Diesel Fuel Filter Problems: Avoid "Knackfrosch" Issues

A week ago, I checked the glow plugs on the AHF because it had been starting increasingly poorly. So, I removed the glow plugs, inserted them into the bridge, and connected them all to ground using a wire, then turned on the ignition (preheating time adjusted to about 6 seconds). Sure enough, none of them glowed at all; they were all dead. I installed Beru glow plugs, and the result was immediately very clear.

Then I thought about the fact that you might need to drain the diesel filter after about 30,000 km.
Pour out the contents, put the lid on, add 100ml, mix it all together, and you're done.

Engine started, ran wonderfully, a few small bubbles in the clear tubing between the DiFi and the VP37 fuel inlet. Test drive - I only made it 500 meters before it stopped. Pushed it home, removed the fuel filter, no diesel .

I hadn't refilled anything and I thought it would automatically adjust and add the missing 100ml. So, I filled it up, put the frog in (presumably a reference to something specific), the pump contained diesel, and after 30 seconds, it started up again. It ran perfectly at idle, but after driving 100 meters, it stopped.

It was then noticed that water was dripping from the bottom of the filter. The damn drain plug wasn't sealing, even after being completely re-tightened. Furthermore, I had the feeling that the frog was now letting in air into the system due to all the repeated opening and closing.

Since I was completely fed up and VW didn't want to charge me 20€ for a new pre-filter plus a new filter, I ordered a diesel filter without the pre-filter attachment and a hose connector for the return line on the same day.

"I sealed the screw with sealant, and that fixed it for a while - until today. The filter arrived this morning by post, along with the connector. Thirty minutes later, my wife called: 'Honey, I'm stranded.' I had a complete internal meltdown. So, I grabbed the filter, some hose clamps, diesel, a syringe, tools, and changed the filter on the sidewalk in the city center. I always had a few small bubbles in the fuel line, but now there are absolutely none."

Once again, it's clear that not all that glitters is gold. In the "Yellow Line" section for edge-controlled ESPs, it states that the "frog" (presumably a component) seems to "only" warm the filter to prevent it from clogging with paraffin crystals in cold weather. Since I only use premium fuel (Ultimate).
I'm not worried about that; the Golf II also had the filter without the pre-filter as standard equipment. Therefore, the mesh size, and thus the quality, of this current filter shouldn't be worse.

And - I will never again drain a DiFi! New or nothing .

Congratulations!
"I also always had problems with draining things... leaks, bubbles, everything coming out."
Therefore, I will never attempt another drainage project in this lifetime.
I think it's probably some kind of internal therapy program, designed to prevent self-repairers and roadside assistance technicians from becoming too alienated from each other.

Clumsy person and plastic screw?

Off-topic question: What are the typical replacement intervals for diesel filters? The one from Spatzendiesel has the number sequence "042006" stamped on it, so it might still be the original equipment and has lasted 170,000 km. I think it might be time to replace it.

The installed filter has quick-release couplings, and so far everything is sealed. The filter is also reasonably accessible. Can I order the replacement part myself and replace it in the garage? Or should I have it done by a professional?

I have never drained the fuel filters in any of my previous diesel vehicles (Fiat 1.25 JTD, Ford 1.8D). I always either replaced them with new ones or made sure they weren't disturbed.

Good morning, 90,000 and 120,000 km for a VW – I would definitely start thinking about maintenance at those mileage intervals, Janek.

@Rainer: The hand is already adjusting well to the material, thread, and diameter, so don't worry. } Nevertheless, the difference this morning when starting the engine is remarkable, but not surprising. I've always had small bubbles, and I'm familiar with them in other TDI engines with a "Froschfilter" (a type of air filter), but now there's truly complete silence in the fuel line - just diesel, not a single bubble.

@HatDriver: Considering that a quality filter doesn't cost much as an accessory, I tend to replace them more often. It seems there's hardly any water in the diesel anymore, unless you're filling up at a no-name gas station in the Czech Republic. Ulf has already noted that the drain screws are missing on the filters available from VW.

teileklaus wrote:

Good morning, 90 and 120,000 km on a VW, I would definitely do something about that, Janek

.

"That much? In my service plan, it says to replace the coolant every 30,000 km, and the filter every 60,000 km... I replace it every 30,000 km because I don't bother with the draining process anymore, and the filter only costs 12 euros, so it's not a big deal."

"...so I'll replace it annually based on my yearly mileage. I'll order one and try to do the replacement myself."
Do I need to prime the new filter with a syringe first, or is it sufficient to use the ball pump that is already available in the vehicle?

Hi,
I change this filter every 30,000 km without any issues related to leakage.
The only issue I ever encountered was caused by the filter housing. In the Audi 80, it's designed like a cuff, where the filter is held in place by tightening a screw. This screw also maintains an angle for the connectors for ESP, NHG, and the crankshaft sensor. There's a tendency to tighten this screw so much that the angle becomes fixed. The effect was that the filter would slightly deform, causing a leak at the flange. The solution was to use a spacer between the ears of the filter housing, so that even when the screw is tightened completely, the filter is only held in place lightly.
"Attention points" are the connectors for the fuel lines. The rubber hoses become brittle over time and need to be replaced. I described the dimensions in another thread here before."
"For clamps, I use either ear clamps or hose clamps, both with an inner ring. The cheap clamps with threads in the clamp band will damage the hose."
hg
Herbert.

@HatDriver: You could check out monopoel; they have screw-on filter adapters. That's a good option if you change filters often because it puts less stress on the hoses when you're connecting and disconnecting them, and screw-on filters are also cheaper. I always fill the new filter completely with diesel. That air has to go somewhere, and it's better to put diesel in it than have it forced through the pump.

Okay, I'll take a look. The standard-issue hand pump located in the engine compartment is used for venting. I actually had to live with that for two weeks back then because a hose had become stuck and was letting air in, until the replacement part arrived. I had to pump it for about 15 seconds before starting the engine, and then the feed line would be completely full again. I can still prime the filter, but I'm sure I won't be able to fill it completely.


EDIT: For the price of the conversion kit (filter holder, connecting parts, and two "large" filters), I can also order approximately 2.5 aftermarket filters for the original part and wouldn't need to do any modifications. If those filters only last half as long as the currently installed filter, then my 206 will probably have experienced that too...

Regarding refueling habits: Regular gas stations near home or work, as well as in other European countries, and an automated gas station with truck diesel near my residence. The cheaper, the better! So far, fuel is still passing through the old filter. Diesel filter changes seem to be completely overrated...

What else comes to mind: The current filter has already been replaced once. The reason for this was probably the incompatibility of the original filter housing with the increased biodiesel content that was introduced at some point. It became brittle, cracked, and eventually started to draw air. I need to check my records to find out exactly when the replacement took place. The filter that was installed at that time was probably stock. However, it has certainly been in use for several years.

EDIT 2.0: It hasn't been that long: The change occurred in August 2010 at approximately 105,000 km. Now it shows approximately 170,000 km.

"During oil changes, instead of just adding diesel, I pour in a can of 'Liqui Moly Diesel Purge,' 500ml. This almost fills the filter completely, and it runs perfectly smoothly afterwards."
Does it make a difference? I have no idea, but it eases my conscience, it only costs 10 euros, and it saves me from the diesel fumes.
And one hopes that the ESP/nozzles will be happy about this... better than "refilling spark plugs."

I no longer drain my filter. I've done it a few times and observed that no water or anything else ever comes out. I replace it at most every 90,000 km. Usually, it's done during the timing belt change. The filter itself costs 42€ from Mahle. The subsequent filling process depends on my mood. Turning the ignition on and off a few times also works without any problems...

I also change my DIFI every 30,000 kilometers or sooner if there are too many air bubbles in the hose. I even think I read in the VW manual that the DIFI only needs to be changed every 60,000 kilometers.
....at least not for me. I've never had to dehydrate, thankfully, as I see now.

Please consider the biodiesel content in the fuel. The Difi filter should now be replaced between 30,000 and 60,000 km.
For water injection systems, CR Diesel offers a solution where the fuel is circulated more frequently. (This helps cool the injection process.)
That's why you'll find H2O diesel filters there.
"The problem of premature oxidation of high-pressure pumps and injectors is well-known. Thanks to UFI H2O, the water separation capacity in diesel is over 99% at a flow rate of 160 liters per hour. With a filter area of 7400 cm³, a maximum operating pressure of 5 bar, and a recommended replacement interval of 20,000 km, UFI H20 is the filter of the new generation for the new common-rail injection systems. The filter that you have been maintaining, and which could only be developed by a specialist like UFI."

Here's a translation of the German text:

"This also fits the topic quite well:"

I changed the diesel filter with almost an empty tank (less than 1/4 full). It wasn't a good idea, somehow...

"Since the 1.4 TDI AMF apparently doesn't have an electric fuel pump (because I can't find a fuse), yesterday, at least in my case, the tandem pump failed to pump air out of the common rail injectors, even though the fuel filter was new and the starter motor was working well."
In the end, ether was needed to get the cart running again, and a slightly higher idle speed was used to draw fuel back into the system.

I replaced the filter because it seemed like it was about to fail recently when the temperature was around -20 degrees Celsius. It was already past 90,000 km anyway.

Normally, changing the fuel filter wasn't a problem. Now, after the change, it ran for 30 seconds and then stalled and wouldn't restart.

In another forum, someone who usually knows what they're talking about claims that there's a pump that can also be controlled using the diagnostic tool. What's strange is that I'm not getting any fuel from the tank, even with the ignition turned on...

http://www.lupotreff.de/forum/t/24239

Since there are likely more people here who have some knowledge of this, I'm asking if anyone knows more about it, in order to avoid a similar problem in the future.

I'm not really a fan of the radical method using ether.

Thank you!