To rule out oil contamination as a possible cause of slippage we check under the rear of the engine and the transmission bellhousing for oil leaks. If we see oil on the oil pan or the bellhousing, the rear main oil seal is in all likelihood leaking.
There is however other locations of leak points which include the manifold and valve cover gaskets at the rear of the engine and the transmission input shaft seal.
If there is an oil leak it makes no sense to replace the clutch before the leak has been repaired. Once the clutch linings have been contaminated by oil there is no way to clean them. Replacing the clutch disk is the only way to restore proper clutch operation.
If there does not appear to be an oil leak the next step would be to check the linkage adjustment. Most cars with a cable linkage have an automatic adjusting mechanism that is supposed to maintain proper clearances. Normally if anything the linkage adjustment cable will be too loose rather than too tight. If however someone has been playing around with the linkage adjustment they may have adjusted it too tight. Hydraulic linkages are much the same and there's no way this type of linkage can cause slippage unless it has been misadjusted by someone in the past.
After we have checked the above we are left with the clutch itself. Slippage is caused by either or both of two thing’s worn clutch facings or loss of spring tension in the actual pressure plate. Unless a clutch has really been abused or has a lot of miles on it then it's unlikely the pressure plate is weak. Normal wear over time reduces the thickness of the facings on the clutch disk, much like your brake pads, which in turn reduces the force the pressure plate can apply as it presses the disk against the flywheel. Replacing the clutch disk is the solution to this problem.
The clutch and flywheel will be carefully inspected when the parts are removed. If the pressure plate is worn or damaged we will need to replace it also. Most experts recommend having the flywheel refaced to restore the friction surface. If there are any grooves, discolouration from heat, cracking or other damage then the flywheel will at least have to be resurfaced and possibly replaced.
At National Transmission we are dedicated to providing the best possible diagnosis and repair services for your vehicle’s clutch, serving Calgary and surrounding communities. If your vehicle’s clutch is not performing, schedule an appointment
and we will solve your clutch problems.