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-   -   Engine Decarbonising - Demystified (https://www.team-bhp.com/forum/technical-stuff/133710-engine-decarbonising-demystified-2.html)

Great article once again SST !

I think, rather than using such products, subjecting the engine to "controlled knock" would work better. Knock will remove the carbon deposits which will eventually come out through the exhaust and oil sludge. However doing this ourselves on a modern engine is difficult. Just a thought.

Spike

What is Controlled knock,any insight?

Akshay, by connecting calibration tool with the ECU, one can vary engine parameters so that it knocks. During calibration, developers ensure that engine does not knock in 99 % of its operating range. This is just the opposite.

Spike

In the initial days, the M&M dealers used to con me into doing the "engine flushing" which cost a bomb, but I learnt soon enough to turn them down.

I used premium diesels once upon a time, then switched over to using System D fuel additives.

For almost 1 year, I stopped using both & the fuel pump started developing leaks - which were pronounced as being leakages through the 'O' Ring - many told me the days of my fuel pump were doomed. But this was some 150,000 kms ago! Even as I was suffering the leakages, the engine started having power loss at high rpm. I decided to have an engine flushing done again after a very long time. It worked. The engine felt lighter, more powerful & the power "hiccups" also disappeared. And surprise surprise, the leak in the fuel pump area totally disappeared.

Nowadays, I regularly (1 of every 3 fuel refilling) add System D fuel additive. The engine feels better , the leaks & power losses have gone & the Scorpio returns good FE too. I have never cleaned the injectors - the engine is now 338,000 kms old.

As SS-T says, perhaps it is good to use it occasionally, but measure the impact before continuing its use.

SS-T, do fuel additives like System D/ STP do the same function as the flushing chemicals?

A superb article SS-T! Rated it five stars! Having gone through this circus of engine decarb on both the petrol zen and diesel swift, i can confidently state that the advantages are very minuscule compared to the cost. Regular oil change, clean fuel and air filters give much more life to an engine than these decarb methods. Once in a while doing some high RPM also does clear up the exhaust side of the engine.

As far as injector cleaners goes, i have had mixed feedbacks. System G used to work well with my iKON 1.6, but G made the Swift D gruff. 3M fuel additive works well for Swift, but till it remains in the tanks, so after a fill or two everything is back to the way it was. The MUL dealers use some petrol to clean the injectors these days, this seems to give some minor rejuvenation to the cylinders, but i wont completely rule out placebo effect after a service for this feeling :)

That's right, dhawcash, what an engine flush does in 15 minutes (removing sludge), a new engine oil does in 1000 km. Leave that engine oil in for another 14,000 km, and the sludge it dissolved out will be deposited right back, along with some interest.

No, I don't recommend engine oil changes at 1000 km - but I prefer oil changes earlier than recommended, just because it prevents sludge build-up.
Engine flush would not reach anywhere near where your fuel pump was leaking diesel. I would think a decarb job might have fixed it.
System-D/STP and other additives which are mixed into the fuel tank, have a similar effect to decarbonising, at a much lower scale - but do not have any effect related to what an engine flush does.

Many authorized service stations recommend and insist for engine flushing along with oil changes even during the free services (meaning at very low mileages). These flushing oils cost more than double of the engine oil price. Needless to mention that sales commissions are much higher for these products and the dealers thrust these on unsuspecting customers. The best method is to change engine oil at less than recommended intervals. Even using a ltr of the same engine oils would suffice if needed.
A thread is needed on "How to deal with service centers" pretty soon to put a stop to such antics by them.

Excellent article. We really need more article on the maintenance side which is where now the money making has turned to. Before reading T-BHP, I had been fleeced by Maruti twice for de-carbonizing and engine flushing many times on my 56k kms run petrol Baleno. After being aware from T-BHP, I denied a de-carbonizing at 30000 kms for the Hyundai i10.

But one doubt I have - I had worked on many 2 stroke petrol engine de-carbonizing the mechanical way. No, not the motorcycle one, but the chain-saw one. Most of the time, the carbon deposit was difficult to remove; had to scrape it hard using a screw-driver. So my doubt is whether any chemicals can actually dislodge it or even the hard running or even controlled knocking. The harder engines to de-carbonize were the ones that were poorly maintained - externally; so I guess the oil mixing were also poorly supervised for those engines.

Great article ! Most dealers try convince the car owner that doing engine decarb every 20k km is a great boon whereas there is hardly any requirement or benefit even after 100k km. It's more or less another scam. Many Hyundai A.S.S. push customers to decarb at 20k or 40k.

My Lancer has done 108k km with no decarb done on it and seems to be in fine fettle. Thankfully, HM Mitsubishi A.S.S. never recommend it. They did recommend a mild flushing agent Bardahl which is much cheaper and better alternative done every 30k or 40k km.
Using synthetic engine oil and timely servicing takes care of almost everything though. I changed my car's engine oil to synthetic post 70k km, and am most happy with the results.

This implies and contradicts what latest gen car manufacturers say, fill up normal fuel and not the premium one with fuel additives, as the vehicle which did 800k + km in the above mentioned blog had only premium fuel and fuel system cleaners added to the fuel every 10k miles. Conspiracy theory can be that if vehicles start running this far miles without engine and wear and tear issues, there will be fewer car sales, so obviously they want us not to do things which will save the vehicle for longer miles.

Dont do the engine flush , if you are changing engine oil at 5000 kms interval . These engine flush when are poured in the engine , some amount gets left which make the fresh oil thinner . Changing oil at 5000 km interval is the best to keep the engine healthy and clean , this interval is for mineral oil . :D

Correct. I would say that on a modern car which has had regular oil and oil filter changes this would be a complete waste of time.
I doubt very much if knock would remove carbon deposits. Knock is just poor ignition really (too early). I've opened up a few engines that had mechanical problems due to knock (e.g. hole in the piston) and they all had surprising amounts of carbon built up. I think the effect of poor ignition (e.g. knock) brings more built up of carbon deposits than the theoretical effect of knocking removing carbon built up. Bear in mind that the mechanical effect of knocking tends to be very localized in one or two spots in the cylinder/piston/head surroundings. Hence the mechanical damage in a particular spot.

Jeroen

Note from the Team-BHP Support: Please use the EDIT or MULTI-QUOTE buttons instead of typing one post after another on the same thread.

Thanks for the wonderful article SST! 5 stars again!
I always had a question in mind as to these detergents like system-G and the works. If they don't really work, why are people insisting on it?
Secondly, As far as i am concerned, i really don't pour stuff into a vehicle if it doesn't belong there. Premium diesel, system-d are off my lists for ever.
I just know for a fact that timely oil changes and some precautions that we, as drivers, take will prolong the life of the engine and she will purr as happily as a kitty who has had her fill.

OT: could anyone suggest at what interval should i switch to synthetic oil on ford figo tdci?

Engine decarbonizing, engine flush, fuel additives, are the big money spinners for dealerships (maruti ones particularly) in NCR region atleast. Every service they create a job card, by default they add these items unless you specifically ask them to remove em. Service costs for my maruti vehicles(old zen, swift P) invariably crossed those of my honda city or fiat punto, untill i personally made it a point to remove these unnecessary items. So much for cheap maruti service. I mean maruti's are cheaper to buy initially but their service suck big time, they make up all the money lost in selling business in servicing. Atleast this is what i feel for the service centres here in NCR, dunno abt others regions.:OT Another practise of not allowing customers inside service bays is also a big money spinner. You would never know whether what you were chrged for, did actually went inside your car. Sorry for deviating from topic but it is really a big issue here in NCR.

Thanks! Very enlightening article.

On the same note, how about decarbonising for bikes? Is that also not necessary? At about 40k kms mark the service centers recommend a decarb process and the amount is non-trivial as well.