Changed Diff Fluid - Grinding noise still there

[leebske]

Hi Everyone

I have the common grinding noise coming from the rear on low speed right-hand turns.

I just changed the fluid with 2 1/2 new bottles with special FM booster.

I have driven the car for about 60-100 Miles on the new fluid and still get a loud grinding noise.

Is this common or could there be another issue with the car?

Thanks in advance

[pnbmw]

time for the shop?
with limited slip diffs there is resistance to slip and when making slow hard turns the outside wheel travels more than the inside which will cause the diff will slip but generally makes a low groan noise.

[leebske]

Yes it is a groan I guess.

There is quite a bit of vibration.

I'm guessing from your response you think it may require more than just diff fluid?

[SenorFunkyPants]

The dealer will first go to a parking lot and make 10-20 tight figure of 8 turns to encourage the oil in-between the clutch plates. You could do this yourself before taking it to the dealer.

[leebske]

Okay thank you.

It seems the noise is actually more prominent since changing the fluid.

Perhaps by draining it but not letting the fluid to travel through the clutch plates is why the noise is now more pronounced?

[pnbmw]

if you have the old oil have a look through and slowly pour it from one container to another and see if there is any residue remaining. If it's a grinding noise there would be some residue and if it picks up with a magnet consult a good diff mechanic. Better get it looked at before something more expensive happens. Why not ask the dealer to diagnose and quote if there is a problem?

[leebske]

No longer have old oil unfortunately.

It's hard to explain the noise - more like a rubbing with vibration.

I will take it to the dealer for sure. Just wanted to see whether I should be giving it a longer period with new fluid to see if that would remedy the issue.

[jphughan]

FYI there are two kinds of diff fluid, the standard one and the fluid they put in for people who complain about noise because that variant is supposed to make less -- but the default fluid is still the original, which tells me maybe there's some way the regular fluid is better (or maybe just cheaper)? Anyway, look at your work order and see which part number they list for the fluid they installed and compare it against the numbers listed in various threads here. Either way though, I agree give it time on the new fluid, the worst thing is to have your dealer muck around with your car unnecessarily.

[dparm]

Originally Posted by jphughan

FYI there are two kinds of diff fluid, the standard one and the fluid they put in for people who complain about noise because that variant is supposed to make less -- but the default fluid is still the original, which tells me maybe there's some way the regular fluid is better (or maybe just cheaper)? Anyway, look at your work order and see which part number they list for the fluid they installed and compare it against the numbers listed in various threads here. Either way though, I agree give it time on the new fluid, the worst thing is to have your dealer muck around with your car unnecessarily.

I was under the impression that BMW now specs only the version containing the FM in the M3s.

I don't think you need to "give it time". If there's still noise, or it's even worse, you need to have it looked at. There's either an internal problem with the differential, or it's the wrong fluid/under/overfilled.

[jphughan]

Originally Posted by dparm

I was under the impression that BMW now specs only the version containing the FM in the M3s.

I don't think you need to "give it time". If there's still noise, or it's even worse, you need to have it looked at. There's either an internal problem with the differential, or it's the wrong fluid/under/overfilled.

I've heard that people who don't ask for the diff fluid with the new additive still get the old one, but I guess that could be dealer error. After all, people with 1Ms got 10W-60 oil for a while because the techs simply assumed that that's what the 1M took because it was an M car.

[SenorFunkyPants]

I understand from Castrol that the SAF-XJ (with friction modifiers) was the oem first fill oil for the E9x M3 diff until the end of production. The BMW modified SAJ-XJ with extra FM is only provided to customers who complain about any diff noise.
Mine has been making the RH turn, tepid oil temp, medium load, groan for the last 46000 miles with no ill effect - it may even be slightly less noisy than 5 years ago....I refused the dealer when they offered the BMW oil with extra FM.
No need to panic...try the figure of 8s and see how it goes over the next few hundred miles.

[dparm]

Originally Posted by SenorFunkyPants

I understand from Castrol that the SAF-XJ (with friction modifiers) was the oem first fill oil for the E9x M3 diff until the end of production. The BMW modified SAJ-XJ with extra FM is only provided to customers who complain about any diff noise.
Mine has been making the RH turn, tepid oil temp, medium load, groan for the last 46000 miles with no ill effect - it may even be slightly less noisy than 5 years ago....I refused the dealer when they offered the BMW oil with extra FM.
No need to panic...try the figure of 8s and see how it goes over the next few hundred miles.

Hmm, I thought I read on here that it was the other way around: they did not use the SAF-XJ +FM at first, then started adding it per a TSB if people complained, and eventually just used only that as FF.

[SenorFunkyPants]

Originally Posted by dparm

Hmm, I thought I read on here that it was the other way around: they did not use the SAF-XJ +FM at first, then started adding it per a TSB if people complained, and eventually just used only that as FF.

I talked to Castrol tech support a few weeks ago and the person I talked to said that they have/had a contract with BMW as oem first fill oil provider and to be the recommended oil provider. I believe the exclusive contract is coming to an end or is being altered and hence the change in oil recommendation recently announced.
The BMW modified SAJ-XJ is nothing to do with Castrol and the tech was somewhat bemused that they were adding even more Friction modifiers than were already present.