[va121mir]

I was not able to find a commercially available "disaster prevention kit" for a CP4.1 so I made one using the same principles that the ford, etc CP4.2 kits use. After lots of protyping and waiting for the parts to arrive, I finally installed the kit in my ride yesterday. Below are the pics of the final product and it installed. So far everything runs perfectly. I am also working on a filtering setup for the return fuel line to take care of the debris if the pump grenades but may have to get another part machined to get the filter I want hooked up. Based on how the testing goes, I may start selling these kits. Let me know if you would be interested picking up a kit. Ballpark prices will be around $200 for the kit and an extra $150 for the filter addition.

[eugene89us]

This is quite interesting. Curious how this works. What purpose does this part play? Of course, the concept of return fuel filtration makes sense.

[va121mir]

eugene89us

The CP4 pump is prone to "grenading" and contaminating the fuel system which then requires a full replacement that can run 10K plus. This piece stops fuel flow to the metering valve from the chamber that contains the failure prone roller. If the pump does grenade the contaminated fuel will be returned back to the tank. The next step for me is to put a filter on the return line that way the contamination does not reach the tank. With this part the metering valve is fed fuel directly from the inlet line.

Reference the link below for a more in depth explanation of the problem. Although this has been a big issue for Fords and GMs with the CP4.2, there are cases where this has happened to BMW and VW engines with the CP4.1.

https://www.dieseltechmag.com/2017/1...s-the-cp4-time

[va121mir]

Above is the CP4.2 version which I based this design off of.

[eugene89us]

Once you design and test the filtering kit, I will be interested in getting the combo. It would be great if you made a video on how to install this kit once both become available for purchase. Now another question, do all 328d variants come with CP4.1, and not 4.2? Would this fit all CP4.1 variants, including redesigned post LCI pumps? Appreciate your hard work on this. Where are you located?

[eugene89us]

I also have a 2014 Passat TDI with the same pump, would be fantastic if your kit fit both cars.

[HighlandPete]

Serious question, is this a US issue due to poor diesel quality, contributing to the fault?

Don't think i'm missing it, but haven't seen this issue filling forums over here, and we've a lot more diesel's with the pump over here in Europe.

[FaRKle!]

Originally Posted by HighlandPete

Serious question, is this a US issue due to poor diesel quality, contributing to the fault?

Don't think i'm missing it, but haven't seen this issue filling forums over here, and we've a lot more diesel's with the pump over here in Europe.

Likely. Enabled has taken apart some higher mileage pumps where the internals looked pristine. Contamination is likely a big root cause.

[va121mir]

eugene89us

It will likely be about 3 months before I will get around to being done w the full setup. All the 328d with the same motor should have the CP4.1. The CP4.2 is larger and has a second pressure chamber for use in larger V type engines with 2 common rails.

If the housing and the metering valve are the same then it should fit other CP4.1 variants. I personally do not have the bandwidth to verify fit for other makes and models (since it requires either buying different pumps or having access to the vehicle in question)

As far as the video...I dont think it would really work because the pump is kinda buried on the back drivers side of the engine. Most of the work area would be covered by my hands since its a pretty tight squeeze. I can definitely provide detailed instructions tho.

I am in texas for now anyway.

[va121mir]

HighlandPete

I think the fuel quality has def been a big factor. The other issue, at least with the CP4.2 driven engines was not enough inlet flow causing lack of lubrication. So essentially if the low pressure pump fails then it could cause the grenade as well.

I remember reading a few consumer reports with the grenade problem back about a year ago when I bought the 328d.

I figured I might as well try to prevent the possibility instead of having a repair bill that is more than what I paid for the car.

[project_x]

I'd be interested in the plate and filter when available.

[eugene89us]

va121mir please correct me if I am wrong and I apologize in advance for my arrogance - S&S kit comes with 2 "nipples" compared to your kit - is that because of the twin rail system, as you said, on those engines? My understanding is that normally fuel is delivered to the main (lower) part of the pump first, then distributes to metering valve (that leads to injectors) and also to return line out of the same area. This kit allows the fuel to be delivered to the metering valve directly (clean fuel), while blocking the connection from the main part to the injectors. How does this plate route fuel to the main part that is prone to failure? I would imagine you'd have to create a second pathway from fuel supply through the old entry point of fuel? Or does this plate change the fuel flow properties so it receives fuel from metering valve instead of the old direction? If so, does the previous entry point for fuel get blocked? What part of this kit ends up blocking the current main-to-injectors path? And lastly, is there any modification to fuel lines? I think S&& kit requires lines to be cut and spliced with their braided hose. I appreciate your explanations, and I am really excited to be one of your customers once it is ready to market.

[va121mir]

eugene89us

The way the CP4.2 is setup requires the other nipple. On my design the nipple blocks off the port to the metering valve from the inside of the pump. Fuel is supplied to the inside of the pump thru port B. Fuel to the metering valve is supplied thru port C. Port A remains the outlet port of the pump.

Cutting stock lines with this design is not required. I connected ports B and C via a tee to the fuel supply from the tank (originally attached to port B in stock configuration).

For the filter connections, the line from port A goes to a multi tee. I plan on running a line to the filter from that tee and back to the return line to the tank.

Once I get some more time ill post another pick with the lines in place on the pump out of the vehicle.

[eugene89us]

You did fantastic work, va121mir, this is well thought out. Does your kit use any gaskets or o-rings like the one for S&S 4.2? And I assume it is aluminum, same as the body of the pump?

I look forward to hearing from you once this setup is done. I am approaching 40K miles, so hope to get this in place before I reach out of warranty status to protect my investment. Unfortunately, my MY2018 is not included in warranty extension, so I fear all repairs will be on me if HPFP grenades and I am over 50K miles. Would also like to test fitment on 2014 Passat and 2017 X5 35d. As you can see, we are a diesel family here in deep South.

[FaRKle!]

Originally Posted by eugene89us

You did fantastic work, va121mir, this is well thought out. Does your kit use any gaskets or o-rings like the one for S&S 4.2? And I assume it is aluminum, same as the body of the pump?

I look forward to hearing from you once this setup is done. I am approaching 40K miles, so hope to get this in place before I reach out of warranty status to protect my investment. Unfortunately, my MY2018 is not included in warranty extension, so I fear all repairs will be on me if HPFP grenades and I am over 50K miles. Would also like to test fitment on 2014 Passat and 2017 X5 35d. As you can see, we are a diesel family here in deep South.

MY2018 should have a more updated pump design with more durable coatings on the internals and larger diameter roller.

[eugene89us]

@FaRKle!, do you still think these updated pumps can implode if circumstances are right? I haven't heard of failures for updated versions, but I still worry since I get my diesel at Kroger (instead of truck stops where diesel is $0.40 more per Gal), I may be unlucky one day to get old or contaminated fuel that can still ruin the pump. Of course, I would also hate to modify the pump resulting in its demise, but it doesn't seem this bypass would have any negative consequences since it just provides external routing vs internal channel. Am I thinking right about this?

[FaRKle!]

Originally Posted by eugene89us

@FaRKle!, do you still think these updated pumps can implode if circumstances are right? I haven't heard of failures for updated versions, but I still worry since I get my diesel at Kroger (instead of truck stops where diesel is $0.40 more per Gal), I may be unlucky one day to get old or contaminated fuel that can still ruin the pump. Of course, I would also hate to modify the pump resulting in its demise, but it doesn't seem this bypass would have any negative consequences since it just provides external routing vs internal channel. Am I thinking right about this?

Nothing here decreasing chances of pump failure. This "disaster prevention plate" doesn't protect the pump. What they're supposed to protect are the components downstream of the pump. With this plate you'd still need to replace all the upstream components (fuel tank, lines leading to HPFP) if your pump spewed metal, that's why va121mir was talking of trying to fit a filter on the return line.

It'll take preventative habits (filling up from high diesel turnover stations) to prevent contamination. I'm not sure if it's the same for you, but at least around me there are lots of high turnover stations that aren't necessarily truck stops (and they also tend to be the cheapest too).

[eugene89us]

Yes, that is what I figured. It seems to be cheaper and easier to flush the tank and return lines than having to replace every single injector should the metal contaminate everything downstream. As you said, with updated pump, the hope is that it will not self destruct, but if fuel contamination is the culprit and I end up getting stung by it, then at least I can save thousands by only needing to replace simple lines and flush the tank instead of dealing with fuel injectors, which will cost an arm and a leg to replace. But even if shrapnel were to reach the tank and pump miraculously were to continue to operate for a short time, hopefully the filter will catch all the contaminants before they can make another attempt at damaging fuel injection system. I do hope the return line filter becomes a success, so HPFP failure will only lead to replacement of a pump ($600-1000) instead of any other components ($10K). What am worried about is that the updated pump that may not prematurely fail (if I succeed at avoiding bad fuel and these pump improvements do translate into better longevity), would these fail-safe modifications increase the risk of failure themselves? For instance, if bypass valve were to be more or less restrictive to fuel, leading to some other method of failure or if the new filter kit somehow increases return pressure that leads to failure of low pressure pump or other component. That is the conundrum. The pre-LCI pumps tended to be more likely to implode with bad fuel (community is still at crossroads as to the culprit) and will certainly benefit, but if post LCI pumps are proven to be "bulletproof" (up to a certain reasonable throw-the-car-away mileage), would the risk of installing an item that is not as widely tested result in other related or unrelated component failure due to simply physical modifications? The bypass plate seems to closely mirror existing passageways, so hopefully not much added or reduced restrictions compared to stock - just different area of fuel intake; now the filter will undoubtedly result in some increase in back pressure. Would that be negligible or result in worse outcomes, I reckon my guess is as good as yours. Risk vs. benefit is unclear given unclear success of Bosch pump update post LCI. With lower reported HPFP failures on post LCI models, I am inclined to say extra fail safe is probably not cost effective, but that is a pure guess. I reckon fear, reasonable or not, is leading my decision making.

[va121mir]

eugene89us
Yes, my kit uses o-rings in the same exact locations as the metering valve...since it mounts where the metering valve goes. You would not be modifying the pump at all. This kit is completely removable.

The filter part of the kit is just waiting on a simple part to be manufactured.

I dont forsee any risk associated with adding this kit. It does not restrict flow to the pump body. Additionally it allows for a larger volume of fuel to be directed directly to the metering valve.

As far as the LCI upgrades...I am not sure if this kit will fit. I have not looked at the pump form factor.

[heynow328D]

FaRKle!, I'm in your area, I-580/680. What stations do you recommend?

[va121mir]

Update

I finally had some time to work the return fuel filter setup. Here is what I came up with.

The filter is a Canton Racing 1 micron fuel filter assembly (part 25-911B). I used Canton's mounting bracket but had to modify it to accommodate a larger diameter clamp. Here is the parts list:

Filter: Canton 25-911B
Mount: 26-891B
Adapters: 6400-06-12 from hydraulics direct
90 deg fittings: 759166ERL
Hose: 3/8 fuel line
Union: 3/8 to 3/8 straight barb....I would suggest using the next size up

[eugene89us]

Man, va121mir , this looks really great! High end. That filter looks similar design (albeit smaller) as the OEM filters on TDI VWs. Any data to suggest restricted flow or higher amp draw on low pressure fuel pump?

What part of Texas are you at? We may be going by Austin sometime soon via Dallas or Houston, if you're not far from those places we could stop by to test fit on LCI pump.