How can you check if the starter is bad?

Look for mold, unusual colors, foul odors, a slimy texture, or no activity after feeding. If you spot any of these, discard the starter. If it looks and smells normal and bubbles appear after feeding, it’s usually safe to continue using.

This guide walks you through practical checks you can perform—visually, aromatically, and in terms of fermentation activity—to determine whether a starter is still viable or should be discarded. It also covers steps to revive a borderline starter and when to start over with a fresh culture.

Visual signs to watch

Visual cues are the quickest initial indicator of trouble. Look for these patterns during your routine checks.

• Mold or fuzzy growth in green, black, pink, or blue hues on the surface.


• Unusual colors such as pink, orange, or muddy patches that don’t appear in healthy starters.


• A slimy, gelatinous film or an unusually slick texture that seems different from normal bubbly activity.


• Liquid separation with a dark or opaque layer that persists after stirring, especially if the starter smells off.

Visible signs like mold or persistent odd coloration are strong reasons to discard and start anew. Even minor changes in color or texture warrant caution.

Smell and texture cues

Smell and texture reveal whether the starter’s microbial balance remains healthy. Here’s what to assess.

• Pleasantly sour, yeasty, and bread-like aroma; a tiny tang is normal.


• Rotten, ammonia-like, nail-polish-remover, or chemical odors that persist after feeding.


• Discomforting or rancid smells that don’t improve after a feeding and stirring.


• Unusual sliminess or a sticky, mucus-like surface that doesn’t accompany normal bubbling.

Off odors or persistent sliminess are common red flags and typically mean the starter has gone bad. If the smell never normalizes after regular feedings, discard.

Activity after feeding

Fermentation activity is a strong indicator of vitality. Use these checks after you feed your starter.

1. Observe for bubbles throughout the starter and on the surface within 4–8 hours at room temperature.


2. Expect the starter to rise and ideally double in size within 6–12 hours under typical room-temperature conditions.


3. Note whether the starter falls back after peaking, which is normal as fermentation stabilizes.


4. Consider a float test as an optional quick check, but remember it’s not definitive for viability or health.

Healthy activity means regular bubble formation, consistent rise after feeding, and a normal aromatic profile. Lack of activity after a full feeding cycle suggests the starter may be failing or dead.

The float test: a quick, but imperfect, gauge

The float test is a commonly used quick check to gauge gas production, but it should not be the sole criterion for determining health. A floating mass indicates some gas production, but a non-floating starter can still be viable in some cases, and a floating starter can be weak or unstable. Use it in conjunction with other signs.

When performing a float test, drop a small spoonful of starter into a glass of water at room temperature. If it floats, it suggests active gas and leavening potential; if it sinks, it may benefit from a refresh or may be past its prime.

What to do if you suspect the starter is bad

Decisions depend on what you observe. Here are practical steps to take if signs point to trouble.

• Discard and start over: If you see mold, persistent off odors, or significant color changes, it’s safest to discard the starter and begin anew with clean equipment and fresh flour and water.


• Try reviving a marginal starter: If there are occasional signs of life (bubbles after feeding, mild sour aroma) but not robust activity, remove a portion, discard the rest, and feed consistently for several days to rebuild vigor. Maintain a stable temperature (around 24–26°C / 75–79°F) and use a reliable feeding schedule.


• Use a thorough cleaning and re-feed plan: When reviving, use clean containers, weigh ingredients carefully (e.g., 1:1:1 by weight for starter:flour:water or adjust to your usual ratio), and feed twice daily until stable activity resumes.

In most cases, a completely spoiled starter should be discarded to prevent contamination. A borderline starter can often be revived with disciplined feeding and proper temperature control.

Summary

To determine if a sourdough starter is bad, inspect for mold or unusual colors, sniff for foul or chemical odors, check for sliminess, and monitor fermentation activity after feeding. If any strong red flags appear, discard the culture and begin anew. A healthy starter should be bubbly, rise predictably after feeds, and carry a pleasant, sour aroma. When in doubt, err on the side of caution and start fresh, or seek guidance from experienced bakers.

How to start a car when the starter is bad?

You can try to start a car with a bad starter by push-starting it if it's a manual transmission, or by physically tapping the starter motor while someone tries to turn the key. These are temporary fixes, and if the problem persists, the starter will need to be repaired or replaced by a professional. 
Push-starting a manual car
This method uses the car's own momentum to turn the engine over. 

1. Ensure you have space: Make sure you are in a safe area with enough room to get the car rolling. 
2. Turn the ignition on: Place the key in the "on" position, but do not try to crank it. 
3. Depress the clutch and shift: Press the clutch pedal all the way in and shift the car into second gear. 
4. Get the car moving: Have one or more people push the car, or have it towed, until it reaches a speed of about 5 to 10 mph. 
5. Release the clutch: Once the car has enough momentum, quickly release the clutch pedal to engage the engine. 
6. Press the accelerator: Lightly press the gas pedal and press the clutch back in to prevent stalling. 
7. Secure the car: Shift to neutral, engage the parking brake, and release the clutch and brake pedals. 

This video demonstrates how to push-start a car with a bad starter: 57sDespair RepairYouTube · Sep 7, 2025
Tapping the starter 
This method can sometimes free up a starter that is stuck due to worn-out brushes. 

1. Locate the starter: The starter is a cylindrical component bolted to the transmission. 
2. Access the starter: You may need to get under the car to reach it. 
3. Tap the starter: While someone turns the key to the "start" position, gently tap the starter motor with a hammer or a long stick. Do not hit it forcefully, as you could cause damage. 
4. Attempt to start: The vibration may dislodge the stuck components, allowing the engine to start. This is often a temporary fix and may need to be repeated. 

This video shows how to tap the starter to try and start the car: 59sFixing With PassionYouTube · Jun 20, 2017
Other temporary solutions

• Jump-starting: While a bad starter can prevent a car from starting, a jump-start might provide enough extra power to get a weak starter working again. You can use jumper cables from another vehicle or a jump-start box, but this is not guaranteed to work. 
• Jump the solenoid: With extreme caution, you can attempt to jump-start the starter by using an insulated screwdriver to briefly touch the main power terminal and the smaller S (start) terminal on the starter solenoid. This can cause a spark, so be prepared. 

This video explains how to jump-start the starter solenoid: 59sJoe StoeYouTube · Jun 8, 2022
Important note
These are only temporary emergency fixes. You should have a mechanic inspect and replace the starter as soon as possible to prevent future problems.

How do I know if my starter is spoiled?

A starter is likely bad if you hear a clicking or grinding noise when turning the key, the engine cranks slowly or doesn't crank at all, or starting the car is inconsistent. Other signs include a burning smell or smoke from the engine, dimming lights when you try to start, or an oil-soaked starter. 
This video explains the symptoms of a bad starter, including sounds and slow cranking: 43sEasyAutoFixYouTube · Feb 19, 2022
Common signs of a bad starter

• Unusual noises: A single loud click, rapid clicking, or grinding/whirring sounds when you turn the key are all common indicators. 
• Slow or failed cranking: The engine may crank very slowly or not at all when you turn the ignition. 
• Intermittent starting: The car may start sometimes but not others. 
• Smoke or burning smell: This is a strong sign of an overheating starter and is a serious issue that requires immediate attention. 
• Dimming lights: If your dashboard or interior lights dim significantly when you try to start the car, it can point to a bad starter drawing too much power. 
• Oil-soaked starter: If you notice oil leaking onto the starter, it can cause electrical or mechanical failure. 

This video demonstrates how to test a car starter for potential problems: 1mproclaimliberty2000YouTube · Mar 7, 2022
What to do

• Rule out the battery: Before assuming the starter is the issue, make sure your battery is good, as a weak battery can cause similar symptoms. 
• Seek a professional: Since a bad starter can prevent your car from starting, it's best to have a mechanic diagnose the problem to prevent further damage and get you back on the road safely. 

How do I test if my starter is bad?

You can test a starter by listening for signs like clicking or no noise when you turn the key, a slow cranking engine, or a grinding noise. To further test, you can check if the battery is good and then use a multimeter to see if voltage is reaching the starter. A simpler test is to gently tap the starter with a wrench and try starting the car again, as this may temporarily free up a sticking starter. 
Before you begin

• Check the battery: Make sure your battery is fully charged and the connections are clean and tight, as many starting issues are caused by a weak battery. 
• Safety first: Wear safety glasses and ensure the vehicle is in park or neutral with the parking brake engaged. 

Test the starter's functionality 

• Listen for the signs:
  • Clicking: A rapid series of clicks often indicates the starter solenoid is trying to engage but can't, pointing to a bad starter. A single click is also a sign of a bad starter.
  • Grinding: A grinding noise suggests a problem with the starter gear not engaging correctly with the flywheel.
  • Whirring or freewheeling: If you hear a whirring sound without the engine cranking, the starter motor may be bad or the starter's gear may not be engaging.
  • No sound: If you get no sound at all, it could be the starter, or a problem with the battery, relay, or ignition switch. 

This video demonstrates how to test a starter by listening to the sounds it makes: 42sJust Call Me EddieYouTube · Oct 18, 2025

• Try tapping the starter: Locate the starter (usually on the engine block) and gently tap it with a hammer or wrench while someone else tries to start the car. If the car starts, it's a strong indication that the starter is faulty. 
• Use a multimeter: If you have a multimeter, you can test the voltage at the starter solenoid wire while the key is in the "start" position. If you have good battery voltage there, the starter is likely the problem. 
• Perform a push-start (manual transmission): In a manual transmission car, if the starter is bad, you can try pushing the car and then releasing the clutch while in first gear. This method can bypass the starter and confirm it's the source of the problem. 
• Check for smoke: If you see smoke from the starter when you try to start the car, it's a sign of an electrical issue that requires immediate professional attention. 

This video explains how to use a multimeter to check the voltage at the starter: 40s Easy Car ElectricsYouTube · Jan 12, 2024
What to do next

• If you suspect the starter is bad, it's often best to have a professional mechanic diagnose it and make the repair.
• If you're uncomfortable with electrical testing or working on your car, it's safer to consult a professional. 

Why does hitting a starter make it work?

Hitting a car's starter works temporarily because the impact can dislodge stuck internal components, such as a jammed solenoid or worn brushes, which are causing the failure. The vibration from a tap can free up these components, allowing them to make the necessary electrical contact to turn the starter motor and start the car. This is a short-term fix, and a permanent repair is needed to replace the worn or faulty part. 
You can watch this video to see the inside of a starter motor and understand why tapping it can help: 48sMike's Garage ShopYouTube · Jul 14, 2024
How hitting a starter motor helps

• Stuck solenoid: The starter's solenoid can become stuck due to rust, dust, or corrosion, preventing it from making the proper electrical connection. Tapping the solenoid can shock it loose and allow it to engage. 
• Worn or stuck brushes: The starter uses brushes to conduct electricity to the armature. These brushes can wear down over time or get stuck in their holders. Hitting the starter can free up the brushes, allowing them to make contact with the commutator again. 
• "Dead spot" on the armature: The armature can develop a "dead spot" where electrical flow is interrupted. A tap can sometimes cause the armature to move just enough to get past this spot and begin spinning, with its own momentum carrying it through the rest of the rotation. 
• Debris or corrosion: Minor debris or corrosion can build up on internal parts, creating a poor connection. The impact can break this buildup, temporarily restoring contact. 

This video shows how a stuck starter solenoid can be temporarily fixed by hitting it: 59sNaptownTunerYouTube · Oct 26, 2023
Important considerations

• Use a gentle tap: Use a hammer or a sturdy stick for a gentle tap, as hitting it too hard can cause permanent damage, such as breaking the starter's magnets. The correct place to hit is the solenoid, not the main body of the starter. 
• This is a temporary fix: Hitting a starter is not a solution and will not fix the underlying problem. You should plan to have the starter motor serviced or replaced as soon as possible, as the failure will eventually happen at an inconvenient time. 

You can watch this video to see how to hit the starter to get it started: 57sEasy FixYouTube · Feb 5, 2019