Working on Mercruiser 120, where to start?

[dfalk]

Last Oct. I bought a '76 Aristocraft with a Mercruise 120 in it. The guy I bought it from had it for a year, and didn't know anything about it, and sold it cause he got a newer boat.

All I know about it is that I poured a little gas down the carburetor and it fired up and ran till it was out of gas. So before I put alot of work/time/money into this boat what are the major things I need to check first to make sure its even worth it? I dont want to put alot of money into the engine just to find out later the drive is totally shot. If this was your boat where would you start?

Thanks Derek

 

["G"]

Re: Working on Mercruiser 120, where to start?

Like a house there are important parts that mean big money thus they tell you if the sale is worth the money.

Compression checks and lower unit checks tell the story on boat motors.

 

[lab1484]

Re: Working on Mercruiser 120, where to start?

trust me with that engine check right side of block for crack/dripping water -standing in front of engine

 

[Bondo]

Re: Working on Mercruiser 120, where to start?

what are the major things I need to check first to make sure its even worth it?

Ayuh,... Rotten stringers,+ transom...

 

[ziggy]

Re: Working on Mercruiser 120, where to start?

main things i did was compression test to determine if engine is at least somewhat healthy. look for water in the oil. do be critical of the manifolds and riser. when i got mine. ya could tell the manifold was on the way out as it had rust on the outside bottom port side. it failed within the first couple weeks i had it too. then a drive pressure test to be sure the seals in the drive are good. check the gear lub for water and metal fragments. feel it as soon as you remove the drain plug. feel for fragments.
on the boat, go over it with a fine tooth comb. waxing it by hand is a good start to touch every part of it.

an aristocraft nineteen don't have stingers. they are unique in design. http://www.aristocraftboats.com/fiberglassbrochures/Incomparable19page4.pdf
they also don't have much wood in the transom. best i can tell it may have wood right where the drive attaches but other than that, i don't think they have a wood transom in the conventional way.
biggest major problem with the boats that i've read is water intrusion between the inner liner and hull. the foam gets saturated and holds water making them real heavy. i don't know how to test other than weighting it or cutting a hole in it to go see or feel the foam. perhaps ride height too. how it sits in the water statically. or hard to get on plane. mine planes in 2 or so sec. from stand still.

check to make sure everything works. turn it on, turn it off.

what color did ya get?
some oem boat parts are still available from the oem. http://www.aristocraftboats.com/AristoCraftNineteenPartsList.pdf

hope she turns out to be a winner for you. they are some very versital boats that are real head turners at the boat ramp. be prepared to be approached with questions about what ya got. folks seem to like them..

 

[bigskiohio]

Re: Working on Mercruiser 120, where to start?

change the oil and run it on muffs it should idle forever, clean the fuel filters and run new gas first, then you can shift it and look and listen. a little leak from th exhaust no big deal, water in oil not good or a big crack anywhere. if you ran it without any water hooked up, you fried impeller and will need a new one off the bat,or engine will over heat.

 

[Fishermark]

Re: Working on Mercruiser 120, where to start?

if you ran it without any water hooked up, you fried impeller and will need a new one off the bat,or engine will over heat.

Just to add to what bigskiohio says - since you don't know the history of any maintenance, one of the first things to do is to drain the gear oil from the outdrive, pull the outdrive off, then pressure test it for leaks. If good, replace the water pump in the outdrive and check the engine alignment before re-installing.

If you haven't already, go to the Adults Only sticky at the top of the page and download the appropriate manual for your engine and drive. Do some reading and familiarize yourself with the basics.

 

[fishrdan]

Re: Working on Mercruiser 120, where to start?

Check the biggest "head ache" things first and in their order of difficulty and expense. As the other guys have pointed out.

1- stringer and transom rot (search old threads on how to check)
2- drive oil level, water intrusion and pressure/vacuum check
3- engine

No sense in dumping a ton of time and money into the drive and engine if the hull is going to require major overhauling. The same can be said for the engine and drive too if the hull is solid.

Something else you should be aware of, the outdrive upper gears are spinning any time the engine is running, so make sure the outdrive gear lube is full. Not sure if you checked, but you should since this boat is used.

 

[dfalk]

Re: Working on Mercruiser 120, where to start?

Thanks for all the info. So it sounds like first Ill do a compression check. That will be easy, im really good with engines.

Second I will remove the drive and do a pressure check? That sounds like it might be a little tough, ill have to do some reading on that. I do have the manual for this setup that I got in the Adults section. Know of any good links off hand that show your how to do this?

 

[Fishermark]

Re: Working on Mercruiser 120, where to start?

It the same Adults Only section you will find a post about pressure testing your drive. It is here

 

[frank246]

Re: Working on Mercruiser 120, where to start?

All I know about it is that I poured a little gas down the carburetor and it fired up and ran till it was out of gas.

Start with a new impeller.

O/D oil, engine oil, grease the zerks on the O/D, fresh Gas.

 

[ziggy]

Re: Working on Mercruiser 120, where to start?

Second I will remove the drive and do a pressure check?

you don't have to remove it to test it.

if it leaks ya may need to remove it to find the leak though.

you do have to remove the drive to do pm.
my nineteen needed all the stuff inside the bellows and a shift cable..

 

[bigskiohio]

Re: Working on Mercruiser 120, where to start?

http://forums.iboats.com/showthread.php?t=334630


Her is some tools imade and bought for maintenance and the pressure tester i made .

 

[dfalk]

Re: Working on Mercruiser 120, where to start?

Forgot to ask, when do a compression check is it necessary to warm the engine up first? I really dont want to have to run water into the engine because its still cold outside. If I just turn it over cold and all 4 cly are within 10% will I be good to go?

Also this is gonna sound real stupid but how exactly do I ground the ignition coil do it doesnt spark?

 

[ziggy]

Re: Working on Mercruiser 120, where to start?

Forgot to ask, when do a compression check is it necessary to warm the engine up first?

from #13 in the adults only section. see #9...
http://forums.iboats.com/showthread.php?t=295070

Also this is gonna sound real stupid but how exactly do I ground the ignition coil do it doesnt spark?

remove the coil tower wire from the dist. and ground it to the block. i've got a empty bolt hole close by and just stuff it in that. you'll have to find a convenient place on yours.. or see #9...

 

[dfalk]

Re: Working on Mercruiser 120, where to start?

Again thanks for all the helpful info. I got all the info I need for the compression check.

For the pressure check im just gonna build a little tester/gauge, which looks simple enough except for one part. The fitting that screws into the gear oil plug, where do you get one of them at? Are they a special fitting or can I pick something up at home depot or something?

And finally to do a pressure check you

-drain gear lube oil (check for contaminants while its draining)
-attach gauge and pump it 15lbs of air
-wait a few hours and check gauge, if its at 15lbs still im good to do, if not I have a leak that needs to be found.

 

[dfalk]

Re: Working on Mercruiser 120, where to start?

...

 

[ziggy]

Re: Working on Mercruiser 120, where to start?

The fitting that screws into the gear oil plug, where do you get one of them at?

i used the end off a gear lub pump. even came with a hose.

And finally to do a pressure check you

-drain gear lube oil (check for contaminants while its draining)
-attach gauge and pump it 15lbs of air
-wait a few hours and check gauge, if its at 15lbs still im good to do, if not I have a leak that needs to be found.

yep, and i'll add that while it's under pressure, ya might give the drive shaft a few twists (assuming the drive is off the boat) so everything rotates inside the drive so your picking up a new surface on the seals while testing + i let it sit for about a day under pressure. same with the vac. test. it's gotta hold at whatever pressure/vac you set it at and not leak at all to pass. then i was convinced it was sealed internally.

fwiw. not related to this post. but ya might enjoy checking out the aristocraft forum. there's interesting info on aristocrafts in there. http://forums.iboats.com/forumdisplay.php?s=&daysprune=-1&f=224

 

[dfalk]

Re: Working on Mercruiser 120, where to start?

fwiw. not related to this post. but ya might enjoy checking out the aristocraft forum. there's interesting info on aristocrafts in there. http://forums.iboats.com/forumdisplay.php?s=&daysprune=-1&f=224

Cool sounds like I got all the info I need to see if my boat is worthy, ill let you guys know sun how it goes.

Ya I been to that section of the forum, you were actually the first person to get me headed in the right direction when I first got my boat.
http://forums.iboats.com/showthread.php?t=356736

 

[dfalk]

Re: Working on Mercruiser 120, where to start?

So I did a compression check today and all 4 cylinders were good, all right around 115lbs. I also did a pressure check on the drive and its held the 15lbs for a good 16 hours now, so Id say all the major stuff is good to go. Got a few questions now.

I was gonna rebuild the distributor but it looks like it was just done, take a look at the pic and see what you think (ill link to the big pics so I dont mess up margins)
http://img.photobucket.com/albums/v388/dfalk/Boat/0306101454.jpg

Second I found some "stuff" sitting on the bottom way in the back. One is a bilge pump, and the other is.. well i have no idea. It looks like a motor, and has 2 wires going it. Any ideas? Also how do I test the bilge pump, well I pull the lever on my instrument panel nothing happens, does it have to be submersed in water first?
http://img.photobucket.com/albums/v388/dfalk/Boat/0306101516a.jpg

I also found a big hole, it is pretty much right under the starter, any ideas why that is there?
http://img.photobucket.com/albums/v388/dfalk/Boat/0306101516.jpg