1994 mariner 115, oil injection

[Ifishmuskie2]

I’m running a 1994 mariner 115 with oil injection and it runs very well.
Are these engines getting enough oil from the oil injection? Any known issues with using the oil injection?
I do have a small leak of about 1 teaspoon when I tilt it up for a while. I’ll have to pull it apart and fix that.
Thank you for any help.

 

[Texasmark]

What's the origin of the leak......the seal for the fill cap? On OI being any good or not I have a 90 I disabled and later a 115 that I didn't, both 2002 engines. I'll bet you find a lot of folks sitting on both sides of the fence on that subject.

 

[redneck joe]

The injection debate has raged on since the internet was born.

I am zero help with your question(s) but I am a fan of simplicity. The less stuff to go wrong will result in less stuff going wrong.

Im going to look at a 74 Ford truck today.

Disconnect the oil and premium is my 1.25 cents worth of opinion.

 

[Ifishmuskie2]

It doesn’t seem to be leaking from the top. It seems like near the bottom. I’ll have to look into it more.
I understand to disable the oil injection has been debated for years. I was wondering more about this specific engine having known problems.
I would like to use the oil injection because it uses different mix amounts over the rpm range.
Thanks for your help so far.

 

[racerone]

The gear that drives the oil pump is a plastic material.

 

[Ifishmuskie2]

When I pull the tank out I guess I’ll replace everything I can reach. Like the plastic oil pump gear.

 

[racerone]

The plastic oil pump gear is on the crankshaft.----Just a little bit more than a 10 minute fix !!

 

[jimmbo]

When I pull the tank out I guess I’ll replace everything I can reach. Like the plastic oil pump gear.

I think that Gear is on the Crankshaft...

Edit: Racer beat me to that

 

[Ifishmuskie2]

Alright great info thanks.
I’ll have more questions when I pull the tank off.

 

[cyclops222]

HOW would you be perfectly sure. A pump is mixing the correct ratio at all speeds ?
Why I mix the oil to gas ratio.

 

[Ifishmuskie2]

more reading and I’ve found a data sheet that says the oil injection mix changes with rpm.
It also shows a check for correct oil amount by running premix. And disconnecting the oil injection and pump oil into a cup to measure.

I think I’m going to mark the tank and then fill oil to the mark while measuring.
Then I’ll try and figure out gas. Burned.

 

[flyingscott]

The 3 and 4 cylinder mercury engines have excellent oil injection systems. No need to disable it.

 

[jimmbo]

The Engineers that designed the Oil Premixing System did a Good Job on it. The Pump Gears are just above the Lower Crank Bearing so they are always well Lubricated, even if the Lower Bearing Seal leaks a bit.

 

[Ifishmuskie2]

The oil tank is half full no leak while not running and sitting level.
I’m taking it out in a few days to see about the oil leak.

 

[Texasmark]

The oil tank is half full no leak while not running and sitting level.
I’m taking it out in a few days to see about the oil leak.

You just nullified finding the top cap seal as your potential problem if it's the problem. It shows up on a full tank (or near full) with the engine tilted all the way up sitting overnight or longer. First clue is you have oil in the bottom of the engine compartment when you take the cowling off and peer down at the front of the engine.
The gear is Phenolic. It's a reinforced resin material. It made up some of the components with which we were associated at work. It's akin to Matt reinforced fiberglas and is tough. Reason for using was probably because it was quieter than a metal gear to gear drive mechanism and there isn't much load (ft-lbs) on the oil pump shaft.

There are 3 bolts as I recall holding the oil pump in place. One hose and the bolts have to be removed and the pump comes out far enough to pull the drive gear with its connecting shaft out of the housing. Reconnect the hose and bolts and that's it. A word of caution, if you choose to pursue this avenue, install premix in your tank prior to undertaking.

The oil ratio of the pump output varies from about 80:1 in the idle area speeds and increases to 50:1 as the RPMs increase....per a note in the service manual.

 

[Ifishmuskie2]

Hopefully I can see where the leak is without disconnecting any of the oil system.

 

[racerone]

Have seen more than one of those gears stripped / damaged.

 

[jimmbo]

I've seen a few on the V6s, likely because the Gear is not continuous, and had a Split that has to be lined up, and secured, but not on the inline Loopers. Using Nylon for the Drive Gear was probably done to reduce Noise

 

[Ifishmuskie2]

I was able to get out today and no oil leak.
I only tilted up as far as I needed to not all the way and the oil tank is only half full.
I marked the tank before I went out and I used 1” of oil which seems about right.
I’ll just keep an eye on it.
Nice boat ride with the wife.

 

[flyingscott]

The plastic gear can last a lifetime. What kills them is overheating.