Remanufactured is cheaper. Probably has a warranty. I would
A lot cheaper for sure as long as you trust him no mistake about it as long as its a marine long block

 

Remanufactured 5.7 300hp is fine as long as your mechanic is standing behind the warranty.

 

There are a lot of parts that will swap over and once done, the aftermarket one will be the same as the OEM.
Sometimes a reman is better than new, since the reman is already a "seasoned" block and will maintain tolerances better than a raw new one.

Of course the dealer would state it is a "massive mistake" to not use the one they sell for a lot more money. OOff

 

Great input and thank you. I am more familiar with vehicles and rebuilts and was not sure if there was some marine component that I was not taking into account.

 

You have to get a MARINE block, obviously. Other than that it's the same as buying a reman engine for a vehicle. As with a vehicle, the quality of remans VARY greatly. As examples, my mechanic tells me the Jasper Engines has a poor reputation for quality. Don't know about Michigan Motorz, which is another big one. Remans from the big reman distributors are hit and miss. I've heard stories of someone buying a reman and the inside of the valve covers were never cleaned properly and are still covered in oil varnish. You pay more for a Mercury reman block, but you know what you're getting. It's basically brand new. Overall, however, it's really a judgment call.

 

And price difference

 

Engine rotation?
Do both engines of a twin Vee drive Sundancer rotate the same direction?

 

The engines turn the same direction, however the propellers turn opposite directions, the direction is changed in the transmission - one runs in reverse.

 

Super interesting and thank you for that insight!

 

so I just received two new crate remanufactured engines. The boat comes out of the water this week for a dual engine swap. It will be interesting to tear down the current engines afterward to really understand what was going on.
Both have 450 hrs. Stbd is the one with the dead cylinder, but the port engine ran and sounded great.

Open to any great swap tips. Plan is to leave the shaft (Vee Drive) and transmission in place and pull engines only.

 

I would recommend doing everything that is easier to reach while the engines are out. Specifically that might mean things like shaft seals, rudder packings, etc. Also unless the manifolds and risers are brand new I would do them to along with new plugs and wires. I you have raw water pumps I would also do the service on them too. This will add to the cost but the labor will be much less since they are all readily accessible.

Also, unless these were full dressed motors it should only be the parts cost since they would need to be removed and reinstalled anyway. So the installation time should be the same.

-Kevin

 

On my last boat I replaced my Merc engine with exactly what you got, a 5.7 Marine engines for less Reman Long block, Ran like a champ until I sold the boat.

 

Let us know about the dead cylinder. Not to common on a small block

 

I certainly will. Engines are coming out tomorrow, so by the end of the week, I should have details.

 

I lost #7 cylinder on my 5.0 last summer. Rebuilder says valves were shot and rings leaking. I've owned the boat since 2020 and not sure how well it was maintained by the previous owner. Previous owner had the boat from new and always serviced by MM.

 

A lot of times ,valves on big blocks stick and lose compression.

 

Small blocks are usually bullet proof when taken care of. Technically all motors are is they are taken care of properly

 

I definitely want to know what killed that cylinder. Also since you have the motor out get some spray nine and spray your bilge let it sit for 15-20 minutes and hose it out and clean your bilge up make it nice and pretty

 

Verdict is in with a blown head gasket. (see photo) A channel developed between #4 and #6 causing #6 with increasing damage and ultimate failure to follow.

 

For status, the plan is to reinstall both engines this week.

 

Of note, one importance and an easy to overlook item for a crate long block replacement it to fill the engine block dip stick tube hole.

I had not noticed the steel plug in the side of my original MerCruiser blocks and my engines have the dip stick attachment to the oil pan drain plug so for my new blocks, there was an unplugged side hole.

We are waiting on plugs to tap in so fingers crossed they are the correct fit.

 

Water got in somehow, so if it wasn't a rotted exhaust it could be a crack in the head. Hardware store has plenty of plugs

 

Leaking Stuffing Boxes on both shafts??!!
You kidding me? Any thoughts?

The engines when in well, mated with the transmission and got nice shaft coupling alignment.
Put into water and they fired right up but whoa, water was coming in at the shaft seals like crazy on both engines.

Are we missing something or did the Lip Seals dry up and die during the month of dry dock?

Thoughts are welcome.
1.) Yes there was a spare bearing on the shaft which was placed on backwards with the lip facing the transmission. Bad luck!
2.) Both Port and Starboard are leaking a lot at the seal from the lake water pressure while floating.

We had to pull the boat back out to dry dock on blocks and regroup.

Here is a photo of the shafts and stuffing boxes as it sat awaiting the engines.

 

How would you get to the shaft seals with engines there

 

Nearly impossible!
The mechanic is very skinny and now I see why. I think that is a requirement to be a boat mech in some of the "engine rooms".

Anyhow, another cautionary note to others.

When the engines were pulled, the boat waited a few weeks on blocks.
Over that period, the lips of the shaft seals stuck to the shaft so that when it was engaged, the rotation tore the lip seals on both Port and Starboard.

In the future, with the engines removed, I would take the cover off the shaft seals and lube them good to not get dry and sticky. I asked the mechanic, after the engines were pulled to inspect the shaft seals and cutlass bearings to decide if we should pull the shafts and replace. "Ya they look good man" was the response. Had an actual inspection been preformed by a mechanic, they would have pulled the SureSeal cover and actually checked the bearings, and should have also noted that the back up set of seals in the carriers were placed backwards with the lip pointing toward the transmission.

Instead we learned all of this after the engines were in and the boat back in the water! Very costly oversight!

 

If them drying out and sticking after a few weeks was such a problem, there are tens of thousands of boats pulled out every year to spend winter on the hard. Then they would need new glands after the "4 or 5 month dry season", too.

Something else here is at play.

 

That's why I made a comment