For this you will need the following:
A plug socket which contains a rubber cushion:
You will also need a ratchet handle, an extension (2 are useful one about 2″ – 50mm and one 4-6″ 100-150mm and a set of plugs. Different people have different opinions as to what make to use. I personally find three makes are good namely Volvo, Bosch and NGK. I am sure others will have other preferences.
The other thing you will need is a set of feeler gauges.
Replacement of plugs can be in any order but I tend to start with no 1 at the front of the engine. First the lead needs taking off the plug. Only pull on the rubber with a slight twisting motion – do not pull the lead itself or you may find the end coming off the lead.
Next fit the socket onto the plug ensuring it is properly on, then the extension (the longer one fits ok here) and finally the ratchet.
This can then be slackened with the ratchet:
As soon as its is loosened you will probably find it easier to take the ratchet off and spin the plug out using the extension bar:
The gap on the electrodes of the plug need to be checked against that specified for your engine using the feeler gauges. Select the feeler gauge(s) to make up the required size. These should just fit between the electrodes to clear with just a little resistance. The electrodes can been adjusted by tapping very gently to close or using a suitable blade to open them a little. Often they will be ok out of the box or packet.
Next put the plug into the socket with the extension on it and it can then be spun in by hand most of the way. This way you should not be able to cross thread it.
Then tighten up using the ratchet but avoid over tightening. For those not sure there should be a torque figure in your manual and you can torque it in – experience will help to know how much too tighten.
It is now time to refit the lead carefully pushing it onto the plug by the rubber. Make sure it is firmly on.
Repeat the process for cylinder no 2.
On cylinder no 3 a shorter extension is needed. You can do it without if you don’t have one.
Next comes the one that often doesn’t get changed as it is hard to do. The secret is to remove the lead and then put the socket onto the plug and then put the ratchet onto the socket – there is only a small amount of movement for the ratchet. Once loosened the ratchet can come off and the socket used to spin the plug out.
Again to fit the new plug place it in the socket and spin it in – look at the angle of the other plugs to help get the socket at the correct angle to spin it in. Tighten it with the ratchet once hand tight.
At this stage it is a good idea to start the engine and make sure there is no misfire. For the less confident you can do this after each plug. The only downside is the exhaust manifold is likely to get hot with risk of burning yourself on it.
The instructions in this tutorial will work in the following models / years:
-1974, 1975, 1976, 1977, 1978, 1979, 1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989, 1990, 1991, 1992 and 1993 Volvo 240, 242, 244 and 245 with petrol engines