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Wednesday, August 4, 2010

I had to tap on the Starter to get it to work!

I get this all the time. People will bring in their Starter with anything from a few spots of chipped paint, to beat it up with a hammer so bad that there are no usable parts left! Seriously! A guy came in to my shop a couple of months ago that had a starter that was so deformed from beating it with a hammer that it was nothing but scrap. No salvageable parts at all! And he was the type of guy that had no money and had bought a defective starter from a salvage, to replace his bad one and wanted me to fix it too!

Tapping or hammering on starters is old school and something that went out in the 1970’s. Let me explain what tapping on the unit does and why it had helped in the past. Usually with most starters, if a little moisture gets in the housing and rusts up the brushes and brush holders or the brushes are about worn out, tapping will sometimes free them up a bit, letting them make enough contact to make the starter work temporarily. That’s all tapping will do! It is no magic formula to fix anything, doesn’t help with dead spots or other problems that it may have and is only a ‘Temporary’ measure to get you home or to the mechanic! If tapping on the unit doesn’t offer instant results then there are other problems and all the hammering in the world will not make it work. It’ll just destroy the unit!

The problem is, as with most people, if they tap on it and get it to work, instead of pulling it off and getting it repaired when they get home, they keep hammering on it, more and more until they’ve beat the hell out of it. All the time this is causing internal damage as the brushes keep excessively arcing the copper off the commutator and ruining the armature, also deforming the case changing armature clearance to cause possible dragging and shorting out the windings if they are hitting the solenoid. Now their repair will have doubled in price due to the additional damage! I estimated that each hammer blow costs the customer anywhere from 50 cents to a dollar in added repair expenses, depending on the design and cost of the unit!

Now with all the smaller designed units of today, many of them have permanent magnets instead of field coils. They can shatter easily with just one misplaced blow to the case. Many replacement parts for these are not available and completely ruin the starter and without a salvage starter with good donor parts, it is not repairable and will have to be replaced with a new unit! If the parts are available, the cost of repair can exceed the cost of a new unit, so there’s a no win situation!

So, my advice, put the hammer back in the toolbox and get out the wrenches, pull the starter off and take it to the repair shop! If you’re broke down out on the road and need to try something to get you home or to the repair shop, lightly tap on only the back end of the starter and not the side case or the solenoid. That’s where the brushes generally are anyway and where you can do the most good. (The back end of the starter is opposite the nose, which is usually stuck into the bell housing. It is the part that protrudes furthest away from the mounting bracket.)

When I rebuild starters I only charge for the parts and labor that I do and not a whole unit price, so if your rebuilder doesn’t charge a large flat rate for unit repair, not hammering on your starter and pulling it off and getting it repaired at the first sign of trouble, will save you money in the long run!


  1. same advice good with regard to an alternator?

    1996 jeep cherokee. sat up without being cranked or driven for about six months. jumped it off. 15 minutes later it died. replaced battery. the alternator was charging at or below 9 volts. i took the alternator to two different parts stores for testing. why two? first attempt was with a kid that obviously hadn't used the machine much, if ever at all. it past the test. but i was fairly confident it would fail. second parts store... fellow was very familiar with machine. it passed. without hesitation he tested it a second time. passed. i asked if he was sure the machine applied a load during the test. he said it did and asked me if i'd like to go for a best of five test. passed. four tests all indicated alternator was good. take it home re-install. tighten belt. runs like a champ, charging at or around 14 volts for quick trips around town. took it on a road trip. vehicle is in desperate need of a good alignment. (checking account is in desperate need of lots of other things). substantial shake, particularly at good road trip speed. after a couple hours on the road, voltage needle drops to at or around 9. hit passing gear to go around a slow-poke in front of me. the jolt of the motor/transmission being thrown into passing gear threw the voltage needle back up to 14. couple more hours on road does it a few more times. reached destination and along with the destination came a driving environment non conducive for goosing it. been through the whole starter tapping thing before. so i tap the alternator. couple gentle tapes later, back to 14 volts. have repeated the tap procedure several times now. does this mean the alternator is in fact bad? or could these drops be a reflection of loose drive belt. alternator pivot bolt is stripped. belt tension adj bolt is broken. so i only have two of the four nut/bolts originally designed for the purpose of setting belt tension. it is apparent that the shake of the misalignment and uneven worn tires for the extended period of the road trip created a little slack in the drive belt. meanwhile, i'm tapping it back to life with pretty good frequency. it i find a replacement tension bolt and figure a way to get the pivot bolt tightened... do you believe the tap would still be required? is a 1/4 to 1/2 inch additional slack in drive belt capable of creating this tapping situation? was the slack ever capable of creating this condition? or is what i'm observing simply the process of the alternator dying a slow and unavoidable death? if the alternator is replaced and broken/stripped bolts not remedied, could the additional slack burn up the replacement?

  2. It is a better idea to purchase a completely new alternators for vehicle that's incorporated by assurance. Many High quality alternators and starters like Denso, Bosch which have greatest excellent and reliability for many heavy-duty automobiles to boost performance. These brands are available at affordable cost points inside the reliable distributor.