Automotive

Engine carbon cleaning

  • Last Updated:
  • Dec 16th, 2019 4:26 pm
[OP]
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Sep 5, 2010
2324 posts
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Toronto

Engine carbon cleaning

I have a 2013 Mazda CX-5 with close to 240K on it.

In early 2017, I was having a lot of power and acceleration issues, and took it to different mechanics and each suggested something different. Finally took it to the Mazda dealership and they said the engine needed to be decarbonized. I didn’t know much about this before this and I just trusted them with it. Cost me close to $1K and was without a car for over a day (got free rental). That mostly fixed my issues.

Fast forward to last few months, I am having the exact same issues, and now with mileage too (240K vs about 175K back in 2017) . But since I only plan to keep this car for another year only , I don’t want to take it to a mechanic again for carbon cleaning (assuming that is still the same issue). I researched the issue and apparently this is a common issue with direct injection engines? And this is Skyactiv technology engine which is supposed to be better, more efficient etc. Don’t think so when I have to do this twice in about 6 years.

I did buy those fuel injector cleaners (Gumout) and have been pouring one bottle when I am low on gas and just before I fill up.

Does anyone know if I can pour in 2 or 3 bottles of this at once? And instead of putting it through the gas line, can I pour it directly into the engine just like you change oil?

And other than taking it to a mechanic for decarbonizing, does anyone have any other suggestions for me to look into?
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27 replies
[OP]
Deal Addict
Sep 5, 2010
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Toronto
BTW I did take it a local mechanic a month ago after the engine light stated coming on and he did some testing and while he thinks it is engine carbon, he wanted to do more testing on it just in case it is something else, not to mention carbon cleaning takes time and would cost me money. He didn’t specify how much. I didn’t know this mechanic back in 2017 when I did my first engine carbon cleaning.
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Jul 24, 2014
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Ontario
You could try SeaFoam. However, if there’s that much build up that it’s causing issues, you may need to pay for another cleaning... For your next car, consider one that’s direct and port injected.
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Feb 11, 2007
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Woodbridge905 wrote: I have a 2013 Mazda CX-5 with close to 240K on it.

In early 2017, I was having a lot of power and acceleration issues, and took it to different mechanics and each suggested something different. Finally took it to the Mazda dealership and they said the engine needed to be decarbonized. I didn’t know much about this before this and I just trusted them with it. Cost me close to $1K and was without a car for over a day (got free rental). That mostly fixed my issues.

Fast forward to last few months, I am having the exact same issues, and now with mileage too (240K vs about 175K back in 2017) . But since I only plan to keep this car for another year only , I don’t want to take it to a mechanic again for carbon cleaning (assuming that is still the same issue). I researched the issue and apparently this is a common issue with direct injection engines? And this is Skyactiv technology engine which is supposed to be better, more efficient etc. Don’t think so when I have to do this twice in about 6 years.

I did buy those fuel injector cleaners (Gumout) and have been pouring one bottle when I am low on gas and just before I fill up.

Does anyone know if I can pour in 2 or 3 bottles of this at once? And instead of putting it through the gas line, can I pour it directly into the engine just like you change oil?

And other than taking it to a mechanic for decarbonizing, does anyone have any other suggestions for me to look into?
Woodbridge905 wrote: I have a 2013 Mazda CX-5 with close to 240K on it.

In early 2017, I was having a lot of power and acceleration issues, and took it to different mechanics and each suggested something different. Finally took it to the Mazda dealership and they said the engine needed to be decarbonized. I didn’t know much about this before this and I just trusted them with it. Cost me close to $1K and was without a car for over a day (got free rental). That mostly fixed my issues.

Fast forward to last few months, I am having the exact same issues, and now with mileage too (240K vs about 175K back in 2017) . But since I only plan to keep this car for another year only , I don’t want to take it to a mechanic again for carbon cleaning (assuming that is still the same issue). I researched the issue and apparently this is a common issue with direct injection engines? And this is Skyactiv technology engine which is supposed to be better, more efficient etc. Don’t think so when I have to do this twice in about 6 years.

I did buy those fuel injector cleaners (Gumout) and have been pouring one bottle when I am low on gas and just before I fill up.

Does anyone know if I can pour in 2 or 3 bottles of this at once? And instead of putting it through the gas line, can I pour it directly into the engine just like you change oil?

And other than taking it to a mechanic for decarbonizing, does anyone have any other suggestions for me to look into?
Maybe the dealer didn't do a good job of cleaning the carbon, which could be why it didn't last long. $1k is a bit steep though. I thought Ford dealers were doing it for under $500. (ie, that wasn't a free rental).

Your car may be burning more oil and causing the increased carbon deposits. Are you getting regular oil changes with the correct oil?
Do you do a lot of short drives?
Where do you fill up? Are you using Top Tier premium fuel?

If you just want a temporary cleanup to get you past a year, then you could try a seafoam treatment followed by a Ferrari tuneup. Both can be done DIY.
A Ferrari tuneup is when you just get the engine very hot by running it hard. If your car lets you rev to the redline, then you could just do that while parked. Otherwise you'll need to find an empty area where you accelerate hard, then brake, then repeat for a little while to try and clear things out.

You could also just take it to a shop that specializes in walnut shell carbon cleaning, I'm sure it would be much cheaper than the dealer.
seeparks wrote: You could try SeaFoam. However, if there’s that much build up that it’s causing issues, you may need to pay for another cleaning... For your next car, consider one that’s direct and port injected.
+1
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Aug 12, 2007
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Woodbridge905 wrote: I have a 2013 Mazda CX-5 with close to 240K on it.

In early 2017, I was having a lot of power and acceleration issues, and took it to different mechanics and each suggested something different. Finally took it to the Mazda dealership and they said the engine needed to be decarbonized. I didn’t know much about this before this and I just trusted them with it. Cost me close to $1K and was without a car for over a day (got free rental). That mostly fixed my issues.

Fast forward to last few months, I am having the exact same issues, and now with mileage too (240K vs about 175K back in 2017) . But since I only plan to keep this car for another year only , I don’t want to take it to a mechanic again for carbon cleaning (assuming that is still the same issue). I researched the issue and apparently this is a common issue with direct injection engines? And this is Skyactiv technology engine which is supposed to be better, more efficient etc. Don’t think so when I have to do this twice in about 6 years.

I did buy those fuel injector cleaners (Gumout) and have been pouring one bottle when I am low on gas and just before I fill up.

Does anyone know if I can pour in 2 or 3 bottles of this at once? And instead of putting it through the gas line, can I pour it directly into the engine just like you change oil?

And other than taking it to a mechanic for decarbonizing, does anyone have any other suggestions for me to look into?
Do you know what process the dealership did to clean it. there is quite a few ways using additives and engine decarbonising solutions and what not. The only one correct way to do it is with walnut shell blasting. IMHO, the engine additive way doesnt do much. prolly the dealership didn't do a good job as it should last more than a couple of years once done properly.
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Mar 13, 2004
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if its actually carbon build up then using injector cleaner will not help because the way a Direct injection engine is designed the injector cleaner never gets to the intake valves where its actually dirty and causing problems. It will just burn before that. The only way to fix iit is to manually clean it by hand or with walnut blasting. Usually on VW/Audio cars it lasts around 100k give or take then you have to do it again but thats if they clean it all out properly which walnut blasting can do that. We dont know what the dealer did but its possible they cut corners.

My suggestion is take it to a good mechanic that knows what hes doing when it comes to this stuff. I suggest the following two shops which I have been to in the past with my cars & they could easily take care of that for you.

https://www.1conceptautoinc.com
or
http://www.evolutionracing.ca
0_o
<_<
>_>
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Apr 5, 2013
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gulfstream
about 8 years ago, my mechanic at the time just bought a new system that was chemical type system (I cant remember the name)..it involved getting a tube that sent the chemical to the intake and through the motor after the air intake...there was before and after pictures (w/camera) ..cleaned carbon to a shine actually...it stunk, motor had be run about 1 hour with this through the system..then oil change to remove the contaminants..this was made for GM (diesel) trucks at the time only as it was new and each manufacturer had their own little apparatuses depending on engine type....I am sure by now there are many. It worked real good, virtually no motor disassembly. Cost about $500 plus oil change.
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GDI, worst invention ever. Glad my car is lower tier and came with MPI
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Messerschmitt wrote: GDI, worst invention ever. Glad my car is lower tier and came with MPI
GDI isn't to blame, emissions control forcing crankcase fumes to be burned in the cylinders is. If the crank fumes were vented to atmosphere like on old cars, you wouldn't have any carbon problems, but your car would smell like shit.
The reality is a combination of port and direct injection is ideal.
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Dec 23, 2003
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I would try this as I hear good things about CRC products: https://www.canadiantire.ca/en/pdp/crc- ... 8077p.html

Try one can and then see how it goes. You can try the second can as well if there is more buildup. Given that you did a pro cleaning, one can should suffice.
Last edited by hightech on Dec 15th, 2019 9:03 am, edited 1 time in total.
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Messerschmitt wrote: GDI, worst invention ever. Glad my car is lower tier and came with MPI
Nothing wrong with GDI. People just need to maintain the vehicles according to the owners manuals, ie: not change oil more frequently than specified and use the proper oil.

Most of the people who run into the trouble change the oil far too frequently and the oil is often changed with the wrong stuff (which can easily happen at a quickie lube or dealer, BTW).
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Seafoam and the like will do absolutely nothing to clean the backs of the valves that get buildup from DI engines. It needs to be media blasted.
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Sea foam through the air intake while help ya out quite a bit but would need to be done multiple times to do even half the job of walnut blasting but if you only plan on keeping it for a year more do sea foam through the air intake 2-3 times within a week and it should fix it for the year.
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burnt69 wrote: Nothing wrong with GDI. People just need to maintain the vehicles according to the owners manuals, ie: not change oil more frequently than specified and use the proper oil.

Most of the people who run into the trouble change the oil far too frequently and the oil is often changed with the wrong stuff (which can easily happen at a quickie lube or dealer, BTW).
What do you mean by changing the oil far too frequently? I thought doing frequent oil changes is a GOOD thing and not changing it enough can cause issues (i.e. engine damage, bad for timing chain, etc.). Did you mean to say that people DON'T change their oil as frequently as they should?
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hightech wrote: What do you mean by changing the oil far too frequently? I thought doing frequent oil changes is a GOOD thing and not changing it enough can cause issues (i.e. engine damage, bad for timing chain, etc.). Did you mean to say that people DON'T change their oil as frequently as they should?
Stick with the proper oil and OCIs. Even better send a sample off to Blackstone and rely on hard data.
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hightech wrote: What do you mean by changing the oil far too frequently? I thought doing frequent oil changes is a GOOD thing and not changing it enough can cause issues (i.e. engine damage, bad for timing chain, etc.). Did you mean to say that people DON'T change their oil as frequently as they should?
I have done nothing to validate what is stated below so take it with a grain of salt:


Why is it harmful to change the oil too frequently?

In a word; volatility. Oil volatility is at its greatest in the first 3000km after an oil change. After that the volatility reduces and the oil stabilises.

Volatility is particularly bad for a DI engine because all of the lost fractions exit via the PCV system. Much of it goes out through the rocker cover vent, into the intake, through the turbo compressor and intercooler, then puddles in the bottom of the inlet manifold where it combines with the stuff coming through the PCV valve to coat the inlet valves and combustion chambers in gunk.

That black soot you see in your exhaust pipes, don’t assume it’s all caused by rich mixture. Excessive oil changing will contribute more soot.

The presence of oil in the intake also lowers the octane rating of your fuel leading to detonation.

The NOACK volatility test quantifies the extent of oil evaporation. The test standard - ASTM D5800 - 08 Standard Test Method for Evaporation Loss of Lubricating Oils by the Noack Method – also hints at another kind of danger associated with frequent oil changes where it states “Procedure C, using the Selby-Noack apparatus, also permits collection of the volatile oil vapors for determination of their physical and chemical properties. Elemental analysis of the collected volatiles may be helpful in identifying components such as phosphorous, which has been linked to premature degradation of the emission system catalyst.”

A lot of phosphorous is lost in the initial boil-off phase of new oil and it’s likely to be harming oxygen sensors and cats.

Engine manufacturers understand the problem and it would be easy for them to identify the type of damage done by over servicing and potentially result in a warranty claim denial.

Summary
By changing your oil at 5000km, you are subjecting your engine to oil that is almost always in the initial boil-off phase. It's contaminating and filling your engine with gunk. Contrary to popular and uninformed opinion, oil that is 10,000 km old is not likely to be harmful, and would certainly be less harmful than fresh oil.

http://www.ozmpsclub.com/forum/tech-tal ... anges.html

And here is a thread of people discussing the above: https://www.bobistheoilguy.com/forums/u ... er=1900212
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hightech wrote: What do you mean by changing the oil far too frequently? I thought doing frequent oil changes is a GOOD thing and not changing it enough can cause issues (i.e. engine damage, bad for timing chain, etc.). Did you mean to say that people DON'T change their oil as frequently as they should?
No, most of the carbon deposits on intake valves are caused by the stuff that boils off of virgin, brand-new motor oil boiling off. The test for this is called "NOACK" ASTM D5800 and basically measures, after an hour or two, how much of a sample of virgin motor oil is lost. Some lower-quality oils can lose 10-20% of their mass in such test, which, in a real engine, means a lot of material every oil change is depositing in the intake through PCV recirculation.

So the solution is to minimize the exposure of the engine to brand new motor oil, by not changing it more often than the manufacturer specifies. And using a very high quality motor oil that has low volatility.

Unfortunately most of the people who suffer the intake deposits believe they were smarter than the manufacturers, by changing oil more frequently than specified, or alternatively, using poor quality oils.

People owning these engines should change their oil generally *less* frequently than they actually do. Sticking with the owners manual's "normal" service schedule.

The industry has had a lot of trouble fighting the problem simply because its a very hard problem to simulate in the engine testing labs, where maintenance schedules are actually followed with proper oils. Many quickie lubes, and brand-name dealers, despite advertising top-shelf synthetics, actually will dispense from a bulk oil tank containing the cheapest lubricant they can possibly source.
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TrevorK and burnt69

Thank you for the info. This is indeed news to me as I have always changed the oil on my vehicle following the 8,000 KM/6 month interval using 0W20 Synthetic Oil (Pennzoil Platinum, Toyota, Quaker State). I have never owned a DI engine and always a Fuel Injected one.

I think this info would be something dealerships and others might not inform people of as it hurts their revenue.
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