Engine replace or rebuild

P

Paolucci

Member
Oct 1, 2020
34
Boat Info
330 Sundancer
Engines
twin 5.7
Has any one rebuilt or replaced a 5.7L Mercruiser in their boat ? What was the costs to do so ?
 
What issues are you having?

Is it fresh water cooled or raw water cooled?

Stern drive or V-Drive?

Are you doing the work yourself or paying a mechanic to do everything?

Generally the top end can be replaced with the block still in the boat.

New heads and top end components could be in the $4-6k range per motor if you are doing all the labor.

Full replacements could run up as high as $12-$14 each for a mechanic to do everything.
 
One other thing to consider. Are you planning to keep the boat for many years ? If you were to repower you may have invested more than the boat is worth. If it’s due to sea water corrosion you may not have a choice. If the blocks are good you can take the rebuild route. Good luck.
 
Espos4 said:
What issues are you having?

Is it fresh water cooled or raw water cooled?

Stern drive or V-Drive?

Are you doing the work yourself or paying a mechanic to do everything?

Generally the top end can be replaced with the block still in the boat.

New heads and top end components could be in the $4-6k range per motor if you are doing all the labor.

Full replacements could run up as high as $12-$14 each for a mechanic to do everything.
Click to expand...
I have V Drives and I lost oil over the weekend.....it came out of the filter of the lines, I did not hear any loud bang that would have been a piston coming apart.....I replaced oil back in to see how much came and it was only 1.5 qts....so i tried to restart the engine and it did fire right back up. It only ran for 30 sex or so then stoppoed again....I tried to restart but it would not even turn over.....so at a loss
 
If you are at this point and “at a loss” I would assume that you don’t have the mechanical ability to rebuild a motor, please don’t take offense to that comment, not may people can.

I would get a proper diagnosis as to the condition of the motor. Could be as simple as a dead battery, bad starter or in fact it could be a major internal issue where the motor does need to be replaced.

Of you do need a rebuild/replacement, in the long run a complete new motor is less expensive for you if you are paying someone else for the labor.
 
I just replaced one of my 5.0's

To rebuild the old vs buy a new was very close in cost.

The labor cancels out any savings if you are paying to have the work done and if you rebuild you hope what ever caused your issue in the 1st place was found and corrected.

My 5.0 was 22 years old with 920 hours .... after around $8K later I have a new 5.0 with a warranty.
 
It sounds more to me like a hydro locked engine due to water ingestion cause by failed exhaust components. Engine my still be saved by someone that knows what to do.
 
No mystery here, he ran the motor out of oil and now it's seized. Would that not be the obvious thing?
 
Being down 1 1/2 quarts would not normally be enough to lose oil pressure and kill an engine. You would normally get an engine alarm for low OP.
 
My out the door 5.7L rebuild including dyno and haul/relaunch was about 6k.

They used a reman block .30 over, reman heads, turned and balanced my crank, new valves and springs, new pistons/rods/bearings. Reused manifold, disti, exhaust, etc. It made about 265HP on the dyno so really close to the factory spec.

the engine work was around $2,500 of that 6k I believe. I gave those receipts away with the boat when I sold it.

don’t discount a quality engine builder
 
Put a wrench on the front of the crank and see if you can turn engine if not take out the plugs and try again, no guessing involved
 
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