318 iS gearbox rattling when driven hard at 4-6 revs

[flybmw]

Hello guys

When cold, the gearbox sounds and shifts absolutely fine. But after some spirited driving it starts making rattling noises like a bucket of nuts. Noise is unbearably loud especially when you stop at traffic lights after spirited driving. Interesting thing tho is sound almost disappears after you start driving slow and nice. As if the tranny oil cools down and the noise is barely hearable.

What could be wrong please?

Oh, car is 318iS M42 with Getrag 240 box.

[jmc330i]

Is it noisy when you're driving it at 4-6k rpm, or just when you've come to a stop and idling?

[flybmw]

When I come to stop and when I drive. So both.

It is just when I am at 4-6 k I might not be hearing it rattle due to the engine noise.

[Brianmoooore]

Check the exhaust mount off of the rear of the gearbox before you start ripping things apart.

[flybmw]

It is definitely not the exhaust. I feel the noise is coming from down the gear knob somewhere. Could it even be an engine?

[DaniTD]

I have the same problem as you. In this case it's a BMW 318i with M40 engine, but the tranny is the same. When I start the engine all sounds good, but when I get to my destinantion or when after some driving II make a stop, I can hear the gearbox rattling loud. If I press the clutch pedal down, the sound dissapears.

The Getrag 240/5 has a lot of variants. Some use MTF, some ATF, some just plain old SAE80. As my car was from a PO and it needed a bit of maintenance, I changed the gearbox oil. It doesn't have any stickers but I can't trust if it's a SAE80 one or the label is missing and it's a ATF one. I used SAE80 the first time, but on winter and on very cold days (I'm from Spain, for us a very cold day is -5ºC ) the gearbox what so hard to shift... Leaving at night from my university parking lot it was difficult to shift 2º, to the point you had to let the car coast down and keep pushing the shifter to 2º gently until it got there or shift from 1º to 3º. After a couple of meters, the gearbox started working fine.

Then, as I was not very confident with SAE80, tried ATF. No more hard shifting on cold days for 2 years. The gearbox works like a charm, smooth and precise, but with the downside of the rattling noise when warm. On a document about gearboxes from BMW, I read that at the time of our cars, they recommended, if the costumer complained about hard shifting on low temps, to change the SAE to ATF, only for winter, and then change back to SAE in summer.

The problem here is, in winter we can have -5ºC, but in summer we can rise up to 45ºC, and maybe the ATF doesn't like it Will try with some modern 75w-90 or 75w-140 (maybe the first) as it's close to the SAE 80 but with better performance on low temperatures.

Is your running on ATF?

[Brianmoooore]

ATF is absolutely fine for the highest ambient temperatures. The only downside is the increased rattle.

[no1_jazz]

I have the same problem as you. In this case it's a BMW 318i with M40 engine, but the tranny is the same. When I start the engine all sounds good, but when I get to my destinantion or when after some driving II make a stop, I can hear the gearbox rattling loud. If I press the clutch pedal down, the sound dissapears.

When at a stand still after a fair drive and you then park up and hear the rattle noise this could be the clutch release bearing. I had this problem with mine it was rather a loud knocking rattling noise.

At this point I got a new clutch kit installed it and all was fine there after.

For the OP do as Brian said for a start make sure 100% that your exhaust mount off of the rear of the gearbox is OK before digging in deep.

J