Hello to  all

New to this forum , and looking for some advise ,I have a 2006 1.6L petrol 16v Ford Fiesta with 190,000kms on it , which I regularly use as  commute car to get to work in outback Queensland Australia which is a 8hr Journey , with high ambient air temps 

Long story short I have a gearbox rattle at idle which is pronounced when the Ac is switched on , noise disappears when clutch is engaged , this has been going on for some time know and is becoming more audible.

I have no issues with gear selection or clutch , the Ac clutch has been inspected and the bearing is in good shape , I believe the extra load  at idle with Ac on  is what is making the gearbox rattle/chatter , most likely due to worn bearings , the gearbox is original , and the clutch and slave cyl was replaced 10k ago , due to a fluid leak on slave .

The gearbox oil has been replaced at time of clutch change out with 75-90w semi synthetic, as per Ford spec .

I am considering dropping the oil out again filtering and having another look for any debris , and refilling with a higher weight trans oil ie Ep 80-90 W .

Has anyone had any success doing the same thing , or has any suggestions as to oil viscosity choice .

Thanks heaps in advance for any replies 

 

3 hours ago, Marshy-72 said:

noise disappears when clutch is engaged

You do mean the gearbox clutch, not the A/C clutch ?

If the ratle disappears when the clutch is depressed, that normally points to a worn input shaft bearing,

Hi thanks for the reply 

yes your on track about the noise , I was thinking the same about it being worn  , and really is unlike to be anything else , due to it only happening in neutral , and when clutch depressed chatter going away as input shaft stops being rotated .

I can only really  pic the noise myself from drivers seat at idle with Ac turned on , as it disappears when switched off , or clutch depressed , can’t seem to bring the engine revs up gradually with throttle to see what revs the noise is there at as throttle is to responsive .

The clutch was changed 10,000 kms ago and there did not seem to have any play in the input shaft either end float or axial when moved by hand that said I did not have my Dti gauge to carry out any measurements , the input shaft felt  smooth enough when rotated . 
so I guess the wear is minimal at present .

As mentioned my plan is to drop the 75-90w GL5 grade nylon semi synthetic gear oil which was changed  last clutch change out 10,000 kms ago  , run it through some filter paper and have a good look for any crap , and change out oil with a slightly heavier grade more suitable to the driving conditions here in Oz .

Any thoughts on running EP 80-80 W and see how it goes ? 
 

I realise that this may cause a bit more drag on the synchros , and wondered if anyone else has done similar?

On 9/23/2023 at 8:31 AM, Marshy-72 said:

Hi thanks for the reply 

yes your on track about the noise , I was thinking the same about it being worn  , and really is unlike to be anything else , due to it only happening in neutral , and when clutch depressed chatter going away as input shaft stops being rotated .

I can only really  pic the noise myself from drivers seat at idle with Ac turned on , as it disappears when switched off , or clutch depressed , can’t seem to bring the engine revs up gradually with throttle to see what revs the noise is there at as throttle is to responsive .

The clutch was changed 10,000 kms ago and there did not seem to have any play in the input shaft either end float or axial when moved by hand that said I did not have my Dti gauge to carry out any measurements , the input shaft felt  smooth enough when rotated . 
so I guess the wear is minimal at present .

As mentioned my plan is to drop the 75-90w GL5 grade nylon semi synthetic gear oil which was changed  last clutch change out 10,000 kms ago  , run it through some filter paper and have a good look for any crap , and change out oil with a slightly heavier grade more suitable to the driving conditions here in Oz .

Any thoughts on running EP 80-80 W and see how it goes ? 
 

I realise that this may cause a bit more drag on the synchros , and wondered if anyone else has done similar?

 

Did you get this problem resolved or find out anything that may be causing the issue? Friends car is doing almost the same thing...