Power, weight or prop? Help!

[Keeper]

Good evening, wise men.

A new-to-us 1997 2520 Sport Cabin Deep V, w/ a 2007 Merc 225XL Optimax Ser# 1b516434, came with a seemingly seized lower unit back in the fall. We dropped the corroded lower unit and replaced it with a rebuilt 1.75 that the supplier said fit the engine. The engine runs well on the muffs. Power head is very clean, compressions good, air pressure is good. We dunked it today, for the first time. Engine started, idled and taxied out well. Sounded quite good. Here's the disappointing part that we need help with: throttle down, it wouldn't make 2200 RPMs and get the bow up out of the water. Engine was clearly working hard and sounded good. Just wouldn't make power. We had a 15 pitch stainless steel prop on it. We swap it for a 17P stainless steel. RPMs went up to 3300, throttle down, and the bow came up. But, the boat would not make enough power to plane. Felt like the boat was dramatically underpowered. Factory fuel, transmission alarms going off. No computer to test. What could it be? What should we be looking for?

The ideas that were thrown around:

- mismatched lower unit
- the boat is waterlogged, overweight in some way. Get weighed.
- Engine is rigged at the wrong height, despite the fact that it's sitting flat on the notch. May be half-inch up because the transom has been covered over with a stainless steel engine bracket.

There's a lot of advanced thinking here around power, pitch, engine height and prop. Too much for a newbie to digest and make use of.

Would you good folks shoot us any ideas you might have? We are looking for all the help we can get. And, we are standing by to answer any questions.

Thanks so much, to everyone.

 

[Brent]

Change n inspect lower unit oil.

Was a full pump kit installed?

Full tune up n filters.

Using a fuel n water filter with clear bowl to check for water

Trim tabs operating ?

Set motor height correctly.

Go run boat normally loaded as you expect to.use it. What is max rpm?

Check controls n cables, batteries n connectipns.

Check everything- rigging is in order before installing a new prop.

B2

 

[Brent]

Install Tapatalk app to post pics and postings.

Nail down lower unit specs.

Check fuel lines. New, no kinks and restrictions?

Use a notebook.
One page per item
Another page for notes and B.S.

Was boat sunk or storm damage?

There are a lot of smart folks on this list.

To help you, be as a clear as possible with each item.

It will take some time to sort out.

Be sure to purchase a factory outboard shop manual.

Find someone to scan and printout the motor ECM memory and history.

At some point and I don't know when, the fuel Injectors will need full service and printout per each injector.

Don't replace good parts why and keep old ones .

Any useful info from the buyer?

Replace thermostats at some point


B2

 

[PKS1801]

Compression??? Doesn't make sense that a higher pitch prop would raise rpms by 50%

 

[Keeper]

Change n inspect lower unit oil.
Check. AlthoughI am still going to go back and double check what I am certain is the case, that it's a matching lower unit

Was a full pump kit installed?
if you referring to water pump, yes.

Full tune up n filters.
Done

Using a fuel n water filter with clear bowl to check for water
Newly installed

Trim tabs operating ?
yes

Set motor height correctly.
How do I check on this boat?

Go run boat normally loaded as you expect to.use it. What is max rpm?
Max RPM with a 17 pitch prop and the boat normally loaded was 3300 RPM

Thanks so much for responding

 

[Keeper]

Install Tapatalk app to post pics and postings.
Will do
Nail down lower unit specs.
working on.
Check fuel lines. New, no kinks and restrictions?
Done
Was boat sunk or storm damage?
don't know. No history
There are a lot of smart folks on this list.
clearly
Be sure to purchase a factory outboard shop manual.
will do
Find someone to scan and printout the motor ECM memory and history.
will do
At some point and I don't know when, the fuel Injectors will need full service and printout per each injector.
will do. Power had seems to be running cleanly. drain tank, replaced fuel water filter and housing, ran premium gas and and an injector cleaner through on the muffs.
Don't replace good parts why and keep old ones .
Trying. Really getting to the point where the money spent should be going to a new engine. Probably $3000 into it plus our labor
Any useful info from the buyer? I know these boats are susceptible to water logging, due to cracks in the gelcoat, etc. The transom shows some signs of water damage. Previous owner obviously put on the stainless steel transom cover. There are the predictable Parker cracks in the transom, on either side of the motor mount. We have clean those out and will fiberglass properly.
none.
Replace thermostats at some point
Will do

 

[Brent]

Motor height
http://www.veradoclub.com/index.php?topic=65.0


But no pics

Fix is use pc with Chrome or Firefox and extension or add-on to fix photobucket greed. Google photobucket fix extension or search this site n enter photobucket fix..

The anti vent plate needs to be at water level on plane or slightly above it.

Top hole towards sky is #1

What hole is it now mounted?

B2

 

[Brent]

Computer scan will help

B2

 

[got_em_on]

Possibly motor not low enough or the leg is too short. Cavitation plate should be even with bottom this way prop gets a clean flow of water. It looks as though you have to angle that broom stick up from the bottom to get to cav plate. As the boat starts planing the prop loses a clean flow of water and cannot push boat.

I would think that the RPMS would increase beyond 3300 though so that is odd. Can you take a video leaning over transom as boat is trying to plane off?

 

[Brent]

Alarms? Sound, dash or both? Maybe going into limp or safe mode?

B2

 

[Brent]

I use Firefox and installed this extension
Photobucket fixer
https://addons.mozilla.org/en-US/firefo ... ket-fixer/

Photobucket Fixer by jlevers

This extension makes all ransomed Photobucket images visible to the user. It does not access or collect any user data.

Enjoy!

Google Chrome: https://chrome.google.com/webstore/deta ... dkpmcpkaon


Get Google Drive or Amazon Prime for pics

 

[Brent]

If have over heat alarm, replace all thermostats.

Tell tale stream have a good stream?

 

[PKS1801]

Motor looks high. Show a pic with it down so that the anti-vent plate is level. But, the prop being too high would make it suck air and over rev, not under rev, unless it is squatting and staying buried. Not familiar with Optimax, but if the 12 X 21 numbers on the tail end are the recommended prop size, I would guess you have the wrong gear ratio for that heavy boat. Strange how people selling Opti lower units on Ebay don't list the ratio. Quick look at google shows most run 1:87 and 1:75. What is your displacement in liters?
Did you put a wrench on that old lower unit, to see if it was still seized when disconnected from the upper?

 

[fannin]

A new-to-us 1997 2520 Sport Cabin Deep V,

FYI, it appears to be a modified V, not a deep V.

 

[Keeper]

Thanks for that, Fannin. one of the other guys working on it called into Parker giving the serial number. He thought it was a deep V. We will look back into it.

 

[Keeper]

Motor looks high. Show a pic with it down so that the anti-vent plate is level. But, the prop being too high would make it suck air and over rev, not under rev, unless it is squatting and staying buried. Not familiar with Optimax, but if the 12 X 21 numbers on the tail end are the recommended prop size, I would guess you have the wrong gear ratio for that heavy boat. Strange how people selling Opti lower units on Ebay don't list the ratio. Quick look at google shows most run 1:87 and 1:75. What is your displacement in liters?
Did you put a wrench on that old lower unit, to see if it was still seized when disconnected from the upper?

The challenge with that is that it does not seem the motor can come down. it's sitting right on top of the stainless steel transom cover. I honestly don't know what the 12 X 21 number refers to. Were looking into that. The ratio does say 1:75. that's a pretty consistent consensus. I don't know how to get the displacement numbers. We did put a wrench on that lower unit, uselessly. Will include photo.

 

[Brent]

Need more pics of how it mounted and bracket

 

[PKS1801]

By "Lower the motor", I meant trim it down to where the plates on the lower unit are parallel with the handle you are using to show the line off the bottom. Curious how far the AV plate will be above the bottom.
15P and 17P are only half of the prop, what are the diameters, the first number on the prop?

 

[Keeper]

By "Lower the motor", I meant trim it down to where the plates on the lower unit are parallel with the handle you are using to show the line off the bottom. Curious how far the AV plate will be above the bottom.

Actually, PK, that is a selfie tilt. The broomstick is flush to the bottom of the boat. The motor is tilted up a bit for trailering.


Sent from my iPhone using Tapatalk

 

[Keeper]

In reply to the person that asked about whether or not we could turn the shaft on the lower unit, with a wrench. This is that original unit.