Hi all and apologies for a basic question.

Am thinking of changing the spark plugs in my 1990, 3.6 as they are of unknown age (6 years plus?) and mileage. Have never had a car with plugs so recessed in the head before and petrified of breaking a plug or damaging the thread. No leaks from the rocker cover seals so plug chambers are bone dry. Should I squirt a little penetrating oil in before I try to remove the plugs?

I'll use a proper plug socket but do people torque new plugs in or do by feel? Any other tips?

Thanks for reading.

Cheers,
LeeP

 

Hi Leep

Before you even start this job, get yourself a magnetic pick up tool as the chances are you are going to need it to retrieve an undone Plug from down that very deep hole, I also can't see it wouldn't do any harm to give the Plugs a little squirt of WD40 but just try it on one to start with to see how you get on

On my V12 you only give the Plugs a little nip, as in 5 past 12 on a Clock Face, unlike the PO or his Shop did, who put them in so Tight I needed a Scaffolding Pole on the end of a Torque Wrench to undo them and yes I was also worried that something would break although I got them out without any problems

Have a look at Page 94 of my 'Cherry Blossom' restoration thread, to see how I removed the Plugs from my 6 cyl AJ16 engine which might be quite similar to yours apart from the Coil Packs

Removing The Spark Plugs From A 6 cyl XJS with AJ16 engine

 

Thanks OB and also for the link to your super informative thread. I hope Carmen is up and running now.

Good point about the magnet. I have also seen a tip to use a short length of coolant hose pushed on the end of the plug to get it started once reinstalling - just pull of once the thread has bitten.

Cheers,
LeeP

 

Definite "yes" on both the magnet and using the hose to start the threads. And I'm in the "just nip them tight" camp as well.

Add a tiny smear of anti-seize to the threads before installing.

Cheers
DD

 

Hi Leep

Just one more thing

Don't drop anything down the Hole or that will really spoil your day!

Blow compressed air down and around the Hole before you take the Plug out, to clear away any loose crud

 

I use one of these. They work really well and are magnetic to hold the plug in the socket

 

All done with no drama.

Used one of those cans of compressed air for computer key pads to blow crud out of the plug recess (mainly black paint flecks off the rocker cover). Plugs had been properly fitted in the past and not over tightened. Only one was a little tighter but squirted a tiny bit of plus gas down there and left for half an hour - came out fine after that.

Old fuel hose fitted over end of new plugs and really easy to reinstall with this. Had to risk taking the plastic internal support out of my plug spanner as no way to get plug spanner out with it in place after tightening down but as I only "pinched" the plugs up that worked fine. Easy job I know but had me worried beforehand and last night's glass of red slipped down all the easier with the job safely done!

Thanks to Timeisrelative for reminding me of previous US / Canadian holidays and filling suitcase with as many cheap, good quality tools that the wife would permit. Hopefully those days will return soon!

Cheers all,
LeeP

 

Know this is after the fact, but should be mentioned. My experience has been to see if the socket or plug shows any oil. If so, the oil seal for that hole has perished. As with most things, if 1 has then others are sure to follow. A valve cover kit can be had with all the plug seals, as well as the 1/2 moon cam seal at the back. If a plug seal leaks, the oil will seep into the cylinder and burn off. That's both good and bad.
Dave in AZ

 

Thanks 92/93. A good point but fortunately mine were all dry as the seals were replaced a couple of years ago when a leaking rocker-cover gasket was sorted.
Cheers,
LeeP