My local VW dealer estimates $130-150 if it's the same as the TReg. My closest Porsche dealer wants $225 just for the fuel filter work ($575 for the 10k service!).

I have the PIWIS docs and it looks straight forward, but the last time I dealt with a diesel fuel filter was on a 70s tractor...

Suncoast wants $98 plus shipping for the diesel extractor (VAS 9226), but my local VW dealer only wants $90 for it.

I actually would like to give my dealer some non-warranty work, but when I can do the oil for less than $100 and I suspect I can manage the fuel filter for substantially less (including having to buy the extractor) I find it a bit hard.

So has anyone else done it yet? Anything to watch out for?

My biggest concern is bleeding the system. The docs just say drive it, but then it goes into how air in the high pressure side can cause serious damage and you need the PIWIS to bleed that side of the system.

 

I've owned and maintained diesels since 1985, so I'm not afraid of a little fuel system work. That said, I'd have to study on this engine before I broke out the tools. The extractor and filter are not necessarily the same piece of hardware. Some of the better diesels have both: a fuel filter, and a water separator (extractor). Typically the separator/extractor isn't changed, its just drained. Some are an all-in-one device with both a drain and a replaceable filter element. Any chance of me studying on your PIWIS documentation to see if I can figure out how VAG/Porsche does it?

//greg//

 

The extractor I mentioned is the shop tool to extract the water out of the filter housing. The VW parts guy had to ask a tech about it who confirmed what the tool part number was (which I had already given him and in fact showed him the relevant tech page) but said they don't bother to use it in the shop. I'll use the extractor though as it will hopefully be less messy and I don't want to give PCNA any ammunition if questions arise down the road.

 

gnat, is the fuel filter service every 10k? i thought (and was hoping) it was every 20k . . .

in either event, i'll be looking forward to your DIY. many thanks for taking the time to document your work

 

Is the extractor tool you mention a Porsche/VW/Audi specific one or can a generic one be used as well? Can you post a pic of this tool?

Thanks.

 

According to "WM 030400 Oil change service for the Cayenne V6/Diesel/S Diesel/S Hybrid (A, B and C markets)" every 10k (15kms) or 1 year water is to be drained from the fuel filter.

According to "WM 031400 Intermediate maintenance (B markets)" the fuel filter is to be replaced at the 20k (30kms) interval.

All I have is the is the "stick figure" drawing in the manual (this link shows a version of the image from a Golf TDI guide, the Porsche version looks better ). Once I have one I'll of course post a pic.

As the VW guy said the techs at that dealer don't even bother with it I assume it's not really needed or can be improvised, but I'll know better once I get it and perform the service. Of course since I'll have the tool I won't need to improvise it, but I'll be happy to provide my opinions and any helpful information to those that want to.

 

I'd call it a glorified brake bleeder. Doesn't appear to be any reason that a MityVac or similar wouldn't work just fine.

//greg//

 

For anyone interested, here are some shots of the filter housing with and without the plastic shield removed. The housing is located on the passenger side up against the firewall and is clearly visible.

Removing the shield is easy enough. There are just three plastic trim "bolts" (don't know what they are called). There is a piece in the center of them that you pry up and then pull the whole thing out. After they are out you can then remove the shield. It's probably a bit easier if you remove the front shield, but I didn't have to do that (the driver side shield was a much bigger PITA, but I still didn't have to remove the front shield).

You do have to remove the plastic shield to get to all the bolts off. If you look at the pic without the cover you can see a tube that runs on the left side over the housing. It covers a bolt and you can't move the tube with the plastic shield in place.

You might also notice on the right side of the housing cover that I apparently have a friend that has been visiting The air filter (also under the same plastic cover, but it's up front) looks good and I don't see any signs of damage anywhere else.

 

My guy finally got around to getting the tool to me. Here are some live pics for reference.

 

Dropped off my CD this morning at the dealership to have the 10k fuel filter maintenance done. I just received a call that the filter doesn't need to be changed until 20k. When I asked about the draining of the water, their response was that it gets done when the filter is changed at 20k and that there is a sensor that will go off if the water level is too high. The service manager said the manual was confusing but that is how they have been handling all their CDs.

Not sure what to make of it. I'm glad I saved the $$ but I'm worried that they may not know what they are talking about. But who can you trust if not the dealership?

 

Well I would say you can't trust the dealership as they are just as prone to stupid things as anyone else. The upside, however, is that since you had the 10k done by them they can't later make you pay for any problems related to water in your fuel system since they didn't do the work.

As far as if it needs to be done or not, it's been a few months since I pulled the maintenance guidelines off PIWIS and it's possible that they've been adjusted. I'll pull it up and check for updates before I go to do my 10k.

In regards to a sensor, this is the first I've heard of it. It's certainly possible that there is such a sensor in there, but when I pulled the panels to take a look at the filter housing I didn't see anything that suggested there was a sensor (e.g. just fuel lines going in and out as far as I could see).

 

Gnat, did you have to purge the fuel system? Did your diesel start after changing the filter. I do not think that the fuel pump comes on with the key in the ON position, so I heard that PIWIS maybe needed to start the fuel pump. But I also think it may just be OK, and that it will start.

 

I haven't done it yet and 10k is just draining water. The replacement is at 20k (but from what I gather the only difference is you insert the new filter instead of putting the old one back.

As far as the fuel pumps, you have two that you have to be concerned with. The first is the low pressure pump which under most cases should take care of bleeding itself as you drive the car for a few miles. There are some cases, however, that you apparently can need the PIWIS unit to do the bleeding, but the document isn't clear as to what they are.

The second is your high pressure pump. It's really bad if you get air in the high pressure side as (according to PIWIS) it can result in "catastrophic engine damage". This is the pump that you need the PIWIS unit to run the bleed sequence prior to starting the engine.

The filter is on the LP side of the system, so it should just be starting it up and running for a few miles.

 

After self-installing the new/dry fuel filter, make sure to replace the diesel fuel lost from the canister when the saturated/old one was lifted out. This greatly reduces the amount of air that must be removed (bled) to recover full prime. FWIW, the 10k drain water service is in the book to cover worst case situations. I'd be surprised if anyone in the US actually finds a meaningful amount of water at 10k. To me, it's an unnecessary opening of the fuel system. I'll wait till the 20k intermediate service at the dealership, and let them handle it; fuel, water, the whole lot. I mean the 20k and 40k are flat rate services for a list of specific maintenance items, so you're going to pay for it regardless.

//greg//

 

I'm not trying to argue with you Greg since you have far more diesel experience than I do, but I would like to point out that Porsche has different service guidelines for different regions. The water drain is in the service guidelines (or was a couple months ago) for our region.

As far as the 20k goes, as I recall other than the oil and fuel filter its just basic stuff (like the air filter) and a bunch of visual checks. As it gets closer I'll look more into it, but right now it's probably another one I'll do myself.

The 40k is a bit more involved and will be the last major service before the warranty expires, so I'll have the dealer do that one so they can give it a good once over before I jump off the cliff.