Tohatsu 9.8hp lower unit leak.

willows.2@hotmail.com

Seaman Apprentice
Joined
Jun 4, 2018
Messages
34
Hello all.

I recently replaced the impeller on my 2013 9.8hp Tohatsu.
I've just noticed a black oily substance leaking out where the Lower Unit was bolted back to the motor.
I flushed it yesterday, then left it propped up on the shed floor, and noticed oil on the concrete floor this morning.
Never come across this before......only since i changed the impeller.
Wondering if I was supposed to seal the surface where it bolts back on?.
What would the oily substance be.......unburnt fuel perhaps....or something else?

Cheers.
 

pvanv

Admiral
Joined
Apr 20, 2008
Messages
6,500
I assume your model is MFS9.8A3. Year is irrelevant. You may have sloshed some crankcase oil out, and had that run down the exhaust passage to the LU. Check your oil level. No, there isn't any seal at the joint where the LU joins the exhaust housing.
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Is the leak clean or it's a dark and sticky one ? If the latter it's unburned fuel-2 strokes oil leftovers which is normal on 2 strokes OB's. Next time out run it at full throttle for some minutes to clean the internal exhaust sytem.

Happy Boating
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
You're welcome,

If the engine is, was used running at low speeds will collect more leftoevers. If wanting having a cleaner exhaust system buy a can of Carbon Remover Spray. With OB-ON at neutral, spray small bursts of product through carb, follow can instructions.

For a direct application of product, remove carb's plastic air silencer cover. After decarboning go for a wot run as if stealling the combo to fully burn product through exhaust. . Engine will idle and run more smoothly than before.

Happy Boating
 
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