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As you know, a functioning alternator is vital. If you have noticed oil either coming from your alternator, extremely unlikely, or running into it, you’ll rightly be worried.

An oil-sodden alternator won’t be able to convert the engine’s mechanical energy into electrical energy. Oil has a very high combustion temperature, so even though the alternator does get extremely hot, it is unlikely to catch fire. However, you may experience a lot of smoke from the alternator when you get up to speed.

The alternator bracket is responsible for holding the alternator in its place to the engine. This is usually the culprit. 

Do Alternators Have Oil In Them?

No, alternators do not have oil in them.

However, the alternator bracket seal prevents the engine oil from entering the alternator. Any failure in the alternator seal can cause oil leakage in the alternator from the engine.

This can confuse as it can seep out of the air vents and appear that oil is located from within.

The alternator bracket has a gasket  – often made of cork- that prevents oil leakage.

Most of the time, when the oil leaks from the valve cover gasket, it goes down to the spark plug. This will affect ignition and reduce the engine performance.

Some alternators have a vacuum pump attached to them that operates the brake servo motor. 

The pump is directly coupled to the engine and completely lubricated with oil. Sometimes, the alternator oil seal that separates the pump from the alternator fails, resulting in oil leakage.

What Does Oil Do To The Alternator?

As the alternator’s job is to convert mechanical energy to electrical energy, any distortion or disruption to the contacts that allow this flow is bad. Oil will disrupt the flow of currents between the brushes and the slip rings. 

Oil is an insulator and causes high resistance and is, therefore, not something you want inside the alternator. Being an insulator also prevents heat loss from the inner workings of the alternator and can cause overheating.

Because of this, a small amount of oil in the wrong part of the alternator can cause it to fail, whereas a large amount covering the outside casing of it will cause very little trouble.

It’s always worth checking if you have oil on your serpentine belt. If it does, it will slip and not power the alternator sufficiently.   This can sometimes cause the alternator not to charge enough and has nothing to do with oil entering the alternator itself. 

Cleaning or replacing the serpentine belt is much more cost-effective and time-efficient than changing the alternator. 

Broken Alternator Mounting Bolts

If the alternator mounting bolt that connects the alternator to the engine breaks, then remove the alternator and disconnect all the electrical terminals. 

Then loosen the bolts on the alternator and take it out of the car engine. Clean the bracket and alternator bolt holes to remove any dirt or debris using WD-40 or spray rust penetrant.

Tighten the new bolt with the alternator bracket by applying suitable torque. Try to make sure that all bolts are tightened firmly to avoid any excessive vibration. The vibration causes the oil to sometimes leak through the gasket.

Alternator smoking due to an oil leak

Many visitors also read this related article: How Long Can You Drive A Car With A Bad Alternator?

How To Repair An Oil Affected Alternator

There’s a quick time-consuming way and easier, and perhaps less effective, way to clean your alternator if it is soaked with oil.

If we bear in mind that you have nothing to lose because the alternator isn’t working anyway, the simplest way of cleaning the oil from the alternator is to leave it in situ on the car and blast it with water from a jet wash. 

I would only do this if your alternator isn’t working and you don’t want to take the whole thing apart and clean it. It may seem counterproductive to inject water at speed into the alternator but bear in mind that alternators do get wet due to their position in the engine bay and can get wet. 

You are right, though, if you feel that being water-resistant in normal circumstances and having jet water forced into the winding and the stator may not be the best thing to do.

The other option is to use an electrical cleaner. However, some alternator manufacturers recommend you don’t do this  And suggest you use water or soapy water to remove excess oil. Perhaps this is an option if water hasn’t worked for you.

You might feel at this point that it is less hassle to replace the alternator, especially if it has been your car for more than 60000 miles or so. The make and model of your car dictate where your alternator is positioned. 

If you decide to remove the alternator, you’ll be able to get to the inner workings of it to clean it more thoroughly once again though it’s best to try cleaning it with soapy water before resorting to an electrical cleaner or degreaser. Always clean with a soft brush and wipe down with lint.

Be extra careful around the alternator bearing,s as you don’t want to clean out a small amount of oil in them. Although sealed, aggressive cleaners can penetrate them and dry them out. Beware of getting too much cleaner on the brushes, as they don’t appreciate getting wet.

The common reason for alternator bracket seal failure is excessive engine vibration and overheating. 

How To Clean Oil From An Alternator

If you need to clean your alternator, try doing so with water first and a soft brush. If this doesn’t work, you can try an electrical cleaner or degreaser to remove the oil. For best results, you may have to remove the alternator from the car and strip the alternator down.

This can be a real hassle, so it will definitely be worth trying to clean it in situ before removing it. If the alternator is quite old, you may feel it is simply better to replace it. Ensure you have replaced the valve cover gasket before doing this; otherwise, you will be left with the same situation soon after fitting the new one.

In Conclusion

Oil on the alternator is not dangerous, and your car will not catch fire, although it may create smoke. If the alternator is not charging the battery, always check the serpentine belt first to see if it has oil on it, as it may stop powering the alternator sufficiently. 

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