if you've worked on cars you can do all of that yourself, and probably should so you learn the systems a bit. the 3.0 is pretty much an auto engine design with marine parts hung on it. the alpha one is a basic outdrive.
you would need to get the maintenance manual. clymer prints one but i've found the merc manuals to be better. you can probably still find the merc service manuals online somewhere for free.
tune up - basically changing plugs, adjusting carb idle screws (use a vacuum gauge), maybe replacing the rotor in the distributor (depends what ignition you have). i have a pertronix electronic aftermarket, so no more points to replace on mine. change both fuel filters. if you're not sure of history, i'd put in a new thermostat. if the plug wires look old, i'd replace them.
timing - you just need a timing light. this is trivial.
replace all gaskets and seals - i'd ask them for a list. i really doubt they will replace them "all".
oil change - oil & filter, easy to do, just messy depending on your bilge size.
replace the other fluids - what other fluids? i think all that's left is the outdrive gear lube (you always replace that in the fall) and the trim pump hydraulic oil. for the gear lube, you need the little hand pump that attaches to the gear lube bottles. and you want new seal washers for the drain and vent plugs. all of this is very easy.
replace impeller - obviously this comes before putting in the new gear lube. you have to drop the lower unit off the outdrive. read the manual. this isn't that hard if you take your time. it makes NO sense to replace just the impeller. the pump is plastic and it wears out; if it fails, you overhear and ruin your engine. buy the pump kit. it may not include the base. buy the pump base, too. you can consider the globe blue "run dry" impeller. they are pricey but some people swear by them. the navy uses them. but they should be replaced every two years just like the regular black merc impellers. (i run my impellers 3-4 years, shhh, don't tell anyone).
grease u-joints - you have to pull the outdrive to do that. that may sound hard, but you take off a handfull of nuts and it pulls off. trivial. if you're not a strong guy, have a helper or build a stand (plenty of photos and discussions online). you have to pull the outdrive every fall to grease the coupler splines anyway. if you don't, then don't whine when you lose your coupler miles from home (yes, it happens, and very often). the coupler's female splines are designed to be the sacrificial part in the drive system. they are aluminum and should fail before you break gears or wreck the engine. but when you lose your coupler, you will have the honor of pulling your engine to replace it. (actually, pulling the engine isn't all that bad, either. i've done it a few times.) read the manual in advance and go buy the right greases and lubes. for example, the splines need spline grease; regular grease can't handle the loads and will break down and fail. before you reinstall your outdrive, you need to check the alignment of the gimbal bearing with the engine coupler. you need the alignment tool to do this. you can get it on ebay very cheaply.
tighten bolts - no big deal. read the manual and use a torque wrench if in doubt.
for your FIRST TIME through these, i'd say...
tune up... 2 hours
timing... 1 hour
gaskets & seals... ?? this is part of the other operations
oil & filter change... 1 hour
replace impeller... 3 hours
grease u-joints and coupler spline, reinstall outdrive... 1 hour
new gear lube... 1 hour
trim pump oil... i wouldn't bother, just top it off--about any hydraulic oil is fine, but use what is called for.
tighten bolts... 1 hour
admire your work... two to three beers
so i get about 10 hours of your time. you will need to read the service manual first (which every boat owner should do anyway_, so add 3 to 4 hours of bathroom reading. you will need to get the right lubes and fluids, the fuel and oil filters, the spark plugs, and the gear lube pump and the alignment tool. you'll spend maybe 50 bucks on tools, $60 for the raw water pump and probably about $90 on the fluids and filters. for fluids and filters, you can check walmart or your marina, or you could order them online from boatfix or iboats or someplace like that.
so do you want to spend maybe $200 and 10-20 hours of your time, and actually understand your boat, and be able to do the fall and spring maintenance yourself every year?
or do you want to pay through the nose to have someone else do it (and maybe screw up your boat in some other way for you; that's been my experience).
your call!
either way, best of luck.
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