4.2 Petrol Spark Plug Change - How Easy?

[mic]

Hi All

It will soon be time to replace the plugs on my 4.2. petrol.

Has anyone done this themselves?

Are there any special tools required and anything to watch out for or is the job best left to the dealer?

thanks

[Big Kev]

Hi All

It will soon be time to replace the plugs on my 4.2. petrol.

Has anyone done this themselves?

Are there any special tools required and anything to watch out for or is the job best left to the dealer?

thanks

Mic,

Do you know if your plugs are the Iridium tipped ones, which are supposed to last about 60k miles, so what is the mileage?

To answer your question, it really is a dead easy job even for a novice, so don't pay Mr.T whatever you do.

Big Kev

[IanXT4]

It is reasonably straight forward to change the plugs on a 4.2 petrol, but like a lot of modern engines they are deeply recessed and need a long extension bar on the socket. I bought a very long spark plug socket a few years ago which holds the plugs with a magnet, but a plug socket and long extension would be ok. You also really need a torque wrench, as its very easy to over torque spark plugs by hand.

My replacement plugs were NGK IFR6T11 which replaced the IFR6A11 in the engine since new. (which are apparently no longer available).

The plugs cost £30 from a local motor factor. They are long life Iridium and come pre-gapped no adjustment required.

To Replace the plugs - (This was for a 2004 Petrol)

Note the engine MUST be cold,

Remove the front of the air-box completely by releasing the clip on the left hand side. The airbox lid can then be opened and unhooked off its hinge. The air-box lid can then be completely removed from the engine bay by removing the bolt at the front of the engine that holds the air intake tube. Now blow or brush away any loose dirt etc, that could fall in the engine as you remove the coil packs.

Next repeat steps 1-6 for each plug.

For plugs 1 - 3 (left to right) access is easy, plug 4 requires that you remove a bolt holding the air-box to the engine and rotate the air-box anticlockwise just enough to allow the coil pack to be removed. The back of the air-box slides onto a bracket and so is free to move a little. I have attached a picture showing what it should look like with the airbox rotated.

1 Unplug each spark plug coil pack, you have to gently press on the connector tab to release the catch.(sometimes it helps with these connectors to press the plug together, gently press the lock tab and then unplug the connector)

2 Remove the bolt holding each coil pack and carefully remove and place the coil pack somewhere safe, these are easy broken if dropped and are probably expensive.

3 Unscrew and remove the spark plug, it might be quite tight but a standard wrench handle should be ample, if for any reason it will not release give up and let the garage do it :-)

4 Carefully insert the new plug and carefully ensure by hand that the spark plug does not cross thread and goes in smoothly. If in any doubt unscrew the plug and start again. From what if have read from NGK its a bad idea to lubricate the plug thread with anything, as this affects the correct torque.

5 Torque the plug to plug manufactures spec, for the NGK I used it was 26nm

6 Replace the coil pack and re-bolt it in "just tight", I don't know the torque but I used a very short ring spanner .

NB I re plugged in all the connectors in one go at the end. When your finished replace the airbox

I found the job straight forward, but be careful as its an aluminium head and its possible to strip things quite easily.

Any advice given is meant to be helpful and in good spirit. No liability is accepted for loss , damage or injury. WORK SAFELY

[Big Kev]

If you need to buy a ratchet/plug socket/extension (10" is good), don't get from Halfrauds....woeful ££££

Always readily available on eBay, and the plug socket is the smaller size of the two available. If you were near Glasgowshire, torque wrench available to borrow.

Big Kev

[mic]

Wow!!

Thanks for all the replies guys!

Plugs are the Iridium type. Mileage is 54k so not quite 60k but like to prepare in advance.

From the comprehensive guide given by Ianxt4 I think I will have go. Will need to get an extension bar though.

I tend to do all the servicing myself. The only job I haven't been able to do so far is the oil change on the front transfer box - its really awkward to reach even with car on ramps. Dealer only charged me £30 to do it. Not bad ehh.

Thanks again.