Gearbox Whine advice please

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fastjet
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Gearbox Whine advice please

Post by fastjet » 21 Jun 2019, 18:27

My 2004 c5 2.0 hdi (110 bhp) (77000 miles) has suddenly developed a gearbox whine in 4th & 5th only. The whine is worse in 5th than 4th and it is worse between 50 - 60 mph. Below 50 mph the box is quiet, above 60 mph I think that there is a faint whine, but it is hard to tell accurately due to the increased road noise.
The whine is only there on very light throttle maintaining speed, acceleration and deceleration the box is quiet. I have changed the gearbox oil which made no difference to the whine, but gear shift is smoother.

Has anyone else got this problem, just wondered if it a common issue. Can anyone offer any advice on this please?

Peter.N.
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Re: Gearbox Whine advice please

Post by Peter.N. » 22 Jun 2019, 10:52

I was going to suggest checking the oil but you beat me to it. I would leave well alone if I were you, its probably a noisy bearing, could be in the gearbox or the diff, in any case it would be a gearbox out job and it will probably go on making the noise for many thousands of miles yet. I have had a number of cars with gearbox whines but never had one fail completely as a result. Ear defenders would be cheaper. :wink:

Peter

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white exec
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Re: Gearbox Whine advice please

Post by white exec » 22 Jun 2019, 12:31

Might also be worth checking whether there is a part of the engine or gearbox (or gear change mechanism) which is coming into contact with bodywork, depending on throttle position/torque. Check engine mountings for excessive slop.

Gibbo2286
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Re: Gearbox Whine advice please

Post by Gibbo2286 » 22 Jun 2019, 13:13

Any chance it's the fifth gear locking nut loose?

fastjet
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Re: Gearbox Whine advice please

Post by fastjet » 22 Jun 2019, 17:51

Thanks for the advice.
This might be a silly question, but what is the best way to check the engine mountings?
I guess to check the fifth gear locking nut would be a gearbox out job?

Perhaps I should have mentioned that the gearbox whine only starts once the engine and gearbox are both warm. The longer the run, the louder the whine is. A short local run no noise at at all. A 70 mph motorway run for a couple of hundred miles the whine is much more noticeable. I find it real odd that it only happens on light throttle just maintaining speed. I thought that a bearing would whine more underload, like wheel bearings do.

Thanks again for the suggestions and advice.

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Re: Gearbox Whine advice please

Post by Paul-R » 22 Jun 2019, 17:58

fastjet wrote:
22 Jun 2019, 17:51
I find it real odd that it only happens on light throttle just maintaining speed.
That indicates to me gear tooth wear.

fastjet
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Re: Gearbox Whine advice please

Post by fastjet » 23 Jun 2019, 09:34

Thanks for the advice.
I guess the only thing can do is to hope it lasts.
Bearing or gear tooth wear both sound as though another gearbox is going to be required at some point.

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Re: Gearbox Whine advice please

Post by Peter.N. » 23 Jun 2019, 10:09

I think you can actually get to the 5th gear by removing the gearbox end plate - you could on the CX anyway. As the gearbox temperature increases the oil gets thinner and doesn't take up wear so well.

Peter

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Re: Gearbox Whine advice please

Post by Gibbo2286 » 23 Jun 2019, 11:08

Peter.N. wrote:
23 Jun 2019, 10:09
I think you can actually get to the 5th gear by removing the gearbox end plate - you could on the CX anyway. As the gearbox temperature increases the oil gets thinner and doesn't take up wear so well.

Peter


And on the BX and early C5 I think.

Not sure which gearbox the op has.

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white exec
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Re: Gearbox Whine advice please

Post by white exec » 23 Jun 2019, 11:16

Sadly, 5th gear wear and vibration is a common problem on many 5-speed boxes, where the extra gear pair was hung on the outboard ends of the shafts, with no additional bearing or side-thrust support on the outer end. This poor adaptation of previous 4-speed transverse boxes hit not just PSA units, but other makes too, including Toyota. In the latter case, replacing with an 'improved' gear set can get rid of most of the vibration/buzz, but it can return again as wear returns.

fastjet
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Re: Gearbox Whine advice please

Post by fastjet » 23 Jun 2019, 16:37

Gibbo2286 wrote:
23 Jun 2019, 11:08
Peter.N. wrote:
23 Jun 2019, 10:09
I think you can actually get to the 5th gear by removing the gearbox end plate - you could on the CX anyway. As the gearbox temperature increases the oil gets thinner and doesn't take up wear so well.

Peter


And on the BX and early C5 I think.

Not sure which gearbox the op has.

I have a MK 1 C5 2.0 hdi.

fastjet
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Re: Gearbox Whine advice please

Post by fastjet » 23 Jun 2019, 16:41

I think you could be right about the 5th gear. On the gear box there is a pressed steel plate on the end of the gearbox. I guess this plate could be covering the 5th gear which actually sits outside the gearbox. I'll have to try and find an exploded view of the gearbox.

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Re: Gearbox Whine advice please

Post by Paul-R » 23 Jun 2019, 18:04

I think on the Mk1 C5 it depends on whether it's the 90bhp or 110bhp engine fitted.

The 90bhp engine has the BE3 gearbox and this is the one that we're talking about above. Reverse gear position is opposite 5th gear.

The 110bhp engine has the ML5T gearbox (possibly ML5C - anybody confirm?) and this is built differently and eventually spawned a six speed version. Reverse gear is further over to the left beyond the 1st/2nd gear plane.

fastjet
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Re: Gearbox Whine advice please

Post by fastjet » 23 Jun 2019, 19:41

Paul-R wrote:
23 Jun 2019, 18:04
I think on the Mk1 C5 it depends on whether it's the 90bhp or 110bhp engine fitted.

The 90bhp engine has the BE3 gearbox and this is the one that we're talking about above. Reverse gear position is opposite 5th gear.

The 110bhp engine has the ML5T gearbox (possibly ML5C - anybody confirm?) and this is built differently and eventually spawned a six speed version. Reverse gear is further over to the left beyond the 1st/2nd gear plane.

My car is 110 bhp with 5 speed box.

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Re: Gearbox Whine advice please

Post by Hell Razor5543 » 23 Jun 2019, 19:52

I have a late Mk1 C5 and, according to the details sheet Marc dug out for me, she has the ML5C gearbox. She does have the 110BHP HDi engine.