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Okay so I went to take my spark plugs out today and noticed they're kinda difficult to get out. So I read through the haynes manual and its says to use the spark tool that comes with the car, which of course i only have part of. I happen not to have the joint. Anyone know where i can get this tool, or something else i can use thats just as easy.

430 Posts
...best bet is a spark plug socket that fits the plug AND holds it (rubber insert)...with 2 short 3/8" extensions on it....use duct tape to hold the 3 pieces together. Works better than the Nissan tool since it is flexible.

** If you are replacing the plugs, it makes a lot of sense to also replace the wires, cap, & rotor at the same time. If the plugs have been in there awhile, the other ignition components are probably just as old...also you might trash the wires in the process of getting them loose.

** Be careful of the wires going to the injectors...you might break a connector or loosen one.

Redoing the plug wires:

Remove 1 wire from 1 plug at a time and label each old wire at the PLUG END according to it's plug number.......found in the firing order diagram area in any manual. I use some masking or light colored vinyl tape, and a pen.

* Sometimes the plug boots will stick to the plugs...since you are replacing the wire set...best bet is probably a pair of channel-locks or even vice-grips to grab the boots/wires. DO NOT "grab" anything else.




front of engine

When done with the 6 plugs, remove the old cap with all 7 wires intact (including coil wire).

Take the new plug wire set & the new cap out of their boxes.

On a clean surface...orient the new cap in the same direction
as the old cap.

Starting with no. 1 plug, find a new plug wire in the set that more or less matches, in length, the old one...& carefully insert the correct end of this wire into the EQUIVALENT cap tower on the new cap....using some di-electric grease in each boot & being sure that you can hear & feel a solid METAL CONNECTION as they go onto the cap tower. You will probably then have to move the boot down along the wire some so it will fit onto the cap tower snugly.

* Some plug end and cap boots will be different in shape than others...you will need to try & match these shapes as well as the length.

Do this for all 6 plug wires and then the wire that goes to the coil.

Set this new assembly aside.

Keep the old set with it's numbered wires *as is* for reference.

Wire sets I have used in an na:

Xact: 7mm set without spiral core...lasted over 40K miles.

Bosch: 7mm set with spiral core....driver's side wires are about 2-3 inches too long...got them to route OK, but had to use extra wire holders to do it. A real PITA.

R & R for the plugs:

Best bet is to start on the passenger side due to better access, so it is easier to learn as you go.

Use the Nissan spark plug tool provided or tape a good spark plug socket (with a rubber insert to hold the plug) to a ratchet extension.

If a spark plug socket does not have a rubber insert or the one you have doesn't hold a plug very well...it's fairly easy just to make a better rubber insert from a short section of 3/8" oil hose RTVed (silicone caulk) into the socket. You DO NOT want to drop a new plug when trying to put it in...so make sure it holds the plug.

** IMO a made up plug socket duct taped to 2 ratchet extensions (3/8" size) will give you some advantages when removing and installing the more difficult plugs (* #5 & #6?) due to the thinness of the ratchet extension & it's flexibility vs the Nissan tool. Think about it.

* you also can remove the 2 bolts holding the throttle cables so you can get to #6 much easer.

Blow all dirt & so forth out of the spark plug wells before removing the plugs...using an air tank. Possibly a vacuum cleaner with an narrow attachment would work.

* Due to the difficulty of getting the dirt out of the wells and surrounding areas (and the importance of doing so), might be a good move to find a source of high pressure air with a long extension to blow the stuff out, even if you have to pay for the privelege.

* I also used a extendable magnetic pickup tool and a flexible claw pickup tool. Other aids are a length of coat hanger wire and a long narrow stick of wood with a round piece of cleaning sponge stapled to the end of it.

>> Stuff I found in the wells: steel metal particles, small steel washer, brass valve cap, chucks of old plug boot, misc fuzz & crap...none of which you want down in the cylinders....even a piece of hard plastic caught under a valve might bend it.

* I used some stuff like STP on a length of coat hanger wire to fish out stuff that the air and magnet wouldn't get...also the flexible claw helped a lot. A good flashlight allows you to see what's down there...it ain't pretty.

It's a good idea to use some STP type oil down near the plug threads before removing them to help keep some debris out of the engine as a plug comes out...but not too much or it will drag the debris down into the cylinder with it.

* If you can't get the socket to catch on the plug, sometimes something larger can be down beside the plug hex that won't allow the plug socket to get a grip on the "flats". This has to come out...you DON'T want to round the flats.

* If you have any plug removal problems...take them out in steps...1/4 turn out...1/8 turn back in...& use some WD40 or oil. You CAN have a SEIZED plug where the alum is being deposited on the steel plug threads as you remove it...and if you aren't careful, you can BREAK the plug or trash the threads in the alum cylinder head.

* Its a good idea to label each plug according to its firing order number as you take it out...then you have a way of determining where a poor looking plug came from.

Gap the new plugs or check the gap if needed. If they are Bosch plugs...don't.

Use moly-based grease or anti-sieze compound on the new plug threads...covering the threads lightly.

If a plug comes out real hard...it's probably best to find a "chaser" to clean up the threads in the head. These don't cut & leave metal in the cylinder, but will clean up the threads. Use with care. Maybe you could get by with extra anti-seize.

Re-clean around the holes before installing each plug...especially where the plug gasket seats. I used a long narrow stick of wood with a round piece of cleaning sponge stapled securely to the end, with STP type oil on the sponge...turning it while bottomed in the well.

Start each plug by hand using the spark plug tool or socket & ext....trying to get each plug in by several turns before using a wrench.

Using a wrench, snug each plug down...making sure that there isn't a lot of resistance until the plug is close to being fully seated.

* Be VERY sure that you put NO sideways pressure on a plug as you put it in...you can crack the top insulator and you will then need to replace the plug... most likely after it's all together and doesn't run right.

Torque the plugs to to specs:

14 to 22 ft lbs

168 to 254 inch lbs

Plugs I have used in an na:

Bosch single electrode: Lasted over 40K miles and still fired OK...outer electrode was still sharp...center electrode was worn down into the insulator a few thousands of an inch. Gap was measured at .045" and the center electrode was worn in about .005"....for a total of about .050".

Bosch double electrode: Similar to the single electrode except for having two outer electrodes on opposite sides, allowing the spark to be more open to the mixture. Since the center electrode looks to be the same...will likely last about as long.

Putting it all together:

* You might want to adjust the dist air gap at this time...but probably not.

* You might want to test the dist shaft for sideplay.

* Need to check to see if the plate under the rotor has been upgraded...mine hasn't been.

Remove the old rotor (remove bolt with an 8mm wrench & pull off) and install the new one using the same bolt.

Install the new cap in the right position.

* Be careful any time you are mating the cap with the rotor...it's possible to mess up the cap center button....you will then need to buy a new cap. Not cheap.

* Drop the cap straight down only.

Using the old cap & labeled wires, along with the firing order diagram as a guide, run each new plug wire generally to it's correct plug.

If everything looks OK, check that each plug wire goes to it's plug with minimal interference with any other plug wire...keeping each plug wire AWAY from any other plug wire; and away from any 12 V wires or metal of any kind.

The plug wires should NOT cross near each other if possible.

Rubber vacuum lines aren't a problem. Use the plug wire guides/seperators. You can buy more of these if needed.

Also, be sure that the boot at each plug goes in the right direction off of the plug.

Using some di-electric grease in each boot, install them, being sure that you can hear & feel a solid METAL CONNECTION as they go onto the plug top.

Use NO sideways pressure on an installed plug...you can crack the insulation.

Run the wire to the coil using the same method. I always seem to have trouble with the connx to the coil.

* Doing all this RIGHT the 1st time helps to allow your plug wires to last a good while...so you don't have to turn around and do it again 6 months later.

You might want to look & think back thru what you've done and ask the best question.......what all did I just do, did I do it right, and did I forget anything? Check.

At this point you should be able to remove all tools & start it up.

If it doesn't run right...re-check everything you just did, and the injector connxs and any other wiring and connxs. Also check the vacuum lines. You could have easily bumped or moved something.

If all else fails...just ask the dummies at z31.com.

Redoing the injector connxs:

While the plug wires are off and old plugs are still in, it might be a good time to clean & condition the injector connxs.

This isn't an easy job, but it CAN be done. Mine were all green colored (copper sulphate?) and at least one connx would occassionally fail for a period if the wire was bumped.

Best bet is to start on the passenger side due to better access, and so it is easier to learn as you go. A few of the gizmos in the way might need to be loosened or removed to get to some injectors...watch how they need to go back on.

Doing one at a time....remove the wire clip using a small screwdriver....then find it using the magnetic pickup or flexible claw tool. Careful, they can jump.

Pull the connx off using the wire coming from it...this should not harm the wires and is a test for their condition. Also a good idea check the wires where they enter the connectors for condition and lack of insulation. etc.

I used a small bottle brush and a tooth brush to clean up the contacts...then blew the dust out with air.

Then used some contact cleaner to clean & condition them (ProGold).

Also, I used a very small screwdriver to bend the split side of the female side of the contacts IN some to increase tension in the connector (need to be careful not to crack the plastic)...then worked the connx back & forth several times on the injector to help clean it.

Before final assembly I smeared some di-electric grease on both sides...connector & injector.

Then put the wire clip back on each connector...this takes some practice.


Results? Idle lowered down to 700...runs smoother? Should last another 40K if the rest of it does.

430 Posts
Bosch single and double plats work real well in nas.....turbos are essentially a different engine. If I ran a turbo...I'd use the NGKs.

The reason Bosch plugs won't work in a turbo is probably that they are a hotter plug and can cause pinging in some cars...and maybe they can't handle the boost.

I used some single plats for 40K miles and had no obvious problems...the center electrode was slightly worn down into the insulator when changed out though. The cheapo Xact 7mm wire set (without spiral core)...also lasted over 40K miles. No misses.

Post Edited (Jul 12, 5:56am)
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