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Ask Handy Andi: Replacing Spark Plug Wires

Ask Handy Andi: Replacing Spark Plug Wires

Last time, I explained how easy it is to change your own spark plugs, and mentioned that you may want to change your plug wires at the same time. Most car manufacturers recommend changing your plug wires about every 30,000 miles. As with changing the plugs themselves, changing these wires is both simple and inexpensive. In the vast majority of cars, you won’t even need any tools.

First, you’ll need to know what kind of wires to buy. You should be able to find the recommended model in your car’s manual. If you aren’t able to find it, just ask the staff at your local auto parts store to look it up for you. In general, there will be one wire for each cylinder in your car’s engine (the cylinders are where the spark plugs are housed). Once you have the new wires, lay them out where they will be handy. If they are numbered, lay them out in numeric order, otherwise, lay them out in order of length.

Open your car’s hood (or leave it open, if you’ve just changed your sparkplugs), and find the existing wires. They will be on your engine, leading into the cylinders. While most wires are black, they could also be red, orange, or blue.

Make sure your engine is cool before attempting to touch it. Now, take hold of one — and ONLY one — of the wires and follow it back to the spot where it inserts into the cylinder (this is called the “boot”) and pop it out.

Now, follow the wire back to the other end, where it connects with the distributor cap. Give it a sharp tug. It should come off without difficulty.

The most important thing to remember is never to take out more than one wire at a time. One you’ve removed the first one, be sure to replace it before moving onto the next. Otherwise, you could inadvertently cross wires, which can affect your engine’s performance.

Once you’ve got the first wire off, find the new wire that matches its length and/or number. Slip the new wire back onto the distributor cap, pressing on it until you feel it pop into place, then slide the boot into the cylinder and press it in.

Repeat with each of the additional wires, always making sure to remove only one old wire at a time.

Once you’ve replaced all of the wires, close the hood and fire up your engine. You’re done!


1 Bill Hoffman { 09.26.12 at 4:02 pm }

I hold an AA Degree in Automotive Technology and an NHRA track record. I wholeheartedly agree with Robert G. Handy Andi’s instructions are accurate, but don’t really apply to anything built after 1975, especially in California. Wires are not numbered (certain Asian 4 cyl. applications may be an exception) and NEVER give a pulg wire a sharp “tug”. Doing so can separate the wire from the boot and/or break the distributor cap. If operational heat has “welded” the wire to the plug or distributor cap, CUT it off ! Be sure to apply a thin coat of hi-dialectric grease to the inside of the plug and distributor boot to keep things from being “welded” on again and to also enhance voltage transmission integrity. If you replace with OEM wires, then indeed, replace them with each plug change. However, 2 or 3 brands of aftermarket wires consistently outperform OEM and give a surprising increase in performance and fuel economy to say nothing of a reduction in tailpipe emissions. A good set of after-market plugs wouldn’t be bad either. Sorry, but Handy Andi’s instructions just don’t apply to today’s “plumbing nightmares”.

2 Robert G { 09.26.12 at 8:44 am }

Sure wish your write-up was as easy as it really is these days. For the engine you have in your pic, I would definitely agree easy, however, engines of today are monsters for this kind of work. I had to remove the engine braces on my 2001 M/C SS to rock the engine forward to be able to even get to the wires and plugs. Then, the wires, all of them, were glued to the spark plugs and would not budge. Three hours later and tore up hands the back three were completed – the front a bit easier but still wires glued to the plugs. It can be done, just do not think it is a 30 minute job with how “easy” it is as mentioned in the article above.

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