Information needed on swapping a 4.3L Mercruiser engine

[almstsobur]

Hey all, new here. I was hoping someone could help me out with a few questions. I have a 1991 17? invader boat that has a 1991 4.3L Mercruiser with an Alpha Gen2. I have rebuilt and swapped a couple car motors in my day but never any boat motors. I got my hands on a brand new 2006 4.3L Mercruiser motor I want to swap with my tired original motor.

My old man is coming from well out of town to help with this motor swap and I want to make sure I have everything I need in place so we don?t have any unforeseen hold-ups.

My first question.. Any reason this swap will not work? From what I have read this motor should hook up just fine to this outdrive, correct?
Do I need any special tools? I read about the alignment tool in the service manual, if this just one single tool is this necessary? Any other oddball tools or strange size sockets or wrenches etc I may need for this swap?
Can I use a standard automotive cherry picker? Or will I need something taller or a different type of motor hoist?
Any special or particular lubricants needed?


Anything else I should be aware of? Any information is greatly appreciated. I tried to google for a write up on this and didn?t come across anything useful, if anyone knows any good links that might help me out, please by all means.

Thanks Again,

-Rob

 

[almstsobur]

Re: Information needed on swapping a 4.3L Mercruiser engine

Can anyone link a forum maybe more suited for these questions? Thank You, completely new to boating.

 

[cr2k]

Re: Information needed on swapping a 4.3L Mercruiser engine

From what is the new motor out of? Several say a motor out of a truck will work OK. Remember automobile engines are made to run hotter and leaner for smog reasons. Marine engines are not. Do a search as this topic has been run to death several times.

 

[almstsobur]

Re: Information needed on swapping a 4.3L Mercruiser engine

The motor is a brand new crate Mercruiser TKS. It's been sitting a few years as a "stock" motor at a local repair shop, they are letting me have it for a steal.

 

[WILSONS88]

Re: Information needed on swapping a 4.3L Mercruiser engine

Should be any easy swap. You really need that alignment bar. Check your gimble bearing, u-joints and belows while your in there also. Does the new motor have a new coupler on it? If it were me I would invest in a new coupler while the engine is out. Cheap insurance! You wont have to pull the motor again if the old one went bad.

 

[StevNimrod]

Re: Information needed on swapping a 4.3L Mercruiser engine

Can you be more specific about the new engine (i.e., long block, long block + tin, or complete turn-key package)?

We need to know exactly what you have (serial numbers are always helpful) in order to give you any meaningful answer.

 

[almstsobur]

Re: Information needed on swapping a 4.3L Mercruiser engine

as far as I know it is full turn key from Merc. I do not have the new motor yet, I pick it up Friday so i have no numbers from it. As far as the coupler, I have no idea what that is maybe these pics of the new motor can help. Is it a good idea to just change the gimble, bellows or U-joints while I am in there? is there a brand or type you all recommend?

 

[StevNimrod]

Re: Information needed on swapping a 4.3L Mercruiser engine

Put it this way - you're never going to have easier access to some of the stuff. How far in you go is entirely up to you. What starts out as cheap insurance can easily add several hundred bucks in parts. In addition to the usual suspects already mentioned, now might be a good time to do your upper swivel shaft seal (especially if it's leaking), which also buys you into a transom seal (the seal itself), and while you have the thing on the bench you might as well do everything that looks suspect. And, while the engine is out is a good time to do any cleaning/repairs/painting of the bilge. Point being, how far you take this really depends on how far you want to go. I took mine so far over the top that putting the engine back in became almost an afterthought. But now I'm glad that I did everything while I had it out. Just know that if you're forcing yourself to get this done in a certain timeframe, Murphy will show up and you'll need something you don't have.

As far as parts go, Mercruiser parts are the "by-the-book" standard, but you will see that quite a bit of their stuff is actually made by some other company. To my knowledge, this applies to bearings and u-joints. For that stuff, your local bearing house will probably be able to fix you up if you bring them the old ones. Or you can pay Merc for their bag and label.

Before going into even more detail, what is your final goal for this project?

 

[almstsobur]

Re: Information needed on swapping a 4.3L Mercruiser engine

Before going into even more detail, what is your final goal for this project?

Strictly reliability. I want to take the dogs and the woman out camping, hopefully to some fairly remote locations. I'm not too worried about performance but obviously fuel economy is a huge plus. I'm quite mechanically inclined, but I'm also quite aware some things you just can't repair out on the water, those are the issues I hope to prevent. I've had Jet ski's for years, but this is my first boat. I know the water well, but we never could take the camping gear and the dogs with the ski's so I moved up to this boat. I don't plan on really any ski'ing wakeboards or water toys, maybe a tube once in a while. But if i'm boat camping in the middle of nowhere I obviously need the thing to start and run as well as possible.

Infact the motor that's in the boat now runs fine, getting a little tired 120-140 compression in every cylinder. But the deal on this new motor was too good to pass up and I'm one of those people that prefer to know what I have, right now i'm guessing based on other peoples accounts.

 

[StevNimrod]

Re: Information needed on swapping a 4.3L Mercruiser engine

Awesome. Normally you get things like "I want it to have a killer top end, make eleventy billion HP, have a good idle, and be under $50."

I'm just thinking out loud, but if the deal is that sweet, you could possibly flip the new engine and take some of the proceeds to go over yours with a fine toothed comb, and use the rest to dispose of as you see fit.

The way I see some of the newer engine packages is that it's more stuff to break that is beyond my ability to fix out on the water. I have a carbed engine, and like the simplicity when it comes to fixing. The trade off, of course, is fuel economy.

Whatever you ultimately do with the engine, I'm sure this forum will be a great resource to you. A lot of what you end up doing will depend on the current condition of things; so you might want to start inspecting stuff now to determine what you will/will not want to replace. I'll look tonight for my complete list of notes of what I did, and my best estimates on what it ended up costing.

 

[almstsobur]

Re: Information needed on swapping a 4.3L Mercruiser engine

I'll look tonight for my complete list of notes of what I did, and my best estimates on what it ended up costing.

I would really appreciate that. I know it's an older boat, but the hull is in great condition and it's just the right size for my yard. I see it as a keeper for quite a while. I took 10 days off on labor day week to try to sort out everything I can with this boat and the motor swap. My retired (former auto mechanic for a living) father is coming down to throw some wisdom my way Things like the gimble bearing and coupler etc are all just foreign to both of us, but it certainly sounds like just the type of thing I need to at least inspect if not replace during this process. just the info i'm looking for and I certainly do appreciate the help.