A4 sounds like a diesel

[ConroeS4]

When I start my A4 up for about the first 45 seconds it sounds almost like a diesel. What is the cause of this or is it normal? Sorry if it is a common topic, never seen it before though.
Thanks!
Cameron

[blackbox619]

2.0t? its because of the bigger injectors. its normal.

[ConroeS4]

nope, it's the 1.8

[n7plus1]

mine started sounding like this as soon as the weather turned much colder during morning starts.

[a4mafia]

same here.

[aaaudiprotein]

Are your rpms around 900 after the start-up? When usually they are about 1200?

[LampyB]

how many miles on the car? living in a dry climate can dry out seals in our engines much quicker than anyone in the midwest or on the east coast where it's humid. the worst i can think of is that your cam chain is running a bit loose because the tensioner isn't functioning properly. had this happen to me on my B5, and it ran permanently with a very loud ticking until it was fixed. simplest thing i can suggest is running a Seafoam treatment in your crank case, this can clean up your pistons and reduce the ticking sound.

the problem you're having could be many different things...you need to be more specific as to when it started, is it only upon warmup, only in cold weather, etc...

[JMRQuattro]

if it sounds like a bunch of rapid "thunk thunk thunk" and you get a flashing CEL it's probably cylinder misfires. Mine did the same thing, i had cylinder 2 misfires. Had to replace the spark plugs, fixed the problem for a couple days, but it's started happening again so i need to replace my coilpacks.

Also that would make sense because mine didn't start doing this until cold weather hit either. But it goes away once the car warms up. Is this the same with your car? I would imagine that even if the coil pack(s) isn't completely gone it still might be going bad, thus the cold weather must be making it apparent on cold starts and while the engine is cold.

But it sounds really weird and the car shakes a little bit when it idles. I freaked out the first time it happened.

[vdubstreets]

What weight oil are you running?

[docurley]

I would guess its the oil pump as I had this on my facelift B5 where you get a lazy oil pump due to the oil pick up pipe getting blocked reducing the amount of oil being fed to the head.

In some cases you may see the oil light flick up for a while or in worse cases it sound like a diesel and it wont go away.

My car would sound like it at start up then becous quite after a long run you will then detect a tapping noise.

Only way to Sort the problem is a new oil pump and pick-up pipe with the filter on the end. To do this you are going to have to remove the sump and thats a pain as the subframe is in the way.

[agart]

When I start my A4 up for about the first 45 seconds it sounds almost like a diesel. What is the cause of this or is it normal? Sorry if it is a common topic, never seen it before though.
Thanks!
Cameron

My assumption is that this is only under cold starts. In that case, its the secondary air pump and is normal. IIRC it's to warm up the cat faster to bring the exhaust to emissions standards faster.

[romell]

cold start.. it happens.. now if this is happening usually while you are driving.. .and its not the misfiring... well that sound like the good old audi oil sludge recall issue. get it checked. =)

[Papachristou]

My assumption is that this is only under cold starts. In that case, its the secondary air pump and is normal. IIRC it's to warm up the cat faster to bring the exhaust to emissions standards faster.

the SAI just raises the idle to warm the cat faster. if he is getting a rattling noise then there is a lack of oil to the head, either from a slowing clogging pickup tube, sludge or failing oil pump. i would run some seafoam immediately and see if it helps then start a auto rx cycle. if you dont hear it getting better then

[CyberPMG]

If it was anything like my old 3.0, that sound could be a valve that's sticking due to either sludge or a failing oil pump. For my car, it ultimately led to total engine failure due to the value wearing down a cam lobe and having the metal shards tear up the cylinder walls and loose total compression.

I would have it checked out ASAP.

[A4TUNE]

so many different answers in here so lets add one more. could be a blown gasket.

[mike-2ptzero]

Could be that the valve on the back of the head for the SAI is leaking causing the sound you hear. If it doesn't have pressure from the SAI pump it will suck in air causing it to sound like a diesel till it shuts.