If your late model Pajero, Challenger or Magna is due for it’s 100 or 200,000km service it is possible to save yourself quite a bit of dough by replacing the spark plugs yourself.
It is a reasonably straight forward job to do and can be done with a basic spanner, screwdriver and socket set. Allow yourself plenty of time though, quite a few hours will be needed to finish the job.
There are a few precautions that you need to be aware of, nothing too drastic just little things that will make the job easier for you and they are outlined below. I had actually got halfway through this job before growing a brain and realising that this information might be useful to our readers so I’m all the steps in reverse so please don’t shoot me if there is anything I have left out! I will try my best to cover everything.
OK, dust off the tools and let’s get down to it.
Important Notes to Remember.
- Allways replace the spark plugs with Platinum or Iridium plugs. Yeah they cost a bit more but you do not want to be doing this job every 20,000km or so. Good deals on these can be found on EBAY
- The spark plug leads will be quite difficult to remove. Try twisting the leads first, a little each way until they come loose and then pull them out.
- A smear of anti-sieze compound or even a smear of engine oil on the spark plug threads will prevent the new plugs from binding up in the alloy heads and make removal easier next time.
- When you remove a component sit the bolts back into the holes where they came from. Because we are dealing with a lot of bolts this will make the re-assembly so much easier. No more trying to guess which bolt went where!
- A foot-long length of hose that fits over the porcelain section of the spark plug is useful for extracting the plugs once you have them loose.
- If you find it necessary to remove any of the leads from the coils be sure to mark them clearly, both on the lead and it’s coil. You don’t want to find out later that you don’t know which lead goes to which coil.
The first step is to remove the air intake. Release the four clips around the air filter housing, release the throttle cable from the intake, remove the electrical connector from the air flow meter, remove the PCV hose from the intake and undo the clamp around the throttle body.
Time to remove the throttle body. Number and remove the three vacuum hoses on the top of the tb, remove the 10mm bolt holding the throttle cable and earth strap, loosen the two 12mm nuts holding the throttle cable to it’s mount and remove the cable from the tb, remove the electrical connector from the air bypass at the bottom of the tb, and then remove the four 12mm bolts holding the tb to the intake manifold. Take a note of which way the gasket sits between the two and do not remove the two coollant hoses from the bottom of the throttle body, there is enough slack in them to simply move the tb to the side out of the way.
Now to remove the wiring harness that comes across the manifold. This is self explanatory, if it’s plugged in and in the way – unplug it! Once you have all connections and harness mounts undone move the harness out of the way.
Remove the four 12mm bolts holding the bracket in place and remove the plug leads from their holder.
Remove the fuel pressure regulator vacuum hose and remove the 10mm bolt holding the electrical connection and harness bracket – this allows access to the first plug lead.
Remove the 10mm bolt holding the two connectors to the intake manifold. One thing to rememer here is that when re-assembling, the wires for these two connectors go under the black bracket in the second picture up.
Time to remove the three coils. My advice is to remove the 10mm bolts holding them down but do not remove the plug leads unless you absolutely have to. With a bit of manouvering the coils can be moved enough not to cause any problems with the leads still attached. There is also two 12mm bolts holding the fuel supply and return lines to the manifold that have to be removed. Remove the PCV hose from the manifold at this time also.
Working on the left side of the manifold, remove the brake booster vacuum supply, 10mm bolt holding another earth strap, the charcoal canister vacuum hose and the vacuum hose at the rear of the manifold. (Yeah, ok, I’m not sure where this last one goes to!)
On the same side as above, remove the two 12mm bolts from the manifold bracket and the two 12mm bolts holding the hot air intake – this has a gasket that usually falls down when the bolts are undone so be careful!
Working from the front of the car again, undo the three 12mm bolts holding the electrical connectors and bracket. Sit them back in their respective holes in the bracket once it’s removed to avoid confusion when re-assembling.
Getting there! Now remove the remaining 12mm bolts securing the manifold. Some will be hard to see but if you look in the location of the arrows they shouldn’t be too hard to find. On the front of the manifold there is two bolts that hold down a small bracket and this can be tricky to remove. A magnetized screwdriver or small magnet works wonders for removing this.
Once all the bolts are removes the manifold should be easily lifted up and out of the engine bay. If it is stuck do not force it, have a look to be sure all the bolts are removed. Be careful not to damage the gasket between the two parts of the manifold if you plan on re-using it.
And this is what things should look like. Don’t pay any attention to the timing covers being off, I was doing the timing belt at the same time on this engine. BEFORE doing anything place a rag over the intake runners of the lower manifold to avoid getting any dirt or heaven forbid, any solid object down there!
Re-assembly is the reverse of what we have just done with attention paid to the precautions I listed at the start of the article. Visually check the spark plug gap before fitting them and use the length of hose to lower them into their holes. You don’t want to find out that one plug has a closed gap after re-fitting everything!
Doing this job yourself would save you many hours in labour charges and we all know how much mechanics need to charge these days to make a living!