Reply
 
Thread Tools Search this Thread Display Modes
 
Old 10-19-2018, 09:52 AM   #1
Guru
 
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 860
Not getting full RPMs

Last June hauled the boat and painted bottom. On way back to Marina I was able to get full rpms and speed or of my twin Cummins 330s. 2800 rpms at 15 knots.

Today I put the boat back in the water after hauling for hurricanes and can get only 2650 - 2700 rpms and 12 knots. Between the two events I disassembled and cleaned racor 1000s. There is some kind odd check ball/valve on the racor. Any chance a mis install could be causing my issue?

Thanks for thoughts suggestions?

Thanks
Gordon
__________________
Advertisement

Gordon J is offline   Reply With Quote
Old 10-19-2018, 10:01 AM   #2
Guru
 
C lectric's Avatar
 
City: B.C.
Country: Canada
Vessel Name: Island Pride
Vessel Model: Palmer sedan 32'
Join Date: Oct 2007
Posts: 2,368
Don't know if that check ball would have caused this but there is a right and a wrong way to install the seat it 'seats' on. THere is printing indicating orientation and done incorrectly it can cause trouble.
Mike Negley has written many times about this seat and the need for attention to orientation.

Do you have a vacuum guage on the engine side of the filters? If not they can often help troubleshoot. You just want one with the telltale needle which stays at the highest reading achieved so you don't need to watch it.

Racor offers one as does Designated Engineer, a better one but needs some more fittings usually.
If you have any kind of fuel restriction that will limit power from the engines.

One question when you were down on power/speed, were you getting ANY BLACK OR DARK SMOKE?

If no dark smoke that usually means a fuel supply problem. If there is dark smoke that usually means an air restriction or overload for what ever reason.
__________________

C lectric is offline   Reply With Quote
Old 10-19-2018, 10:49 AM   #3
Guru
 
djmarchand's Avatar
 
City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23- outboard
Join Date: Aug 2012
Posts: 4,410
The following are probably more common reasons for low power/rpms:


1. Fouled bottom or prop.
2. Corroded turbo exhaus throat due to water intrusion from exhaust.


To check for #2, pull off the exhaust from the turbo and look inside. Any pitting or rust spots is a sure sign of sea water corrosion.



David
djmarchand is offline   Reply With Quote
Old 10-19-2018, 11:00 AM   #4
Guru
 
cafesport's Avatar
 
City: Miami
Country: USA
Join Date: Jul 2013
Posts: 597
Sounds like you may have installed the check valve gasket upside down which is easy to do if you donít follow racorís instructions. The lip goes up and the ball needs to sit on the flat edge of the seal not the dished edge. Very counterintuitive.
__________________
Via iOS.
cafesport is offline   Reply With Quote
Old 10-19-2018, 01:24 PM   #5
Guru
 
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 860
Thanks for the reply. Favor vacuum gauges read near zero. At max rpm lots of grey smoke, when running normal rpms no smoke
Gordon J is offline   Reply With Quote
Old 10-19-2018, 01:27 PM   #6
Guru
 
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 860
Not bottom

[QUOTE=djmarchand;707805]The following are probably more common reasons for low power/rpms:


1. Fouled bottom or prop.
2. Corroded turbo exhaus throat due to water intrusion from exhaust.


To check for #2, pull off the exhaust from the turbo and look inside. Any pitting or rust spots is a sure sign of sea water corrosion.




Thanks David. New exhaust risers two years ago. They are built so even if they leaked water would go to muffler. Just came from the yard. Bottom is clean as is the running gear.
Gordon J is offline   Reply With Quote
Old 10-19-2018, 02:08 PM   #7
Guru
 
High Wire's Avatar
 
City: Cape May, NJ and Englewood, FL
Country: USA
Vessel Name: Irish Lady
Join Date: Dec 2007
Posts: 2,581
So what changed?
Disassembly and re-assembly of Racor.
Boat hauled and blocked.
Boat splashed back in water.
Anything else? Bought fuel, bumped bottom, air intakes clogged, tank vent clogged, etc?

Affects BOTH engines?

9 of 10 its the Racor somehow.
Do you have a second racor with a selector? If so, valve in second racor and test run.
__________________
Archie
1984 Monk 36 Hull #46
Currently in Cape May, NJ
High Wire is offline   Reply With Quote
Old 10-19-2018, 02:11 PM   #8
Guru
 
djmarchand's Avatar
 
City: Litchfield, Ct/Punta Gorda, Fl
Country: USA
Vessel Model: Atlas Pompano 23- outboard
Join Date: Aug 2012
Posts: 4,410
[QUOTE=Gordon J;707842]
Quote:
Originally Posted by djmarchand View Post
Thanks David. New exhaust risers two years ago. They are built so even if they leaked water would go to muffler. Just came from the yard. Bottom is clean as is the running gear.
Exhaust risers failing and leaking salt water back into the turbo are a lesser concern. I appreciate that yours will drain down to the muffler if it fails. The more prevalent problem is sea water backing up from the transom exhaust and getting back into the turbo.


David
djmarchand is offline   Reply With Quote
Old 10-19-2018, 02:28 PM   #9
Guru
 
Brooksie's Avatar
 
City: Cape Cod, MA
Country: USA
Vessel Name: Island Seeker
Vessel Model: Willard 36 Sedan
Join Date: Oct 2007
Posts: 1,001
The Racor ball is hollow aluminum and floats on water closing off the passage. I doubt that is your problem. Although it's funny both engines are affected the same, first completely bleed your system up to and including each injector.



Could be that when the hauled the boat they tipped it bow down so water flowed into the engines. I happens but I hope not to you.
Brooksie is offline   Reply With Quote
Old 10-19-2018, 03:57 PM   #10
Guru
 
OldDan1943's Avatar
 
City: Aventura FL
Country: USA
Vessel Name: Kinja
Vessel Model: American Tug 34 #116
Join Date: Oct 2017
Posts: 3,043
Quote:
Originally Posted by Brooksie View Post
The Racor ball is hollow aluminum and floats on water closing off the passage. I doubt that is your problem. Although it's funny both engines are affected the same, first completely bleed your system up to and including each injector.



Could be that when the hauled the boat they tipped it bow down so water flowed into the engines. I happens but I hope not to you.
Check the oil for signs of water, drain the muffler.
__________________
If you must love me, don't love me for my beauty. Love me because I know how to cook.
The burial for my intuitive gene was last month.
OldDan1943 is offline   Reply With Quote
Old 10-20-2018, 06:34 AM   #11
Guru
 
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 860
Still no issue

[QUOTE=djmarchand;707861]
Quote:
Originally Posted by Gordon J View Post

Exhaust risers failing and leaking salt water back into the turbo are a lesser concern. I appreciate that yours will drain down to the muffler if it fails. The more prevalent problem is sea water backing up from the transom exhaust and getting back into the turbo.


David
I cant imagine a scenario on this noat that would make that possible. Thanks for brainstorming with me.

Gordon
Gordon J is offline   Reply With Quote
Old 10-20-2018, 08:55 AM   #12
Guru
 
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 860
Ski, you there?

Any ideas?

Gordon
Gordon J is offline   Reply With Quote
Old 10-20-2018, 09:03 AM   #13
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,602
Quote:
Originally Posted by cafesport View Post
Sounds like you may have installed the check valve gasket upside down which is easy to do if you donít follow racorís instructions. The lip goes up and the ball needs to sit on the flat edge of the seal not the dished edge. Very counterintuitive.

OK, you guys have me going here. I was unaware of any check valve in the Racor filters. Where and why? Are we talking about Racor 500, 900, 1000 filters or maybe something else?
__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Old 10-20-2018, 09:14 AM   #14
Guru
 
cafesport's Avatar
 
City: Miami
Country: USA
Join Date: Jul 2013
Posts: 597
Peter all three have them to prevent the fuel from draining back to the supply side resulting in loss of prime. Hereís a nice article that explains it

http://www.racornews.com/single-post...s-Fuel-Filters

*And a brief excerpt for those who canít access the link.

UNFILTERED THINKING
*
The first misunderstanding about fuel filters revolves around the ball. Many believe the ball serves

*
as a check valve to keep water from going up into the filter element. As the theory goes, the ball is plastic and floats, blocking water. In fact, the ball is aluminum, doesnít float, and has nothing to do with water.
*

The engineers put it there to prevent fuel from draining out of the filter and back into the supply line when the engine is shut off. The flow of fuel back toward the tank pushes the ball into a seat, acting as a check valve to stop the flow. In some applications, such as when the filter has been installed below the tank pick up, this back flow would not be a concern. But in many applications the filter can be at the high point, and fuel running back to the tank can easily lead to a loss of prime.
__________________
Via iOS.
cafesport is offline   Reply With Quote
Old 10-20-2018, 09:41 AM   #15
Guru
 
twistedtree's Avatar
 
City: Gloucester, MA
Country: USA
Join Date: Jan 2013
Posts: 4,602
Quote:
Originally Posted by cafesport View Post
Peter all three have them to prevent the fuel from draining back to the supply side resulting in loss of prime. Hereís a nice article that explains it

Mythbusters: Fuel Filters | Racor News

*And a brief excerpt for those who canít access the link.

UNFILTERED THINKING
*
The first misunderstanding about fuel filters revolves around the ball. Many believe the ball serves

*
as a check valve to keep water from going up into the filter element. As the theory goes, the ball is plastic and floats, blocking water. In fact, the ball is aluminum, doesnít float, and has nothing to do with water.
*

The engineers put it there to prevent fuel from draining out of the filter and back into the supply line when the engine is shut off. The flow of fuel back toward the tank pushes the ball into a seat, acting as a check valve to stop the flow. In some applications, such as when the filter has been installed below the tank pick up, this back flow would not be a concern. But in many applications the filter can be at the high point, and fuel running back to the tank can easily lead to a loss of prime.



Cool, you learn something new everyday - hopefully. I never knew that was there.
__________________
www.MVTanglewood.com
twistedtree is online now   Reply With Quote
Old 10-21-2018, 04:36 PM   #16
Guru
 
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 860
Thanks for taking

Quote:
Originally Posted by cafesport View Post
Peter all three have them to prevent the fuel from draining back to the supply side resulting in loss of prime. Hereís a nice article that explains it

Mythbusters: Fuel Filters | Racor News

*And a brief excerpt for those who canít access the link.

UNFILTERED THINKING
*
The first misunderstanding about fuel filters revolves around the ball. Many believe the ball serves

*
as a check valve to keep water from going up into the filter element. As the theory goes, the ball is plastic and floats, blocking water. In fact, the ball is aluminum, doesnít float, and has nothing to do with water.
*

The engineers put it there to prevent fuel from draining out of the filter and back into the supply line when the engine is shut off. The flow of fuel back toward the tank pushes the ball into a seat, acting as a check valve to stop the flow. In some applications, such as when the filter has been installed below the tank pick up, this back flow would not be a concern. But in many applications the filter can be at the high point, and fuel running back to the tank can easily lead to a loss of prime.

Thanks for taking the time to explain. I can scratch this issue of my list. Even if wrongly installed Racors are lower than tank pick up.

Gordon
Gordon J is offline   Reply With Quote
Old 10-21-2018, 10:59 PM   #17
Senior Member
 
kapnd's Avatar
 
City: hawaii
Country: usa
Vessel Name: #31
Vessel Model: ex-Navy MUB 50 fish/cruise
Join Date: Aug 2013
Posts: 494
Cables are known to stretch, limit screws sometimes move, so go through the control system, possibly remove cable at throttle lever and turn by hand to verify top rpms.
__________________
You can lead a horse to water,
But you can't make him ski...
kapnd is offline   Reply With Quote
Old 10-22-2018, 08:00 AM   #18
Guru
 
Vashon_Trawler's Avatar
 
City: St. Petersburg, Florida
Country: USA
Vessel Name: M/V Sherpa
Vessel Model: 24' Vashon Diesel Cruiser
Join Date: Jun 2013
Posts: 535
I learned that it doesn't take much to decrease one's WOT RPM. I recently experienced a 200 RPM drop in WOT. I replaced all of my fuel filters and a few fuel lines that were due for replacement, changed the air filter, verified the bottom was clean, etc. My prop received a few coats of bottom paint a year or so ago, which was beginning to flake off in large areas. Combined with some barnacle remnants, I suspected the prop was the issue. I had the prop pulled, cleaned, and dynamically balanced; I used the Velox system for anti-fouling. I now achieve 3600 RPM at WOT, which is 200 RPM over my previous "normal" WOT of 3400--400 RPM over where I was prior to the prop being pulled.

A side note on the prop... My prop is a 16x8 bronze Chinese made Hung-Shen HTP-3 heavy thrust. The prop shop said it was "all over the place" and needed balancing--poor quality control I guess.
__________________
ďGo small, go simple, go nowĒ
― Larry Pardey, Cruising in Seraffyn
Vashon_Trawler is offline   Reply With Quote
Old 10-22-2018, 11:23 AM   #19
Guru
 
City: Hampton, va
Country: USA
Vessel Name: Didi Mau
Vessel Model: 2003 Ocean Alexander 456
Join Date: Jul 2015
Posts: 860
Ok, i am going to tell on myself. Of course the problem was easy, and i am kicking myself in the tail. My trim tabs did not deploy. Why, one might ask?. I failed to flip the circuit breaker to on. I thought i did not feel the bow go down because we were going so slow. I was wrong. Once trim tabs engaged, she was back to normal.

Gordon
Gordon J is offline   Reply With Quote
Old 10-26-2018, 01:25 PM   #20
Newbie
 
City: newport beach, ca
Country: US
Join Date: Oct 2012
Posts: 3
Embarrassingly cheap, great resolution.
__________________

Mrdi 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





All times are GMT -5. The time now is 08:55 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2006 - 2012