Rick's Free Auto Repair Advice

Alternator installation tips

Alternator installation

Alternator installation tips

So you’ve determined you need a new alternator and you’re going to install it yourself. Great. Here are some alternator installation tips.

Disconnect your battery

Before you start working on your alternator, disconnect the

alternator installation

Disconnect negative battery terminal

negative battery terminal and store it away from the battery post. Making one little mistake while removing the output wire from the alternator can cause a huge short and blow out large fuses or even melt a fusible link.

Remove the alternator belt or serpentine belt

Most late model cars have a serpentine belt driving the alternator. To remove a serpentine belt, rotate the tensioner and slide the belt off one of the smooth pulley. Note the ease of rotating the belt tensioner. If it rotates smoothly without any binding, it’s probably in good condition. If it makes creaking noises or binds in certain places during the rotation, it’s a candidate for replacement.

Measure serpentine belt wear

Most late model engines are equipped with an EDPM style serpentine belt. EPDM belts don’t crack like the older nitrile belts, so it’s very hard to determine if they’re worn. You need a belt wear gauge to tell if it’s time to replace the belt. The wear IS NOT VISIBLE to the naked eye. You MUST use a wear gauge. This is really important for the proper operation of your new alternator.

See these posts on how to determine if the belt and belt tensioners need replacement

Serpentine belt drive systems

When to replace a serpentine belt

Diagnose a belt tensioner

Disconnect the electrical connector and output lead from the alternator

The electrical connector often has a depress to release clip. Depress the clip and remove the connector. The output lead is usually attached to a stud on the back of the alternator. The lead will usually have a nut and washer. DON’T LOSE THEM!.

Remove the alternator retaining bolts

This is pretty simple. Use a socket and ratchet or ratcheting wrench to remove the retaining bolts. You may have to remove the coolant reservoir to fully remove the bolt.

Transfer the pulley, if needed

Some new alternators don’t come with a pulley or fan. In those cases you must transfer your old pulley and fan to the new alternator. Do NOT use an impact wrench to tighten the pulley nut!! Pulley torque is 60-90 ft/lbs. If you over-tighten the pulley nut, it will pull the shaft forward and damage the bearings and brushes. This will shorten the life of your alternator.

Push the bushing back in place

Many alternator brackets have a split ring bushing as a space filler. To fit the alternator back in place you have to tap on the bushing to move it back into the bracket. Failure to do this will make alternator installation MUCH harder. If you have trouble moving the bushing, use a large drift punch or a long bolt with a nut screwed onto the end. Insert it into the bracket and tap it against the bushing until it moves.

Charge the battery

An alternator needs power to generate power. Not charging the battery before installing a new alternator is the single most common DIY mistake. The battery should be fully charged and reading 12.6 volts in order to the new alternator to operate properly. If the battery isn’t at full charge, don’t expect the new alternator to charge it!

Clean the battery terminals

High voltage drops due to battery terminal corrosion are responsible for many alternator failures. It doesn’t take long to clean battery terminals and posts. Do it before you install the new alternator to avoid problems later.

Install the new alternator

Simple reverse the removal steps, installing the output lead last.

Re-connect the battery terminals

Install the newly cleaned battery terminals and tighten. Then start the engine and check battery voltage with the engine running. It should read at least 14.2 right after starting.

©, 2018 Rick Muscoplat

Posted on by Rick Muscoplat

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