Sorry I am just getting on to this site and saw a picture of these things that were listed as Filters and thought that they were water traps, like the spare one that I have here that is all. I will have to get on to the site better before I as questions I guess. Sorry about that did not want to appear stupid, but I guess it is too late for that now huh?
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
Yeah, you can edit a post for as long as you want (unlike other sites), so you can re-write history
I missed that the eBay description read "oil filters". I looked at them and knew them for what they are: Secondary Fuel Filters (1982-86). Take a minute to read that post, it's some of my better work.
This later Secondary Fuel Filter has provision for a Water-In-Fuel sensor, hence the threaded hole in the bottom. The "sensor" is merely a steel probe. The real sensing is done by a module under the dash, that measures the resistance of the probe to the filter shell: water at the bottom will conduct (a little) from the probe to the shell; fuel will not. There's no float switch, as in a brake fluid reservoir.
To be fair, the sensor hole is not shown in any pictures on this site yet. I'll see if I can remedy that today.
Just read through this and used the links to go to different posts pictures etc. I guess this 87 that I have is a bit of a weird duck! In fact I think it is a freak. The first thing is that there is "NO" primary filter. There is a "Sedimentor" or water trap only, like what Al was bidding on from EBay. There is no element, screen, media or any means of filtering anything to this point or within it, only a "float" type water sensor. It is not a "steel probe" in this case but in fact a small plastic float. You loosen it and allow the water to drain out in the event that any is present. The filter housing that holds both the water trap and the "Only" fuel filter also has the fuel heater in it as well. The fuel heater is situated over the water trap. There is no "Air Purge" pump on the fuel pump but a pump on the filter housing with a small plug that you remove to allow the air to escape. It is, or was, a real PITA to get all the air out and I ultimately installed a small inline fuel plump (6 psi) that will simply pump all the air out of the system and fill the water trap and filter at an idle by pumping the air through the return system as the fuel system on this engine is self bleeding, but will not get the air out of the filter housing on its own. I let the pump run for a minute or two when I change filters and then start it. It complains a bit and stumbles for a minute or two but smoothes out nicely. The pump also has a built in bypass so that once the system is pressurized it simply bypasses through itself. I hooked this small pump to the fuel shut off solenoid with a small relay. (Only draws approx. 4 amps but as mentioned before the electrics on these little guys seem pretty fragile). The water sensor then puts a light on the dash if there is any present, but has yet to come on. I did test it and it works just no water at this point. Dad had installed a RACOR 100 as a "Primary Filter/Water Trap" ahead of the Nissan water trap and filter and it turned into a PITA as well, especially in -23C weather so I removed it.
The heater is pictured as the black object in the top of the housing. The sensor pictured with the wire on it is the temp sensor that reads the fuel temp and if cold enough closes and enables an oil pressure switch which in turn fires a relay to turn the heater on, but only if there is enough pressure above idle. As mentioned before a bit convoluted but works pretty well.
Sorry about the focus on the size comparison but I tried a Macro while holding the camera instead of on a tripod and it blurred a bit but you get the idea of the size.
Retired Pauly
Problem with being retired is that you never get a day off.
1987 D21-J SD25 KC
KJLGD21FN
