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

When is the last time you checked under the hood and inspected your alternator’s housing?

Though it does not appear to be a common issue, some car owners have discovered that their alternator housing has a crack upon inspection.

Now, this can be worrisome, especially if you consider that this crack presents a potential point of weakness on the fast spinning alternator that is already under tension from the belt and mount.

So, do you leave the alternator as is, repair it or replace it with a new one? The advice out there is mixed.

So, in this guide, I will share with you my thoughts on whether you should repair, or replace the cracked alternator housing and what can cause the cracking to help you avoid situations that can result in damage to the housing.

Should You Repair the Cracked Car Alternator or Replace with a New One?

This is a judgment call best made by a qualified and experienced mechanic.

The crack may be superficial or deeper and close to either the mounting or the bearings. Some people have repaired the cracked housing with mixed results.

Repairing it saves you money (in the short term) and can probably buy you some time until you get to the next stop but it is difficult to tell if and when it will fail again and what additional damage it can cause.

In my opinion, It is probably best that you replace the cracked alternator with a new one, covered by warranty so that you have peace of mind.

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

Risks of Cracked Car Alternator Housing

Depending on the extent of the crack, it can significantly increase the chances of the alternator failing and causing more damage if, for example, the car hits a bump.

At a minimum, should the car alternator fail, the battery will not be able to charge and therefore your car will fail to start when the battery is drained or lose electric power as you drive.

How Long a Cracked Alternator Lasts?

It is difficult to estimate how long a cracked alternator will last. There are a number of factors involved. For example, is the

  • crack superficial or deep,
  • Is it close to the mounting or otherwise,
  • how good the repair job has been

Signs that your Car may Have a Cracked Alternator Housing

Depending on the nature of the crack – whether superficial or deep, your car’s alternator may be able to continue working well without any challenges.

In fact, several people only notice there is a crack when during belt replacement or as they are investigating an unusual noise in the engine.

So it is possible to have an alternator with a cracked housing that still supplies power to the car’s electrical system as expected without any problems whatsoever.

That said, sometimes you may notice the signs below. Note that they are not conclusive and it is possible that the fault is not a result of the crack in the housing.

#1. The battery light comes on occasionally signaling a problem with the car’s charging system. This problem may also be caused by a loose battery or alternator wiring, or a bad ground connection.

You can check this in-depth article: Why your battery light keeps coming on and off

#2. Rattling noise coming from under the hood. Depending on the extent of the crack, you may hear a rattling sound as the loose parts vibrate.

What Causes an Alternator Housing to Crack?

Good quality alternators can last for many years but occasionally you may find one with a cracked housing. Should you find that your car’s alternator is cracked, here is a list of possible causes you can investigate.

#1. Stress on the alternator as a result of it being misaligned. Your alternator may be misaligned because the mounting bolts are unevenly tightened applying uneven stress on the alternator causing the crack.

So, check that the alternator bolts are properly tightened and that the alternator is aligned properly.

#2. Alternator belt not tightened properly. If the belt is not tightened properly you can have some vibration which overtime applies uneven stress on the alternator creating a crack.

#3. Metal fatigue. Sometimes the metal build of the alternator fails after many years of use after being subjected to vibration and stress.

This appears more common with used or refurbished car alternators.

#4. Hitting the alternator housing to align the belt. Repeated hitting the alternator housing to correct misaligned belts can also damage the housing over time.

Final Word

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

The signs of a crack are not always obvious, sometimes you have a battery light flashing or a rattling noise from under the hood.

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

Make sure it is properly installed and well-aligned to prevent a repeat of cracking the housing.

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