Piston Slap: Oil Burning and Carbon Cleaning?

Sajeev Mehta
by Sajeev Mehta

Arley writes:

Sajeev,

I have a 2003 Jetta TDI with 178k miles. Runs 100%. My mechanic recommends a carbon cleaning. What are the positives and negatives? To be more succinct, what can go wrong?

You can tune a piano but you can’t tuna fish. (Good to know! – SM)

Sajeev answers:

Conventional wisdom (for both diesel and gas engines) is carbon buildup occurs more often when the owner subjects the engine to excessive idling and a severe lack of full throttle acceleration. Today’s direct injected, EGR equipped diesels (and direct injected gas engines lacking a piggyback port-EFI setup a la Toyota V6s) are sensitive to carbon buildup due to idle time, EGR design and cooling system inadequacies, and perhaps even fuel (i.e. varying quality of bio diesel). Don’t take my word, this company’s blog did a good job assessing the problem.

Whew!

So carbon cleaning is commonplace and a good idea. And be it a seafoam-alike treatment or physical removal/cleaning of critical parts, there’s no downside if performed with even a modicum of care.

Question is, do YOU have a problem?

Considering your mileage (less idling and more highway driving?) and engine performance: probably not. Watch this video (go to 1:39) and DIY if you are even the least bit handy. From the video, make a trip to the parts store for vacuum lines too!

Or just do nothing aside from performing an Italian Tune-Up. That’d work for sure, and it’s totally fun.

[Image: Shutterstock user sasha2109]

Send your queries to sajeev@thetruthaboutcars.com. Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.


Sajeev Mehta
Sajeev Mehta

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  • 415s30 415s30 on Jun 17, 2015

    One of the first things I did when I bought my W123 was cap off the EGR. Diesels are exempt.

  • TammyRice39 TammyRice39 on Mar 13, 2019

    Engine Carbon is headache for me, but you clear my thought regarding Carbon. thanks for the information. bets of luck for future.

  • Fahrvergnugen cannot remember the last time i cared about a new bmw.
  • Analoggrotto More useless articles.
  • Spamvw Did clears to my '02 Jetta front markers in '02. Had to change the lamps to Amber. Looked a lot better on the grey wagon.I'm guessing smoked is illegal as it won't reflect anymore. But don't say anything about my E-codes, and I won't say anything about your smoked markers.
  • Theflyersfan OK, I'm going to stretch the words "positive change" to the breaking point here, but there might be some positive change going on with the beaver grille here. This picture was at Car and Driver. You'll notice that the grille now dives into a larger lower air intake instead of really standing out in a sea of plastic. In darker colors like this blue, it somewhat conceals the absolute obscene amount of real estate this unneeded monstrosity of a failed styling attempt takes up. The Euro front plate might be hiding some sins as well. You be the judge.
  • Theflyersfan I know given the body style they'll sell dozens, but for those of us who grew up wanting a nice Prelude Si with 4WS but our student budgets said no way, it'd be interesting to see if Honda can persuade GenX-ers to open their wallets for one. Civic Type-R powertrain in a coupe body style? Mild hybrid if they have to? The holy grail will still be if Honda gives the ultimate middle finger towards all things EV and hybrid, hides a few engineers in the basement away from spy cameras and leaks, comes up with a limited run of 9,000 rpm engines and gives us the last gasp of the S2000 once again. A send off to remind us of when once they screamed before everything sounds like a whirring appliance.
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