Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 01-05-2015, 13:18   #1
Registered User

Join Date: May 2014
Location: USA
Boat: 41' yawl
Posts: 609
How does self bleeding work?

My Westerbeke is "self-bleeding", but I have no idea how it works. Where does the air go?

As I think about this, I realize I never understood why (on my old yanmar) you needed to bleed the fuel lines on the _output_ side of the high pressure pump, wouldn't the problem just take care of itself? Maybe when air is in that leg, the pressure never builds up to the point where the injector opens, so it just sits there unless you let it out manually...

__________________

__________________
chris95040 is offline   Reply With Quote
Old 01-05-2015, 13:28   #2
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,426
Re: How does self bleeding work?

Westerbekes are "self-priming" not "self-bleeding". It uses an electric fuel pump... when you turn the key it energizes the pump and off you go.

I have found that you still need to crack the injectors to let the air bleed but you do not need to hand pump the fuel.
__________________

__________________
zboss is offline   Reply With Quote
Old 01-05-2015, 13:56   #3
Registered User

Join Date: May 2014
Location: USA
Boat: 41' yawl
Posts: 609
Re: How does self bleeding work?

Hmmm Westerbeke calls it self-bleeding, and I've had situations that would have normally required bleeding "take care of themselves" with this engine, so I'm not so sure.

Follow on question, why's an electric lift pump able to be "self priming" but a mechanically driven one isn't? Just no way to get that kind of suction from it?
__________________
chris95040 is offline   Reply With Quote
Old 01-05-2015, 14:21   #4
Freelance Delivery Skipper..
 
boatman61's Avatar

Community Sponsor
Cruisers Forum Supporter

Join Date: Jan 2010
Location: UK/Portugal
Posts: 20,211
Images: 2
Send a message via Skype™ to boatman61
pirate Re: How does self bleeding work?

Sharp knife across the wrist is effective I believe..
__________________


Born To Be Wild
boatman61 is online now   Reply With Quote
Old 01-05-2015, 14:31   #5
Senior Cruiser
 
SkiprJohn's Avatar

Cruisers Forum Supporter

Join Date: May 2006
Location: Kea'au, Big Island, Hawaii
Boat: Cascade, Sloop, 42 - "Casual"
Posts: 14,192
Re: How does self bleeding work?

Quote:
Originally Posted by chris95040 View Post
My Westerbeke is "self-bleeding", but I have no idea how it works. Where does the air go?

As I think about this, I realize I never understood why (on my old yanmar) you needed to bleed the fuel lines on the _output_ side of the high pressure pump, wouldn't the problem just take care of itself? Maybe when air is in that leg, the pressure never builds up to the point where the injector opens, so it just sits there unless you let it out manually...

I'm watching your thread to see if there is some very knowledgeable folks who have experience with your engine will respond.

I too don't think it can be self-bleeding if the air is in the lines between injector pump and injector. Might be wrong about that though. Will air pop the injector enough to bleed through the injector nozzle?
__________________
John
SkiprJohn is offline   Reply With Quote
Old 01-05-2015, 14:44   #6
Senior Cruiser

Cruisers Forum Supporter

Join Date: Nov 2012
Location: Long Beach, CA
Boat: Tayana Vancouver 42
Posts: 1,854
Re: How does self bleeding work?

Quote:
Originally Posted by boatman61 View Post
Sharp knife across the wrist is effective I believe..

Sounds like frustration with hydrolic steering!


S/V B'Shert
__________________
Tayana42 is online now   Reply With Quote
Old 01-05-2015, 14:59   #7
Senior Cruiser
 
roverhi's Avatar

Cruisers Forum Supporter

Join Date: Aug 2005
Location: Kona, Hawaii, Carlsbad, CA
Boat: 1969 Pearson 35 #108 & 1976 Sabre 28
Posts: 6,005
Send a message via Yahoo to roverhi
Re: How does self bleeding work?,

Quote:
Originally Posted by boatman61 View Post
Sharp knife across the wrist is effective I believe..
You get some really bad advice on this site. If you are really serious about ending it, slice up, not across the wrist. You'll open a much larger area of the artery and will bleed out faster.
__________________
roverhi is offline   Reply With Quote
Old 01-05-2015, 15:36   #8
Registered User
 
glenn.225's Avatar

Join Date: Jan 2008
Location: Kingston, ON
Boat: Albin Vega 27'
Posts: 342
Re: How does self bleeding work?

Not a lot of westerbeke experience but the only diesel I know of that could be called self bleeding is the Detroit 2stroke. They use an "unit injector" located in the head. that controls fuel delivery and rate and do not need to be bled. A mechanical and/or electrical pump will supply fuel through the filters, these may have to be bled depending on setup.
__________________
Glenn
glenn.225 is offline   Reply With Quote
Old 01-05-2015, 16:17   #9
Registered User
 
Yeti's Avatar

Join Date: Apr 2008
Location: San Diego
Boat: Cascade 36
Posts: 246
Re: How does self bleeding work?

I have recently installed a M25XPB and as I understand it the engine is self bleeding up to the something like the injector pump. The idea being that the electric pump runs way more fuel than the engine needs and will flush air bubbles through back to the tank via the fuel return line. This also more or less helps "polish" the fuel as well.

I'm not 100% sure off the top of my head if the electric pump will clear the injector pump. Probably doesn't, but when I installed mine I had no issues.

When you hit the "preheat" button the electric fuel pump starts. I believe the manual says to hold the preheat button for around 10 seconds at a time several times with breaks to let the glow plugs cool down if you need to clear some air.
__________________
Yeti is offline   Reply With Quote
Old 01-05-2015, 16:30   #10
Senior Cruiser
 
osirissail's Avatar

Cruisers Forum Supporter

Join Date: Feb 2009
Location: A real life Zombie from FL
Boat: Gulfstar 53 - Osiris
Posts: 5,416
Images: 2
Re: How does self bleeding work?

Be it air or diesel when the pressure delivered to the injectors reaches the proper amount the injector will open and let the air or fuel into the cylinder.

However, as other have said, having an electrical fuel pump instead of a manual lift pump you can deliver fuel or air to the injection pump. I would think that the manufacturer's use of "self-bleeding" or "self Priming" is there to indicate that the injection high pressure pump and handle a load of air and pass it through to the injectors. There are injection high pressure pumps that cannot process air so these would not be referred to a "self-priming" or "self-bleeding."

Having that feature would make life a lot easier as you would not have to open the bleeding ports on the high pressure pump or loosen the fuel line to the injector. You would just use the starter to rotate the engine and any air would be processed through the pump and the injectors and the engine would start running.
__________________
osirissail is offline   Reply With Quote
Old 01-05-2015, 16:47   #11
Registered User
 
Stu Jackson's Avatar

Join Date: Jan 2011
Location: Cowichan Bay, BC (Maple Bay Marina)
Posts: 6,389
Re: How does self bleeding work?

We have a Universal M25 engine.

It is NOT self bleeding.

It DOES HAVE an electric fuel pump.

One has nothing to do with the other.

I have to turn a knob on the top of my injector housing to bleed the air out of the fuel lines.

Later Universal diesel engines, the M35s, are self-bleeding. Whether or not they have fuel lift pumps. No manual intervention is required to get the air out of the fuel lines all the way back to the tank.

I am not an expert on just how the mechanics of the self-bleeding work, but it's odd that confusion appears about the engine's bleeding and a lift pump. The pump just makes bleeding easier - without trying to run the engine you can get the air out without having to push the ridiculous finger pump on so many filter housings.
__________________
Stu Jackson
Catalina 34 #224 (1986) C34IA Secretary
Cowichan Bay, BC, (Maple Bay Marina) SR/FK, M25, Rocna 10 (22#) (NZ model)
Stu Jackson is offline   Reply With Quote
Old 01-05-2015, 17:00   #12
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,426
Re: How does self bleeding work?

I HAVE a westerbeke 46. They may call it self bleeding but it really is just self priming. Ask me how I know. During a normal change of the fuel filters it will self bleed just fine but if you run out of fuel you will need to bleed the injectors... and that takes quite a while.

A mechanical fuel pump will do the same thing but you need to pump that little sucker on top of the fuel filter about 3 billion times to get the fuel through the system.
__________________
zboss is offline   Reply With Quote
Old 01-05-2015, 17:16   #13
Jd1
Registered User

Join Date: Aug 2011
Location: Victoria, BC
Boat: Catalina 36 MKII
Posts: 1,096
Re: How does self bleeding work?

If you have air in the high pressure lines then your injectors will not fire. Air is compressible, diesel isn't - you can not build sufficient pressure to fire the injectors with air in the lines as the amount of diesel pumped by the injector pump is small. The pressure goes up a bit but the air compresses and acts as a cushion. The pressure can't get high enough to fire the injector.
Man this is difficult to explain considering how simple the concept really is!
As far as self bleeding, I can only speculate that the high pressure pump is fed by the electrical lift pump and will pump it's tiny volume as long as there is fuel on the pump input. The output pressure will be too low to fire the injectors but fuel flows through the fuel return system back into the tank which flushes air out of the system. Once sufficient air is removed the injectors fire.
__________________
Jd1 is offline   Reply With Quote
Old 01-05-2015, 17:28   #14
Senior Cruiser
 
hpeer's Avatar

Cruisers Forum Supporter

Join Date: Dec 2008
Location: Philadelphia
Boat: Murray 33-Chouette & Pape Steelmaid-44-Safara-both steel cutters
Posts: 3,900
Re: How does self bleeding work?,

Quote:
Originally Posted by roverhi View Post
You get some really bad advice on this site. If you are really serious about ending it, slice up, not across the wrist. You'll open a much larger area of the artery and will bleed out faster.
I dunno, maybe I just a sick jerk, but this interchange gave me the best laugh I've had in days!

Thanks guys!
__________________
hpeer is offline   Reply With Quote
Old 01-05-2015, 17:37   #15
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: Van DeStat Super Dogger 31'
Posts: 7,331
Re: How does self bleeding work?

Jdi, your explantion is quite correct however let me add one more comment.

The HP pump (injector pump) can only deliver a very small VOLUME of fuel into the injector line thus if this line mostly full of air which is compressible, the pressure created by adding a small amount of fuel into the line into the line remains low.

Only when the line is full of fuel, can the HP pump deliver the required pressure by adding a small amount of fuel into the already full line of uncompressible fuel.

OPPS...
EDIT...

Just re-read your post above and see that you have already covered this aspect in full .
Sorry and please disregard my waffling on...
__________________

__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Reply

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

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
Do Self-Sealing Valve Couplings Work ? svpresent Plumbing Systems and Fixtures 3 24-10-2010 17:26
Bleeding Fresh Water System rjarrell Plumbing Systems and Fixtures 5 09-08-2008 05:24
Bleeding 4-108 jimisbell Engines and Propulsion Systems 21 24-05-2007 16:36
Bleeding keel seafox Construction, Maintenance & Refit 16 09-05-2007 22:06
Bleeding the fue lines on a Yanmar 3YM30 chesapeakesailor Engines and Propulsion Systems 10 18-09-2006 06:55



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 07:04.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.