W123 Water Separator??? - PeachParts Mercedes-Benz Forum

tomm9298 · #1 10-07-2004, 07:49 AM

I know VW diesels have a water separator on the TDI engine. Is anyone running one on their 300D? Is it necessary on this engine? If you are running one where did you get it and what was the cost?

oldnavy · #2 10-07-2004, 09:03 AM

You must be talking about the standard fuel filter on the VW TDI that has a water drain on the bottom. On the TDI forum I guess maybe 1% have ever gotten water to drain out of the water seperator section of the filter. I have never had any water in any of my OEM filters or my Cat 2 micron absolute fuel filters I run now. OEM is 10 micron nomanal and 20 micron absolute and rated at 20,000 mile change period. The Cat filter stops water also but has no drain point, so it will plug and stop fuel flow. At the present the Cat fuel filter on our VW diesel has about 15,000 miles and should easy make 30,000 miles. The OEM VW filter is about $45 at dealer and the Cat filter is $10.50 at any truck repair center. I plan on adapting one to the 240D in the spring.

tomm9298 · #3 10-07-2004, 09:10 AM

So the CAT filter has no way to drain the water from the filter? How much water can accumululate before it stops up? I am assuming you have faith in these filters. Is this an in-line filter or the can type? What needs to be done to run a filter such as the CAT one? What kind of mods must be done, or is it plug and play? Let's hope it is not plug and pray!!!

oldnavy · #4 10-07-2004, 09:51 AM

There is an adapter that is sold to adapt the Cat filter to be used instead of the OEM filter or it can be used as a final filter with the OEM as prefilter. There has been no reports of any failures or problems with the filters in the year or so that people have been using them on the TDI forum. Some people have had instalation problems, but that has nohing to do with the filter.

What's really nice is the fuel sample testing that has been done on these filter, talking about cleaning dirty fuel.

As far as how much water required to block the filter I have no idea, the filter holds about a pint of fuel so go from there. I did see a filter removed from a TDI at the last GTG at my house that had a few drops of water in the fuel filter when removed. However that was not the problem as it was the dirt & trash in the filter. The car had been running bad since the guy had filled up last before coming to the GTG. The fuel when dumped out of the filter was full of small particiales of crap and what looked like grains of sand and about 3 drops of water. Needless to say we change the filter (OEM) on the car.

Here's a link to filter adaptor and having both ordered the adaptor from Greg and been to his home and visited with him while he installed new injector kits and pop tested them prior to instaling. He has my vote of confidence.