1996 Mercury 100 HP

A conversation among Whalers
R DAVIS
Posts: 5
Joined: Thu Oct 22, 2015 10:33 am

1996 Mercury 100 HP

Postby R DAVIS » Fri May 04, 2018 10:43 am

Does a 1996 100 HP Mercury outboard have oil injection ?

jimh
Posts: 4785
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 1996 Mercury 100 HP

Postby jimh » Sat May 05, 2018 8:07 am

Mercury outboards had an oil-gasoline mixing system. They never had oil injection. They just mixed oil and gasoline prior to their induction into the engine cylinders.

Some people may have called their oil-gasoline mixing with various names.

By 1996 it would be typical for a two-stroke-power-cycle engine to have automatic oil-gasoline mixing.

A Mercury engined rated at 100-HP seems very odd. Is this engine in Europe?

R DAVIS
Posts: 5
Joined: Thu Oct 22, 2015 10:33 am

Re: 1996 Mercury 100 HP

Postby R DAVIS » Sat May 05, 2018 10:57 am

Jim--Thanks for the reply. A friend bought this engine from the son of a deceased private party near Houston. It is on a 1997 Montauk 17. The son is no help; he doesn't know the history of the engine. As far as I know it is original equipment.

I saw the boat and engine briefly, but wasn't feeling well, so I didn't pay much attention to it. The boat and engine appeared to be in pristine condition. I don't know the engine serial number, but will try to find out when my friend returns from Ireland where he is currently vacationing and pub-crawling. It's my understanding that the serial number is key to all things Mercury.

Do these engine typically have a separate oil tank, or is it under the cowling?

Is the system reliable?

I will post the serial number when I get it, perhaps that will help. I searched the internet and found very little info on 100 HP Mercury motors. They must be rare.

jimh
Posts: 4785
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 1996 Mercury 100 HP

Postby jimh » Sat May 05, 2018 3:08 pm

Maybe someone put different decals on the cowling of the Mercury engine you describe as a 100-HP and it is really a 90-HP.

If the engine is a two-stroke-power-cycle engine from Mercury, it is likely a three-cylinder 90-HP engine. That is a good 90-HP engine. If the engine is a four=-stroke-power-cycle engine with Mercury decals, it is likely a Yamaha power head mated to Mercury midsection and gear case, with Mercury cowling and black paint job.

Sometimes an engine marketed by Mercury in the USA as a 90-HP would be marketed in Europe as a 100-HP. But typically those engines were four-stroke-power-cycle engines, and Mercury called them FOURSTROKE engines.

In 1996 Boston Whaler was not owned by Brunswick, and they typically did NOT sell boats from the factory with engines pre-installed. A dealer would likely install the engine, or the boat owner would install the engine himself.

Regarding use of term "injection" with relation to oil lubrication and gasoline-oil mixers: modern two-stroke-power-cycle engines have oil injection pumps that inject or force under pressure lubricating oil not mixed with gasoline via a manifold and hose distribution system to multiple oiling points in on the engine block. This is how I use the term "oil injection."

Engines of all brands that just mix oil into the gasoline in their fuel system before the fuel is then introduced by some method into the air stream leading into the intake ports of the combustion chambers are not "oil injection" systems; they are gasoline-oil mixers. For certain brands the use of the term "injection" has been often ascribed, but, again, in those systems there is no injection, just a mixing of oil and gasoline into the fuel supply hose to the carburetors or a very simple throttle-body single-point electrical fuel injector.

There is a very detailed description of the Mercury oil mixing system in the REFERENCE section.

Also in the REFERENCE section is an article that compares the oil mixing systems used by OMC and Mercury on their legacy two-stroke-power-cycle engines.

FISHNFF
Posts: 42
Joined: Thu Oct 29, 2015 3:38 am
Location: San Francisco

Re: 1996 Mercury 100 HP

Postby FISHNFF » Wed May 09, 2018 9:39 pm

The 1996 Mercury 100-HP is the in-line four-cylinder also marketed as a 115 and a 125-HP.

I believe the all had the system of dropping cylinder sets at lower RPM.

I don’t this model is especially desirable as say a 3 cylinder Mercury because of roughness at lower motor speeds and a surge when added cylinders kick in.

FISHNFF

R DAVIS
Posts: 5
Joined: Thu Oct 22, 2015 10:33 am

Re: 1996 Mercury 100 HP

Postby R DAVIS » Sun May 13, 2018 12:12 pm

jimh--the engine [has stickers on it and is] titled as 1996 Mercury 1000 ELPTO SN 0G372385.I still have not had a chance to examine it. It is a 2 stroke.

My friend says deceased-previous-owner's son stated they always mixed oil 50:1 directly into fuel tank.
The motor has a round rubber cover on top of motor cowling. Don't know if it's a cover for an oil tank or what. Maybe the previous owner didn't know it was an oil tank, or if it's something else. If it's an oil tank cover, I would think the previous owner would have been hearing an alarm horn for low oil if he was pre mixing into fuel tank instead of using a built in oil mixing system.

I hate to sound ignorant, but for that motor I am clueless. I was unable to turn up much info on 100 HP Mercury 2 strokes, and there is no owner's manual included with purchase, and my friend has not run the motor, except for a couple minutes on a hose. I didn't try to examine the motor the one time I saw it. My arthritis was bothering me so bad I didn't even open the cowl, or climb up into the boat. We were just concerned on seeing what was needed to set up the trailer properly. I'm not sure if it's a 3 or 4 cylinder, in-line or V-4. From shape of motor cover, it looks like a V-4. My friend is vacationing in Ireland, so I won't see the motor for 2 or 3 weeks when we set up the trailer properly for the boat. Have ordered keel rollers and guide-ons to make launch / retrieve easier. We are both in our 70s, so want it as easy to deal with as my 1982 Sport 15 which loads unloads like magic with keel rollers and 4 vertical guide posts.

jimh
Posts: 4785
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 1996 Mercury 100 HP

Postby jimh » Sun May 13, 2018 3:28 pm

That in 1996 Mercury was making a two-stroke-power-cycle engine that could only run on pre-mixed fuel is hard to believe. Perhaps it has been modified.

If the engine is a four-cylinder, it likely is an in-line four with a rather clunky variable displacement system. Mercury used this system on this four-cylinder engine block. At low engine speeds only two cylinders will have combustion. Combustion is suppressed by having no low-speed fuel jets in the carburetors for those cylinders. No fuel, no combustion. When the engine accelerates to higher speed, the high-speed jets in the carburetors for those cylinders supply fuel and in a very rapid transition the engine jumps to operating on four cylinders instead of two.

If you eventually figure out what engine you have bought, let us know more about it. Good luck.

jimh
Posts: 4785
Joined: Fri Oct 09, 2015 12:25 pm
Location: Michigan, Lower Peninsula
Contact:

Re: 1996 Mercury 100 HP

Postby jimh » Sun May 13, 2018 3:48 pm

Also--if you need an owner's manual for an outboard engine, you should consult my article in REFERENCE. See

http://continuouswave.com/whaler/reference/

Then look in the INDEX listing for the article about outboard engine owner's manuals:

http://continuouswave.com/whaler/refere ... nuals.html

Then follow the link I give in the article to download the manual for your engine.

I downloaded a PDF copy of a manual for a 100-115 HP engine. Of course, since I have no idea what engine you have, I correspondingly have no idea if the manual is appropriate. You can find the manual under the notation

"MERCURY 100-115 _ 13537910"

It might be helpful. It's dated 1990, so probably is appropriate for a c.1996 engine.

ASIDE: while the forum has a lot of information, the REFERENCE section is a great collection of information that has been collected, organized, and carefully researched and written.

FINALLY: a whole internet search for "1996 Mercury 100" produces hundreds of results. Here is a sample:

https://www.bing.com/search?q=1996+Merc ... 777B8627E7

Over one million resuls.

Mattwarner
Posts: 26
Joined: Sun Sep 25, 2016 1:57 pm

Re: 1996 Mercury 100 HP

Postby Mattwarner » Tue May 15, 2018 10:18 am

Sorry to Hijack, however I was offered a similar motor and it was oil injection (mixing) with a built in oil tank and had the oil level visible from the cowling.

I often wondered why dont these motors burn cylinders as surely at low speed, no fuel = no lubrication to these deactivated cylinders??