Torque and Chrome

Torque wrench for spark plugs?

Is a torque wrench necessary for replacing spark plugs? Why does the bolt have to have a specific tightening? What type of torque wrench is recommended for this type of routine?

Public Comments

1. You could use one, but it's cumbersome trying to fit the torque wrench in the limited space available to install spark plugs sometimes. So many mechanics simply tighten, but not over-tighten spark plugs when they're installing them. "How much the spark plugs should be tightened depends on the size of the plugs and the type of plug seat. Spark plugs with gasket-style seats require more torque than those with taper seats. Always follow vehicle manufacturer torque recommendations, but as a general rule: * 14-mm plugs with a gasket-style seat should be tightened to 26 to 30 ft.-lbs. in cast iron heads, but only 18 to 22 ft.-lbs. in aluminum heads. * 18-mm plugs with gasket-style seats should be tightened to 32 to 38 ft.-lbs. in cast iron heads, but only 28 to 34 ft.-lbs. in aluminum heads. * 14-mm taper seat spark plugs should be tightened to 7 to 15 ft.-lbs. in both cast iron and aluminum. * 18-mm taper seat spark plugs should be tightened to 15 to 20 ft.-lbs. in both types of heads. Courtesy Robert Bosch Corp."
2. Overtightning of spark plugs makes removing them later a big problem. Sometimes they snap off and you are in trouble then. So just do them up gently, give them a 'little pinch', because they don't need to be tight at all. There is no need to be hard with them, that's why usually a hand turned T bar is enough to remove and re-fit them. A torque wrench helps you achieve this, but just do them up gently and then check them after a feww weeks to make sure they have not worked loose, then they will be fine.
3. no not a torque wrench,,,but something similar a plug spanner....its designed to fit over the plug protecting the ceramic parts but allowing the plug to be tightened/loosened utilising the 'nut' shaped part....the spanner is quite cheap...a torque wrench could be pricey ..say if you need more info
4. if you know what your doing then no you don't need to torque them up, but if you are a complete novice then it would be a good idea to use the torque wrench and correctly set it!
5. a toque wrench is not require for tightening spark plugs. when tightening plugs just make sure they are tight but no special wrench is required. use plug spanners
6. On newer engines its very difficult to tighten spark plugs with a torque wrench. However, the reason it is recommended is that overtightening plugs can damage the cylinder head and make it difficult to remove them when they need replacing. Also overtightening can cause problems with the ignition process of the engine. Stretching of the spark plug from overtightening can cause different heat ranges in the plug and possibly cause misfiring. Normally a small torque wrench is recommended for tightening. An easy way to tightening plugs is this: Turn all the plugs until they are pinched by hand. Then tighten 180 degrees with a spark plug socket. When all are tightened, turn all the plugs another 90 degrees with a spark plug socket. This doesnt overtighten them, and you will know that they will all be at the same tightening torque. Hope this helps!
7. Simply ...no. It is possible that the user manual suggests a torque setting.Just ignore it. Normal ratchet,turn till it stops then a little tap to nip it up.
8. they are ceramic and break easy, and once you get a piece of that in your cyinder. haha.... just use a 3/8 drive ratchet and go a quarter turn pass snug
9. Not necessary, just tighten them by hand and "nip up" a bit more using a plug spanner - usually only about 1/8 extra turn is necessary.
10. The plug needs to be tightened to the correct specification. If you don't know what than feels like then yes you need to use a torque wrench. All fasteners have a torque spec; over-tightening can deform and brake parts, under-tighten and it will fall apart. A click type torque wrench that has the range you need is all that's needed. While a mechanic can put alot together without a torque wrench, it comes with experience. As a mechanic I see plenty of screwed up spark plugs and threads by amateurs, don't assume you have the equivalent of 10 years experience, use the torque wrench and do a good job.
11. You can use on and in the past with old cars it was required, however new cars have limited space to use a torque wrench. All new spark plugs are fitted with a metal gasket that deforms when the plug is tightened. This removes the requirement for getting a specific torque on the spark plug. The reason why bolts require a torque setting is that they hold two pieces of metal together and the torque setting ensures that there is a great enough force to hold the two pieces together. Ja.
12. see the answer bobweb gave spot on!