Rattle from engine on throttle tip in?

[helix]

I had a similar problem about a year ago on my 2004 330xi.

Basically I would hear a clunking sound when throttling and would only happen at certain rpm's and after the engine was up to temperature. I struggled trying to find the problem but just ended up being the engine mount. Not sure if you're having the same issue but the symptoms sound similar. Worth a look. Good luck.

[jabela]

Originally Posted by helix

I had a similar problem about a year ago on my 2004 330xi.

Basically I would hear a clunking sound when throttling and would only happen at certain rpm's and after the engine was up to temperature. I struggled trying to find the problem but just ended up being the engine mount. Not sure if you're having the same issue but the symptoms sound similar. Worth a look. Good luck.

That's a good possibility. It certainly could fit the symptoms. Thanks for the suggestion.
What RPMs did it occur at for you? Which engine mount was it?

[helix]

Originally Posted by jabela

That's a good possibility. It certainly could fit the symptoms. Thanks for the suggestion.
What RPMs did it occur at for you? Which engine mount was it?

It was most prominent at about 1700-1800 rpm, and only when up to temperature, but did occasionally occur at other engine speeds. It was particularly noticeable under load while driving on a rough patch of road. I don't recall which engine mount it was but I had similar mileage on the car when when I had this problem.

[jabela]

Thanks. Well I'll definitely look into the mounts. I may as well replace them all anyhow. Maybe with some heavy duty ones. Hopefully they're an easy DIY.

[jabela]

I had a good look at the engine while someone revved it to make the rattle. It sure sounds like it's coming from the the VANOS area. There also did not seem to be excessive movement with the engine. However, I still think that changing the engine and transmission mounts would be a great idea, so I'm going to still go ahead with it.

[jabela]

So the low rpm rattle has mostly gone away after filling up with PetroCan Ultra 94 gas (I had Shell 91 before).
This suggest carbon deposits (likely from the poorly designed CCV). I'm going to try some BG44K injector cleaner, then Seafoam spray and see how that works.

However, at 3-5000 rpm I've been getting quite a bit of harshness (felt through shifter, clutch pedal, etc.) I'm pretty sure that this is the engine mounts, especially since it goes away when I turn left, but not when I turn right (due to engine leaning on/off mount).

[jabela]

Originally Posted by jabela

However, at 3-5000 rpm I've been getting quite a bit of harshness (felt through shifter, clutch pedal, etc.) I'm pretty sure that this is the engine mounts, especially since it goes away when I turn left, but not when I turn right (due to engine leaning on/off mount).

So replacing my motor and transmission mounts have made a world of difference. No more harsh vibrations under load. Motor mounts were not completely shot, but the passenger side was compressed about 3/4" and the driver side was 3/8" compressed.
The engine was low enough that the powersteering pump fitting was lightly rubbing on the sway bar.
Engine feels sharp and responsive now, with no vibration under load.
Replacing the transmission mounts with M3 mounts have also cured the sloppy clutch/shifter feeling I was getting. The clutch is very accurate now. The non-m mounts are very soft compared to the M3 mounts.
I highly recommend everyone does the tranny mount swap. It's super easy too.

[canukgtp]

Well that's cool, glad you found a solution...when you can't find the source of a noise it can drive a man nuts hahaha!

[T.Dot_E30]

Do I win the closest guess award?

Either way glad you found the problem! See you at the next solo event at DDT.

[jabela]

lol... yes, you win my thanks

I still have the original rattle issue, though isn't as bad since I've started using Petro 94 instead of Shell 91.

I still need to replace my valve cover gasket and do the vanos seals. Also going to replace the spark plugs while I'm in there.