Engine sounds more like a diesel after a long trip?

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alexman

Member
Went for a 200 mile round trip at the weekend with my new RPI exhausts. After some soundproofing of the boot, the drone is kept down and higher revs sound fantastic. Overall very pleased for now. However, while I can hear my engine from the front just under the exhaust noise, it did sound very smooth during the outset of this journey, but on the 2 days that followed the journey, the engine sounds more like a "bucket of bolts" - more of a diesel sound after this long trip.

Has anyone had a similar experience where it just doesn't sound happy on a particular day? I considered this might be because of the oil I used during the trip, but every time I've checked the oil in 14 months of ownership it's been at a similar level (and I had an oil change a couple of months ago).

Any suggestions? Could it be oil use and a little top up might help? I read elsewhere the Vanos system can make it sound a little more gruff - can the sound of this change and if so, what affects it?
 
I wouldn't say mine sounds like a diesel. But once the engine has warmed up it does make a slight 'tappety' sound that seems to be coming from the top / front of the engine. Sometimes it is a bit more noticeable than others but is never too intrusive.

I'm not much of an expert on the engine, but from what I've read on here it sounds like this might be the normal sort of noise the Vanos makes.

The oil in mine is still fairly fresh (about 7,000 to go before the next service) and I'm still running the standard exhaust.

Cheers
 
Engine is a bit tappety at the best of times but i would be a little concerned if it has suddenly started to sound like a diesel!Mine's due inspection 1 in a couple of weeks and I expect they may do some adjustments but I can't say it sounds worse after a long run, in fact I'd say it's noisier when it's warming up.
 
Start by locating where the noise comes from, you can use a metal rod with a hose attached as a stethoscope (is that spelled right?)
M3's and Z4M's have solid valve lifters, if not adjusted properly or on time they make noise, I worked at a dealership and lots of times the cars went in for inspection II (adjustment required) and some of the the mechanics (I don't dare calling them technicians) where too lazy to adjust the valves as it is somewhat involved, so they skipped that part. It's also critial because sometimes valves are too tight and this can cause valve overheting and damage. If this is the case you should hear a bit more noise when the engine is cold.
Vanos also makes noise but usually just at start up, Vanos also has a small filter screwed in front (allen head) that has to be changed and sometimes isn't because the dealer doesn't have it in stock.
 
I need to rephrase this...

it doesn't sound *exactly* like a diesel - I mention "diesel sound" simply to illustrate that it sounds a bit grumpy - the engine sounds "rougher" after this long journey - so when revving up for example, it sounds just rougher than it usually would. I've noticed this at different times, but it's odd that it would sound "rougher" after a long drive and being warmed up.

Any thoughts? Does oil level affect the smoothness of the sound of the engine (if lower oil level and less lubricated perhaps??)

Could this be something else? Nothing is perfect all of the time - I'm just curious what might be affecting it in this way. This is a minimal difference but noticable.
 
Has it got the right grade of oil in?
S54 is not a quiet engine, none of the M engines usually are. I've also had two old M3's in the past (S14) and those always sounded quite harsh at low RPM's when the engine was up to temp.

I'm not expert at all, but might it be that the valves were not adjusted or not adjusted correctly so when up to temp they're noisey?
 
All M Engines i've heard personally all sound a bit ruff.Just the way they are....

My mates 2007 m6 Sounded terrible at tickover with 20k on the clock..lol

Though it would sound a bit bette than its straigth 6 counter parts being V10..but i guessed wrong.. :lol:
 
As an aside are you certain it's not related to the new exhaust (since it appears at the same time) and once hot and now bedded in it's not touching something. I know having fitted my custom system once hot it expanded by around 1cm and touched bits that needed easing. Also one of the brackets was touching metal to metal and sounded aweful.

Whatever the cause as mentioned earlier you need to identify the exact location of the noise and rods or a stethoscope are the real way to do that.
 
Guys...I know what my engine sounds like!

The key word here is "rougher" not just "rough" - any further thoughts? Would valve timing do this?

I wouldn't imagine it's the oil as I recently had an oil change done by BMW..
 
alexman said:
Guys...I know what my engine sounds like!

The key word here is "rougher" not just "rough" - any further thoughts? Would valve timing do this?

I wouldn't imagine it's the oil as I recently had an oil change done by BMW..
Click to expand...

You may need to be a lot clearer in the description of the noise. You're initial post describes it as a 'bucket of bolts' now 'rougher'. To me they are very different things.

Could be anything from valve gaps, little ends, wrong grade of oil, too much oil, too little oil.
 
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