1st Gen R53 Cooper S Most liked posts in thread: Strange sounds, cold starts, and more!

Is this a stick or auto trans car?

Rear main seal usually means pulling the transmission and clutch assy. At 85K I'd plan on replacing the clutch if you pull the tranny. (stick shiift only, of course)

Idle problems could be temp sensor related, is it throwing any codes? Maybe stop by an Autozone or such and have them check if there are any codes stored.

Transmission oil seals are different than boot and don't come with. If you have the axle out to fix a boot, that's the time to replace the stub axle seals too - even easier if the tranny's out.

If you have the front end off to gain access to remove the tranny, that's the time to check and see if the supercharger still has oil in it - both ends. You can buy S/C oil from a GM dealer. Same stuff used in Cobalt SS and such....

 

If you have an aftermarket differential, the leak is more likely from the transmission input shaft seal than the rear main. Collect the drip and smell, gear oil has a distinct odor, or a florescent dye can be introduced in the gearbox and checked with a black light.

If you have a boot tear (radial grease marks flung on the case, control arm, and subframe), replace the boot and lube; $500 less costly than an axle set, which does not come with output seals. Without lube in the tripod or CV joint, wear occurs rapidly.

The list is long for idle inconsistencies, for an erratic hunting idle suspect the supercharger intake duct profile gasket, for hesitant idle change the spark plug wires (if older than 50k-miles change anyway), corrosion on the coil pack terminals, worn spark plugs (incorrect gap also), dirty injectors, poor seal on the IC bellows, crack in the MAP sensor tube, have an associate start the car while observing the BPV to be sure it is opening and not fluctuating, also press its actuating arm and test for free movement, if after addressing those parts the poor idle continues, come back and ask the question again and we’ll go from there; I haven’t even mentioned the elephant in the room yet.

To test the crankshaft vibration damper, remove tension from the belt, and grasp the pulley, if it wiggles or moves the slightest, the pulley is failing. Grasp the idler pulley and feel for wiggle and spin listening for grating or roughness, if loose, try tightening to 33 lb-ft and check again, if noisy, replace. Perform the same procedure to the tensioner pulley. If no problem there, start the car without the belt on and listen, if the noise is no longer present, replace the belt, if the noise remains after changing the belt, pull the supercharger and have a look while changing the oil in both reservoirs.

 

For me the whine was a power steering fan about to fail. You can check with the car on jack stands or ramps at idle. With my car, you could hear it as soon as the fan kicked on. See: http://www.motoringalliance.com/forums/cooper-s/1921-engine-sounds.html

 

Do you have an Oil Catch Can? If you do you should check if any of the hose is pinched at all. I was having a super bad oil leak because a hose was pinched...