2001 Suburu Outback Engine will turn over with jumper cables but it won't start

JESHUASCHILD

MEMBER
2001 SUBARU OUTBACK
120,000 MILES

It was 7 degrees this morning, went out to start the car and she wouldn't turn over. Some battery juice as doors dinged when I got in, etc. AAA came and said it won't start because battery cable had too much corrosion on it. Cleaned it off a few hours later and had a friend try jumping it and same thing happened, it would turn over but not start. Eventually ran down. Is it possible it is the alternator or do I need to take the cable completely off the battery to clean it.

2 Replies

CARADIODOC

MECHANIC
33,742 POSTS

You mean you just cleaned the residue off the outside of the connectors? That isn't going to accomplish anything. The corrosion gets between the battery post and the cable clamp and prevents a good electrical connection. Over 100 amps has to get through those connections to run the starter motor. That's about five times more current than it takes to run everything else on the car. That corrosion can make the engine crank too slowly to start, but if it is indeed cranking normally, the no-start is due to something else. The place to start is by checking all of the fuses. Often they will blow from the surge of connecting jumper cables or a charger when there is no other problem.

Also be aware that corrosion on the battery cables shows up due to the battery being about to fail, usually within six months. So much lead has flaked off the plates over time, (which is normal and can't be avoided), that the charging current going back in heats up what little lead is left. That causes the acid to bubble harder than normal, and those bubbles reach up to the top of the battery case where the liquid seeps out next to the posts and forms that corrosion. You'll find there is no corrosion on good or fairly new batteries.

Once the engine is running, use an inexpensive digital voltmeter to measure battery voltage to test the charging system. It must be between 13.75 and 14.75 volts.