcraft SST project. Blows my mind there is no major resource for learning about these engines, given how long they've been in production and how important they are to the racing/high perf community.

Is there a "main" thread anywhere?

**NZ Sidewinder** · 05-19-2021, 03:11 PM

One of the first things to do, before you get a motor is to buy a flywheel lifting eye.

**rgsauger** · 05-19-2021, 06:42 PM

And then a top dead center indicator! Jay smith sells a good one for $75.

**rgsauger** · 05-19-2021, 06:44 PM

Originally Posted by ADDvanced

Sleekcraft SST project. Blows my mind there is no major resource for learning about these engines, given how long they've been in production and how important they are to the racing/high perf community.

Is there a "main" thread anywhere?

That's the thing...you're reading a major resource on them! There's tons of stuff in many places. You can honestly learn anything you need to know about a Merc V-6 right here. Do a search on Merc Tech in the Tech section and make yourself comfortable...

**rprinzo** · 05-19-2021, 08:06 PM

Originally Posted by ADDvanced

I have a recently rebuilt 200 that I'm looking at that is local, but I'm just wondering if there is a main site that has all the main information on these, what midsections (some have built in trim, some require external trim pump, etc) so I can just read up on everything, know what issues to look for, etc.

im doin the same thing just a few steps ahead of you. first thing i did was download the service manual for my motor and learned about what i had to start with. then i tore it down and sent the long block in for a rebuild.all the while soaking in as much info i can from this site and a couple hi perf builders sites. theres a ton to learn about the v6 mercs, no 1 being they re THE motor to build. the resources and minds that know are endless on this page,just ask em,lol. but seriously, theres all you need on this site

**flabum1017** · 05-19-2021, 08:38 PM

A resource: http://www.biggerhammer.net/mercury/

**JPEROG** · 05-19-2021, 09:52 PM

I can save you a lot of time and money. Buy a 300XS with an offshore clamp assembly and 1.62 sport master gear case. It will have the torque that your SST needs, its oil injected, its dependable as long as you don't turn it over 6400 rpm, and it will get you close to 100 mph for less then any other option out there. I have owned more 2.0, 2.4, and 2.5 motors then you would believe and had overall extremely good reliability from them but I was running light weight boats like everyone else back then. Today, we are dealing bigger boats on every body of water out there, and consequently performance boats are getting bigger and heavier. The 3.2L 300 opti max is also very fuel efficient in comparison to the 260 and 280 2.5L motors. Parts are also very expensive and becoming scarce for the High Performance 2.5L motors. If you have the financial capability, the new 300R 4 stroke V8 is even better.

Just friendly advise from a guy that has traveled the road you are about to enter.

Joe

**ADDvanced** · 05-20-2021, 11:41 AM

There should really be a wiki / FAQ built by the community on these engines. I'll read as much as I can but I'm super surprised such a thing doesn't exist that goes over the introduction, and major updates/options available.

**ADDvanced** · 05-20-2021, 11:54 AM

So in terms of midsections, some require a trim pump, others are integrated. I'd like to read up on this but I'm not finding a good topic through searching the forums. Can anyone give me the lowdown?

**25two.stroke** · 05-20-2021, 12:05 PM

A ll early and hi-po have hull mounted trim pumps. These hull mounted pumps go along with "single ram" trim units. I think there were also some "2 ram" units real early on and they may have been those that have the hydraulic trim fluid running through the transom mounting bolts. Those you will see next to none of. I may have the 2 ram and the fluid-thru-bolts mixed up but you never see that stuff and I wouldn't really want to run it if I came across it.

In 1986 (or maybe 1985 1/2) they came out with the integral trim pump which people call the 3 ram. Thats similar to what they still use today. The same trim unit, with electric pump and triple rams come in one piece ad mount between the two transom clamps. The 3.0s used the same unit, some I-6s and I think some later I-4s may have also.

The "ram" number we refer to is the number of hydraulic cylinders you see lifting the engine. Early ones you just see one, the three ram has one main and 2 additional short trim rams.

The hi-po mids were beefier and had 2" of setback built into them. So even the "bass-style" 260 mid which appeared like a consumer mid was not actually the same.

The 3 ram trim units, even though they have the weight of the hydro pump integral, are lighter than the single ram trim cylinders. The 3 ram tend to loose seals and leak down much more readily than the single ram.

Only one I know of is willing to cut down 3 ram mids while single ram many people cut them down.

Sorry, probably more info than you wanted, but figured I would throw it out there for anyone else.

**rprinzo** · 05-20-2021, 12:13 PM

Originally Posted by ADDvanced

There should really be a wiki / FAQ built by the community on these engines. I'll read as much as I can but I'm super surprised such a thing doesn't exist that goes over the introduction, and major updates/options available.

what year motor are you lookin at?