Spark Plug Replacement on a ’99 4.0 SOHC

[aldive]

It’s been 79.5k miles since I last changed the spark plugs on my 1999 4.0 SOHC.

Prior to starting the job, I recommend gathering all the tools that will be needed as well as the plugs and wires. I would never change the plugs without changing the wires ( unless using Magnecor wires ).

The first step was to jack up the truck and place it on jack stands. This was followed by removing the inner fender rubber skirts. There was no reason to remove the entire finder liner. Nothing else was removed or moved.

Always change the plugs on a cold engine.

I decided to do the most difficult passenger side first. This in reality was trouble-free; it only took about 20 minutes. The spark plug wires were removed with a spark plug boot tool. New Motorcraft SP500 AGSF22FM spark plugs (http://www.motorcraft.com/products.do?item=18 ) were gapped to 0.065” instead of 0.054” ( to take advantage of my Screamin' Deamon coil pack (http://www.explorerforum.com/forums/showthread.php?p=1535138#post1535138 ).
Dielectric grease (http://www.permatex.com/products/au...auto_Permatex_Dielectric_Tune-Up_Grease_1.htm ) was applied to the spark plug wire ends and
anti-seize compound (http://www.permatex.com/products/au...ubricants/Permatex_Anti-Seize_Lubricant_a.htm ) was applied to the spark plug threads. The only problem encountered on the passenger’s side was with the new Magnecor spark plug wires; each one was about 4 inches too short. I have e mailed Magnecor about this problem.

The driver’s side was the easiest. The only tools needed were a 3/8’ ratchet, a 5/8” spark plug socket, a 1” and a 3” extension as well as a swivel. All plugs were accessed through the wheel well. Plug number 4 ( the plug closest to the front ) is somewhat tricky due to the lower EGR tube. This side also took 15 minutes. The plugs and wires were treated the same as the passenger’s side. The wires were a perfect fit on this side.

All 6 old plugs had a 0.055” gap ( they were gapped at 0.054 when new ) and were in great condition. There was virtually no wear ( the old plugs were Motorcraft double platinum ). This was with 80k miles on them. They could have easily gone another 20k or more miles.

No first aid for cuts and scrapes was need since there were none. No editing out swear words was needed.

The ease of this job was due in part to the use of anti-seize and dielectric grease on the old plugs and wires.

After buttoning everything up, a turn of the key instantaneously established the job was successful. A brief ( 5 mile ) road test confirmed.

A gas mileage assessment will be conducted during a 1500 mile road trip this weekend. The first 500 miles will be with the 0.065” gap and the remaining portion of the trip will be with stock ( 0.054” ) gap on new plugs. Details will be reported on my return.

 

[CDW6212R]

Good for you Al, any job on a car with no busted knuckles means success.

I wonder if the plug wire length issue is because of the three SOHC choices. Ford moved the coil packs around and it must be hard to keep up with the variants. Those on my 302 fit very well, I like that they made them the correct length, most aftermarket sets are too long.

 

[Jakee]

I'm thinking bout trying the Magnecor wires. I guess I'll wait until they resolve the problem with the lengths.

Thanks, Aldive.

 

[jimbo74]

the magnecors i jsut put on my 96 ohv worked awesome, the only issue i had was one might have been a couple inches too long, but it was the same length as the oem i removed, so this was not the fault of magnecor

 

[CDW6212R]

The three possible SOHC wire set lengths suggest that they mixed up the models etc. I'm sure with a consultation with them that the correct wires are available.

 

[aldive]

Got this reply from Magnecor this morning:

I am happy to supply the correct wires... but I will need to know which
of the 3 wires need to be longer (i.e. give me the measurement of the
exposed wire between the boots; I assume it is either the 3 longest or 3
shortest but the actual measurements would be best, just in case someone
put the wrong wires in the box) - as for why it is too short; either
you have the wrong wires or there is some Ford mystery set (which we
have seen before for other engines).

Now thats customer service ....

 

[dmcman1]

I just did my plugs last night for the first time, it was a hellish experience for me. While changing the drivers side front one, i broke off the little plastic hoop for the oil dipstick, then not more than a minute later, stabbed the little sharp remnants of it through my hand. I was soo pissed off, i grabbed that EGR pipe and tried to rip it out with my bear hands out of anger. Bah, live and learn.

 

[aldive]

Got this reply from Magnecor this morning:

I am happy to supply the correct wires... but I will need to know which
of the 3 wires need to be longer (i.e. give me the measurement of the
exposed wire between the boots; I assume it is either the 3 longest or 3
shortest but the actual measurements would be best, just in case someone
put the wrong wires in the box) - as for why it is too short; either
you have the wrong wires or there is some Ford mystery set (which we
have seen before for other engines).

Now thats customer service ....

My new wires arrived today as promised.

What a great company.

 

[gijoecam]

I know it's going to come up, but anti-sieze on spark plug threads is not recommended by Ford. Yes, there are thousands of people that have been doing it for umpteen years, but as I've said before, unless someone knows more than the engineers that designed the engine, I'll stick with their recommendation.

My reason is that the anti-sieze changes the required torque on the plug, as well as the clamping force on the threads and seat. By lubricating the threads, then tightening to the recommended torque, you run the risk of damaging the seat, stripping the threads, or both. Again, I realize people have been doing it for eons on some motors, and some motors do, in fact, call for it; but that doesn't necessarily mean that it's right or best for all engines.

-Joe

 

[CDW6212R]

Yes it does affect the needed torque, but the trick there is to learn what works. So far after about fifteen sets of plugs, about half in aluminum heads, I haven't had any issues. I turn them about wrist tight, no check, just good and snug, don't use any arm leverage.

 

[aldive]

Yes it does affect the needed torque, but the trick there is to learn what works. So far after about fifteen sets of plugs, about half in aluminum heads, I haven't had any issues. I turn them about wrist tight, no check, just good and snug, don't use any arm leverage.

Same here; never had any problem whatsoever.