Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

[dixie189]

I am rebuilding my 1979 3.0. The question I have is, should I get the master kit, which includes new pistons and new cam shaft and lifters, or can i get by with just the basic kit that includes just the bearings, rings, oil pump and gasket set? I am rebuilding because the engine seized from sitting with water in the oil due to a missing exhaust shutter. My thought is that I should replace pistons and all since I will have the engine out and broken down anyway. Any thoughts on this?

 

[Bt Doctur]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

What size pistons ?

 

[dixie189]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

What size pistons ?

That engine has a std. 4" bore. Correct me if im wrong.

 

[dixie189]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

What I am asking is... Can I use my exisiting pistons and cam shaft or is it a good idea to replace?

 

[Bt Doctur]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

If this is a brand new block, never used ,it has a new bore .If your rebuilding a used motor you need to mic the bore to determine what size piston you will need and also if the block will need to be bored and honed to the correct oversize.

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

Yeah, I've always brought the engine to the machine shop, had them tank it, and check it and they tell me if I need std. or oversized pistons, rings, and bearings. If the crank has any damage to it, it can be turned and then you get oversized bearings for either the mains or rods or both. Maybe shave the deck if necessary to get a flat surface. Have them do the necessary machine work and then either they or you can assemble the parts.

 

[Fishermark]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

That engine has a std. 4" bore. Correct me if im wrong.

Unless you have had the boat since it was new, there is no way of telling if someone has already bored out the engine or not. By asking what size pistons, he means standard - thirty thousandths over, etc.

Like mentioned above, the best thing to do is have a machine shop evaluate it first. Then order your parts as necessary.

If you plan on simply running a hone on the cylinders and putting new parts in, then you may be able to tell from the pistons what size they are. If they are oversized, they will usually be marked. (But the best way is to let a machine shop measure and evaluate).

 

[Bt Doctur]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

My questions are designed to evaluate your skills for the task you ask about.The only stupid question is the one NOT ASKED.
Your response tells me you have never rebuilt a motor or drive to ask this:

"I am rebuilding my 1979 3.0. The question I have is, should I get the master kit, which includes new pistons and new cam shaft and lifters, or can i get by with just the basic kit that includes just the bearings, rings, oil pump and gasket set? "

You need to know sizes to order parts and you can`t do that untill everything is measured. Cams may or may not need replacing depending on the wear and if you kept the lifters matching .Cams and lifters must be replaced as a set, or reinstalled in their same positions to avoid flat spotting the cam.You can get pistons from STD. to .070 oversize,and the ring size must match the piston size.
You omit honing and crosshatch questions in relation to finished bore size.
This is somwhat of a rant but.............................

 

[dixie189]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

My questions are designed to evaluate your skills for the task you ask about.The only stupid question is the one NOT ASKED.
Your response tells me you have never rebuilt a motor or drive to ask this:

"I am rebuilding my 1979 3.0. The question I have is, should I get the master kit, which includes new pistons and new cam shaft and lifters, or can i get by with just the basic kit that includes just the bearings, rings, oil pump and gasket set? "

You need to know sizes to order parts and you can`t do that untill everything is measured. Cams may or may not need replacing depending on the wear and if you kept the lifters matching .Cams and lifters must be replaced as a set, or reinstalled in their same positions to avoid flat spotting the cam.You can get pistons from STD. to .070 oversize,and the ring size must match the piston size.
You omit honing and crosshatch questions in relation to finished bore size.
This is somwhat of a rant but.............................

Yep you are right. I have never rebuilt a engine. I probably would not be here asking questions like that if I had. I did how ever work 10 years as a mechanic in the Army.. so I do know a thing or two. Unfortunatly we never rebuilt or engines.. they were just pulled and sent away and a new engine dropped in. But thanks for the information. I havent even pulled the engine yet, so I have no idea on the condition or wear of the internal parts. Im just asking a general question here.. Do most people replace the pistions and cam shaft when rebuilding an engine or in most or some cases can the exsisting pistons and camshaft be used again?

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

In my opinion... it depends on what you want to do and what condition the stuff looks like when you take it apart. If you want a brand new bottom end like factory, and the cylinder walls look good, and just need to be cleaned up you can reuse the pistons. If one cylinder wall is damaged, you would have to bore all to match and get new pistons.

The machine shop might not charge too much more to do the assembly and you can just bolt the complete engine back up. They will check the clearances of the bearings and end play, and ring gap.


It's all pretty easy to do, but I would want someone there with me whose done it before on a 1st build.

 

[stonyloam]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

IMHO Master kit, take the block to a machine shop, tank, measure (bore and grind if needed) and press in new cam bearings. Take the head in too, valve job, valve seals and guides if needed, have them put in hardened exhaust valve seats, and you should be good for another 30 years LOL.

 

[playpool]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

Depending on your money situation I would consider looking for a replacement engine. I put about 1000.00 or so into my 3.0LX including a hot tank and rebuilt head. Also consider hours spent in a hot garage (unless you have a nice climate controlled man cave). I rebuilt mine for two reasons. #1 to learn & #2 to save on costs. BTW, the ONLY thing I did not have to replace was the manifold, carbs, and block. Everything was toast. Thanks to a cam bolt walking out. If I were to do it again I would look for a replacement. Nice to have a warranty and something shipped to your door sometimes. Good luck.

 

[playpool]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

BTW, these 3.0 are easy to rebuild but do take the block to a machine shop. Make sure they spec it out for assurance that you can rebuild it.

 

[achris]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

... I am rebuilding because the engine seized from sitting with water in the oil due to a missing exhaust shutter. ...

A missing exhaust shutter will NOT cause water to enter the engine under normal conditions... I suspect you have something else going on, like a corroded elbow and/or manifold... Have you checked them yet?

Chris.........

EDIT: There also appears to be some misunderstanding about 'undersize' and 'oversize'. I found an article on-line that should clarify the situation....

http://www.freeasestudyguides.com/crankshaft-bearing-inspection.html

In essence, if you grind the crank, the journals become UNDERSIZE, and so the bearings will be undersize. If you line bore the block, the bore for the bearings are OVERSIZE, so the bearings will be oversize.... Not sure what you would call the bearing if you did both... ....I hope this helps someone...

 

[dixie189]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

Thanks for all the info and help guys. I have weighed the cost of a complete rebuild VS. a replacement engine.. Going with a replacement.

 

[Eric 3.7LX Alpha 1]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

Already decided without even breaking down the engine and looking at what's wrong?

 

[dixie189]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

Already decided without even breaking down the engine and looking at what's wrong?

well i know is seized.. so no matter what i will be putting some money into it.

 

[achris]

Re: Mercruiser 3.0 rebuild - Master rebuild kit or just the basic?

And until you strip it down and inspect the bores and crank you have no idea what you're going to need....