939010108 - S028 REAR NOISE (KNOCKING)

Whilst driving, especially on unmade roads, there is knocking coming from the rear suspension. This diagnosis can only be made after See table . Carry out the latter first.
If the problem is only on one side, carry out the checks and any operations on the appropriate side only.
Results of the tests
0PRELIMINARY CHECKSAll OKProblems encounteredOperation
Having carried out the road test, see the Table    S15 RUMOROSITA'' in condizioni di marcia, there was a knocking noise from the back.Continue depending on the circumstances in which the noise occursEnd of diagnosisThe noise disappears when the handbrake is operatedRestore the correct tightening of the rear brake calipers to the stub axle.
The noise only occurs during acceleration or braking.Move on to Step 1
The noise is also present in other conditions.Move on to Step 1
1OIL LEAKS CHECKAll OKProblems encounteredOperation
Raise the vehicle on a two column lift and check that there are no oil leaks from the shock absorber stem.
Slight dampness on the stem is considered normal because there is evaporation during the operation of the shock absorber.
If there is a persistent oil leak on the shock absorber stem, make sure that it is not coming from other parts of the vehicle that are lubricated
Move on to Step 2Leaks from other parts that are lubricatedSearch for the cause of the leak following the appropriate diagnostic procedure
Leaks from the shock absorber stem.Replace the shock absorber Op.    Op. 4420A12 REAR SUSPENSION DAMPER (ONE), LH OR RH - FOR MCPHERSON STRUT SYSTEM - INCLUDES DISMENTLING/REBUILDING OF ASSEMBLY AT BENCH R R
2HANDBRAKE CHECKAll OKProblems encounteredOperation
Check that the handbrake cables or outer casing do not knock against the fuel tank, heat shields or bodywork during oscillations.Move on to Step 3Inteference between outer casing or cables and other elementsCover the outer casing with foam rubber tape in the area of the interference or lubricate the cable
3INTERFERENCE CHECKAll OKProblems encounteredOperation
Check that there are no signs of interference between the suspension elements or between the latter and the bodyshell.In particular, check that there are no signs of wear on the suspension springs and that they do not show signs of abrasion
Move on to Step 4Inteference due to incorrect fittingEliminate the interference and restore the correct fastening. If this is not possible, replace the defective components
Abrasions or non conformity of the springReplace the spring Op.    Op. 4420A12 REAR SUSPENSION DAMPER (ONE), LH OR RH - FOR MCPHERSON STRUT SYSTEM - INCLUDES DISMENTLING/REBUILDING OF ASSEMBLY AT BENCH R R taking care to fit it correctly
4TIGHTENING TORQUE CHECKAll OKProblems encounteredOperation
Locate the area of the possible noise source: top or bottom.Starting from the area where the knocking was identified, check the tightening torques See Test    4420B Verifiche corretti serraggi sospensioni posteriori

Of the bolts fixing:

  • longitudinal anchorage strut bushes to the hub;
  • longitudinal anchorage strut bushes to the bodyshell;
  • bushes for front/rear track control arms to the shock absorber;
  • bushes for front/rear track control arms to the crossmember;
  • shock absorber to steering knuckle lower fastenings;
  • brake caliper to steering knuckle fastenings;
  • brake disc shield fastenings;
  • anti-roll bar to crossmember fastenings;
  • crossmember to bodyshell fastenings;
  • stub axle to hub upper/lower fastenings.
  • connecting rod between anti-roll bar and shock absorber fastenings.
Move on to Step 5Torque tightenings not correctRestore the correct tightness
5CHECK ON FRONT AND REAR TRACK CONTROL ARMSAll OKProblems encounteredOperation
Check that there is no clearance between the front and rear track control arms and the crossmember.Also check the condition of the suspension bushes.Move on to Step 6There is clearance or the front arm bushes are not intact.Replace the front track control arms
There is clearance or the rear arm bushes are not intact.Replace the rear track control arms
6CHECK ON LONGITUDINAL ANCHORAGE STRUTAll OKProblems encounteredOperation
Removing the protection for the fastening on the bodyshell side for the longitudinal anchorage strut

Check that:

  • there is no clearance between the anchorage strut and the bodyshell;
  • there are no glycol leaks from the bush secured to the bodyshell;
  • the rubber part of the bush, on the fastening securing the strut to the hub, is not detached from the steel outer casing.
Move on to Step 7There is clearance.Replace the anchorage strut
Glycol leaks from the bodyshell side strut fastening bush.Replace the anchorage strut
Rubber part of the bush detached from the steel outer casing.Replace the bush with a new one which has an aluminium outer casing (as described in Service News 44.03.04)
7ANTI-ROLL BAR CONNECTING ROD CHECKAll OKProblems encounteredOperation
Check that there are no signs of wear or tears on the connecting rod boots.Move on to Step 8Signs of wear or tears on the connecting rod boots.Replace the connecting rod
8SHOCK ABSORBER UPPER MOUNTING TIGHTENING TORQUE CHECKAll OKProblems encounteredOperation
When the luggage compartment interior lining side panels are removed following theOp. 7040B06

Check the tightening torques for the following bolts:

  • shock absorber to turret upper fastening;
  • damping plate to shock absorber fastening.
Move on to Step 9Torque tightenings not correctRestore the correct tightness
9CHECK ON CONDITION OF SHOCK ABSORBER TO TURRET MOUNTINGAll OKProblems encounteredOperation
The shock absorber must be removed in order to carry out this checkOp. 4420A10 L/H OR R/H REAR SUSPENSION SPRING/DAMPER UNIT (ONE) R+R, then check the condition of the shock absorber mounting on the turret.Move on to Step 10Rubber detached from the metal parts of the mounting.Replace the mounting.
10CHECK ON CORRECT OPERATIONAll OKProblems encounteredOperation
Check that the fault is no longer present.End of diagnosisThe fault persistsThe knocking is caused by another system (e.g. the fuel float in the tank). Carry out the appropriate checks to identify the cause of the noise.