Odd click­ing

Car Mechanics (UK) - - Help! -

My Clio 182 is mak­ing an odd click­ing noise, which I re­ally hope is not gear­box-re­lated. It oc­curs when com­ing off the throt­tle in gear, mostly when driv­ing straight ahead, and also when turn­ing left when mov­ing at speed. How­ever, if I dip the clutch, the noise be­comes much faster – prob­a­bly twice as fast – and it makes no dif­fer­ence if I put the gear lever into neu­tral. The noise does not oc­cur when I go back on the throt­tle or when turn­ing right, and it stops when I press the brake.

The noise first started af­ter I had the car jacked up to check the sus­pen­sion com­po­nents with a pry bar, as I had been get­ting knock­ing/clonk­ing noises when go­ing over bumps and turn­ing right, but I couldn’t find any wear. I know the en­gine mounts are a bit of a weak link on these models, par­tic­u­larly the lower twist­ed­type one, but I’ve had my pry bar on it and there is a bit of move­ment back­wards and for­wards of about sev­eral mil­lime­tres.

My MOT tester had a look at it and didn’t seem to think it was a prob­lem. What con­sti­tutes ex­ces­sive move­ment on those mounts? I couldn’t hear the en­gine knock­ing against any­thing when lev­er­ing the mount for­ward and back. How­ever, if I sort of jab the throt­tle in, say, sec­ond gear at low speed, I can hear a knock.

I also re­moved the off­side front brake caliper when check­ing the sus­pen­sion as I have an is­sue with massive un­even disc wear on the in­ner face of the discs on both sides. I found that the up­per caliper car­rier guide pin bore mea­sures 10.3mm and the bot­tom one is fairly even all the way round at 9.6mm. I lu­bri­cated the pins with cop­per grease and re­fit­ted the caliper the same way I’ve al­ways done. Could it be the caliper chat­ter­ing away if it hasn’t gone on square? But why would it get faster when dip­ping the clutch?

Also, I had to put a new off­side drive­shaft gaiter on the outer joint. When do­ing this, I washed the joint out with co­pi­ous amounts of brake cleaner. I later re­alised this was prob­a­bly a bad idea, be­cause when I was ma­nip­u­lat­ing the joint to work in the grease, there were dry points on the cage where it meshes with the outer body of the joint. The joint also had fair amount of slop in it, but I don’t get any click­ing noise when driv­ing round in a cir­cle on full right or left lock.

The Clio has cov­ered 65,000 miles and has its orig­i­nal shafts and joints. I changed the gear oil at 60,000 miles with fully-syn­thetic Cas­trol SLX which I be­lieve is 75w85. It is a lit­tle bit thicker than the Tran­self, but I did con­sult with a me­chanic and he said it would be fine be­cause he uses a 75w90 semi in these boxes. An­thony Pat­tin­son

You will ap­pre­ci­ate that di­ag­nos­ing a noise without hear­ing it is not easy. The fact that de­press­ing the clutch al­ters the noise is a good start­ing point. When de­press­ing the clutch, you are ef­fec­tively dis­con­nect­ing the en­gine and any brak­ing force it is ex­ert­ing. This will re­sult in the tor­sional pres­sure be­ing re­leased from the en­gine. If the noise was due to en­gine mount­ing prob­lems, I would have ex­pected it to stop when the clutch was de­pressed.

This leaves the clutch and trans­mis­sion sys­tem. As the noise starts be­fore the clutch is de­pressed, it is un­likely this is the cause, al­though I would try ex­ert­ing a very light pres­sure on the clutch pedal to elim­i­nate the pos­si­bil­ity of it be­ing a clutch bear­ing.

The re­main­ing com­po­nents that could be caus­ing the noise are the gear­box and fi­nal drive sys­tem. It would ap­pear from the de­tails you have given that the in­put shaft bear­ings may be fail­ing. By de­press­ing the clutch you are al­low­ing this to over­run without be­ing se­cured by the clutch plate. Free play in the bear­ing could be al­low­ing this to whip slightly, in­creas­ing the noise.

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