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Changing spark plugs on a 4.0 SOHC


bodkin1

Well-Known Member
Joined
Oct 7, 2007
Messages
167
Age
40
City
Carbondale, Illinois
Vehicle Year
2002
Transmission
Automatic
Is there any good way to change the spark plugs on a 4.0 SOHC? Looking at the engine from the top it would be next to impossible, and dread the eventual time they will need to be replaced... hell and I thought the ones on my '93 2.3 were a PITA to change.

So just short of sending it to a shop to save my time and sanity how have you DIYers been able to change them?
 
yep, through the wheel wells. next to impossbile to get to from the top
 
Don't be scared, it's super easy.

Step one, pull passenger wheel and inner fender plastics

DSCF1966.jpg


Step two, remove, they are right there and don't get any easier.

DSCF1975.jpg


Driver side you can get from the top.
 
This is the setup I use at work to change the right side plugs, just pull the inner fenders and they are right in front of you.
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I just did all the plugs in my 94' 4.0 4WD. And I did them all from the top. I just disconnected the tiny vaccum lines on the passengers side so I could get my arms down there. For the farthest one back on the passengers side I needed a swivel. For the others, I used either a 6" or 3" extension, or both on a couple. It was actually pretty easy.
 
Last edited:
Kloque, In case you don't know, the 94 4.0 is not SOHC unless you did an engine swap.
 
Don't be scared, it's super easy.

Step one, pull passenger wheel and inner fender plastics

DSCF1966.jpg


Step two, remove, they are right there and don't get any easier.

DSCF1975.jpg


Driver side you can get from the top.

I take it the way to remove the inner fender is to remove the 3 bolts up front, and the two that run up the middle of the wheel well, and then it should come out? After I have it jacked up and the wheel removed of course.
 
Finally completed it, it was almost right at a 3 hour job. Went thru the passenger side by removing the inner fender. Driver side from the top. Only trouble was getting the plug wire boots loose (I believe it still had the factory plugs/wires), especially the middle one on the passenger side, with the trans dipstick tube right in the way. Sprayed the boots to kingdom come with WD40, to help aid in the removal process. Of course made sure to coat the threads of the new ones with anti-seize.
 
Last edited:
Don't be scared, it's super easy.

Step one, pull passenger wheel and inner fender plastics

DSCF1966.jpg


Step two, remove, they are right there and don't get any easier.

DSCF1975.jpg


Driver side you can get from the top.

The obstructions(Heater radiator, etc.) on my 2003 4.0 SOHC are much lower than that pictured.
 
On a 2011 SOHC 4.0... Are you removing just the rubber flap? Or the entire plastic inner fenderwell? Can't tell w/ the blurred photobucket pictures.
 
You should only need to move the rubber flap.
 
I checked the EZ sparkplug to get to, on drivers side. It was a Motorcraft AGSF24N. Reading on the net, I might well find a diff p/n plug (same base # but with diff suffix ending) on pass side.

Fordparts.com website says to use SP-412, which is nickel plug. Reading about waste spark... what is correct dbl plat motocraft plug to get? SP-500? Which all the auto parts palces says "Not A Fit" for my 2011 4.0 Ranger.

Had no idea p/n's are so convoluted. Getting the p/n straight looks harder than changing the plugs. LOL!
 
The nickel plugs are supposed to have a similar life to platinum. I have been running the SP-412s in both mine for a while and have yet to have an issue. I think the worst thing that has happened so far is one cracked an insulator.

The big thing is that in a waste spark system the spark moves in one direction, so one plug fires the traditional way, from the plug wire down, and the other plug the spark jumps up towards the plug wire. If you don't have properly matched plugs one side wears out faster than the other.
 

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