Do I need a water separator? Why are these things used?

[sparkoid]

Maybe you saw my other post surrounding my recent engine freshening.  I would like this go around to last, so I have a question:

I've heard reference to fuel / water separators for diesels.  My 1.6 does not have a stand-alone water separator, though the filter has a water drain on the bottom.  Does the filter provide sufficient water separation for my engine?  Would adding a "dedicated" water separator be worth the investment?

My 1.6 na diesel has only 80K mi on it, but needed valves and rings (and a *flat* cylinder head).  Wondering why the wear when I hear of diesels getting well past twice this mileage before needing attention...

[bajacalal]

I've heard reference to fuel / water separators for diesels.  My 1.6 does not have a stand-alone water separator, though the filter has a water drain on the bottom.  Does the filter provide sufficient water separation for my engine?  Would adding a "dedicated" water separator be worth the investment?

Are you sure? A lot of our cars have (or had) a water separator box under the car, by the tank. They are prone to leaking and are not available anymore so the solution is to delete them. It was considered necessary during the the 80s, but I think the quality of fuel available has improved since then. This was an issue with the GM diesels of the era. They did not have a good water separator. Diesels need a water separator but IMO, a combined fuel filter/water separator, which is what your car has, is fine for most use. I've never found any water anytime that I've changed filters on any of my diesels.

My 1.6 na diesel has only 80K mi on it, but needed valves and rings (and a *flat* cylinder head).  Wondering why the wear when I hear of diesels getting well past twice this mileage before needing attention...

I'm assuming you didn't buy the car new, right? Diesels have close tolerances due to the nature of being a very high compression engine. This means they must be maintained competently. If the car was neglected by a previous owner, for example, if the oil wasn't changed of if the person allowed the engine to overheat, it will not last. If you bought the car used, it's also possible that the odometer mileage does not reflect the car's actual history.

[bbob203]

take it off place it in the garbage can run straight hose in it's place. completely worthless junk.

[R.O.R-2.0]

if you want a water separator, get a racor..

[sparkoid]

The Bentley for this beast shows no fuel separator.  There is an expansion tank and relief valve in the back by the tank, but the line from the tank to the fuel filter is a straight shot, then another right to the IP.  Maybe California versions had to have them?

Yep, I bought mine used, so who knows what the PO did or did not do.  The general condition of the truck (very good) seems to corroborate the odometer.

Some further googling seems to indicate water separators are more about preserving the injection pump than valves / rings, and (knock on wood), my IP has been worry free.  So far.

[burn_your_money]

Only mk2s had a dedicated water separator. And they nothing more than a headache.

[RabbitJockey]

Ive tried to drain my filter/seperator combo a few times but only fuel comes out

[Dakotakid]

Well, before long, you will get some plastic along with the diesel (out of the drain) because the plastic ages and disintegrates and then you no longer have a choice about deleting the water drainer. Usually, this happens when it is very cold outside and you have somewhere to go...................

[92EcoDiesel Jetta]

The MKII Water separator is great thing to have If everything is working properly and not leaking. It is well engineered and has a built in water in fuel sensor that flashes ur glow plug LED when water is present. it is located at lowest part of the car so water settles there and can be easily drained. If not damaged I'd keep it.

[bajacalal]

The Bentley for this beast shows no fuel separator.  There is an expansion tank and relief valve in the back by the tank, but the line from the tank to the fuel filter is a straight shot, then another right to the IP.  Maybe California versions had to have them?

Yep, I bought mine used, so who knows what the PO did or did not do.  The general condition of the truck (very good) seems to corroborate the odometer.

Some further googling seems to indicate water separators are more about preserving the injection pump than valves / rings, and (knock on wood), my IP has been worry free.  So far.

You did not specify what kind of car you had so I assumed you thought it should have come with the water separator. They came with certain years (starting in 84 I think) and were pretty much universal after that).

No, a few drops of water in the fuel will not affect the rings but it can be bad for the injection pump and injectors.

The latter stuff, I think is neglect or abuse by a previous owner, either lack of maintenance (oil changes, valve adjustments, running without an air filter) or doing something that causes high exhaust gas temperature like turning up the pump too much or even just flooring the gas pedal driving up long grades.

[R.O.R-2.0]

the water separator on a mk1 was the fuel filter bowl.. theres a drain on the bottom.

the mk2, had one under the car. it sucked ass, and was a waste of time..

the mk3, im not so sure.. but i dont think they used the same thing as the mk2.

if you WANT a water separator, get a racor filter..

ive got a racor filter after my stock mk1 filter..

the stock mk1 filter is the water separator, and catches all the big pieces..

the racor is a 2 micron unit, and almost never gets dirty.

there is a bolt on racor filter for the mk2 VW as well.. its a bit pricy, but it has water-blok media, and a drain on the bottom of it.