Cruisers Forum

Join CruisersForum Today

Thread Tools Rate Thread Display Modes
Old 29-01-2007, 13:00   #16
Registered User

Join Date: Jun 2005
Posts: 1,901
Always glad to help where I can.

never monday is offline   Reply With Quote
Old 29-01-2007, 14:58   #17
Registered User

Join Date: Feb 2006
Location: nyc/chesapeake
Boat: gozzard 44
Posts: 287

Right you usual.


ronbo1 is offline   Reply With Quote
Old 07-02-2007, 00:22   #18
Moderator Emeritus
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 32,211
Images: 240
If you want to add a Secondary filtre prior to the on engine Primary filtre (between the tank and engine) you should use at least a 10 micron filtre. If you use a filtre that is known to be of good quality, then 10 micron will likely be sufficient. If you are at all suspicious about fuel quality, you could go to larger 15 or 30 micron elements.

Depending on engine make and model, the final filtre (primary), mounted on the engine just before the injection pump, will have a single-pass retention (pore size) rating of 2 to 10 microns*1. This is the size that most*2 engine manufacturers figure will protect injector pumps and nozzle tips from damage.

*1: A micron is a thousandth of a millimeter. A grain of salt is roughly 100 microns in size, a human hair about 70 microns, and a single grain of talcum powder about 10 microns.

*2: I understand that Westerbeke recommends 25 micron filtres.
Racor filtre elements have a code number (2010, 2020) followed by a letter or letters: PM is for primary, which is 30 microns; SM is for secondary, which is 2 microns; and TM is 10 microns.

The Secondary fuel filter must offer low restriction because it is mounted on the suction side of the fuel pump, where normally a suction pressure of only 5-6 pounds per square inch is available. This filter has the job of protecting the transfer pump and lightening the load of theprimary fuel filter (if installed). Secondary fuel filters typically have a nominal rating of 10 - 30 microns.

Primary fuel filters are mounted between the transfer pump and the injectors. The primary fuel filter is designed to offer full protection to the fuel injectors. Since these filters are mounted after the transfer pump they tend to see much higher pressures than primary filters. Primary fuel filters typically have a nominal rating of 2 - 10 microns.

The Primary filtre is ALWAYS finer (smaller micron size) than the Secondary filtre.

Some other tips:

Filter units are also sized by flow rate, expressed in gallons per minute. A handy rule of thumb is to multiply peak engine fuel consumption by 3.5 or 4, then divide by 60 to get the fuel flow rate in gpm for a four-cycle diesel. Another is horsepower × 0.18 = gpm.

Asphaltenes can be formed, when diesel fuel is heated and pumped. Asphaltene sludge can be mistaken for bacterial contamination, but it obviously will not be eliminated by a biocide. Accordingly, if you're experiencing filter plugging, you should test to see what is causing the problem.
ie: Dieselcraft "Fuel Bug" Kit ($10): Oil and Diesel Fuel Purification Systems for all diesel engines

Ideally, you should refuel at the end of day or run because today's diesel engines (depending on make) recirculate as much as 75-85% of the fuel delivered to the engine. Each "trip" to the engine and back increases fuel temperature, and sources tell me that in-tank fuel can reach up to 100 degrees F. Hot fuel, in a mostly empty tank, leaves hot air, which cools and condenses, forming water droplets that are added to the fuel. Refueling, before shutting down, is desirable.

Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"

GordMay is offline   Reply With Quote


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

Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 21:50.

Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2018, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.