A Comprehensive Guide to Spark Plugs for the 1975-1980 Volvo 245
Keep your classic Volvo's B-series 'redblock' engine running smoothly with the correct set of spark plugs.
- Stick to standard copper core spark plugs from reputable brands like NGK or Bosch for best performance.
- Avoid using platinum or iridium plugs, as the older ignition system was not designed for them and they can cause running issues.
- Always check and adjust the spark plug gap to between 0.028" and 0.032" before installation.
- This is a very simple and inexpensive DIY job that can be done in under an hour with basic tools.
Symptoms of Failing Spark Plugs
Worn-out or incorrect spark plugs can cause noticeable problems. Because the ignition system on the 1975-1980 Volvo 245 is straightforward, symptoms are often easy to spot.
- Rough Idling: The engine may shake or vibrate more than usual when the car is stopped.
- Engine Misfires: You might feel a hesitation or stumble from the engine, especially under acceleration. A consistently misfiring cylinder can cause a rhythmic shaking.
- Reduced Fuel Economy: If you're filling up the gas tank more often, failing plugs could be the cause. Inefficient combustion wastes fuel.
- Hesitation or Loss of Power: The car may feel sluggish and slow to respond when you press the gas pedal.
- Difficulty Starting: A weak spark can make it harder for the engine to start, especially in cold weather.
- Black Soot on Plugs: When removing an old plug, if it's covered in black soot, it can be a sign of a rich fuel mixture or a weak spark.
Choosing the Right Aftermarket Spark Plug
For a classic vehicle like the 1975-1980 Volvo 245, original is often best. The ignition system was designed for a specific type of spark plug, and using modern, "premium" plugs can sometimes cause problems.
Stick with Copper Core Plugs
Owners and mechanics strongly agree that the Volvo 'redblock' engine runs best on standard copper core spark plugs. Copper is an excellent electrical conductor, which works well with the 245's original ignition system design. While platinum and iridium plugs last longer, they are not necessary and can sometimes cause drivability issues in these older engines.
Recommended Brands
Based on owner experiences, some brands consistently perform better than others in the Volvo 245.
- Top Tier (OEM-Equivalent): Brands like NGK and Bosch are highly recommended by Volvo 245 owners. In many cases, Genuine Volvo plugs are simply rebranded Bosch plugs. These brands offer excellent performance and reliability that matches the original factory parts. Specific recommended models include NGK BPR6ES and Bosch Super Copper.
- Standard Tier: Brands like Denso, Champion, and Autolite are also available and will function correctly. However, they are less frequently recommended in Volvo communities compared to NGK and Bosch.
Always Check the Gap!
The most critical step when replacing spark plugs is to ensure the gap is set correctly. The gap is the small space between the center and ground electrodes. Even if plugs are advertised as "pre-gapped," you must check and adjust them with a gapping tool before installation. The correct gap for a 1975-1980 Volvo 245 is between 0.028 and 0.032 inches (0.7mm - 0.8mm).
Cost of Aftermarket Spark Plugs
Spark plugs are an inexpensive maintenance item. For a full set of four, you can expect to pay the following:
| Plug Type | Estimated Cost (Set of 4) |
|---|---|
| Standard Copper (NGK, Bosch) | $12 - $20 |
| Premium (Iridium, Platinum) | $30 - $65+ |
Note: As discussed, standard copper plugs are the recommended choice for this vehicle.
Frequently Asked Questions
How often should I change the spark plugs on my Volvo 245?
For standard copper core spark plugs, a good replacement interval is every 20,000 to 30,000 miles or every 2-3 years. This ensures your engine always has a strong, reliable spark.
What is the correct spark plug gap for a 1975-1980 Volvo 245?
The recommended spark plug gap is between 0.028" and 0.032". Always use a spark plug gapping tool to verify this measurement before you install new plugs.
Are expensive iridium or platinum plugs better for my classic Volvo?
No. The consensus among long-time owners is that these engines perform best with basic, inexpensive copper core spark plugs from a quality brand like NGK or Bosch. The ignition system was not designed for the characteristics of platinum or iridium plugs.
Is replacing the spark plugs a difficult job?
No, this is one of the easiest maintenance tasks you can perform on a Volvo 245. It requires only basic hand tools and can be completed in under an hour, making it a great DIY job for beginners.
What tools do I need to change the spark plugs?
You will need a ratchet, a few extensions, and a 13/16" (or 21mm) spark plug socket. A spark plug socket has a rubber insert to protect the plug's porcelain insulator. You will also need a spark plug gapping tool to set the gap correctly.
Technical Specifications
OEM Part Numbers: 273597 1367529 272464
Spark Plug Type: Copper Core Spark Plug Gap: 0.028" - 0.032" (0.7mm - 0.8mm) Socket Size: 13/16" or 21mm
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The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.