2micron Return Fuel Filter

I wanted to post my initial impressions of 2micron's return fuel filter kit. I received my kit in a few days after purchasing it and installed it this afternoon. Today, I'll post my initial impressions of the kit and then follow up with further comments when I have used it over some miles.

The kit is very complete and high quality. It comes with a color illustrated clear set of installation instructions. Installation is very easy and straight forward. If you feel comfortable with replacing your main fuel filter you easily have the skills to install this add-on filter. It took me an easy 30 minutes to install the kit and I was not rushing at all. I'd say 20 minutes install time if I had kept on task.

Andrew has some pics already posted in another thread and I didn't take pics of my install so a quick search will help those of you that want to see what it looks like.

I'll provide updates after I drive for several tankfuls of fuel.

Once I add Andrews HPFP adapter that he has under development I will have isolated the HPFP from taking down the entire fuel system in the event of a HPFP failure.

Thanks Andrew!

Here's the quoted forum post with pics....

2micron said:

Sorry seamus,
I certainly will help you out. The return filter is very simple and well worth the effort. You must understand it will not save the pump from failure. It will not save the rail, HP lines or injectors.
It will help contain the damage of a failed pump away from the tank, lift pump, lines and boost pump.
I will get back to your PM, apologies for the last couple of days.Here is a couple of pictures:

All the best,

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I am waiting for my kit to arrive (it is in transit). I found a good source for the filters (if you didn't order it from 2micron). AutohausAZ sells the Bosch 0 450 906 172 filter for about $20 (US). I paid $47 for 2 of them including shipping. I have the filters already since they are only one state away from me. I can't wait for the rest of the kit to arrive. It left Illinois on Friday - that's the last tracking info I can get on the weekend. I am also on the list for the pump mod whenever it is perfected. Great guy, great design and just what our cars needed from the beginning.

Have Fun!

Don

schultp said:

I wanted to post my initial impressions of 2micron's return fuel filter kit. I received my kit in a few days after purchasing it and installed it this afternoon. Today, I'll post my initial impressions of the kit and then follow up with further comments when I have used it over some miles.

The kit is very complete and high quality. It comes with a color illustrated clear set of installation instructions. Installation is very easy and straight forward. If you feel comfortable with replacing your main fuel filter you easily have the skills to install this add-on filter. It took me an easy 30 minutes to install the kit and I was not rushing at all. I'd say 20 minutes install time if I had kept on task.

Andrew has some pics already posted in another thread and I didn't take pics of my install so a quick search will help those of you that want to see what it looks like.

I'll provide updates after I drive for several tankfuls of fuel.

Once I add Andrews HPFP adapter that he has under development I will have isolated the HPFP from taking down the entire fuel system in the event of a HPFP failure.

Thanks Andrew!

Click to expand...

looking forward as many members are I am sure to your review over next few months.....

The kit looks really good!

Suggest you keep an eye on the small perforated-band hose clamps as they can damage the hose jacket if over tightened. I'd replace them with OE-style spring clips.

What is the aux filter replacement interval? What is the filter's (original, in the kit) or Bosch replacement micron rating?
Are the replacements available in Europe too?

halfast3 said:

The kit looks really good!

Suggest you keep an eye on the small perforated-band hose clamps as they can damage the hose jacket if over tightened. I'd replace them with OE-style spring clips.

Click to expand...

I agree, those supplied clamps are terrible. I am out of my stockpile of small clamps off older toyotas from back in my 4x4 days.

Kits looks great otherwise, I should probably do more searching about it for a piece of mind mod

Henrick said:

What is the aux filter replacement interval? What is the filter's (original, in the kit) or Bosch replacement micron rating?
Are the replacements available in Europe too?

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I asked 2micron this same question and he recommends replacing the aux filter at the same time you replace the OEM filter (every 20k miles). This filter is the same fuel filter used in 1985-86 Jetta diesels (without pre-heat port). These filters (KS or Bosch) are made in Germany, so they should be easily available in Europe too. I do not know the micron rating. You could substitute another filter (with better micron rating), but if it is physically larger, you might have to put it someplace else. The big advantage of this particular filter is that it fits in the available space.

Have Fun!

Don

So is this being used as another pre-cautionary measure against an HPFP failure? I'm assuming it will help with filtering out any "metal" in the fueling system? Any information is helpful.

gotdesl? said:

So is this being used as another pre-cautionary measure against an HPFP failure? I'm assuming it will help with filtering out any "metal" in the fueling system? Any information is helpful.

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Yes.

The HPFP has a constant "return" flow that returns unused fuel to the tank. This filter is placed in this return line to filter any shrapnel that gets into the fuel from a failed HPFP. This filter would remove the need to clean out/replace the tank, replace the low pressure fuel pump (located in the fuel tank), and clean out/replace all of the fuel lines between the HPFP return and the standard OEM fuel filter when a HPFP fails.

This filter does not prevent a HPFP failure in any way. It only contains the damage to lower the cost of repair.

What was the kit cost? Link?

30Bones said:

What was the kit cost? Link?

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There is no link (yet?) and 2micron is working on getting vendor status here. Until he has vendor status, he cannot advertise his modification for sale here. Your best bet would be to send him a PM and ask him directly. The cost of the kit depends on whether or not you want him to sell you the filter or just the kit to install it. The filters themselves are available from many vendors online. You could also make your own kit if you have the ability to bend a piece of stainless steel to make the bracket, buy some fuel line, the filter, and some hose clamps.

Have Fun!

Don

One important thing.

My previous PD had same filter system. But the fuel filter canister was always hot after a drive. Now in CR the fuel filter canister is always cold, even after a long trip. What does that mean? Does CR fuel system run cooler? Maybe there isn't anything returned to the fuel tank?

Anyone else notice the 'cold fuel filter' or is it just me / my engine?

JSWTDI09 said:

I asked 2micron this same question and he recommends replacing the aux filter at the same time you replace the OEM filter (every 20k miles).

Click to expand...

Yep...I asked the same question and got the same answer

JSWTDI09 said:

This filter is the same fuel filter used in 1985-86 Jetta diesels (without pre-heat port). These filters (KS or Bosch) are made in Germany, so they should be easily available in Europe too. I do not know the micron rating. You could substitute another filter (with better micron rating), but if it is physically larger, you might have to put it someplace else. The big advantage of this particular filter is that it fits in the available space.

Click to expand...

A bigger filter definitely would need relocating if you have AC. The AC line runs very close to the filter as it is now. Anything bigger would not fit.

I can report that there are no issues or leaks after running this set up for several days. And, by following the great installation instructions there is no rubbing with the AC line. (I did have to gently push the AC line toward the grill to ensure it subtly bent away from the filter...bending is too strong a term. You just place enough pressure to teach it to stay about 1/8" away from the side of the filter...no loss of structural integrity of the hose with this small adjustment.

Hello All,
Good topics and hope this will answer some questions / concerns:

halfast3 said:

Suggest you keep an eye on the small perforated-band hose clamps as they can damage the hose jacket if over tightened. I'd replace them with OE-style spring clips.

Click to expand...

30Bones said:

I agree, those supplied clamps are terrible.

Click to expand...

Good Point and well taken, Thanks for the healthy feedback. This is good. An original prototype tester also identified this deficiency.
I will make sure no future kits are sent out with these style of clamps. I agree, over time they will "eat" into the outer casing of the hose. The couple of prototype kits out there will also be sent better, upgraded clamps. Thanks!!
.

Henrick said:

What is the aux filter replacement interval? What is the filter's (original, in the kit) or Bosch replacement micron rating?
Are the replacements available in Europe too?

Click to expand...

The German K/S filters I supply are 10 Micron Nominal. I have not been able to get an answer from Bosch about the rating of their filters. These filters were originally used on 1985 to 1989 VW Jetta diesels, with no Pre-heat Port. They are available anywhere, but be cautious of the really cheap ones. you will see them online for less than $25, but i can only suggest to use a better quality brand name filter. I can provide a cross reference list if needed.
10 micron is slightly better than your Factory 13 micron main filter, so this is also offering very marginal secondary filtration. It is wise to change it during your regular 20,000 mile interval as already noted.
.

Henrick said:

One important thing.

My previous PD had same filter system. But the fuel filter canister was always hot after a drive. Now in CR the fuel filter canister is always cold, even after a long trip. What does that mean? Does CR fuel system run cooler? Maybe there isn't anything returned to the fuel tank?

Anyone else notice the 'cold fuel filter' or is it just me / my engine?

Click to expand...

Sorry Henrick, can't really answer all this, but our cars do have a Thermostatic valve that maintains a certain temperature in the fuel return to the tank.
Here are some interesting temperature related specs:
http://forums.tdiclub.com/showthread.php?p=3769661#post3769661
.

schultp said:

Yep...I asked the same question and got the same answer



A bigger filter definitely would need relocating if you have AC. The AC line runs very close to the filter as it is now. Anything bigger would not fit.

I can report that there are no issues or leaks after running this set up for several days. And, by following the great installation instructions there is no rubbing with the AC line. (I did have to gently push the AC line toward the grill to ensure it subtly bent away from the filter...bending is too strong a term. You just place enough pressure to teach it to stay about 1/8" away from the side of the filter...no loss of structural integrity of the hose with this small adjustment.

Click to expand...

Thanks for the updates Paul!!
Glad to hear you are happy and all is well.
Please keep the questions coming, the more questions, the more we will all understand our Fuel System!!
All the best!!

So how much would this device save you in the event of the HPFP failure?

With the provided filter being 10 microns, is there any advantage or availability of a 5 or 2 micron filter, like available for the ALH or PD? Would this even be "better"?

Thanks

Airbus320 said:

So how much would this device save you in the event of the HPFP failure?

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Hello Airbus,
Not sure of the dollar value, but the return filter will definitely save much aggravation.
When the HPFP fails, all of the pump contaminants travel through the return lines to the tank. The heavier shrapnel will settle in the tank and the rest will be sucked up through the mesh filter in the lift pump, then sent back to the main Filter on the inner fender at the front.
Dealers have been cleaning the tank lately and flushing the lines. One of our members was quoted $350 for this.
The lift Pump and screen should also be replaced.
Even if you did all this yourself, and found a deal on a lift pump,it is a great deal of hassle.

whatnxt said:

With the provided filter being 10 microns, is there any advantage or availability of a 5 or 2 micron filter, like available for the ALH or PD? Would this even be "better"?

Thanks

Click to expand...

Sure, but be careful going "Too Fine" IE -1 or 2 micron.
The fabulous kits from Nictane or the defunct CAT filter kits would be wonderful, but a bit too long (tall) to fit in the small space in the cramped engine bay. It is possible, closer to the fuse block on the other side.
I did get some encouraging news today from Mann-Hummel about the Micron Rating of their version of the same filter - WK 842/3:
Hello Andrew,

The micron rating for WK 842/3 is :

Filtration efficiency, ISO/TR 13 353* at h 3-5 µm >67%
* Spec. Test flow rate: 0,02 l/(cm²h)

Operating pressure: 300kPa

Merry Christmas and a Happy New Year
Sandra


Best regards,

Sandra Schembera
Product Manager

MANN+HUMMEL USA, INC.
6400 S. Sprinkle Road
Portage, MI 49002-9706

Phone: +1 (269) 329 7238
Fax: +1 (269) 329 7201
sandra.schembera@mann-hummel.com
www.mann-hummel.com
.
The Nominal Rating of 5 Micron with a Mann filter would be ideal for this application. I have flow tested these Mann Filters in the Past and found good results. They usually cost a few dollars more than Bosch.
These two Gauges on the fender sill are part of my testing, to monitor the pressure differential across the filter:

These gauges are not necessary for everyone, but very helpful in testing and measuring restrictions.
Here is a historical link to some serious filtration experiments back in April:
http://forums.tdiclub.com/showthread.php?p=3747602#post3747602
Thanks again, keep the questions coming!
All the best!!

That filter holding bracket really needs to be painted black when it'll be put in production, otherwise it looks odd.

Also, could anyone check and report back if their stock fuel filter housing is cold or hot after a drive?

2micron,

Thank you for the update.

Does the install require the same installation steps as replacing the stock filter, i.e. the cycling operation?

Could you please provide me with a PM with price.

Sorry, a little off topic but... Funny you should post that e-mail from Sandra. I've met her through work before.

cd_booth said:

Sorry, a little off topic but... Funny you should post that e-mail from Sandra. I've met her through work before.

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Glad you are here cd_booth, you most likely understand the most about filters!!
A while back, you helped us determine the Micron rating for the replacement Filters on our cars:

cd_booth said:

@2micron, I work for MAHLE. The 2.0 TDI MAHLE fuel filter media has a pore size of 13 +/- 3 microns. Granted, they are not OE on these filters, they are OE on many other VW, BMW, Volvo, and Mercedes applications and always design to OE specifications. However, there could be a difference in the OE (MANN + HUMMEL) design. The MAHLE part numbers are KX 178D and KX 228D depending on the chassis.

1K0127177A = KX 178D
1K0127434A = KX 178D
1K0127434B = KX 228D

Also, the water separation efficiency specification is >95% for the MAHLE filters.

Click to expand...

Thanks again,
All the best,

2micron said:

I did get some encouraging news today from Mann-Hummel about the Micron Rating of their version of the same filter - WK 842/3:
Hello Andrew,

The micron rating for WK 842/3 is :

Filtration efficiency, ISO/TR 13 353* at h 3-5 µm >67%
* Spec. Test flow rate: 0,02 l/(cm²h)

Operating pressure: 300kPa

Click to expand...

For anyone who is interested, these Mann WK 842/3 filters are available from Amazon for US$20.49 each. Buy 2 and get free shipping. This will be my source when the Bosch filters I already have are replaced.

http://www.amazon.com/Mann-Filter-W...&qid=1356037873&sr=8-1&keywords=Mann+WK+842/3

Have Fun!

Don

2micron said:

Glad you are here cd_booth, you most likely understand the most about filters!!
A while back, you helped us determine the Micron rating for the replacement Filters on our cars

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No problem. After checking out your latest progress I checked the efficiency of MAHLE's equivalent to the WK 842/3 (which is part number KL 41) and our specification is 50% at 5 microns. Our filters will be available through Amazon very soon. From the looks of it, it should be a little less expensive too. I understand the desire to use MANN's filter due to the lower micron rating but this could also be an alternative depending on what you're looking for. Feel free to PM me if you have any questions!

Since we have gone that deep... Wouldn't there be any need to replace the factory fuel filter (which is rated for >10 microns) with a total of two MANN WK 842/3 filters (~5 microns) - one for the return and one for the main filtration? Wouldn't this result in cleaner fuel both, going to the the engine and returning to the tank, besides probably extending injector life?

Henrick said:

Since we have gone that deep... Wouldn't there be any need to replace the factory fuel filter (which is rated for >10 microns) with a total of two MANN WK 842/3 filters (~5 microns) - one for the return and one for the main filtration? Wouldn't this result in cleaner fuel both, going to the the engine and returning to the tank, besides probably extending injector life?

Click to expand...

Hello Henrick, Good Thought, but just be cautious eliminating the Thermostatic Valve we discussed earlier. If you are serious about filtration, it is best to have primary and secondary filters. 10 micron primary and then 2 micron secondary is very common: (these are located under the driver headlight)

.

This is great, but gets a bit expensive come service time!!

All the best,

2micron said:

Hello Henrick, Good Thought, but just be cautious eliminating the Thermostatic Valve we discussed earlier. If you are serious about filtration, it is best to have primary and secondary filters. 10 micron primary and then 2 micron secondary is very common: (these are located under the driver headlight)

.

This is great, but gets a bit expensive come service time!!

All the best,

Click to expand...

Is this a separate project from the two mainly discussed (pump adapter and additional filtration on return)?

Wow, this is getting too complex.
2micron, where's the thermostatic valve located? Is it inside the stock fuel filter housing?

Hi guys, any chance that this modification could increase the chance of an engine fire during a front impact collision?

I don't think so. Diesel does not burn that easily.