masquernom

I'm considering buying a new Q5. I'd like to get the 3.0 liter engine, but I'm a bit concerned about the carbon buildup issue. Does that seems to be solved now in the newer models?

masquernom

I had a co-worker with the 3.2 L, and he had the problem. I didn't know if it carried over to the 3.0 L or not. Thought I'd ask before I bought one and found out the hard way.

idale

On the Q5 side it's the 3.2 that has the issue, though earlier revisions of the 3.0T apparently have it as well (mainly pre-facelift RS4/5 or S4/5, don't remember which had the 3.0T). It was supposedly solved by the time the Q5 got the 3.0T engine, though, so it shouldn't be any more of an issue than any of the other current options. (Which doesn't mean you won't necessarily get some buildup going over time, just that it shouldn't get problematic. Sounds like it's an inherent issue with direct injection so without specific countermeasures you'll always have at least some buildup likely.)

ex-quattro PETE

Hard to say as most people haven't accumulated significant miles on their 3.0T Q5s yet. Most people don't buy the 3.0T version if they're going to be racking up a lot of miles because this engine doesn't deliver the best MPG.


But as the other poster noted, this being a DI engine is by default exposed to some carbon buildup risk. Time will tell how bad, I guess.

tomaszp72

I've been looking at the A6 forum to see how the 3.0T holds up. Some people there with high millage and so far so good.

raj99

I wrote about this specific issue in the past here: https://www.audiworld.com/forums/a6-.../#post24493861

Simply put the 3.0t is a Forced Induction (FI) engine and is not as susceptible to carbon build-up, the reason being the much higher compression and thus higher cylinder and valve temps if you do get it out and run it for at least 10-20 minutes at normal running temps. As opposed to the standard FSI (Direct Injection) engines (i.e. 3.2) which will suffer from carbon build-up.

ex-quattro PETE

This is going to be a big issue for ours. Wife has a very short commute, 3-4 miles, and maybe 6 minutes. During winter, coolant temp does not even reach normal, much less oil temp. And even on weekends, the car doesn't get driven much. Things are very close by here, where we live. I'm expecting some issues down the road...

plat27265

Not exactly true. The VW MK5 and MK6 GTI's use force induction 2L FSI and TFSI engines, respectively, that run into issues with carbon build-up. Earlier models were more susceptible to carbon build-up. Later TFSI models 2011-12 onwards no so much. I have read that this can be credited to much improved PCV and Oil Separator design.

plat27265

Whenever I do short commutes like what you described above, I tend to take the long route home just to bring the engine temp up and run the engine for, at least, 20-minutes. I know it is a pain but it helps with preventing water build-up in the oil. Otherwise, you'll need to change your car's oil more frequently to keep it fresh so it will protect your engine.

ex-quattro PETE

Moisture build-up is one thing. But I thought we were talking about carbon build-up here specifically.

In any case, I think I'd rather pay for an occasional carbon cleaning instead of wasting 20 minutes and additional gasoline and racking up extra miles on the car every day.