Expert: tyler boehner - 2/6/2008

Question
QUESTION: When I replace a impeller for a 90 HP outboard mercury while I am in there is there anything else I should do being this engine sat for about 5 years?

ANSWER: In the gear case itself, there isn't much else to do.  You are going to want a new impeller as you have said, and change the gear lube.  That should do it for the gear case.  After setting for 5 years, the engine may need a few things.  I would at least look at the spark plugs and see how bad they look, they may be fine.  The gas left in the carbs is going to be your biggest issue.  The gas may have "gummed" up and could cause some clogs inside your carbs.  Best way to see if you need to clean the carbs or not is to fire it up and run it.  Make sure it is hitting on all cylinders, idling smoothly, and when you get the boat on the water, see if it will run wide open.  If it is running rough, you probably need to clean the carbs.  If it has one, a new inline fuel filter is a good idea, and it wouldn't hurt to run some engine tuner through it either.  If you need any further explanation on anything or any more questions, give me a shout.

---------- FOLLOW-UP ----------

QUESTION: What is the procedure in changing the impeller and changing the gear lube.

Answer
to get to the impeller, you have to take the gear case off.  Disconnect the shift linkage before you take the gear case off.  The impeller is on top of the drive shaft.  Once you get the gear case off it is really easy to get to.  To change the gear lube, take out the bottom drain screw on the gear case and then take out the top vent screw.  Let all of the oil drain out then fill it back up from the bottom to the top.  you can change the gear lube without taking off the gear case.