ALEKS

Hey guys,

For the last 3-4 cold starts, there is a grumling metallic sound (not the usual roam) coming from just under the air intake, on your left, when you face the engine bay. It does it for 30sec. than it's stop. I't only on cold starts. Once the car ran, it does not come back till the next "day" nor till it cooled down for at least 5-6 hrs.

Could be usefull to know that:
- 1.8T 2005 A4
- I only take the car 2-3 times a week mainly on weekends. So it explains why i noticed it late
- sleeps in a garage
- I went for my 115k maintenance 2 weeks ago.
- Prior to this, the car ran #1.
- Right after the 115k maint., there was a burned coolant scent. I didn't mind, knowing they had flushed the cooling system and some of it could have dripped. But 2 weeks later, there still was a smell so i look under the hood and the main hose to the radiator was leaking...And coolant was spraying a bit. coolant level was just under the min. line. Went back at the shop and they fixed it right away. But i forgot to tell about the noise, as I heard it once before that episode.

So, could it be all related?
AND mostly, what is under the air intake that kind of warm or pumps itselfs up (that would be much helpful!)

Thanks!

AleKs, Montreal

ALEKS

For what i've found on the net, could be the secondary air injection pump... anyone?

adamstasiak

How is your AC fluid? When the air pressure changes like right now from summer to winter the fluid is pumped around, and if the AC gas pressure is too low it could be grumbling all day because it can not equalize.
I am thinking maybe they touched the line somwhere.

Your car diverts the air through turbo on cold starts. Was it like this last winter as well, or is it a new vehicle for you?

Secondary Air Injection Pump is definitely not grumling. Watch some video of A1 Abrams Tank engine. This is how it sounds in miniature version. It is rather healthy high pitched sound that is gone shortly after it starts.
You would not hear it at the engine start but rather later like 3 minutes later.

cheeba

A failing SAI pump makes a turbine-like sound during cold-starts. It can be fairly high-pitched, and you can hear it tail off as the high-idle transitions into regular idle. It would help a lot if you could record some audio and upload it to YouTube (or wherever) for us to check out. You can also try searching sites like that for other people's uploaded 1.8T-noise videos and compare it to your own.

That said, if you had a problem develop right after having a shop work on it, you should be taking it up with them!

ALEKS

Allright, went at the shop. It's the SAIP. And yes in fact itwas more of a screeching high pitched sound than grumling, sorry

So, The pump is fairly accessible, and i'm looking to do the job myself. Any good online parts aside of ebay?

cheeba

The SAI pumps usually fail because the rivets work themselves loose - if I were going to replace it with an OEM unit, I would drill the rivets out and put bolts in. Since the SAI pump is so accessible on the A4, you can consider trying this with your failing unit to see if it resolves the problem.

When mine was failing, I just yanked the piece of crap and never looked back All you need is an SAI block-off plate ($30), and a 10W, 330Ω resistor will eliminate any codes.