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1989 merc 100hp oil line routing

I bought a 115 tower on a new rig in 1989. Titles said both were '89 models. Some folks on here said that tower production ceased in '88. Ok fine! No reason why an engine built in '88 can't be sold in the '89 calendar year and titled as an '89 in my thinking. If you are talking about a 4 cylinder looper, which is said to be a production change for engines manufactured in '89, then my comments below may not be for you. However, if it is a 4 cyl., they are equipped with an under the cowling oil tank and the lines are internal to the engine....just need a gas line input.

I had a separate tank located adjacent to the engine containing oil and I don't remember the plumbing. Don't remember how the oil was introduced into the gas stream but recall only one line going to the engine. If somebody doesn't jump in here and direct you properly, just run your gas directly to the engine, through a priming squeeze bulb equipped fuel line and premix your oil into your gas when you fill your tank at a 1 pt. oil to 6 gallons of gas. Besides that's the best way to not worry about the engine not getting oiled properly.
 
The 100 HP inline 4 may have used a plastic type gear to drive the oil pump.-------Look this all over carefully if you decide to trust the " automatic " oil mixing system.-----Best seek help at a shop.-----Mistakes can be expensive.
 
racerone said:
The 100 HP inline 4 may have used a plastic type gear to drive the oil pump.-------Look this all over carefully if you decide to trust the " automatic " oil mixing system.-----Best seek help at a shop.-----Mistakes can be expensive.
Click to expand...
Going to pre-mix solves those apprehensions and is how I would approach the situation. I converted a 2002 90 to premix so I would have something else to worry about and didn't look back.....but I did mark the boat adjacent to the fuel filler to use premix so I wouldn't forget.
 
tank under the hood, not changing to premix. still need to know where the oil lines connect. pulled a parts diagram but it is not specific.
 
Texasmark said:
Going to pre-mix solves those apprehensions and is how I would approach the situation. I converted a 2002 90 to premix so I would have something else to worry about and didn't look back.....but I did mark the boat adjacent to the fuel filler to use premix so I wouldn't forget.
Click to expand...
tank under the hood, not changing to premix. still need to know where the oil lines connect. pulled a parts diagram but it is not specific.
 
racerone said:
The 100 HP inline 4 may have used a plastic type gear to drive the oil pump.-------Look this all over carefully if you decide to trust the " automatic " oil mixing system.-----Best seek help at a shop.-----Mistakes can be expensive.
Click to expand...
tank under the hood, not changing to premix. still need to know where the oil lines connect. pulled a parts diagram but it is not specific.
 
Texasmark said:
I bought a 115 tower on a new rig in 1989. Titles said both were '89 models. Some folks on here said that tower production ceased in '88. Ok fine! No reason why an engine built in '88 can't be sold in the '89 calendar year and titled as an '89 in my thinking. If you are talking about a 4 cylinder looper, which is said to be a production change for engines manufactured in '89, then my comments below may not be for you. However, if it is a 4 cyl., they are equipped with an under the cowling oil tank and the lines are internal to the engine....just need a gas line input.

I had a separate tank located adjacent to the engine containing oil and I don't remember the plumbing. Don't remember how the oil was introduced into the gas stream but recall only one line going to the engine. If somebody doesn't jump in here and direct you properly, just run your gas directly to the engine, through a priming squeeze bulb equipped fuel line and premix your oil into your gas when you fill your tank at a 1 pt. oil to 6 gallons of gas. Besides that's the best way to not worry about the engine not getting oiled properly.
Click to expand...
tank under the hood, not changing to premix. still need to know where the oil lines connect. pulled a parts diagram but it is not specific.
 
Haven't looked lately but remembering, the tank drain tube goes to the oil pump. Out of the oil pump is a Y (molded tube) whereby the fuel line bringing fuel into the engine and the oil are mixed then routed off to the carbs.
 
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