TheSilverBullet

I've noticed a new whining noise coming from my 2.7T recently, and I actually don't think it's the turbos. I say this mainly because it ONLY happens when I take my foot off the gas in the low-mid RPM range (1000 - 3000). It also only seems to happen (or is only audible) when in a low gear (1, 2, or even 3) and at lower speeds (under 30 mph).

It also doesn't sound anything like what I would expect to hear if it were the turbos (not high-pitched or excessively loud), and there is no noticeable amount of smoke from the exhaust or loss of power. So, anyway, I'm fairly sure it's not turbo-related.

If I had to describe this sound, I'd say it sounds the most similar to the whining noise you hear when moving quickly in reverse ... or the whine of an electric motor. It does change with engine speed ("winds down" as the rpm's drop).

Now, I did try to STFA, but the only post I found that sounds similar is this one from 2006:

https://www.audiworld.com/forums/sho....php?t=1709379

The thing that jumped out at me the most in this post is that I actually also had a weird occurrence with my oil level lately...

About a weeks ago, I was driving on the highway at normal highway speeds, just cruising in 6th gear after the car had been fully warmed up and everything was completely normal. Then, I got a warning light on LCD that said "oil level at minimum" (a yellow warning). I was fairly close to home (~ 5 mi) so I took it real easy until I got home. Upon arrival, after letting the car sit for 5-10 minutes, I checked the oil level via the dipstick and sure enough, it was below the "min" line. Fortunately, I had a few extra quarts around (I always keep one in the trunk) so I added a quart, ran the engine for a few minutes, let it rest, and checked again. The oil level didn't seem to have gone up so I repeated the process twice more (adding a total of about 2.5 quarts). Finally, the oil level seemed to go up to a normal level (and was near the "max" line), so I stopped there.

The next day, I drove around (taking it easy) for a while to warm the car up fully, then stopped, let it rest, and checked the oil level again. This time, it read WAY too high (well above the max line). Knowing too much oil is very, very bad, and since I was due for an oil change anyway (4k since the last one), I took it to my indy for an oil change. I didn't mention anything to him about the oil warning light or overfilling it, and the oil level has been fine since then (about a week ago).

I had written this off as some kind of weird fluke or maybe a sensor starting to go bad and figured I'll just keep an eye on my oil level for a while and see what happens. I never considered that this might somehow be connected to the weird whining noise I've been getting until I saw that other post. It seems like an odd coincidence to me that we both have similar odd whining problems and low oil problems at the same time.

Sorry for writing such a long post. To summarize, I'm concerned about the whining noise I get ONLY when taking my foot off the gas, which is only audible at low speeds. Does anyone know what this could be or have troubleshooting suggestions?

Also, there may be some kind of connection between this whining noise and the oil level anomaly I experienced. I should note that the whining noise started at least a week before the oil incident.

Other possible items of interest: I'm about to hit 100K with no mods and I've owned the car for a year and a half now. During that time, the only work I've done is the TB, SAI pump, oil changes and tires. Also the weather has been cold lately but no worse than a typical winter in DC.

TIA for any ideas and for reading my long post!

frankinstyn

Simple problem.

First off is check your pvc system for leaks. This system will especially have problems in the cold with moisture freezing problems.

Next check for vacuum leaks. These will cause quite a bit of whistling noise.

Something to always to check with a forced induction engine is for boost leaks.
I would lay my bet on a boost leak. If you have a minor leak you might not even notice power loss.

I seriously doubt the oil has to do with this problem unless its the pvc system. That can cause oil loss.

Also, when the dipstick shows at the low mark it usually means add one quart. You added way too much oil. It being low one quart may have been as simple as a little burned oil. There's alot of pressure kicking around in that boosted engine.

2.7Lturbo

whine when letting off the gas can come from pretty much ANYTHING on the acessory belt too.... just food for thought, i know my cars fan clutch makes alot of noise as i think i broke it when i did the timing belt. from my understanding the fan clutch works so that no matter how high you rev your car the fan stays at a certain speed, mine however speeds up with the engine and makes a horrible howling noise lol

TheSilverBullet

Thanks for the responses. However, after writing up a long post describing my problem, it has gone away (and not because it got any warmer -- in fact it has gotten even colder).

I'm wondering if this is going to be an intermittent problem that increases in frequency until something breaks, and also hoping that it just never comes back. If it does, I'll check the items you guys have pointed out.

One question about the PCV system, though: I've seen some posts recently about PCV problems and I was under the impression that I'd be seeing a lot of smoke if the PCV system was frozen. Is that not necessarily the case?

I guess I should also mention that I have the "vented" oil cap from ECS, which is is supposed to increase crank case ventilation. Not sure if that makes any difference.

TheSilverBullet

OK, so during my lunch break I drove around a bit trying to see if this problem has really gone away or not. It turns out that it has not, but I can also be a little more precise in my description of the problem now:

1) It turns out that the "whine" sound only occurs with 2nd gear engaged (not in 1st or 3rd as I had previously thought, and only when the gear is engaged and not in neutral or with the clutch pedal in).

2) The whine also only occurs between 1000 and 2000 RPM. Typically, when taking my foot off the gas at or above 2000 RPM in 2nd gear, the whining begins at 2000 RPM and continues to "wind down" all the way to around 1000 RPM. If I press the gas in while it's whining, the whine stops and restarts as soon as I lift my foot off the gas again (provided I'm still under 2000 RPM).

As I said before, the whine sounds similar to the sound you hear when accelerating in reverse. Since it only happens when the car is in 2nd gear and in a certain RPM range, I'm starting to think that this is transmission/clutch/diff related.

Any thoughts?

kenyel

[QUOTE=2.7Lturbo;24093811]whine when letting off the gas can come from pretty much ANYTHING on the acessory belt too.... just food for thought, i know my cars fan clutch makes alot of noise as i think i broke it when i did the timing belt. from my understanding the fan clutch works so that no matter how high you rev your car the fan stays at a certain speed, mine however speeds up with the engine and makes a horrible howling noise lol

So if my fan gets loud *** i give it gas my fan clutch is bad?

thecyclonewarrior

[QUOTE=kenyel;24095211]Yes, sounds like the fan clutch has failed. They only die one of two ways, either staying unlocked all the time and not really pulling any air through, or they lock and howl as they go past their intended operating speed. I have seen this many times on my own and friends vehicles of all makes and manufacturers.

As for the second gear howling, I am betting it is just gear lash howl in the second gear set. More then likely this is not any kind of issue, just an occurance that happens with many gear systems as they wear over time. I would try a good approved synthetic fluid for the gear box, this has solved the one trans I had that did much the same thing in 3rd gear. Never heard from it again.

In any case, the whine I am pretty sure is not fatal or something to really worry about, until it becomes hard to shift into the respective gear.

JUST my .02

Bruce

TheSilverBullet

Thanks, Bruce. I was hoping it would be something this minor. I'll look into changing the fluid and we'll see if that quiets 2nd gear down.