Water separator question

glennm01

Active member
2004 FG649 -- Starting from an empty water separator reservoir, I'm getting an inch or so of diesel in there within a minute or two of running the engine -- literally just driving it across the yard. Would this suggest that the screen element is damaged? Or possibly just clogged and needing to be cleaned? Is this a part that periodically needs to be replaced, or just removed, cleaned, and reinstalled? Anyone dealt with this before?
 

gait

Explorer
I've never tried from empty separator.
However, I did have difficulty running a tank to empty a few years ago. There was a small crack in the plastic "glass" which let in a fine string of bubbles that collected in the filter on top of the engine.
 

PKDreamers

Adventurer
Hi, the water separator filter part number is SF-1001 in Sakura or OE ME121653.
They do crack and you could be better off replacing it with a CAV set up.
CAV 296 has a glass/plastic which clear and a filter on top and you can get all parts for them. There is heaps of brands that do this type of filter set up.
I am about to change mine over to it as the water separator is bloody hard to pull apart.
 

glennm01

Active member
No, there aren't any electrical connections on my OEM separator -- it looks like a pretty simple in-line mechanism. What's up with the dual filter assembly above (second link)? Is that just to provide an additional level of filtration, or are there some vehicles that require that for some reason? I would think that two stages of filtering would be universally better than just one, but since the OEM separator only uses one filter, I wonder if an additional filter would place a slight mount of restriction or delay on the fuel line that the Fuso engine wouldn't like? Just speculating...anyone know?
 

SkiFreak

Crazy Person
I am just guessing, but the twin filter may just be two filters in parallel, to cater for higher fuel flow, not a primary and secondary filtration system.
If that is the case, the design may be driven by form factor (two smaller filters, opposed to one large one), which would allow for fitting into more confined spaces.
 

PKDreamers

Adventurer
Make sure you order the right size fitting with those filters because most of them do not come with fitting.
 

gait

Explorer
I am just guessing, but the twin filter may just be two filters in parallel, to cater for higher fuel flow, not a primary and secondary filtration system.
If that is the case, the design may be driven by form factor (two smaller filters, opposed to one large one), which would allow for fitting into more confined spaces.

my guess is they are two independent filters on the same bracket. There's an in and an out for each filter. They could probably be piped externally in series, in parallel, or for two independent tanks to a changeover valve, or ........... I'm sure I've missed something.
 

PKDreamers

Adventurer
The twin is just a twin head filter in parallel , there is two outlets and two inlets you block off which ports you don`t need.
 

dlh62c

Explorer
....but since the OEM separator only uses one filter, I wonder if an additional filter would place a slight mount of restriction or delay on the fuel line that the Fuso engine wouldn't like? Just speculating...anyone know?

I applaud you for considering the fuel system as a whole and not as discrete parts. The integrity of the low-pressure side is essential for the entire fuel system to work properly. Things to consider are the cost of the replacement part, it's form, it's fit and it's function. While the cost of the OEM part can be high, you'll have no doubt in it meeting the other three.
 
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glennm01

Active member
Yeah, the more research I do on this, the more confused I get. Think I'll just order the OEM replacement filter element, stick with the stock assembly, and see if that doesn't solve the problem.
 

lanceatm

Founder and CEO of EarthCruiser
Check the micron of your filter choice. Fuso use as low as 5 micron as there standard, 10+ is very common in after market filters.
 

PKDreamers

Adventurer
Guys a FG649 IS NOT common rail , the water separator filter he wants to replace is just that a water separator the filter in the OE unit and it is just a graze and they are a pain to service.
The filter unit he is looking to replace the OE separtor would have a mircon 5-10 depending on whos filter you buy and very easy to service.
 

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