What Are The Signs & Symptoms Of Bad Rectifier On Outboard?

Rectifiers on outboard motors are responsible for converting alternating current (AC) voltage that the stators generate into the direct current (DC) voltage so that the engine batteries can stay continuously charged.

Today’s article will help you detect a bad rectifier and fix or replace it before it can cause any major damage to your outboard engine or battery –

What Sign You Should Look For To detect Bad Rectifier?

When the rectifier turns faulty or bad, it can damage the engine battery and force the engine to shut down completely.

However, some common indicators give the warning of rectifier damage, and one of the most common signs is when you realize your outboard motor’s battery is draining quicker than usual.

What Are The Symptoms Of Bad Rectifier On Outboard?

The symptoms of having a bad rectifier on your outboard are usually associated with the following indications:

Outboard Battery Drains Out:

Generally, the battery drains out when the diode burns out, and it happens because of a faulty or damaged rectifier in your outboard motor. Since a damaged rectifier tends to generate overheat, that excessive heat eventually burns the diode metal.

When the battery unusually drains out, it also directly affects the engine’s performance so, if you notice closely, you will see the difference very easily.

Engine Struggles & Accessories Malfunction Occurs:

Another symptom that people commonly encounter when the rectifier fails is struggling with starting the engine.

Even if the engine starts after several tries, you will see that the engine is performing poorly and stalling in between.

Some also claim that the outboard motor eventually dies and does not re-start again.

Accessories Malfunction & Meter Reading Fluctuate:

When your outboard rectifier is bad, you may also notice certain accessories are malfunctioning, such as faulty ground gauges, wires, etc.

When the meter reading constantly fluctuates, that is also another considerable indication of a faulty rectifier.

If you ever encounter any of the above-discussed symptoms, along with other major inspections make sure to investigate the rectifier’s condition too.

How Should You React If You Detect A Bad Rectifier On Outboard?

To get rid of the damages a bad rectifier may have caused, you need to act quickly but calmly.

Also, follow the below-mentioned instruction for an easy & quick solution-

Immediately Disconnect The Battery & Check Your Service Manual:

As soon you notice any of the mentioned symptoms of a bad or damaged rectifier, turn the multimeter onto the diode function and disconnect the battery.

Always remember, based on your outboard motor’s model number and brand, the test of determining whether your rectifier needs a replacement may vary since the used diode feature varies.

So, it is better to double-check the procedures and other specifications, such as wire colors with the engine’s service manual.

Therefore, before you start the detailed inspection of your existing rectifier, check the service manual for the correct and specific instructions.

Investigating The Diodes:

Now, to do the proper investigation, take several readings with the connected multimeter.

First, you need to connect the positive lead to the positive diode and the negative lead to the stator input. Then, check whether the reading shows empty or not because there should not be any reading on the meter.

Next, you need to disconnect those leads and connect them in the opposite direction, like the positive one to the stator input and the negative one to the positive diode.

Once again, check your meter reading, and you should be able to see numbers on the meter reading this time. Follow the same instruction for checking the negative diode, and the result should be similar as well.

Check Battery Readings:

After checking the diodes reading, it is time to inspecting your battery readings too. But remember, you should test the battery reading when the battery is running.

To run the battery reading test, connect the leads to the battery, and after connecting check the reading meter. The standard rate of battery reading should show either more than 14.3 volts or less than 13.5 volts.

If you see higher reading than the mentioned rate, it means the battery is overcharging. If that is the case, you have to replace the rectifier.

Replacing With New Rectifier:

After the testing, if you find the rectifier needs to be replaced then do it. First, make sure the negative terminal to your battery is disconnected. Now, you need to open the engine’s top cover on the rear side and find the rectifier. Then, remove the left screw to pivot the rectifier.

Before pulling out the old one, you will notice a positive sign on the top upright position and follow the same form during the installation of the new one. Also, make sure all the old rectifier wires are removed.

Now, bring the new rectifier and back the knots out by using a 3/8 socket and shift the wires from the old to the new one. Start hooking them up accordingly, and hook up the muffs to the actual engine.

You can replace the rectifier by following your service manual since the wiring diagram is mostly included in the manual with all details. But better to hire a professional, if you are not good with technical activities.

Are Replacing Bad Rectifiers Typically Expensive?

Fortunately, replacing the outboard rectifier is very affordable, and even the rectifiers do not cost much. They will surely fit in your budget range, and if you do the whole servicing task by yourself, it will be cheaper.

However, if you are not familiar with the task and it’s your first time, I strongly recommend hiring an expert or professional. It will be a bit costly than doing it by yourself, but worth it since you will not wish to ruin your new rectifier to save few dollars.

How Often Should You Check Rectifier On Outboard?

Technically, you should do a thorough inspection test on your outboard rectifier whenever you notice any symptoms that I have discussed earlier.

However, to stay on the safe side, always do the regular required servicing or maintenance of your outboard. Also, read your product’s service manual to confirm when and how to do the servicing of essential parts.

Final Thoughts

A faulty rectifier causes an imbalance in the voltage, which can overcharge the batteries, or the engine may shut down because of overheating. But if you are aware of the symptoms that indicate a faulty rectifier preventing those damages becomes less stressful.

Therefore, you should keep an eye on any possible scenario that indicates fault or damage in your rectifier to prevent severe engine battery failure.

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