Reply
 
Thread Tools Search this Thread Display Modes
 
Old 07-28-2009, 11:25 PM   #1
Ensign
 
Join Date: Jul 2009
Posts: 1
Default Max Speed 1997 2700SCR w/single 5.7 L Engine

Hello,

I've owned my 1997 2700SCR with a single Mercruiser 5.7 liter engine and Alpha One outdrive for a little over a year. The performance is driving me INSANE but my boat mechanic says it is as expected. My MAX speed is 16.5 knots at 4,000 RPM (there is very little extra weight on the boat beyond two regular size people, minimal fresh water and minimal fuel). That speed isn't even on a good plane.

Anything above 4,000 RPM and the engine temperature spikes way above 225 degrees which scares the bejebuz out of me. It is fresh water cooled.

What speed should I be seeing at 4,000 RPM on this small single engine? The engine -and- outdrive were just serviced a month ago.

My mechanic also said that the impeller is fine and the temperature is normal when the engine is pushed that hard, although from what I read the normal operating RPM for this engine is 4400 - 4800. He also said it has the correct prop spec'd for the boat.

Suggestions? Would love to hear what speed and temp this should be at. Also can I increase the size of the heat exchanger, put a lower temp thermostat or something else because it's running so hot?

Does anyone know a good boat mechanic in Seattle that I can call and make sure my other mechanic isn't missing anything obvious?

Thank you!
__________________

azankich is offline   Reply With Quote
Old 07-29-2009, 03:41 AM   #2
Admiral

 
seapuppy's Avatar
 
Join Date: Nov 2005
Location: Everett Wa
Posts: 4,681
Default Re: Max Speed 1997 2700SCR w/single 5.7 L Engine

welcome to the zoo....unfortunately what your saying tells me a couple of things is possible....1)the hi temps is wrong for freshwater cooled...I think your mechanic is hoping it blows up on you so he can suck the wallet dry....with that said...it should run at all speeds 4200-4800 rpm and not overheat......so...what can cause it...bad impeller...yeah..he says that it's good...but the alpha one impeller is easy to replace and will only cost under a hundred bucks to install...25bucks if you do it yourself...6 bolts and the lower unit is off.....get a maintenance book and check it out....
2)speed...alot of things can cause this....at 4k rpm you should be hitting about 25-27mph....that is after it's all trimmed out properly and on smooth water....
timing on the engine....if it's not advancing all the way to spec..then your not going to get up to wot......is the hull clean??...I'm assuming your in a lake....check the bottom for any growth...i mean any kind of growth will slow that boat down dramatically.........
prop...what prop do you have on the drive now??...I'm thinking it should be about 23" pitch...however if your not getting wot...on plane..then something is definitely not right and it should be lower...like 21" pitch.......you should be able to hit min of 38mph wot.......
now for a mechanic....I've been working with one mechanic I've known for yrs...he's about the best there is around the seattle area is Art at lake union sea ray in everett.....phone is 425-347-6000....talk to either jim on parts or dale who runs the place....all 3 guys are about the best around here....I've been going to these guys for 10 yrs....
buy them a pizza and they will totally rebuild the boat in a week.....haha...ok..just kidding.......but they are the best!!...

SP :hello:
__________________

__________________
Don't compare your life to others. You have no idea what their journey is all about.
------------------------
SSN683 Association member
Par Excellence
------------------------------
2008 Bayliner 340 - "Wild Whim"
--------------------------------------
I live in my own little world....but it's okay-they know me here!!!

Avid practitioner of the martial art: KLIK-PAO.
Tap-Rack-Bang

Anyone that sez "Size doesn't matter" has never owned a boat!
seapuppy is offline   Reply With Quote
Old 07-30-2009, 12:22 AM   #3
Lieutenant
 
Join Date: Dec 2007
Location: Florida
Posts: 64
Default Re: Max Speed 1997 2700SCR w/single 5.7 L Engine

I would guess that this has been checked already, but is the prop spun? That could cause slower than expected speed. But wouldn't explain the high temperatures.

Has the heat exchanger been cleaned and backflushed recently? If it has never been cleaned out since new, it could possibly have quite a build up of crude on the raw water side of the exchanger tubes. And/or some sort of obstruction.

A lower temperature thermostat won't change anything because your thermostat should be wide open as it is. The thermostat might be stuck closed though. They are pretty simple but I suppose it could happen. Something to check.

You should be able to run the engine wide open all day without overheating. Your mechanic is feeding you a line about being normal when "working that hard". All boat engines work hard. I have a 5.0 ltr and when I run wide open at 5000 RPM the temp stays about 175.
__________________
- 2009 Bayliner 340

- 2004 Maxum 2400 SD (traded in August '09)
Dave is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
What do you all think about this boat??? NH badboy1166 Maxum Owners General Discussions 1 08-30-2009 03:41 PM
1991 Maxum 2300 SCR water Pump/Sewage Pump Access for winter Ocean Escape Maxum Maintenance 7 10-24-2008 09:56 PM
New Owner - 1992 Maxum 2300SC Chef442 Maxum Owners General Discussions 7 01-28-2008 01:54 AM
PSA - Keeping Your Head at the Public Docks racer2c Maxum Owners General Discussions 9 08-28-2007 06:55 PM
trim tabs vs. hydrofoils/planing plates scoutonwater Maxum Owners General Discussions 3 03-14-2007 05:12 PM

Powered by vBadvanced CMPS v3.2.3

All times are GMT. The time now is 04:14 AM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.