Mercury Outboard ID Help

[matth121]

Hey guys, sorry to post another one of these threads, but here goes. I've got a canadian made merc outboard. sn- 7178637. I just got this motor with a boat. It's got a 25HP cowl over the motor and the previous owner told me it was a 25(although he couldnt tell me much and only had it a year himself). My local parts shop shows this as an 18HP, based on the serial #. They also show it as a belgium model which i figure has to be wrong since the ID Plate says it was made in Ontario, Canada. Is there a way to figure this out? Im looking for a full gasket kit(entire powerhead, and midsection, as well as an adapter plate(i think its called) with the exhaust tube for the midsection(long shaft). I figure I better have this sorted out before ordering anything. According to the info i found here-
http://www.maxrules.com/models/Merc_model_files/15-25.html

it would appear to fit into the range between 1981 and 1982 25HP's but then if you look at the 18's, it looks like it would fit in there too. I appreciate any help you can offer.

2cyl, manual start, long shaft, no tiller.
Thanks

 

[Laddies]

Re: Mercury Outboard ID Help

It's a canadain built engine the serial number makes a 1980 or 81 there is no ending number for 80 or starting number for 81. It is difficult to tell horsepower from the serial number and parts art ordered by the serail number not the year. As far as the 3 horsepower engines 18-20-25 the only differances are a differant high speed jet and the tuning pipe for the driveshaft housing which is NLA, so just go to a online Mercury parts dealer and order your parts or look up the numbers and buy locally. Just don't use the one that thinks the engine is Belgium built.

 

[matth121]

Re: Mercury Outboard ID Help

so, if i'm getting this, your saying the parts for those 3 HP models are all the same, or interchangeable? So then, all the gaskets are the same? That's good to know if thats the case. The dealer was just going by what the sn brought up, they're not bad to deal with, i explained the difference and he's going to get it looked into by someone who'd know. but all the parts i was looking for were NLA so i'm not sure what i'm gonna be able to do there. Do you have any advice for an online parts dealer? Am i even going to be able to find what i need? since it is so old i mean, runs great but i think i've got a pretty bad exhaust blockage, think my exhaust tube is gone. full revs in neutral, but it only hits 2700rpm in gear. appreciate any opinions people reading this have on any of these matters. Thanks
Matt

 

[Laddies]

Re: Mercury Outboard ID Help

Yes, the 18-20-25 are part for part interchangealbe except for carb jetting and tuning pipe. Don't free rev your engine it don't prove anything and will damage it. If you think the pipe is plugged pull the powerhead and clean the pipe poor quaily oil will carbon them up here's one we cleaned. Never have replaced one.

First you should make sure the engine is running on both cyls.
Heres a parts link - http://www.ishopmarine.com/ishop/js...cCatFilter=MM&eCatSupFldr=supplier-050-025-MM
or - http://www.mercruiserparts.com/selectDocs.asp?doc_nbr=13286
If you notice the first item lists Belguim engines thats parts that differ on Belguim built engines as many early engines were built there.

 

[matth121]

Re: Mercury Outboard ID Help

Great info, thanks for the pic. I was planning on pulling the powerhead, but i'll need replacement gaskets 1st right? The engine is firing on both cylinders, for sure- compression test shows a diff of 18psi between cylinders which depending on who you talk to is either fine or requires a full rebuild, lol. never free rev it, just bumps on the throttle, but it's clear that it has full rpm potential while in neutral, and it doesnt get any higher than 2700 ever when in gear. that works out to about 4mph on the water, won't come close to planing off. the reason im thinking the pipe is gone is the pieces of metal ive pulled from behind the prop and also from one of the vents on the prop itself. theyre big enough that i know theyre not from the engines internals, and i'm guessing, based on where they were, they could only have come from the exhaust pipe. One last question, im still a bit of a noob when it comes to this stuff, but what's a tuning pipe? is that the exhaust tube or something else?

 

[matth121]

Re: Mercury Outboard ID Help

so the gasket set i found here
http://www.ishopmarine.com/ishop/js...eqph=Unknown&reqItemCode=MM-2741499A87&ts=Sun Jul 3 11:56:11 UTC-0300 2011

is the one i need? regardless of if its an 18,20 or 25HP. If you'd be able to confirm this is what i need, i'll be ordering it today. I just want to be sure as these are for an XD model, and mine isnt an XD, just a merc 25 ML(manual start, long shaft)

 

[Laddies]

Re: Mercury Outboard ID Help

Yes, here's the pipe item #1 - http://www.ishopmarine.com/ishop/js...cCatFilter=MM&eCatSupFldr=supplier-050-025-MM
Ck the picture or the carb if your float bowl is not square and is round the your engine is a little older but the gasket kit is universal and will work.

 

[matth121]

Re: Mercury Outboard ID Help

great, thanks for your help, ordered the gaskets and i'll pull the powerhead when they arrive. Any thoughts on the metal chunks? my float bowl is square. Thanks again,
Matt

 

[Laddies]

Re: Mercury Outboard ID Help

Is it tin or aluminum? If is tin (steel) it would have to be pieces of the tuning pipe, you can remove the lower unit without a gasket and check the inside of the driveshaft housing with a flashlight.

 

[matth121]

Re: Mercury Outboard ID Help

i believe its tin, but not certain, didnt save the pieces. I guess i'll get my flashlight out. I'll keep you posted on the findings, thanks again for the help.