Diesel problems in cold weather

ULMarc

It's lovely and mild right now, so I feel it's a good time to ask...

In cold weather our diesel car has problems with fuel flow. There are 2 things I know from experience are guaranteed to fix it:

• Changing the fuel filter.
• STP fuel system cleaner.

Both have had good results in our case. We've changed the fuel filter twice, and we've tried the STP cleaner twice also. But they've both been done under panicked circumstances, where we've just wanted to get the car in reliable order again. Part of me wonders if committing to an Italian tune-up would have sorted it out.

So my question for those who know about this is, what do you do when you get power problems, waxing, gelling etc?

• My mechanic suggested adding a bit of petrol to the tank, same effect as the fuel system cleaner. And I've heard since that this a common solution with farm machinery, construction machinery etc.
• Diptane. WTF is Diptane? Is it just an emissions test cheat code? Or does it treat the fuel system similarly? It would be a quarter the cost of the STP product.

Hellrazer

Seems a bit strange - Ive never seen cold weather affect "fuel flow" here in Ireland - it doesnt get cold enough - our diesel is rated for -15 centigrade - friend of mine worked in Volvo in Sweden sent me pictures years ago of a waxed up fuel filter and its very obvious - looks lie a candle!!!

. Have you actually seen the waxing on the fuel filter? Have you taken a sample of the fuel out - look for crystals in it.

If you can confirm it is waxing Id probably add some kerosene rather than petrol as kero will lower the freezing temperature further and still give a bit of protection to the fuel lines.

ULMarc

Oh, I thought it might not be a very visible thing, clogging the pores of the filter material. I'll cut open the filter next time, if there is a next time.

10-10-20

Dipetane is a fuel lubricant, not much else. Claims on the website do claim that it cleans the soot and deposits off the innards of the engine. I use it on every second tank on a PUG 508 diesel, but I've never heard of diesel waxing in Ireland either. Chuck in some dipetane (200:1) for January and see what happens on some of the colder mornings, but I'm not convinced that you have much more than a weak-ish battery or glowplug.

tabby aspreme

There was some issues with diesel waxing during the prolonged cold spell in 2010, and that was with tractors and machinery which have diesel tanks and filters exposed to the weather, but haven't heard of it since

Hellrazer

https://www.boards.ie/discussion/comment/121543107#Comment_121543107

Couldnt really see dipethane making a difference if the fuel is waxing - its really only a cleaner.

To stop waxing you need to lower the temperature at which the diesel waxes at or make it thinner which kero or petrol would be better at in my opinion.

Hellrazer

Personally I think theres something else going on. Whats the symptoms? Hard to start? Lack of power?

What car is it?

10-10-20

https://www.boards.ie/discussion/comment/121543258#Comment_121543258

Well, that's what I'm saying - it does not prevent waxing (if that's what's happening in our mild climate) but I have seen it improve overall engine operation. Plus it got my old Alfa through a number of emissions tests which were clear failures without it.

Hellrazer

https://www.boards.ie/discussion/comment/121543291#Comment_121543291

Im with you all the way - Id an old FTO that I could not get to pass an NCT - failed multiple times but very borderline.

2 litres dipethane in half a tank and it passed every time. Theres a place for dipethane but just not sure if it would help the OP.

ULMarc

https://www.boards.ie/discussion/comment/121543262#Comment_121543262

It's an IX35. It can exhibit sudden loss of power while driving in cold conditions. It'll continue to worsen and has to eventually be willed home. It's happened 3 times over the course of a number of years. The first time I replaced the fuel filter myself. 2 years later was the second instance and we brought it to our local mechanic and he replaced the fuel filter on his recommendation. This is when he also gave advice to put petrol in the tank. He commented it's a common problem from his point of view.

A year later, it happened again. Just a few weeks ago during the cold snap. I treated the tank with the STP stuff I mentioned and it appeared to resolve.

I agree with the sentiment I shouldn't jump to conclusions. And that's why I've asked here.

I'm not majorly fussed about it, just looking for others' experiences. I was hoping to hear more similar anecdotes. Just so I can have some preemptive advice on hand.

ULMarc

I've always addressed it at the times it happened. So I've no info on whether it can resolve itself unfortunately. I've tried driving a bit heavier footed to get more heat into the system of course, but that had seemed to provoke it further.

Diptane in every odd tank would seem a more economical option than the STP treatment of course. But I've a fear of it being a placebo.

POBox19

I put petrol into the tank accidentally in January a few years ago, 3 or 4 liters before I noticed. I finished the fill with diesel. The car, 07 Mondeo 2D, ran noticeably better for another couple of fills afterwards. A liter of petrol is a lot cheaper than Dipetane.

Kerosene and Green Diesel are marked oils and if you had your tank dipped by Revenue/Customs it could show up in their chemical test and that might be expensive.

bazz26

Do not put petrol in a modern diesel car or you maybe forking out for a new fuel injector system.

jmreire

https://www.boards.ie/discussion/comment/121543454#Comment_121543454

In a 2003 Audi A6 1.9 Tdi I once had, I'd add about 400 ML of 2T to each full tank, and never had a bother with it after that. Previously, it had a habit of going into Limp Mode occasionally, but it cured that completely. This is more a cleaner than a prevention of diesel fuel gelling. But in the Balkans where I was for quite a while, the temps could and often did drop down to the - 15 to -20's. We added kerosene to 240Ltr drums in a heated room (the diesel had to be warm to accept the kerosene) 20% Kero to 80% diesel and filled the trucks next morning before the trip. And during the trip, if we were delayed, it was common practice to light a small fire under the tank while it was parked, to make sure that it would get you home in the evening. Of course, it was also inevitable that some of the plastic fittings on the tank would get damaged, but one way or another, we managed to do it OK.

tabby aspreme

OP are you using genuine fuel filters, some cars are fussy about fuel filters and need genuine filters to run correctly

Del2005

https://www.boards.ie/discussion/comment/121544064#Comment_121544064

How much fuel is in the tank when this happens? Have you had the tank checked for water or other debris?

UrbanFret

https://www.boards.ie/discussion/comment/121544295#Comment_121544295

By modern what exactly do you mean? theres a lot of scaremongering around this issue.

ULMarc

https://www.boards.ie/discussion/comment/121544423#Comment_121544423

Yes. It is genuinely a fuel filter.

Hellrazer

https://www.boards.ie/discussion/comment/121544064#Comment_121544064

Forget about the cold issue - I feel you are getting hung up on that - I think that whats happening is that you are just at your fuel filter intervals - 3 times over what - 3 years?

Fuel filter on the IX35 is due every 60000 kms but they never last that long - usually between 30-40k - Lack of power is the number one symptom.

I cut my teeth on these so know a good bit about that 1.7 diesel engine. It could also be the fuel pump on its way out - very common on them.

Check and see if your oil level is increasing - shows that the seal in the pump is gone and will mean fuel filter needs changing more often as its contaminated with oil

jmreire

https://www.boards.ie/discussion/comment/121544519#Comment_121544519

For water in the fuel, there's a specific test paste that can be smeared on a piece of stiff electrical cable and dipped into the tank, (Water will always sink to the bottom of the tank) and it will show on the test paste. Most motor factors will have it in stock. " Water Miscible Paste" I think it's called.

monkeybutter

https://www.boards.ie/discussion/comment/121544532#Comment_121544532

A litre or 2 in a 60 liter tank, a full tank of petrol no

The dilution means no damage but it also means it's pointless doing it in the first place

ULMarc

https://www.boards.ie/discussion/comment/121546038#Comment_121546038

Ah. We don't do that amount of distance on it. But the comment from my mechanic had been that it could be an annual replacement. Which, to be honest, I had not believed totally given it's a step less accessible than the oil filter. Thanks for the comment. I'll keep that in mind to check

Spook_ie

Just as a side thought, does washed diesel still have the same freezing temperature etc. or does the washing remove some of the additives beside the dye?

10-10-20

https://www.boards.ie/discussion/comment/121550613#Comment_121550613

It all depends on how the process was carried out as washing diesel using bentonite clay mainly picks up the colouring agent rather than the active ingredients as they are polar substances, but the more bentonite added the more active ingredients are pulled from the diesel.

Well documented here:

https://www.researchgate.net/publication/340087211_Purification_of_Biodiesel_from_Waste_Cooking_Oil_Using_Bentonite_as_Dry_Washing_Agent