Essential Spark Plug Guide for the 1985 Volvo 745
Keep your classic B230 engine running strong with the right plugs and know-how.
- Only use standard copper-core spark plugs from brands like NGK (BPR6ES) or Bosch (WR7DC+).
- Avoid platinum and iridium plugs as they can cause running problems in the 745's older ignition system.
- Always verify and set the spark plug gap to 0.7mm-0.8mm (.028"-.032") before installation.
- Replacement is a very easy DIY job that should be done every 30,000 miles for best performance.
Symptoms of Failing Spark Plugs
When your spark plugs wear out, your Volvo's engine performance will suffer. The signs are usually easy to notice. Worn plugs have a harder time creating a strong spark, leading to incomplete combustion.
- Rough Idle: The engine may shake or sound uneven when the car is stopped.
- Engine Misfires: You might feel a hesitation or stumble from the engine during acceleration or even at a steady speed.
- Difficulty Starting: The engine may crank for longer than usual before it starts, or it may fail to start at all in severe cases.
- Poor Acceleration: Your 745 may feel sluggish and less responsive when you press the gas pedal.
- Reduced Fuel Economy: Inefficient combustion means wasted fuel, so you'll find yourself at the gas pump more often.
A Note on Check Engine Lights
While modern cars will almost always trigger a Check Engine Light for a spark plug issue, your 1985 Volvo 745 predates the OBD-II diagnostic system. It may not have a reliable warning light for this specific problem, so it's important to pay attention to the physical symptoms.
Choosing the Right Aftermarket Spark Plug
For a classic vehicle like the 1985 Volvo 745, newer doesn't always mean better. The ignition system was designed around a specific type of spark plug, and using the wrong one can cause more harm than good.
Material Matters: Stick with Copper
The overwhelming consensus among long-time Volvo owners and mechanics is to use standard copper-core spark plugs. These engines were designed for them. While modern platinum and iridium plugs last longer, they can cause running issues, fouling, and misfires in the 745's ignition system. Save your money and stick with what works.
Brand Tiers for Your Volvo 745
- Top Tier (Highly Recommended): NGK and Bosch are the go-to brands for this engine. Many believe the original "Genuine Volvo" plugs were simply rebranded versions of these. For a non-turbo B230F engine, the NGK BPR6ES is a community favorite. For Bosch, the WR7DC+ is an excellent equivalent.
- Mid Tier (Good Quality): Denso is another reputable Japanese brand that makes quality plugs compatible with the 745. They are a solid choice if NGK or Bosch are unavailable.
- Economy Tier (Use with Caution): Brands like Autolite and Champion are available and will work, but they are not as highly regarded for longevity or quality control in Volvo circles compared to NGK and Bosch.
Always Check the Gap!
Never assume a spark plug is gapped correctly out of the box. For the 1985 Volvo 745 (both turbo and non-turbo models), the spark plug gap should be set between 0.7mm and 0.8mm (.028" - .032"). Use an inexpensive gapping tool to measure and adjust each plug before installation. An incorrect gap is a common cause of misfires.
Cost of Aftermarket Spark Plugs for 1985 Volvo 745
| Brand Tier | Material | Price Range (per plug) |
|---|---|---|
| Top Tier (NGK, Bosch) | Copper | $3.00 - $5.00 |
| Mid Tier (Denso) | Copper | $3.00 - $5.00 |
| Economy (Autolite, Champion) | Copper | $3.00 - $4.00 |
| Not Recommended (Any Brand) | Platinum/Iridium | $6.00 - $17.00+ |
Frequently Asked Questions (FAQ)
How often should I replace the spark plugs on my 1985 Volvo 745?
For standard copper plugs, a replacement interval of every 30,000 miles is recommended to maintain peak performance.
Is it hard to replace the spark plugs myself?
No, this is one of the easiest maintenance jobs on a Volvo 745. The spark plugs are easily accessible on the passenger side of the engine, and the job requires only basic hand tools. The entire process should take less than an hour for a beginner.
What tools do I need to change the spark plugs?
You will need a ratchet, a short extension, and a 21mm or 13/16" spark plug socket (which has a rubber insert to protect the plug). You will also need a spark plug gapping tool. Applying a small amount of anti-seize to the new plug's threads is also a good practice to prevent them from getting stuck in the aluminum cylinder head.
My old spark plugs were stuck. How can I remove them safely?
If a plug is stuck, apply a penetrating oil and let it sit. Use a long breaker bar for steady, even pressure instead of jerky movements to avoid damaging the threads in the aluminum head. Always work on a cold engine.
What's the difference between turbo and non-turbo spark plugs for this car?
While the gap is the same, turbocharged engines (B230FT) run hotter and may benefit from a slightly "colder" heat range plug, like the NGK BPR7ES, to prevent detonation. However, for stock or low-boost applications, the standard BPR6ES often works perfectly well.
Technical Specifications
OEM Part Numbers: 1367529
Engine: B230F, B230FT. Spark Plug Gap: 0.7mm - 0.8mm (0.028" - 0.032"). Thread Size: M14x1.25. Tightening Torque: 28 Nm (approx. 20 ft-lbs). Socket Size: 21mm (13/16").
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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.
- Volvo 745:
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- Symptoms of Failing Spark Plugs
- A Note on Check Engine Lights
- Choosing the Right Aftermarket Spark Plug
- Material Matters: Stick with Copper
- Brand Tiers for Your Volvo 745
- Always Check the Gap!
- Cost of Aftermarket Spark Plugs for 1985 Volvo 745
- Frequently Asked Questions (FAQ)
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