I disagree about the swap and it's one of the only times I've ever disagreed with Maine Sail; if you find it please post a link to it.
I just finished running a 2 micron Racor for over 900 hours, i.e., over eight years on my Universal M25. When removed and inspected it was still pristine. The REASON is that the fuel flow ratings are for much higher volume than our small diesels ever use.
Look, folks, this argument comes up so often it's why I wrote those links. Two basic choices: 1) 2 micron primary 'cuz they are usually much easier access than the one on your engine and change the engine filter less often; 2) anything less efficient that would "load up" the engine filter sooner - which seems counter-productive to me.
And for the past decade or six, those engine filters have been reliably reported to be somewhere between 25 and 30 micron, Which makes a 2 micron primary even more reasonable. And screw the fuel pump filters, because they should be after the primary anyway.
Your boat, your choice.
Stu, Maine Sail's thnking about this is a little bit covered in his response to this post. Is that what you wanted a link to?
May 04, 2016, 04:18:42 AM
Quote from: Jim Hardesty on May 02, 2016, 04:39:01 AM
I hope someone can explain my ongoing experience with my factory set of filters on my 2001 MKll. I use a 2 micron Racor filter element, R15s, and a Universal factory filter spin on, or a Wix 33390. The first filter to plug is the always the factory spin on. The max engine rpms will start to drop, then if I change the on the engine, spin on, filter the engine will run normal again. This happens using a variety of filters on the engine, spin on. Neither filter looks dirty, or to have water in them. The Racor bowel looks clean. My logic says that the first filter should get dirty first. Also I think that the Racor 2 micron is much finer filtering than the spin on.
Now I change the spin on every season and the Racor every 2 seasons. A few times I've had to change filters during the season. I use 2 or 3 tanks of fuel each seasons. Seems like not much fuel being filtered to dirty a filter. I do have confidence that the fuel I buy is clean.
Something just doesn't seem right to me.
Jim
Something is wrong with either how it is plumbed or the filter or filter head itself. A 2μm primary should load up well before the secondary even begins to discolor. You may also have an air leak. Even with
really dirty fuel it takes a long while to plug a secondary 15-17μm filter... If you're not pulling a vacuum, you may want to insert a drag needle vac gauge after the secondary temporarily, then the system is not restricted....
Primary filters should ideally be 10μm or even 30μm there is no need for 2μm unless you are running a common rail diesel and it only works the lift pump harder over its life and leads to premature clogging and high vacuum.... 2μm primaries can actually be dangerous because they can plug significantly faster than owners expect. I had one customer nearly loose his boat to a lee shore when his 2μm plugged very unexpectedly up off Cape Breton Island in NS. If you want clean fuel, clean the tank and install a polishing system, you could run this to 2μm if you wanted, and run a 10μm primary.
I know I have repeated this story many times but.....
Having been on a delivery when the engine failed at multiple inopportune times due to a "
new", owner stated less than three weeks, 2μm filter I propose that this can be as much of a safety issue as anything. Most boaters really don't know just how clean the fuel tank is. Clean tanks should be a first priority but in certain situations, like this delivery, it's not always possible.
We did this delivery on a Down East style boat that had essentially been used as a
floating condo. The fuel was in horrible shape but this delivery was well before commercial tank cleaners existed as a business. The new owner stocked if for the delivery, with a
case of 2μm Racor 900 series filters. This guy pretty much bought everything by the case but that is another story....
Long and short is we went through all the 2μm filters in 1/4 of the trip. We stopped and bought some 30μm filters and we made it all the way to Maine, in 4-8 foot seas, on a single 30μm filter. The big diesel engine ran perfectly.
-Maine Sail
Casco Bay, ME
Boat - CS-36T
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