Petrol in ur diesel - mythbusters time!

Did I just get lied too?

This little old Cornish farmer just told me I could put a little petrol in my diesel to clean it out?

My td5 has started smoking and he just grabbed me and I quote said "you wanna be putting some petrol in there you do"

So does the statement carry any weight Or is he talking waffle? He gave a convincing argument about the petrol cleaning the injectors and the like!

Thanks Matt

i have heard that before, but i would prob just use injector cleaner,

A few months ago when i was on the forecourt in my 2.5 D transit there i was putting petrol in it when i thought sh.. !!!!! about 6 or 7 lts poss more .. of petrol had gone into the tank,so then i added some diesel .What do i do now then i thought s or bust and drove off,My transit van ran the best it has ever gone lol.

depends how much the ratio is too much can harm

Putting a little petrol in a diesel is something that used to be done long ago to stop the diesel waxing in winter.This doesn't happen with modern fuel.Diesel engines rely on the fuel to lubricate the system,while petrol effectively does the opposite,meaning possible trouble for pipes and seals too.Less than 10% petrol put in can just be topped up with diesel and run through generally without a flush.

Firstly, what colour is the smoke, and it is at startup or all the time?

Blue - oil in combustion (bad)
White at startup - unburnt diesel, should stop soon (not a problem)
White continuous - water in combustion (bad)
Black - Injector issues or overfuelling (potentially bad)


Rather put in some 2-stroke oil. It will clean any carbon deposits and lubricate the pump at the same time. Petrol will remove any built-up lubricity.

You can also run your truck with 2SO at 1:200 ratio on a permanent basis to prevent carbon build-up and premature injector/pump failure.

jamesmartin said:

depends how much the ratio is too much can harm

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Especially if you do it to bosch common rail pumps-I have one in a box to send back that appears to have suffered that fate

When it starts it kicks out a little black smoke, then every time I put my foot down it belches out for a couple of seconds and then it's fine.

I'm going to do the EGR removal and was considering putting petrol in the engine aswell to clean it through.

Have just bought some redex - fuel system cleaner I'm going to dump that in when I next fill up.

Thanks for the replys thus far.

Matt

fanatic said:

Especially if you do it to bosch common rail pumps-I have one in a box to send back that appears to have suffered that fate

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Some people say that you can run it on 2SO alone, since it's a light oil *shrug*

I run my Puma and A3 2.0 TDi (pump duse) on 2SO at 1:200, if anything they run much better than other similar vehicles I've driven.

Also, quality of diesel in SA is quite poor (50ppm), so if you have good diesel probably not an issue.

BIG_GINGA_BEARD said:

When it starts it kicks out a little black smoke, then every time I put my foot down it belches out for a couple of seconds and then it's fine. I'm going to do the EGR removal and was considering putting petrol in the engine aswell to clean it through. Have just bought some redex - fuel system cleaner I'm going to dump that in when I next fill up.

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That sounds quite normal. EGR and cat should be removed from any TD as soon as it is out of warranty. RedEx is a good product, let us know how it turns out.

No, he wasn't lying to you! It is an old lorry drivers' trick from many moons ago that helped prevent mould forming on trucks whilst stood up. So farmers also adopted it for their combines and so forth.

You can run a diesel engine at a maximum of 20% contamination without doing any damage - what it will do, is clean the system!

So by adding a quid or two to a full tank, you can clean the system right through.

northstar555 said:

Putting a little petrol in a diesel is something that used to be done long ago to stop the diesel waxing in winter.This doesn't happen with modern fuel.Diesel engines rely on the fuel to lubricate the system,while petrol effectively does the opposite,meaning possible trouble for pipes and seals too.Less than 10% petrol put in can just be topped up with diesel and run through generally without a flush.

Click to expand...

auto said:

No, he wasn't lying to you! It is an old lorry drivers' trick from many moons ago that helped prevent mould forming on trucks whilst stood up. So farmers also adopted it for their combines and so forth.

You can run a diesel engine at a maximum of 20% contamination without doing any damage - what it will do, is clean the system!

So by adding a quid or two to a full tank, you can clean the system right through.

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Thought I just said that!

So having just got a mate to drive behind me and video this black smoke issue. It appears to be just when the turbo kicks in!

I hope my turbo isn't shot to ****!

Filling up in the morning for the long drive back to brum(from penzance) so I'll add that redex stuff and I'm driving to wales on the Sunday so I imagine I'll have to fill up sometime then aswell so will try the petrol in the tank thing if the redex docent make a difference.

Matt

are you sure its only just started doing it as it is normal for turbo diesels to do this as it takjes time for build up of air pressure from turbo to reach valves whereas increased diesel is already there giving puffs of black smoke when accelerating,the bigger the intercooler the greater this is ,faulty egr gives dirty smoke

Ok, so there has always been a little smoke but it seems to have got worse although I haven't been aware of it until a mate told me. And now I'm watching it all the time.

The fender has had an ECU upgrade and does have a massive intercooler in front of the rad.

I have recently fitted my winch in front of the intercooler and I'd say a good 40-50% of it Is now covered. Would this have a bearing?

Matt

i think your mate has got you worried as with ecu upgrade your fueling will be higher (but maybe more effecient) and air will take a longer time with bigger intercooler as it has to be filled with pressure before any gets to engine ,bigger cooler longer lag ,any ineffecienties will show up with black smoke while crusing watch other cars when overtaking

I like my carbon deposits as it seals the slight wear in the engine that can be expected with an older diesel engine. Maybe thats an old wives tale?..... sure, a dose of redex twice a year does no harm. Last winter my diesel started freezing and as per advice on here added petrol and instantly sorted it.

funny cos running on wvo cleans out the system to, mind you I just added some white spirirt to the last fill up, goes like a train now

Have you checked the MAF??

MrJC said:

Last winter my diesel started freezing and as per advice on here added petrol and instantly sorted it.

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I did that as well, I think I put 3 litres in a full tank and my 300tdi started on the button every time afterwards. Seemed to run a bit better as well, but that could be my imagination, either way certainly didn't do any harm

I would not recommend running a TD5 with any amount of petrol but a small amount you should be able to get away with as a one off.
That said DO NOT PUT ANY PETROL IN A DIESEL COMMON RAIL SYSTEM it will damage the high pressure pump because it requires the diesel to lubricate it whilst petrol has the opposite effect and washes any lubrication away.
As the rotors in the pump become damaged tiny amounts of swarf start being sent around the complete fuel system and causing lots of damage in the process.