How to fix the alternator problem of a classic car
If you have a classic car from the late 1950s to the late 1970s, then the car should be equipped with an alternator. If it is older, it may have a generator. If you are interested in learning more about generators, we have a very popular article explaining why generators are converted to alternators.
In this article, we will address charging system problems caused by alternator failures. For decades, we will also answer questions that plague car owners.
Should you rebuild the original alternator or replace it with a refurbished unit or new part.
Replace or rebuild the alternator
In the classic car, I firmly believe that original equipment parts are retained as much as possible. In many cases, alternators offer the opportunity to replace internal defective parts while maintaining external originality. This is a must for those who participate in the protection-level auto show.
In classic cars, they installed the alternator in the front and center to make it highly visible. The picture above shows the engine compartment of the Porsche 356 1600 Super Roadster. This is an example of a textbook that explains why you want to keep the original components. The patina obtained from years of operation is often appreciated by the auto show judges. However, in some cases, it is not possible to save a factory-installed device.
An example is the case damage.
Most alternators are cast in aluminum. This strong but fragile metal can crack. Another problem area is the mounting location around the enclosure. Threaded holes with soft aluminum threads can be easily peeled off. The integrated mounting bracket may also break or be damaged.
Welding aluminum is a difficult operation and is not recommended in these cases.
Another problem that can damage the outer casing is the rotation of the inner bearing. All alternators will be equipped with front and rear axle bearings or bushings. If the part fails, it may spin in the aluminum casing and wear away the material. This damage may prevent the replacement parts from being properly installed. If the alternator casing is damaged, it is a viable alternative to replacing it with a new or rebuilt unit.
New alternator and remanufacturing
I am not a big fan of making alternators again. This comes from my experience of replacing them many times before receiving a good one. Having said that, my point of view should be considered a professional mechanic who has performed hundreds of operations. Remember that good experiences are human.
New replacement parts are available for popular model cars in the 1960s and 1970s. This is an example of a brand new alternator on the 1970 small 340 CID Mopar engine. Owners can even go crazy and provide high quality chrome plating for almost any muscle car. The new alternator costs more, but it can cost money. They usually offer a longer warranty and therefore get better tests before leaving the manufacturing facility.
Reconstruction of the original alternator
Although there are many components inside the alternator, the faulty components fall into two broad categories. Mechanical components such as bearings and shafts may wear like engine components. If the bearing fails, you may hear a click or even a grinding sound as the alternator rotates. These parts are almost always replaceable. You can purchase Timken alternator bearings separately at an average cost of about $20.
The next major fault group belongs to the electrical component category. When an electrical component fails, the alternator stops charging the battery. One of the main electrical components inside the alternator is a set of brushes. They are constantly conducting to the rotating rotor slip ring. These spring loaded brushes are designed to wear over time.
If your car is long enough, you need an alternator brush. Another common fault component inside is the diode Trio.
This device allows current to flow through one direction. When it fails, it allows current to pass in both directions. The diode Trio can be easily tested with a continuity checker on a car multimeter. Another component that may fail is the voltage regulator. In the 1960s, when they switched from the outside to the inside, this was a tricky part. This is what the external voltage regulator looks like. These components can be replaced at any time, whether inside or outside the box.
Rebuilding the original alternator will preserve the precious space of your classic car history. This is how much you can save at the same time. The new alternative Valeo alternator from the Porsche 356 Speedster shown above is priced between $600 and $800, depending on the year. The average replacement cost of the new Valeo 70Amp alternator’s new regulator and brush kit is approximately $20