TOPIC: "New" 40hp

Got a great deal on a 40hp Merc for my new classic boat. No idea what year it is, so got some pics here and was hoping some of my old Merc buddies could help me figure out year of this baby. Oil injected, got all the controls and wiring harness with it. Got one weak cylinder and a bit too long shaft, but these are all things I want to figure out.

This is not really a project I need right when I'm in the middle of building another street rod, but what's a guy to do?

Thanks for any help!

Frank

The 40hp of that flavor was made in around '89-'90, according to a Merc HP/Serial # chart. The oil injection is driven off the crankshaft and is mounted in the side of the block, like a V6.

To shorten shaft length you're gonna have to have the correct-length mid and lower unit, or pull the shaft out of the 40hp L/U and either have it shortened/resplined, or find a short-shaft that fits. I checked Boats.net and they do have the 98179 short driveshaft for under $300 shipped.

It'd be more economical to find another S/S parts motor. Sometimes you can find a short mid on eBay but it probably won't be cheap.

Likely issues on the low compression are carbon buildup on the rings, or overheating. Teardown will tell that story!

And, like you say, what's a fella to do???

A few links:

www.marineengine.com/parts/mercury-outboard-parts/40-4-cyl

www.boats.net/parts/search/Merc2/Mercury/40%20%284%20CYL.%29/parts.html

Cheers.......ed

Thanks Ed. Tried to leave you a message last night, but it did not work for some reason. I gotta get the hang of these forums again.

Many years ago my and a friend took two old '63 Merc1000's apart and used the best from both to make one "new" motor that I ran on a '62 PowerCat 14T for many years. Unfortunately all the time and effort that went into that boat, motor and the trailer that hauled it went up in a barn fire years ago. I lost other things in that fire too, and am busy rebuilding my old street rod because of that fire. The Merc will have to wait.

I built a rolling stand for it this morning so I can get the lift ring back to the marina. I've known the guy that runs the shop for many years, and he knew I had been looking for a motor. If I hadn't taken this, it would have just been tossed. That would give you an idea of what I paid for it, lol. Zippo!

Thanks for the info and the links. Much appreciated. Will be back at some point no doubt for more technical assistance.

Frank

Didn't 89/90 Merc 40's have a vertically split cowl? I think this is a later model. I did find a serial # on a soft plug like thing at the bottom of the block behind the starter. Gotta find my merc lift ring/flywheel puller. It's around somewhere.

PC1000 wrote: Didn't 89/90 Merc 40's have a vertically split cowl? I think this is a later model. I did find a serial # on a soft plug like thing at the bottom of the block behind the starter. Gotta find my merc lift ring/flywheel puller. It's around somewhere.

Here's the cowling of an '89-'90 4-cyl 40hp:

www.marineengine.com/parts/mercury-outboard-parts/40-4-cyl/0c159200-and-up-usa/cowling

As you'll see, it's the same style as yours. Post the serial # when you can get at it, it'll tell all.

OG 212518

Can't get the pic to load. After a number of tries, I give up!

Frank

pic...

OK, so I found some good info at the Mercury site. They have an online parts program and when you enter
"0G212518" into the query box you'll find listings for the 30hp Four Jet, & 40hp Four, with a serial number range that includes your "G" serial number.

Best I can figure yours is a 1989 and something else I found out is that around 1997 or so Merc stopped issuing model/year info and goes strictly by the year listed on the motor's serial # plate. So there's nothing out there for motors newer than that, at any rate.

Here's a link to the Merc online parts catalog:

www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog

Just hit the "Launch Parts Catalog" button, let it load, then plug your serial # into the search box. Note that it's a numeric "zero" or "0" that begins your serial #; and it's all one string of alpha/numerics, i.e. 0G212518 not "OG......"

Anyway, that's as close as I can get to an "official" determination, hope that helps.........ed