howling/screeching rear diff?

[lancerevo3]

on fast long bends and some very tight slow bends

my rear diff is making a howling/screeching noise,put new fluid in saturday and same noise today.
is this a pump prob or is the diff itself starting to scream at me?

any answers appreciated
mark

[elnevio]

Which fluid have you changed?

Does it only make the noise when the AYC is active (i.e. at least one green bar lit up)?

[lancerevo3]

changed all fluids at rear ,yes only when ayc lights on iirc

[elnevio]

All three fluids?

I.e. (1) the gear oil that goes in the normal part of the rear diff, (2) the ATF that goes in the AYC clutch packs in the rear diff, and (3) the ATF that goes in the AYC actuator system in reservoir in the boot and needs bleeding through?


This sounds SO much like no (2) hasn't been completed. Did the noise start gradually and has since got steadily louder?

[waxer]

Have you ruled out wheel bearings? I had a howling from the rear that I was convinced was the diff. Upon investigation, it was only doing it on right-hand bends, and it turned out to be just a wheel bearing. I felt pretty silly, but still, it was a major relief.

[lancerevo3]

All three fluids?

I.e. (1) the gear oil that goes in the normal part of the rear diff, (2) the ATF that goes in the AYC clutch packs in the rear diff, and (3) the ATF that goes in the AYC actuator system in reservoir in the boot and needs bleeding through?


This sounds SO much like no (2) hasn't been completed. Did the noise start gradually and has since got steadily louder?

yes all three and plenty fluid coming out bleed holes.
started gradually now the harder you corner the louder it gets.
also pulled out of a parking spot saturday ,car stalled when i restarted and pulled off all three ayc lights came on a that noise was very loud.
thats the only time it happened in a straight line .wasnt doing more than five mph at the time

[lancerevo3]

Have you ruled out wheel bearings? I had a howling from the rear that I was convinced was the diff. Upon investigation, it was only doing it on right-hand bends, and it turned out to be just a wheel bearing. I felt pretty silly, but still, it was a major relief.

no i have not but ill check it out,mine will do it turning both ways.maybe their both fooked lol

[elnevio]

What condition was the fluid that came out of the clutch packs?

Has the noise got any better since the change? E.g. is quieter than it was?

[lancerevo3]

What condition was the fluid that came out of the clutch packs?

Has the noise got any better since the change? E.g. is quieter than it was?

fluid was black,noise is similar didnt get a chance to test properly yet

[elnevio]

What fluid have you used to replace it? Amsoil ATF?


By the way, you can confirm that it's the AYC by pulling the AYC fuse, and seeing if you get it to make the same noise!

[lancerevo3]

What fluid have you used to replace it? Amsoil ATF?


By the way, you can confirm that it's the AYC by pulling the AYC fuse, and seeing if you get it to make the same noise!

main dealer supplied the fluid.
where is the fuse located?

[elnevio]

Fuse - big 60A one in the engine compartment. Should be labelled 'AYC' on the cover.


The reason I asked about the type of fluid, is that Amsoil ATF massively outperforms the specified Mitsubishi Diamond Queen AYC fluid. The Amsoil is also detergent-based, and will usually strip the varnishes and other built-up crud out of the clutch packs (in much the same way it can rejuvenate an autobox). If you confirm that it definitely is the AYC making the noise, then I would be looking at refilling the clutch packs with Amsoil ATF (it only needs 2/3 of a litre), and running it for a few hundred miles, then dropping it and putting fresh stuff in. If it doesn't work its magic after another few hundred miles, then it looks like the AYC could be worn out.

As I say, that's what I'd be doing.

[lancerevo3]

Fuse - big 60A one in the engine compartment. Should be labelled 'AYC' on the cover.


The reason I asked about the type of fluid, is that Amsoil ATF massively outperforms the specified Mitsubishi Diamond Queen AYC fluid. The Amsoil is also detergent-based, and will usually strip the varnishes and other built-up crud out of the clutch packs (in much the same way it can rejuvenate an autobox). If you confirm that it definitely is the AYC making the noise, then I would be looking at refilling the clutch packs with Amsoil ATF (it only needs 2/3 of a litre), and running it for a few hundred miles, then dropping it and putting fresh stuff in. If it doesn't work its magic after another few hundred miles, then it looks like the AYC could be worn out.

As I say, that's what I'd be doing.

cheers nev

thats a big help and ill follow your tips and report back

mark

[elnevio]

Well, it's worth a try for under 1.5L of ATF and two changes - if it works, it's a lot cheaper (and less work! ) than a replacement diff!

Good luck!

[adaxo]

What fluid have you used to replace it? Amsoil ATF?


By the way, you can confirm that it's the AYC by pulling the AYC fuse, and seeing if you get it to make the same noise!

Sorry for thread hijacked, but is driving with ayc fuse disconnected is safe for ayc components ? and if yes, how back wheels will behave?

[elnevio]

It simply won't activate. It's the same as running without it because you have the red AYC light (e.g. because of low pump pressure). You essentially have an open diff instead.

[chris g]

Black oil and the screeching sounds terminal...

But hopefully change of oil and flush then fresh oil again may revive it...