2007 Jeep Compass about a month ago started hearing grinding. No indicator lights no problems with performance. Yesterday got louder and this morning batt light came on added water to batt started the car waited a while turned it off tried to start again all indicator lights remained on and car would not start. Would not even crank. I thought it was alternator but then waited lights came on security system works radio works. Could this be the starter?
The clue is the battery light. That has nothing to do with water or the battery's condition. That means the alternator isn't recharging the battery.
Worn brushes are common on the silver Nippendenso alternators and they're pretty inexpensive to replace, but that usually doesn't occur until after 150,000 miles unless you drive on a lot of dusty roads.
The place to start when the warning light comes on is by measuring the battery voltage with the engine running. It must be between 13.75 and 14.75 volts. If it is low, measure the two voltages on the small wires on the back of the alternator. That must be done with the engine running.
You might also use a stethoscope to listen next to the alternator's pulley for the grinding noise. If you hear it there, suspect the pulley / clutch assembly. They typically get noisy at around 60,000 miles.
March, 14, 2012 AT 6:43 PM
The problem is limited money (which seems to be everybodies problem these days) I am also no a mechanic nor am I good at fixing things. I think I can replace the alternator but is the pully clutch assembly sold seprate from the altenator or will it be replaced by replacing the alternator. And I dont need a stethoscope it is very loud grinding and clanking I think you are correct in suggesting the pully because I have had an alternator go without hearing that grinding in other cars. But I never had pullies go. But can I replace the pullies without replacing the alternator to save money
March, 14, 2012 AT 8:01 PM
I just went through this with a friend's car. The alternator itself was okay but the intermittent crunching noise was hard to locate without the stethoscope. He tried two new idler pulleys first but they didn't solve the noise. He took the alternator to a local rebuilder who showed him what that clutch is supposed to do and how his was acting differently. It is supposed to reduce the stress on the belt. Seems like the engineers found a solution where there was no problem.
The rebuilder had the special tool for removing and installing the pulley. That solved the noise. I have the old pulley here but haven't had time to autopsy it to see how they work. My best guess is if they start to slip, the electrical load might slow the alternator down which would turn on the "Check Gauges" and / or "Battery" light.
September, 13, 2013 AT 9:39 PM
I have seen the alternator clutch pulley cause the same noise. Very common.