HOW TO CHANGE SPARK PLUGS ON A 1978 VW BUS

by | 2018 | The Lills, VW Bus

There are four spark plugs in our Volkswagen bus, Moksha. Each spark plug sends electric currents from the ignition system to the combustion chamber to start and move the vehicle. They are an essential part of any vintage car and they are a great health indicator of an air-cooled motor too.

In our video below, it is pretty easy to see why our spark plugs needed changing on our Volkswagen bus. They were covered in carbon, which means our motor was running too rich. See the spark plug directions and our How To Change Spark Plugs On A 1978 VW Bus video below!

How To Change Spark Plugs On A 1978 VW Bus:

  • The motor should be absolutely cold before attempting to take out the old spark plugs (this is essential to keeping the threads in the cylinder heads safe)
  • Doing 1 complete spark plug replacement at a time can help from getting the wire order mixed up
  • It is also much easier to work on the spark plugs from above, through the interior hatch, so remove the tin cover and set it aside
  • The first step is to remove the spark plug wires from the spark plugs (always pull by the connector and not the wire itself). A slight twist as you pull will help (the wires should be soft and pliable. If not, replace those too)
  • Once the wire is off, look down into the tin to see the angle of the spark plug you’re working on
  • Place your 13/16″ spark plug socket on a longer extension and attach that to your ratchet
  • Gently fit the socket over the spark plug (if it’s magnetic, two hands will help guide the socket). You should feel the socket lock on
  • Be sure to set your ratchet to “loosen” and gently begin unscrewing the spark plug (keep it as straight as possible. Guiding the extension with the thumb and index finger of your other hand will help keep the ratchet straight)
  • The first loosening may be tough, but when it starts to loosen, unscrew it slowly. If there’s any binding at all, tighten it back up a little and try to unscrew it again, repeat as necessary. Be very careful not to force it! The threads are in the cylinder heads (stripping them means taking out the motor)
  • Once the spark plug is loose and reaches a point that it can be unscrewed by hand, remove just the ratchet and unscrew the spark plug by hand, (turning the extension) until it comes out
  • Inspect the spark plug (look for color and shape. The color should be evenly tan to gray and not misshapen. The electrode in the middle should be flat and even. A black plug, covered in carbon means the motor is running too rich)
  • Double check the gap in the old spark plug. We’re setting ours to .025 with a feeler gauge. The range is somewhere between .024 and .028 (a smaller spark plug gap improves performance at higher speeds under load and helps with starting in cold weather, a larger spark plug gap can improve idle)
  • If your plugs need a smaller gap, press them gently on a hard smooth surface to close the gap and check it with a feeler gauge. To open the gap, use your spark plug gap tool to bend it back (be careful not to damage the spark plug or electrode)
  • Double check the old spark plug for a little screw on the terminal (there may or may not be one). The new spark plugs are shipped with them, but ours do not call for it, so we just unscrewed that little piece of metal with a pair of pliers
  • Once you have the proper gap, insert the spark plug into the spark plug socket, which should be attached to an extension. You can coat the spark plug threads with anti-seize compound, if you like (keep the ratchet off for now)
  • Begin to thread the new spark plug by hand (if there is any resistance, loosen it and begin again). Do not force it (you should be able to thread it by hand easily until it’s hand-tight)
  • Put the ratchet on the extension and tighten the spark plug to its specifications (try not to over-torque the spark plugs)
  • Push the correct spark plug wire onto the terminal of the new spark plug
  • Push on the spark plug seal
  • Repeat this procedure for the remaining 3 spark plugs
Changing the spark plugs on our VW bus helped with performance and fuel consumption, plus it extends the lifespan of our Volkswagen motor. We’ll check the spark plugs and clean them if necessary (a wire brush is all we need) every other oil change (around every 6,000 miles).

We have a unique feature on our bus: a cylinder temperature gauge that comes from our #3 cylinder head and sits under the steering wheel. We put it on the #3 spark plug because that cylinder tends to run hottest, meaning our gauge will likely tell us what the maximum temperature is inside the cylinders.

VW Bus Cylinder Head Temperature Gauge - The Lills

VW Bus Cylinder Head Temperature Gauge Spark Plug - The Lills
VW Bus Cylinder Head Temperature Gauge New Spark Plug - The Lills

The temperature gauge connects to the spark plug with a simple ring connector that slides over the threads and under the gasket of the spark plug. Sometimes, the gasket on a new spark plug won’t come off (without damaging it), so we snip the ring connector and fit it around the plug, under the new gasket. Bringing both ends of the ring connector together and threading the new spark plug into the cylinder head sets the gasket and keeps the connector in place, giving a reliable temperature reading to the gauge inside the cabin. There are many types of temperature gauges you can install to have real-time monitoring of the motor’s health and it adds peace of mind, while traveling on the road.

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