Finally Having My 7.4 Rebuilt

[SDSeville]

It has been a long time, but I am finally going to rebuild the hydrolocked 7.4 gen VI in my 1998 Maxum SCR2700. Been dead for about 18 months now. Since the boat is in a slip and I have no trailer, I was going to be stuck using the local marina and paying $12,000. I have a new friend a couple slips down who just retired after 28 years as an auto and boat mechanic. He has offered to help me get this done as cheap as possible.

The plan is as follows.

-Disconnect and unbolt everything, slide the motor forward (have plenty of room), and have the marina pull the motor while the boat is still in the water.

-They will drop it in the bed of my truck and I am going to take it about 15 miles inland to a very reputable motor shop for a rebuild.

-When the motor is done (about a week), I will have the boat pulled for bottom paint (been 3 years) and install the rebuilt motor while in dry dock for a few days.

-Plan is to do bellows while I am at it.

I am hoping to stay under $6,000 including bottom paint.

I am a CPA, but have done some work on smaller boats in the past, including a a restoration of an old Sea Ray bow rider. I am hoping I can pull this off with the help of my neighbor.

 

[HT32BSX115]

Howdy,

$6000 sounds a bit optimistic......but it's a great goal!

If it's been hydro-locked for that long, it's not likely going to be a "rebuild" but a replacement.

You're probably going to need a "new" (used/rebuildable) block, heads, and definitely new manifolds/extensions/risers (unless you're already closed cooled) I would be hard-pressed to put used manifolds/risers on a "new" engine.

Is it in Salt water?

 

[alldodge]

Make sure (suggest in writing) that the marina/boat yard will allow you to work on your boat at their place. Many won't saying insurance and such

 

[SDSeville]

Howdy,

$6000 sounds a bit optimistic......but it's a great goal!

If it's been hydro-locked for that long, it's not likely going to be a "rebuild" but a replacement.

You're probably going to need a "new" (used/rebuildable) block, heads, and definitely new manifolds/extensions/risers (unless you're already closed cooled) I would be hard-pressed to put used manifolds/risers on a "new" engine.

Is it in Salt water?

The shop says they will bore the cylinders. Should I stay away from that? Yes, it is in salt water.

The rebuild will only cost $2500 if I use my block.

 

[SDSeville]

Make sure (suggest in writing) that the marina/boat yard will allow you to work on your boat at their place. Many won't saying insurance and such

Good idea, thanks. They told be verbally, but I will get it in writing. They said I can work on it, but I can't have other vendors do any work.

 

[alldodge]

Good idea, thanks. They told be verbally, but I will get it in writing. They said I can work on it, but I can't have other vendors do any work.

There is another guy that just posted a thread about his place saying he can, and after the motor was pulled, he can no longer

Always have the motor bored during a rebuild, standard is .030 over and max is .060 over
If the $2500 includes putting it all back together (heads included) that's a good price

Being salt, you may also need exhaust

 

[HT32BSX115]

The shop says they will bore the cylinders. Should I stay away from that? Yes, it is in salt water.

The rebuild will only cost $2500 if I use my block.

That's likely if the block can be "cleaned" up. Salt water for all of it's 21 years? I would be very worried about water jacket rust and cylinder wall thickness after boring (and/or they may even want to sleeve it) if that's the case. Heads too.......

If they regularly rebuild (raw salt water cooled ) marine engines I'm sure the machine shop will be able to tell you if it's even a remote problem although I don't know how they determine the limit where they wouldn't use a salt water block........... That would definitely be something I would ask about.

I guess you're not closed-cooled. (If it is, there's NO cooling system corrosion problem with that block)

I added closed cooling to the 1997 (GEN VI) 7.4L engine before I installed it my 1987 Four Winns. Even though I don't usually boat in salt water, I think I would want it never the less....It eliminates so many problems and only adds a few....

Didn't know some marinas prohibit someone working on their own boats. There's another thread here where a marina told the owner they would let him replace his engine before he bought the boat then told him they don't allow owners to work on their boats while in the marina...... Go figure!

Take some pictures!

We love pictures!

Cheers,


Rick

 

[Scott Danforth]

it will be cheaper to pull a 1996-2000 core motor from your local pick-a-part yard and get the machine shop started on the rebuild now. a new core is about $300, much less money than your current plan

order new manifolds and elbows now

then when you pull your motor, you swap stuff over to your new motor

if your core is any good, you sell it as a core.

verify with the yard you can work on stuff there. if you cant, hire a trailer to take it from their yard to the machine shop to swap the motor

 

[HT32BSX115]

it will be cheaper to pull a 1996-2000 core motor from your local pick-a-part yard and get the machine shop started on the rebuild now. a new core is about $300, much less money than your current plan

order new manifolds and elbows now

then when you pull your motor, you swap stuff over to your new motor

if your core is any good, you sell it as a core.

verify with the yard you can work on stuff there. if you cant, hire a trailer to take it from their yard to the machine shop to swap the motor

That would be my plan! :thumb:

 

[Rick Stephens]

That would be my plan! :thumb:

Me three.

 

[SDSeville]

What brand manifolds and risers do you all recommend?

 

[SDSeville]

The Marina said I should purchase the following items. Am I missing anything?

Oil Cooler

Belt and tensioner

Circ Pump

Impeller Kit

Clean injectors

Plugs, wires, rotor…

risers and manifolds

Thermostat

Gaskets, fluids…

Pulley

 

[Scott Danforth]

since you are building a new motor, I would go with a heat exchanger myself

that would change the thermostat housing, and i believe the belt routing is different (would need to confirm)

are you assembling the motor yourself or having the machine shop do it?


if you are doing it, the following is missing from your list that you should also pick up:
distributor cap

• core plugs (machine shop ?)
• Permatex #1, #2, and #3 (#1 on the core plugs) (machine shop ?)
• New 30# bypass for the oil passage (dependent on your oil cooler and if you run a remote oil filter) (machine shop ?)
• new lifter spider (machine shop ?)
• assembly lube (machine shop ?)
• beer
• play doh from the dollar store (to check clearances of oil pickup, etc.) (machine shop ?)
• new timing kit (machine shop ?)
• new bearings (machine shop ?)
• rotating assembly (machine shop ?)
• New damper (machine shop ?)
• paint (machine shop ?)

 

[alldodge]

If marina is doing the rebuild why are they asking for you to get the parts, not that I would mind, but doesn't sound right?

So far as exhaust mans and elbows, need cast iron for salt and about any of them would work. OEM is no need to check flatness, aftermarket you would

 

[SDSeville]

The machine shop will be doing the rebuild. The marina is suggesting I buy the above parts list from them.

 

[alldodge]

You need a complete marine engine gasket set (suggest Fel-Pro). The set will have everything they need to rebuild the motor. They will determine piston and bearing sizes after machine work is done.

As for everything else on the list, get a price from them "unless" they will be building the entire motor and giving it back complete (not just long block, exhaust installed, etc). If this is the case, then ask them if they want to buy all the stuff or they will allow you to get some stuff. Talk to machine shop, find out what they want/like

 

[Scott Danforth]

The machine shop will be doing the rebuild. The marina is suggesting I buy the above parts list from them.

the Marina suggested you buy the parts from them because they have a substantial markup on them.

As AD stated, talk to your machine shop. if they are doing the complete rebuild, then they are also most likely going to want to pick components.

if you compare prices, most of the time the machine shop prices are same as you and I can get from Summit, etc.

Felpro gaskets is a no brainier. however some shops recommend cometic for the head gaskets. follow what the shop recommends.

my last build, to save some shop labor for the detail work I wanted done, i did the ring gap filing, oil pump setup, assembly, etc. I also did the head porting and other work prior to bringing them the heads and block However I spent a few hours talking to the shop owner on my wants/needs/desires.

some rebuilds, i drop off the motor and pick up a running (dyno tested) motor about a month later.

again, talk to the shop

 

[Lou C]

I would get the boat out of there, I would not want to try pulling an engine with the boat in the water, what if you don't have enough clearance to pull it forward far enough so the coupler comes off the driveshaft splines. Also I'd get the machine shop to source all the parts. They are doing the work, they will want to choose the parts and make some profit on the parts as well. They may not take kindly to using parts someone else made money selling.
Rebuilding a raw water cooled engine that hydrolocked and sat, for that long unless it was drained , the cyls oiled and it was spun over and turned free, is a waste of time and a bad risk. Those engines if raw water cooled in the salt can and will rust thorugh behind the valve seats and guess what happens then, hydrolock again. Your better plan is to start with a reman engine that can be fitted with closed cooling and new exhaust.

 

[Rick Stephens]

Deleted my own post....

 

[H20Rat]

They are doing the work, they will want to choose the parts and make some profit on the parts as well. They may not take kindly to using parts someone else made money selling.

Or in my experience, you are going to pay for the parts from the machinist one way or the other. They are either line items if they provide them, or built into other items if they didn't. As a general rule, never, ever take parts to someone to install if they also sell the same parts, it will always cost you substantially more.