Help with a rebuild on a 3.0 Mercruiser

[snett]

Well just heard back from the marina, looks like i will have to do a rebuild on my 3.0 mercruiser engine, fairly knowledgeable with engines, but wil be my first rebuild, i have the manuals from seloc and clymer for motor. where else might be a good source of info on how to go about the process...<br /><br />A little back ground on it, 1979 3.0 mercruiser, chevy 181 4 cyl. Tech said he saw water in the oil, and had low compression in 1 cyl had 75,50, 50,25. Boat from my knowledge sat with out a cover or engine cover for some time so water in oil may just be from it sitting with no cover not sure on that part yet, as other components i have replaced on boat were wet inside as well, i know boat did not sink, so its not that.<br /> actually had the boat running last fall for a very short period but would not stay running,<br />and will not start at all now. plugs were pulled and water drained from moter last fall.<br /><br /> <br />Kinda looking for a source as where to begin and what to really look for when i get it out and the oil pan off tommorow.<br /><br />Any help is much appreciated.<br />Thanks<br />Shane

 

[Bondo]

Re: Help with a rebuild on a 3.0 Mercruiser

had low compression in 1 cyl had 75,50, 50,25.

Actually,......... You've got 4 with Low Compression...........<br /><br /> This link will get you to a Great Service Manual,.........Even though it's for a newer motor,... The Basics are pretty much the Same...........<br /><br />Good Luck.....

 

[Big-E]

Re: Help with a rebuild on a 3.0 Mercruiser

Shane, I just rebuilt my motor and accualy fired her for the 1st time monday (looking to get her wet on saturday) I just had the clymore manuel and it worked ok. Rebuilding the motor was quite easy but one little word of advice i can give you, Keep the rod caps matched with the rods in the proper orientation!! If you search my post's you will see that i mixed up number's 1 and 3 and delayed starting my motor for a couple weeks. (lession learned) <br /><br />Wow your comp #'s were way lower then mine, I had 90,120,110,100. hehe <br /><br />Just so you know i spent about $1100.00 on everything. That included gen new ign parts from mercruiser and a rebuilt starter. <br /><br />Do you self a favor, go to Home depot and rent there engine hoist (cost's $32.00 for 4 hours) and pull it out. Buy a engine stand at autozone for $52.99 and mount it to the engine stand. You need to remove your flywheel so it will fit on engine stand btw. Other then that just keep track of everything and get motor to machine shop. <br /><br />You could prolly be back running in about 3 weeks if your good. <br /><br />Good luck , and the sound of my brand new motor is sweet!!!<br /><br />Big-E

 

[lowshovel1]

Re: Help with a rebuild on a 3.0 Mercruiser

BIG-E,how high could that rented engine hoist get? reason I ask is top of my transom is 7 feet off the ground----or should I be looking for a barn and a chain fall?

 

[jeff13601]

Re: Help with a rebuild on a 3.0 Mercruiser

I just did mine. A small set of chainfalls and any beam, limb etc will work. Lower it down into a truck and take it where you want. Its not a very heavy engine

 

[Don S]

Re: Help with a rebuild on a 3.0 Mercruiser

You actually need service manual #3 for your engine, do you know for sure if it's a 140 or 120 engine? They both look the same on the outside.<br />That is one reason having the proper manual is always handy. Others may be close, but unless you know where they are different, then you still have a problem.<br />Here is where you can get the manual for your engine. And yes, they give very detailed information in the Mercruiser manuals for EVERYTHING.<br /><br /> Service Manual #3

 

[Big-E]

Re: Help with a rebuild on a 3.0 Mercruiser

lowshovel1 : well my transom isnt that high off the ground but i had the motor hanging about 8 feet off the ground. I was thinking of backing boat into my garage but i didnt wanta chance putting all that stress on my beams. (they have to hold up to hurricanes you know?) On my dads old 21' cc it had a 350 in it and was about 7 feet off the ground and when we had to pull motor we put engine lift on a frame. Consisted of some 4x4's ontop of each other and then pulled boat out of way when engine was way up in air, then lowered and placed on engine stand. <br /><br />Good luck! <br /><br />Big-E

 

[lowshovel1]

Re: Help with a rebuild on a 3.0 Mercruiser

thanks for the input guys.I'll let ya know how it go's---is a 350 just happy it ain't a big block

 

[snett]

Re: Help with a rebuild on a 3.0 Mercruiser

Don, <br />Im sure its a 140 as i have checked the seriel number and also the 140 was the only motor that came in my 79 glastron carlson cvx-16ss. Its the original motor. Motor still has all the badges on it as well and they all say 140. I want to do it my self, just a little unsure of doing it.

 

[Don S]

Re: Help with a rebuild on a 3.0 Mercruiser

I want to do it my self, just a little unsure of doing it.

Nothing wrong with wanting to do it yourself, but equip yourself for the job with the proper manual and tools. Then if you don't understand something, and need to ask a question, you have a reference point you can refer to.

 

[snett]

Re: Help with a rebuild on a 3.0 Mercruiser

Big-E <br />Just curious what all did you do to your motor for the $1100.00 did you have much machine work done or did you just fix a problem you had with the motor, Just trying to get a decent estimate on what it might cost to do it myself I have a quote for a long block of $1400 with my block as a core, but since you did it for 300 less and added a few other parts I dont need since I already recently replaced them, was just curious what all you did or what you replaced.<br /><br />Thanks for a response, and thanks to all who have responded.<br /><br />Shane

 

[KaGee]

Re: Help with a rebuild on a 3.0 Mercruiser

Pulling the motor...<br /><br />Here's what I did:<br />

<br /><br />

<br /><br />The frame cost about $70 in materials and a couple of hours labor.

 

[Big-E]

Re: Help with a rebuild on a 3.0 Mercruiser

Shane,<br />Sorry for the long time for a reply but i was out breaking in my motor this weekend on the lake. What i did for $1100 bucks? Everything!!! Had motor boared over .040 due to motor having water in it and rust pits in cyls. Had head rebuilt, new pistions, oil pump, all electronics, new hoses, water pump in drive and motor, starter rebuilt, crank turned .010 under. (btw those main bearings werent cheap from mercruiser) , had carb rebuilt (that was 200 alone) , only parts i reused were alt, and fuel pump. <br /><br />Alt wasnt putting out any voltage but i just found i had it wired wrong so maybe it will work. <br /><br />BTW. Boat sounds like a beast now and with 2 ppl in it she will rip, i had to control myself to keep her around 3 k for break-in. My speedo said i was doing 30-32 mph at 3200 rpms. Does this sound right to anyone? 16.5 foot bowrider. <br /><br />later, <br />Big-E

 

[wake5150]

Re: Help with a rebuild on a 3.0 Mercruiser

Keith,<br /> I remember seeing your pictures a few weeks ago. I really like that rig...<br /><br />Questions<br />1) What are the uprights made of? Pressure Treated 4x4s?<br />2) What is the horizontal load member made of? It must be 4x8?<br />3) How do you keep the horizontal piece plumb in the crevice of the crossed 4x4s?<br /><br />Thanks<br />Chris