Broken Starter Bolt Hole Fix – Dealing with the Serious Issue

There are various ways to deal with a broken starter bolt hole such as using a Heli-Coil thread repair kit, applying chemical thread filler, replacing the starter, etc. You or your repairer may have to get creative with the fix depending on the type or extent of damage.

Starter motor problems highlights

• Level of urgency:Medium
• Can you drive?Yes, if it starts
• DIY inspection:Possible but complicated
• DIY repair:Impossible
• Price for repair:$300 - $650
• Common Reasons:Internal problems, gear issues, flywheel problems, mount problems
• Ways to fix:Have it repaired by a professional

How Serious Can a Broken Starter Bolt Hole Get

A starter works when you turn the key in the ignition to switch on your vehicle. Turning the ignition will make the electromagnet inside the body engage and push out a rod that is linked to the pinion. The pinion will then meet the flywheel so that the starter motor can turn.

The above sequence will make the engine spin over (crank) and take in air and fuel. Once the engine starts turning over, the following will take place to prevent damage: of

• Disengagement of the starter
• Stoppage of the electromagnet
• Retraction of the rod into the starter motor
• Disconnection of the pinion from the flywheel

You could actually use your car or truck for a long time without realizing that its starter bolt hole has sustained some form of damage. You could even notice a crack in the hole and still be able to use the vehicle for months without it causing a hindrance.

So what happens when the starter bolt hole gets damaged to a point where you can't use your car? The starter won't be able to line up with the flywheel, thereby preventing the vehicle from starting. It may just make a spinning sound which could at least easily bring your notice to the fault.

A starter that can't line up with the flywheel can get you stranded at an inconvenient spot. Worse still, it could be a place or roadside where there's no sign of people, buildings, or vehicles passing. So this area of your car should be checked routinely. And any sign of damage should be treated with urgency.

Various Broken Starter Bolt Hole Repairs

This section has various fixes that can be implemented, depending on the type and extent of bolt-hole damage. We will start with one of the most common ones which is the use of a Heli-Coil thread repair kit.

1) Utilizing a Heli-Coil Thread Repair Kit

Experts have recommended this method as the correct way to repair a broken starter bolt hole. You'll need to order a new starter bolt from your dealership and then take it to a reputable auto parts store in your area. The sellers will measure the thread size of the bolt and offer a compatible Heli-Coil thread repair kit for it.

It's advisable not to go to a discount auto parts store for this kind of product because the attendants usually know little about cars or repair methods. Some have inadequate or no training about the fixes or use of the products.

So it's best to go to an old-time auto parts store that has been in the business of selling auto repair kits for several years and has attendants with a good level of expertise. The attendants will surely know exactly what you want when you explain that you need a Heli-Coil kit to fix starter bolt-hole damage.

The Heli-Coil Thread Repair Kit

Heli-Coil kits feature special spiral-shaped stainless steel springs, thread taps to cut threads for the inserts and installation tools. See how to use a Heli-Coil kit below.

Procedure for Using the Heli-Coil Kit

Step 1: Drill the broken hole larger following the specified measurement on the kit.

Step 2: Thread the hole with the included tap.

Step 3: Use the installation tool to drive the thread insert into the widened hole.

Step 4: Cut the end of the coil to be on the same level as the top of the bolt hole.

Step 5: Insert the new bolt into the renewed hole.

There are times when the bolt may be broken off in the hole. This situation should be resolved by starting with a very small drill bit targeted at the center of the bolt. Then you'll move on to a higher size of drill bit. Use this approach until the hole is drilled to the correct size.

The above explanation is the only way to drill a bolt that's stuck in the hole, but it takes a lot of time and effort. This is why doing it at an auto repair shop will cost you a lot.

The repairer will spend hours drilling, while his or her body will be in an uncomfortable position. Let's not forget the metal shavings flying off and dropping down on one's body.

2) Replacing the Starter

Swapping out the starter is another fix that you could try when one or more of its bolt holes break, especially the outer one. This is suitable for severe damage, where simply repairing the bolt hole won't work.

The replacement should be done by a professional mechanic who can come to where the vehicle is to execute the job. That's unless you can afford to tow the car or truck to the repair shop.

Mechanics disconnect the battery before beginning the procedure. Then the starter's wiring will be disconnected as well. You can proceed to remove the starter bolts after that. The number of starter bolts is commonly two, but there could be three in some vehicle makes and models.

Accessing the starter in a vehicle isn't a job that has a general method. It also depends on your car's make and model. Repairers may have to remove or lower other vehicle parts before being able to conveniently reach and uncouple the starter motor.

Make sure to tighten the bolts (get new ones) according to the OEM factory torque specifications, while installing the new starter. The starter's wiring should be cleaned and reconnected, then you can try to start your vehicle to test it.

Starter motors use more power than any other device that utilizes electrical power in vehicles. Therefore; it's advisable to examine, clean, and tighten the electrical connections that run into the unit. The wires should also be changed whenever it's deemed necessary.

3) Utilizing Chemical Thread Fillers

A chemical thread filler is suitable for fixing moderately stripped bolt holes with little effort. You don't need a drill bit for the procedure. Just clean out the work area before beginning and read the product's instructions.

It will be necessary to use a tap to recut the threads of a hole that has sustained great damage before commencing the chemical filler procedure below.

Step 1: Rub some release agent on the threads of the new bolt.

Step 2: Apply the thread-filling material in the stripped bolt hole.

Step 3: Quickly screw the bolt into the hole.

Step 4: Allow the filler to dry for some time.

Step 5: Detach the bolt.

Step 6: Clean off the release agent from the bolt and work area

About Bolt Thread Patterns

You could ruin a bolt hole's threads if you use the incorrect bolt or force it down the bolt hole. Most modern bolts feature either ISO (International Organization for Standardization) Metric Thread or American Standard Thread classifications. The former is commonly called "metric", while the latter is usually referred to as "standard".

"Standard" is sized in threads per inch and it measures the bolt's greater diameter and length in inches. For instance, the standard 3/8-16×1-78 bolt measures 3/8 inches across its greater diameter. This is with 16 threads per inch and a length of 1-7/8 inches.

On the other hand, "metric" is sized by thread pitch, that is, the distance between each set of threads. Its bolt's greater diameter and length are measured in millimeters. For instance, the metric M10-1.5×45 bolt has a thickness of 10mm with a 1.5mm thread pitch and a length of 45mm.

Conclusion

Try not to put off the engine if you discover that a starter bolt hole is cracked or broken while on the road. Doing so may leave you stranded if the damage has gotten worse and made it impossible for the starter to line up with the flywheel. Repair the bolt hole once you get to a convenient or suitable location.

You should always hire a repairer who has adequate experience and expertise concerning damaged starter bolt holes. For example, look for one that can handle cast iron welding if the target area needs it. Some repairers who perform welding jobs shy away from cast iron welding because of the difficulty level.