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Mercury/Mariner 115 (2+2) oil mixer reliability

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2PBC22

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I have a 1990 outboard and am thinking about ditching the automixing oil system. I was wondering about the automixer reliability in the 115 hp 2+2 mercury?

Everything I've seen says the 135-200 hp mercury's from this time period have the unreliable plastic gear driving the oil pump. Does this issue also plague the 2+2 engines?

The replacement driver gear for the 115 is 43-43019A1 and appears metal from the pictures.

Just wanted to confirm the automixing system on the 2+2 is much more reliable.
 
All the bottom gear driven pumps are pretty much bulletproof. Rarely see any of the inline motors with oiler fail and rarely see it on the 3L V-6 motors. That why they dont have rotational sensors.
 
Ah, thanks faztbullet. So you'd just leave it operational rather than go to premix?

Am I correct in that only the 2.0 and 2.5s from this time period had the plastic gear and were prone to failure?
 
The only oiler problem for the pre 98 motors like yours is the magnet coming unglued in oil tank, make sure low oil alert does work. Yes the 2.0-2.5 have a plastic gear and subject to failing from overheats.
 
I actually have the Low Oil Warning Module disconnected because it's faulty and the tan wire was grounding out and causing the constant beep.

The magnet coming unglued won't clog an oil line or work it's way in to the pump will it? With the oil warning module disabled, a loose magnet shouldn't make a difference?
 
2PBC22 said:
I actually have the Low Oil Warning Module disconnected because it's faulty and the tan wire was grounding out and causing the constant beep.

The magnet coming unglued won't clog an oil line or work it's way in to the pump will it? With the oil warning module disabled, a loose magnet shouldn't make a difference?
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I have a 2002 115 and the magnet fell off and I disconnected the alarm. So, as Faztbullet said keep a sharp eye on the oil level. i keep my tank a quart low and check it every time I come in.
 
Thanks guys. I haven't ran the boat in 3 years. Replaced the impeller, flushed the whole cooling system and it fired right up. I'm going to run premix with the oil pump connected until I can verify it's working properly.
 
2PBC22 said:
Thanks guys. I haven't ran the boat in 3 years. Replaced the impeller, flushed the whole cooling system and it fired right up. I'm going to run premix with the oil pump connected until I can verify it's working properly.
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The service manual tells you how to conduct that test and what is the pass/fail metric.
 
On the 2+2 running double oil might cause a sparkplug fouling problem with 3 and 4 if you spend much time at slow speeds. Using Pennzoil Super Premium Semi-synthetic could help control that problem.
 
Running extra oil is fine in them. 3&4 run such a minute amount of fuel mix that they really can't foul out. Plus the plug is always firing so a pretty slim chance they will foul out.
 
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