Are Sparkplugs a standard size?

da_hambo

Rookie question I know but I plan on servicing my own cars.i think I read the spacing for some cars has to be set perfectly but are sparkplugs for petrol engines all the same thread size and ratchet size for removing?

guil

some are 16mm some are 18mm and afaik there might be a 21mm

i'm nearly sure all the threads are different, i've never checked just asked for plugs for x car

couldntthink

There are many many different types/sizes of spark plugs. you should have no need to worry about this. Ask your motorfactors for plugs for your car.

swhyte027

As stated before spacing and gapping plugs doesn't take place anymore.the come gapped from the factory just state ur make and model to the motor parts dept

Owen

Some are 14mm too, the e90 BMW has a 14mm double hex fitting with an extremely small socket wall - only about 1mm thick.

Atlantic Dawn

For a rookie my recommendation is that you purchase a spark plug specific socket, these have a rubber insert in them so that when you get the spark plug loosened with them they grip the plug and you can then extract the plug out without having hassle. I'd imagine any motor factors should sell these.

Nissan doctor

Spark plugs do not all come gapped from the factory.

Some do, i.e with NGK plugs, with a plug number of say, BKR9ex-11 The the gap is factory set to 1.1mm-denoted by the -11 at the end on the number.

If the number does not have this at the end then that plug is suited to several cars/engines and will need to be gapped according to the specific manufacturer recommendations. Its good practice to check the gap on any plug as its very easy for them to get a knock in the box which can very easily close the gap.

Wrongly gapped plugs will effect fuel economy, cause excess deposit build up and can also cause coilpacks to fail prematurly and its something that so few mechanics do properly these days.

As for the socket size needed, the vast majority of cars need a 16mm plug socket, some(mostly older) use 21mm and some of the latest BMW's need a 14mm spline socket.

colm_mcm

If its your first time doing them, be careful when putting them in. I usually drop then in with the socket, hold the plug straight, not putting any weight, turn anticlockwise (like unscrewing) and wait for the threads to drop in, then gently tighten, otherwise you may cross-thread, which is major trouble.

CJhaughey

I use a piece of rubber hose that fits the plug securely.
This allows you to start the threads but not enough torque to start them cross threaded.

colm_mcm

I used to do that too, as the socket I had at the time was a bit crap and had no rubber ring to hold the plug in

bonzodog2

Its possible to crack the ceramic part of the plug using a plug socket without the rubber insert, if not done carefully !

moodrater

I'd always check the gap too and double check - compare to the original in case the motorfactors gave you the wrong ones - you don't want to put a long reach plug in a short reach hole :eek:

Nissan doctor

moodrater wrote: »

I'd always check the gap too and double check - compare to the original in case the motorfactors gave you the wrong ones - you don't want to put a long reach plug in a short reach hole :eek:

But gapping spark plugs has nothing to do with it being a long or short plug

newfrontier

Just curious , does the 99 maxima take a specific set of plugs and why are they more expensive than the normal set?

Nissan doctor

newfrontier wrote: »

Just curious , does the 99 maxima take a specific set of plugs and why are they more expensive than the normal set?

Because there are 6 of them:D


The maxima can take standard plugs or platinum/iridium plugs, of the correct type for the engine of course.

moodrater

Nissan doctor wrote: »

But gapping spark plugs has nothing to do with it being a long or short plug

It was in response to 'just ask the motorfactors for plugs for your car'
I'm saying compare side by side with the original to make sure they are the same, electrode, insulator length. I've been given the wrong plugs, pads, timing belt kits, oil, transmission fluid you name it usually its just a digit/letter out easy mistake to make.

Nissan doctor

moodrater wrote: »

It was in response to 'just ask the motorfactors for plugs for your car'
I'm saying compare side by side with the original to make sure they are the same, electrode, insulator length. I've been given the wrong plugs, pads, timing belt kits, oil, transmission fluid you name it usually its just a digit/letter out easy mistake to make.

True, but its not just about the physical size of the plug either, you need to make sure they are the correct temperature range and if the car requires the type with built in resisters or not.

dgt

If you do your own plugs, this is your best friend. Usually magnetised



Failing that, the old way we did plugs in deep bores was with a socket and a pronged grab tool



Be weary of cars with platinum tipped or long life plugs fitted, most times they will have been rarely changed and very tight to come out.

Plenty of anti seizing paste/copper grease on the threads when refitting to make life much handier when servicing in the future