Mercruiser 140/3.0L oil pan removal

adruid

Seaman
Joined
Apr 3, 2014
Messages
52
My 1984 GM 140/3.0L likely needs to have the oil pan replaced. Has anyone done this with the engine in the boat? It looks like it is possible if the alternator and bilge pumps are removed, but I would like an experienced opinion on this before jumping in. I've been told the oil pan is identical to a Chevy Nova, but do not know the specs or year. Would like to hear from anyone with that info as well. Thanks!
 

Rick Stephens

Admiral
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Aug 13, 2013
Messages
6,118
I'll tell you what, you can take the motor out in less than an hour - maybe a lot less, last time it took me about 30 min - it is not worth standing on your head to change bottom end parts. It will take longer and the job will be nowhere near as perfect.

RIck
 

bruceb58

Supreme Mariner
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Mar 5, 2006
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30,454
I did it with a 5.0 Chevy in the boat. Never again! Was extremely difficult.
 

Grub54891

Vice Admiral
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Jun 17, 2012
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5,908
And why does it need to come off? Besides it's rusted or just a leaking gasket/
 

ziggy

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Jun 30, 2004
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7,473
sounds painful to R&R the pan with the engine in the boat to me. on my boat, it'd be impossible. i can't even get the oil drain plug out of it without moving my engine up.
so i had to pull my engine to R&R my pan. Rick, you must be a better mechanic than i am. it took me a day to prep for removal and to get my Aframe in place, and to get the boat under the Aframe. then 3/4 of a day to pull the engine and R&R the pan and put the engine back where i found it. another half day to align and hook everything back up. it was easy enough to R&R the pan with the engine out. i just did it on the chain hoist. so i didn't put the engine on the ground, just up enough to do the pan. it's nice on the chain. ya can just spin the engine around while your doing the deed. lay in one spot w/o moving all around the engine.

so anyways. i'd pull the engine if i were you. i'd think one main obstical would be getting the pan off from around the oil pickup. it sits at the bottom of the pan. again, this would be impossible on my boat, yours i don't know....
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
Staff member
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Jul 23, 2011
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47,303
the shortest and easiest path is often the one we percieve to be the hardest.
pull drive, pull motor, change pan, clean bilge, install motor, align motor, install drive - about 4 hours (with a lunch break in the middle)

or

remove a bunch of stuff on the motor, attempt to get oil pan off, swear alot, make a big mess, swear more, get mad, swear even more, then after 6 hours of skinned knuckles and swearing, not to mention the wrench you threw thru the window, you finally pull drive and motor (about 10 hours)
 

adruid

Seaman
Joined
Apr 3, 2014
Messages
52
Thanks for the responses. Looks like I need to rent a cherry picker or A-frame. You folks make it sound so straight forward and simple, but being my first Mercruiser I'm sure It'll take a few days/weeks. I have dropped many a VW engine and replaced in half a day, but this is something quite different. I do appreciate all the personal insights: Ziggy, hit it on the head mentioning the oil pickup. Time to balance the work/cost/frustration/tools/experience equation and figure out if I should just take it to the local yard. It's the "alignment" thing I'm most worried about.
 

Rick Stephens

Admiral
Joined
Aug 13, 2013
Messages
6,118
Yup, have to find something tall enough to lift the motor up and out. That is probably the hardest part.

Pulling a motor is written about all over the forum, basically, pull the outdrive, which pulls the driveshaft out of the flywheel. Then disconnect electrical - a lot easier than t sounds as most of it is in a plug that just pulls out. The rest is several ground wires and a couple hot wires from the battery. Incoming water line. Fuel line. Pull the exhaust riser - you'll need a new gasket on reinstall. Rear mount bolts - (just 2 of em). Front mount bolts, 2 again. I think that it is it.

There are lifting eyes on the motor. Don't use the one on the thermostat housing, that is just for leveling the engine to do rough alignment on a new engine install.


Alignment when you reinstall is really easy on the 3.0L since it has a single adjuster bolt on the front. All you are doing is getting the alignment tool to slide in easy. Even if it takes an hour, and it won't if you have a helper, it is very straightforward and simple.

Rick
 

ziggy

Admiral
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Jun 30, 2004
Messages
7,473
imho, to change the pan, least on my boat. the engine didn't have to come all the way out. just up. i'm sure i had it up a foot or 2, but didn't see the point in taking it all the way to the ground. i guess if ya wanted to be safe for sure, ya'd take it to the ground. as just up, nothing better give way. the chain hoist has it. the Aframe better not break or wobble. nothing can fail w/o very bad results...

i checked my alignment prior to disassembly. i thought it was ok, but not great. i didn't move anything when i had it up, short of the ft. motor mount lag bolts. i thought my fiber washers looked a little worn. i replaced them. after reinstall. i needed no adj. the alignment bar slid in very nice and smooth. better than i started with. i needed no adj. don't know if that's the norm. but that's what happened when i did mine. i was astounded.....
 
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