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Discussion Starter #1
I am trying to troubleshoot this strange grinding noise that only occurs when coasting in gear. The lower the gear the louder the grinding is. Under acceleration it's completely fine.

I have made a video to try and capture it. Not sure how well it comes across though.

 

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I can't open the clip and don't know the year and model and year of your 164. Are you coasting with the clutch pedal in?
 

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If the transmission input bearing hasn't been changed out from the original roller bearing to the tapered bearing, it could be bad. Just a guess...
 

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I'm afraid so, but maybe someone else has some ideas:) Like I said, I can't open the clip to hear it. Where does it sound like the grind is coming from?
 

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I can't open the clip
However, I encountered such a problem that occurs. Clips do not open. I found the reason. When you copy a link, it is necessary to remove one letter s
For example
https://www.youtube.com/......................
Why this happened I do not know. Previously, this was not.
 

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Try jacking the front wheels off the ground and see if you get the same noise with the gear train unloaded during accel & decel. Even if it's less intensity, maybe you can pinpoint the area it's coming from.
 

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The sound from the gearbox clearly heard if you drive slowly with the window open near walls or high curbs.
 

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It's an early model 164 so I would guess in has the ball bearing input shaft bearing and so I would have to guess it is near total failure and needs changed to the roller bearing. Could be something else, but that is my suspicion as well. I don't think there are a lot of other possibilities. A bad inner CV joint would be noisy under acceleration, and outer clicks in turns. A bad wheel bearing hums and changes sound with turns. So we are left with a trans problem and we are familiar with the input shaft bearing failure and fix/upgrade. I suppose it could also be a differential pin/spider gear problem. So, either way the trans has to come out and be inspected and fixed.
Charles
 

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Discussion Starter #13
Incidentally i checked the gearbox oil level last night and it needed nearly a litre to fill it to max. Doesn't seem to be leaking though.
 

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If your gear box is that low on oil, the bearing could be the problem. When you have several things to do on a 164, it's sometimes easier to pull the engine. If I were you, I'd look to see if other things need to be done...steering rack leaks, motor mounts need replacing, when was the starter changed last (you should do it even if your just pulling the transmission), when was water pump last changed. Even things behind the false fire wall are easier to do with the motor out...heater fan motor, heater core, etc.
If very much of that will need to be done in the next 2 years, I'd pull the motor and do it now along with the transmission bearing. How about the clutch?

I do agree with Raodtrip though...put it up on jack stands and see if you can find exactly where the noise is coming from.
 

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Discussion Starter #15
The clutch was last changed in 2003 according to the invoice from the PO. Obviously wasn't done at a specialist otherwise they would have checked the bearing.

The car is my daily driver so whatever I do it cant be off the road for too long. I need a work out a plan of action.
 

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If the clutch was installed in 2003, then it should have plenty of life left. My 91S has 172k miles on it as the original, and it works just fine thank you.

However, having said that, you don't know how the PO drove the car, so it might behoove you to look closely at the plate to see how much wear it has suffered. Some drivers have been known to wipe out a clutch in less than 50k miles, or maybe even less.
 

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Discussion Starter #17
I think that if i'm going to the trouble of taking the gearbox off I will definitely change the clutch no matter what condition just to save having to go through it all again later.
 

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If input shaft bearing failing the noise will be under acceleration and usually more noticeable in 1-2 gears.
 

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Discussion Starter #19
No noise under acceleration at all. The noise only occurs when you lift completely off the accelerator and allow the car to coast whilst in gear. it seems to occur whilst reversing too under both acceleration and coasting.
 

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"I will definitely change the clutch no matter what condition"

Be sure to have the mating pieces resurfaced for best results.

Also take a look at the diff to make sure something isn't adrift in there, esp in the spider assy, ie, the shaft retaining pin. Have been known to come loose and strike the housing.
 
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