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Considering DIY rebuild on 5.7 2bbl Mercruiser - thoughts?

S

Silvertip

New member
I have a 96 Chaparral with a seized motor due to lack of oil. I was given a ballpark estimate of around 7K for replacement, with the disclaimer that it could be difficult to find someone around here that would even take it on. $7K is more than what the boat is worth in running condition, but it is a nice boat and I don’t want to scrap it so I am looking into rebuilding it myself. I have rebuilt a couple of Porsche motors successfully, but have no experience with American iron or with a seized motor, particularly what to look for in damage.

Since even to scrap it I am going to need to pull the motor, I can do a tear-down and take a look before committing any money. I would appreciate your comments as to what to look for and what I am getting myself into.

Thanks,

Kevin
 
Clarify replacement.
What work are you capable of?

You can purchase a new or refurbished long block that comes with ( block, heads, oil pump and oil pan, timing chain and cover.
What is your engine? Carbed, TBI or EFI?
Mechanical fuel pump or electric if carbed???
I
Then swap all the additional parts yourself? Or would you have to pay someone else to do the work?

A new Vortec marine block as described above is around $5000 +
A refurbished marine block is around $3500. (Refurbished cylinders will be bored out to most likely + .040") new + .040" pistons, cam shaft, lifters and push rods, timing chain and bearings, refurbished heads and reconditioned crankshaft)

Whats your ability?

Depending on internal parts condition and based on age,
It will cost a minimum of $3000 to $4500 for machine work, parts and possibly having machine shop put it together!
 
If you look hard on Facebook Market place there are always good deals on drop in 305's and 350's. Plug and play no real swapping any parts.
I have seen $2500-$4000. For complete engines. Drop in and connect, align, start engine and go.....
 
That (drop in engine) may be the best way to go. If you really want to do the whole thing yourself you will need a good machine shop to do the parts of it you can't do and also to check the block, & heads for cracks, etc.
The most I have ever done is a top end overhaul because the bottom end was still ok. That's actually a fairly easy job, you just have to keep all the parts organized and clean. Bolted on a set of reman cylinder heads, new gaskets, new head bolts, and new exhaust. Still running well 9 years later.
Small block Chevrolets are very easy to take apart and put back together, but there are parts of the job you really can't do yourself. So you'd have to find out what it's going to cost you in parts, machine shop services and time. Vs, a drop in 5.7. If you want to do it for the experience/knowledge base that's one thing but to get it done, drop in whether it's used from marketplace or from a rebuilder like Michigan Motorz is the way to go.
 
like others have said if you have swapped engines in cars certainly well within your skill set.

If you have a local machine shop you trust certainly its worth getting a price for a rebuild from them. With out oil can only think you will need crank and rods resized, bored and new pistons, valve job maybe new valves.

If you dont have a local machine shop get a assembled new or reman long block and swap over your accessories.

Michigan motorz is one of several suppliers https://michiganmotorz.com/5-7l-vortec-marine-engine-1996-2020/

certainly if you can do the work you can keep an older boat going. Winter of 2015/16 I repowered my current boat which I bought with a known cracked block. No question if you like the boat, while it may not be worth $4-7k for an engine, you cant get much of a working used boat for that ball park.
 
Agreed, if you like the boat, it meets your needs, repowering makes sense. There is a lot of junk in the used boat market, that way at least you know what have. I haven't had to repower yet, but I did do major structural repairs (2007) and had the old faded gelcoat painted in Imron (2012) the boat is still solid and looks very good for its age. So for me yes it would be worth it, the least expensive way to stay in boating.
For me I'd go with a reman if I stick with the V6, if I decide to upgrade to the V8, I can get new, but it increases costs since more parts need to be changed. For my use and preferences I would require a half closed cooling system and a remote oil filter mount. Those two things take some of the extra headaches of owning an I/O.
 
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