What Causes a Car Alternator Housing to Crack (Should you Repair it?)

A crack in the alternator’s housing or mounting should be a point of concern.

There’s no telling (at least accurately) when the alternator can fail eventually leaving you stranded or cause further and more expensive collateral damage.

What should you do then? it is better to repair or replace?

In this post, I share my thoughts on what can cause the cracking so that you may be able to avoid it (whenever possible) and whether it is better to replace or repair the alternator.

Why an Alternator Housing Cracks

A good quality, properly mounted alternator can last for over several hundred thousand miles performing reliably without any signs of physical damage too.

What then can cause n alternator to develop cracks on its case?

1. The alternator may not have been properly installed. It may have been misaligned with the mounting bolts unevenly tightened causing stress on the alternator (bracket) which then cracks over time.

So, check that the alternator bolts are properly tightened and that the alternator is aligned properly when installing a new alternator.

2. It could be a poor-quality alternator. Is it a rebuilt alternator? Or, has it been in service for several hundred thousand miles?

Wear and tear can take their toll on the alternator over time causing cracks in some cases on the alternator case or mounting bracket.

How Long an Alternator with a Crack Lasts

Trying to predict how long an alternator will last is risky as the odds are you’ll be wrong.

There are several variables involved outside your control. For example,

  • Is the crack superficial or otherwise,
  • where the crack is located – is it close to the mounting or elsewhere,
  • your driving habits – do you drive mostly offroad or not

In my opinion, it’s not worth the risk, better to replace it as soon as possible and have peace of mind.

You may also be interested in the post: What can damage an alternator?

To Replace or Repair an Alternator with a Crack

The short answer is to have a qualified auto mechanic inspect the crack and advise you on the next steps.

It could turn out to be a minor and therefore nothing to worry about at least in the short term.

You should probably inspect it from time to time to check if it’s getting worse or not. Are you ready for this?

Not only will you have to keep an eye on it, but you’re also risking more damage to the car should the bracket or alternator fail as you drive.

The alternator easily spins over 1,500 RPM and over and is under tension from the belt and mount!

This can easily end up costing more than what you’d have spent on replacing an alternator! Is this a risk you want to take?

Signs of a Cracked Alternator Housing

Is there a particular sign that can point to a broken alternator housing?

Not always, in fact, it’s quite likely that an alternator may have a crack and still work well – the battery charge is maintained and the car electricals are powered.

I’d therefore make it a point to inspect the alternator mount when replacing the alternator belt, and hear unusual sounds from or around the alternator.

You can check this in-depth article: Why the car alternator may make a rattling noise

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What Causes Cracks on a Car Alternator belt?

A car alternator belt develops cracks over time from wear and tear. That said, they may form sooner if the belt is not properly tensioned or the wrong belt is fitted.

Should you hear abnormal noises as the car alternator spins, with the car engine switched off and the alternator cool, carefully inspect the alternator.

It is possible that the belt is worn, stretched, cracked, and needs to be replaced.

Make sure you replace it with a recommended alternator belt and that it is properly tensioned.

Closing Thoughts

Though not common with a good quality alternator, a car alternator housing may crack as a result of stress from overtightening mounting bolts, being misaligned, or metal fatigue from the constant vibration of the alternator over time.

The signs of a crack are not always obvious. You should do a visual inspection whenever you hear unusual noises.

While some people can drive with a cracked alternator, it is probably better in my opinion to replace it with a new one for peace of mind.

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