[vigsom]

Summary

A Logan 1.5 DLX that I was travelling in refused to start after a brief stop. The issue that came up was rather strange, but we managed to fix it and were on our way in 2 hours. Read on..

Why the trip?

Four of us were headed to attend a wedding in Erode, and we decided to do the quick day trip in a family friend's car - a 2009 Logan 1.5 DLX that had done 1,60,000km.

We've used this car on 2 trips earlier and found it very reliable and comfortable. However, what we were going to see was reliability going down the drain due to a simple design issue, that almost left us stranded.

A morning well spent

We reached the wedding venue in Erode at approx 9:20am and what impressed me was the acres of space that this venue had to offer - the hall was big, the dining area bigger, and the parking, too big and open for an old set up.

After being part of the festivities associated with the wedding, a sumptuous banana leaf spread, and Jeera Panneer soda as the cooler, we left Erode at approx 1:45pm for Karur.

The Panneer Soda point closing down at 1:30pm


Wedding Venue - pictures of the parking area






We reached the outskirts of Karur at 3pm, met up with a relative briefly, and were ready to leave after a cup of coffee.

Logan wouldn't start

At approx 3:45pm, we got into the car, the friend (owner of the car) fired the car up, and just as he was going to slot the car into gear, the engine stopped, and would crank but not fire thereafter.

He opened the hood, but there was no apparent defect. However, as the primer bulb was pressed, something was seen dripping from under the right front - it was diesel. Stop pressing the bulb and the dripping would stop. When I looked under the front, I could see a black thingy with 2 probes connected to a coupler, and figured out that this was something that had come off the fuel filter. I tried fixing it back but to no avail.

Fuel water detector sensor threaded portion broken


I then got two woven sacks to lie down on, and inspected the front underside, and that is when I discovered that this sensor had actually broken off from its threading and was dangling - what a ridiculous design, where a plastic part was installed at the bottom of a filter, without designers thinking of what would happen if this failed !!

View of the fuel filter from beneath


Diesel dripping from the filter - you can hear the friend speaking in the attached video. He was trying to suggest cutting out a portion of a pencil eraser and pluging it into the leaky bottom

https://youtu.be/L_7H7A36Hk4

The Fuel System

Typically, in a diesel car, the line up is as follows:

Fuel pump in tank -> Fuel primer bulb (eg.Renault) OR Hand pump (most other diesels) -> Fuel Filter -> HP pump -> Rail -> Injectors

In a diesel car, a leak anywhere from the fuel pump to the injectors can cause loss of prime (air in the system). The engine would not fire since the HP pump would not develop the required pressure. Yes, leaks in the high pressure pump and discharge are quite unlikely since this has metallic pipes and pipe joints. Leak prone areas are rubber and plastic parts.

Solutioning

I then evaluated some ways to get out of this issue so that the car could be started up and we could be on our way. The following options were considered:

1. Tapered rubber plug to just plug the opening at the bottom of the filter - rejected it because it wouldn't stay put and the slightest vibration and the plug would fall off

2. Rubber cap to cover the entire surface where the sensor would be mounted on the filter - thought of some rubber cap but knew that would also come off

3. M-Seal to cover the same surface as in point no.2 above, but here the challenge was to ensure a perfectly dry surface so that m-seal could set properly in 30 minutes or so

3. Replace the fuel filter and sensor - that would require a technician plus we were not sure if the parts were readily available

Solution implementation

Just as we were evaluating options, a technician who was called in by someone closeby appeared in 15 minutes. I explained the issue to him and he said M-Seal would definitely work provided the surface was dry. Some M-Seal was available close by, and so that was procured. Meanwhile, the technician went to check if the sensor was available. I knew this was a small town and so the chances of the part being available for the Logan were next to Nil.

Diesel, in the meanwhile had stopped dripping, indicating that the filter was totally empty. The M-Seal mix was prepared and applied after ensuring that no diesel residue remained on the filter bottom. The mix was allowed to set for 45 minutes.

The technician arrived and, as expected, drew a blank and said that the sensor wasn't available anywhere. However, he inspected the M-Seal applied and said that it had set and would work for sure. He then just actuated the primer bulb and asked my friend to start the car. It fired up without fuss, and we were now sure of getting back home. The sedimenter warning light was on on the dashboard as the sensor had been de-coupled but that was expected. We got back home safe, although 2.5 hours late.

Leak fixed with M-Seal - note that the sensor is now decoupled


Good Samaritan technician

The technician, Kumar, was an angel - the type that we don't see these days; young bloke maybe in his late-20s, and just asked for a nominal service charge of 200 bucks since he had to come from his garage which was 4 kms away. Had he not confirmed that M-Seal would work, I might not have tried that solution.

Next Steps

A new fuel filter with sensor has been ordered, and will hopefully ensure trouble free performance for many years. The only way to prevent this issue from recurring is to modify the filter design to prevent this sensor from being a bottom fit.

LFI (Learning From this Incident)

1. All owners of the Duster, Scala, Sunny, Logan, Verito, Pulse, Micra diesels - beware of this sensor. It pays to keep a spare filter-cum-sensor combo handy. I also see some filters with just a drain cock beneath- not sure on which models this applies.

2. Ensure that you inspect the fuel system througly before setting out of town - you never know what can surprise you

3. Keep some adhesive, and M-seal handy

Fuel filter and sensor drawing on the parts catalog


The Water detector sensor - infamous now


The fuel filter-cum-sensor combo (OE Part No.6001552226)


Fuel filter with only a drain cock

[GTO]

Thread moved from the Assembly Line to Tech Stuff. Thanks for sharing!

[yesyeswe]

My friend has an 8 year old duster which he bought used, will share this information with him, thank you for sharing

[DRIV3R]

This is more of a case of the sensor plastic going brittle after multiple heat cool cycles, rather than poor design.

Water sensors in fuel filters are always at the bottom since water is denser and settles down. That's how it is in most cars.

[carthick1000]

Thanks for sharing.

Was it not possible to insert the probes into the same holes where it broke from the plastic thread?

If that would have been possible, you shall have Msealed the whole sensor in place after diesel drip stopped. In that way, the fix is a bit longer usable until you get the sensor and/or pump replaced with another part and a working LP fuel sensor.

[rupdeb]

Originally Posted by vigsom

Summary

A Logan 1.5 DLX that I was travelling in refused to start after a brief stop. The issue that came up was rather strange, but we managed to fix it and were on our way in 2 hours. Read on..

Hi,

Glad that the technician was able to sort it out quickly and you people could continue your journey. Just a thought, had the fuel filter and the sensor not been replaced for a long time which could have led to this situation?

Also can you please confirm if the original filter fitted is from Delphi and has a part number R6353490? If yes, then the following post might help you.

Originally Posted by rupdeb

The side-by-side comparison of the filters.

Attachment 1797339

[vigsom]

Originally Posted by DRIV3R

This is more of a case of the sensor plastic going brittle after multiple heat cool cycles,

Rightly said, @DRIV3R. It is actually a case of the sensor plastic going brittle on contact with diesel, and a case of the filter and sensor not being replaced for long. However, If I were the person designing the filter- sensor set up, I'd have done a DFMEA and realized that the severity of this failure mode was, indeed, high.

Originally Posted by carthick1000

Was it not possible to insert the probes into the same holes where it broke from the plastic thread?you shall have Msealed the whole sensor in place

Good thought, @carthik1000, and I tried exactly that. The probes did go into the holes but M-sealing the whole thing was not possible since the sensor is quite big. I wish these manufacturers had provided a filter arrangement like what is seen in the older Innova/ Fortuner. I would think that a failure and detachment of the water sensor in this kind of set up is unlikely.

Originally Posted by rupdeb

had the fuel filter and the sensor not been replaced for a long time which could have led to this situation? can you please confirm if the original filter fitted is from Delphi and has a part number R6353490?

Thank You @rupdeb. Yes, this filter - sensor combo hadn't been replaced for at least a year / 30,000km. The sensor failed only due to ageing and contact with fuel. Yes, the part number R6353490 does match, and I also saw the Nissan Sunny thread in which the replacement interval of this filter is indicated at 10k kms / 6 months for India, which is very frequent, in my opinion.

[TrackDay]

This is one of the reasons I follow Team-Bhp. In this scenario, you were able to find, diagnose & fix the issue. Had this happened to someone who didn't know about cars, this would be a good chance for the service center folks to fleece an unsuspecting customer.

Also in areas outside service coverage and when no help is nearby, posts like this can help folks to at least drive to the nearest service center using temporary solutions. This is also helpful in knowing what parts need to be changed at certain life of the vehicle.

[pugram]

Glad that you guys were able to arrive at a solution and carry on. Reminder that being nearby and hands-on when car is being worked upon is very very valuable.

I had a Logan DLE with me for 12 years. This car had run around 1.8lakh kms.

I don't remember having changed this sensor. Neither the service station nor FNG had suggested replacement of this sensor on a periodic basis.