1996 AWD 4.0 V6 with 170,000 miles on original plugs. Been missing for awhile under moderate load (although curiously not under full load, generally, which made me initially look elsewhere than ignition), finally the check engine light came on, and the code reader said "misfire in cyl. 3". When I started looking at how to get at the plugs, I realized why the previous owners had never changed them. Took me the better part of two days to do this. Here are some hints on how to do it:

1. Buy the Motorcraft plugs and a wire set (if your wires haven't been removed recently and/or assembled with silicone grease, you'll likely end up breaking one or more to remove them). I would recommend the Motorcraft wire set too, since the ostensible "made to fit" aftermarket set I bought were still too long for clean installation. I also recommend, if you can find it, a "barrel"-type plug boot remover pliers. Preferably a set with variable angles on the end, 'cause things are tight in the engine compartment. And get a tube of silicone spark plug dielectric grease.

2. Raise the front end on jackstands at the frame (not the A-arms), so the front wheels are hanging. This allows adequate access above the tire to get through the wheelwell opening. Remove the tires if you want more room and comfort, although I didn't really need to (just call me pinhead).

3. Access the front two sparkplugs on each side through the wheelwell. You might want to bend the brake line (carefully!) slightly out of the way of the upper part of the left side wheel well opening. You may also want to temporarily remove and cap the vacuum (?) hose in the way of the middle plug on the left side. Access the left rear plug from above and/or underneath; you'll never get at it from the wheelwell. Access the right rear plug from underneath the van.

Notice that I didn't mention removing the so-called access panel inside the cab; you shouldn't need to remove it unless you need to replace wires; in my experience, no effective access to plugs is available here. You WILL have to remove this panel (cupholder and blackbox--computer?--under dash first though) if you need to replace wires.

I identified the plugs by position, not number. That's because I can't abide Ford's insane cylinder numbering system that counts front to back individually on each bank instead of just front to back, which would actually be a universally acceptable approach--end of rant.

4. The hardest task is getting the damn plug boots off. Grab the boots BELOW (closest to the engine) where the connector makes contact with the plug terminal and twist a bit to break the adhesion 'twixt plug and boot. Then pull like hell at the same point whilst trying to rock it back and forth slightly. Since you have no space to "pull like hell" you will feel the need to do some serious cursing. (I'm not a violent man, but if I ever run into the doofus that thought changing plugs on this would be routine maintenance, I'd be happy to draw and quarter him). I made a little hook arrangement so I could pull on the open end of the boot first to try to work it back a bit. But inevitably, I couldn't fit both the hook thingie and my pulling hand on the boot at the same time, so a little of one approach, then a little of the other. When one hand gets tired, use the other. Repeat incessantly. Or just give in to time and/or emotional limitations and indiscriminantly yank the things off figuring you will have to replace them.

5. My plugs were not torqued very high (spec is only 15 ft-#, so don't overdo it when you replace them).

My as-removed original factory plugs had 0.088"-0.113" gaps (0.054" is spec). All left bank plugs' electrodes (P suffix, for those in the know) had worn/eroded down to the porcelain. All right bank plugs' ground tangs (PG suffix) were well worn as well. (A tribute to the damn good iginition systems in these vehicles). I replaced with Motorcraft AGSF42FM (vs. the original replacement AWSF42PP, apparently no longer readily available). Unfortunately Motorcraft's website says the FM (fine wire center electrode) plugs are fine for this application, but doesn't say why the originals were double platinum (center and ground electrodes) and the replacements don't seem to be....

One more thing: Put silicone grease on the plug boots and/or spark plug porcelain (not on the contact terminals). If you and/or the van live long enough, you might have to do this task again.

 

Ah, but think of the sense of pride and accomplishment you now have. Aerostar ownership is not for the weak nor fainthearted. You have dared to go where most mechanics fear to tread. By "pulling the dragon's teeth" you have earned membership in the exclusive Aerostar Busted Knuckles Club. Welcome Sir Maxbarcalounger!

Of course to prove your bravery and skill, you must next confront the dreaded Heater Core - which requires a blood sacrifice.

 

nice write up Max, thank you

I am geting ride of a 91,havent had the pleasure of doing the plugs on it. I bought a 94 with new shiny plug wires, wont be doing them soon

 

170K on original Motorcraft Aero plugs, a new record?

I do my plugs wearing leather gloves, reduces meat and blood loss, all from the top with plug socket with builtin universal, multiple lengths of extensions to 18" and inline universals. use grip type plug wire puller.

actually, the factory original plugs are a single platinum, plugs on one engine side have plat on center electrode, plugs on other side have plat on electrode strap, Ford's electonic distributorless ignition uses a three coil pack, fires into two cylinders at same time, compression and exhaust opposing cylinders. one plug side spark jumps from center electrode to electrode strap., other side fires from electrode strap to center electrode.
one side of engine wears away center electrode, other side wears away strap electrode.
don't imagine there are many original Ford Aero V6 plugs left out there but Ford did have a warning not to mix plugs across engine.
these special mixed up one sided beasts were never available to retail from Motorcraft. I've always wondered how many got mixed up in Ford assembly plant on Friday graveyard shift? all to save a quarter per plug?

a '80 Buick Sklark with transverse V6 is far worse than Aero, traded in so I didn't have to change plugs, shops would not touch it, GM shop quoted me $450 to change plugs in 1986, the original throw away car.

 

I replaced my plugs the 3.0 96 last year 45k on originals the hardest for me was the drivers side rear. I actually got my plug socket stuck on the plug for 2 hours until I got an idea and took another socket slipped it on the hex head of the plug socket to get that plug out.

Those manifolds pipes ALMOST are close enough to allow clearance for my ratchet with the plug socket attached to it but no cigar so the extra socket on the ratchet allowed me to get that plug off without the extra thinkness the head of the ratchet had which was preventing me from turning the socket.

But afterwards I felt the difference in engine performance it was hard to believe. I went against the grain and installed Bosch Platinums and new wires a year as passed and no problems here.

 

I'm trying to get up the nerve and set aside the time to do my 4.0 soon. Would it help to just cut access holes in the fenderwall? They could then be covered over with sheet metal when finished.

 

Hey pbrunner we think alike. If I have to do plugs on my '91 4.0 AWD I'm seriously considering making an access hole for the rear passenger plug. There would be some issues concerning the insulation but otherwise seems doable,at least at this point anyway. Hopefully it won't have to be done for a few years yet. If gas prices continue thru $3.00/Gal. I won't be driving much anyway.

 

Its really not that big of a deal the rear passenger was the easiest of the two rears just reach up past the pipe leaving the manifold and there it is if you remove the extension from the ratchet you will have just enough clearance after loosening it with the ratchet remove it and just unscrew the socket by hand.

Now the drivers rear on the other hand is a real pain and I can see cutting an access hole for that one. But with your right hand on the end of the ratchet to keep it on the plug and your left hand dangling the ratchet behind the throttle cover plate it is doable.

Welcome to the first level of Aero hell for the second level [see oil pan gasket replacement] which involves removing the tranny in any case no mater which route you go if its your first time you will end up with cut or scraped knuckles when you finally finish. Well at least more then the rest of us who have done it before . Aero maintenence is not for the faint of heart.

 

I wouldn't fool with adding access holes. It would be a lot of trouble, I think, to do this cleanly, and, after all, if the plugs will go 170,000 maybe the engine will die before you have to do it again....
And it is true that the passenger side rear is the easiest to access, from below. I can even see doing the driver side ones all from the top...I think it IS feasible, but getting those boots off is a challenge no matter how you do it. The passenger side plugs are well blocked from above by the dual heater and AC lines on my rig. But you can get to the ignition module end of the wires from in front above, and with some contortionism, from the rear through the "access" cover (grrrr--I guess the anger will fade with time...)

 

I was thinking of using a Greenlee punch to make the access holes. Requires only a small drilled hole and a ratchet. I'm reminded of when I was asked to help remove a starter from a 60's era mercedes. My brother had tried for 2 days and gave up. After surveying that no combination of extensions a swivels would get me there, I pulled back the carpeting on the passenger's side to cut a hole. There was an access plate already there! That's the way the engeneers designed it. I think it's the bean counters that eliminate these things.

 

I can do a complete spark plug change on a 3.0 Aerostar in less than 15 minutes, with no blood involved. I use nice tight fitting mechanics gloves, and just jack up the front end on the vehicle. I then do the passenger side first, since they are the most difficult. The one I have the most trouble with is the middle plug on the passenger side (#2), since there is the least room to move there. The rearmost one is easy, but must be done from underneath the vehicle. I have never worked on a 4.0, but if the angles are much different than a 3.0, then it would be more difficult. If I were to help design the Aerostar, I wold have made it like 2 inches wider, and that extra width would have been used to add extra clearance to the sides of the engine. Extra interior room is always nice too. It also might have made the van feel more stable. Despite the flaws and hard to reach areas, the Aerostar is by far the best van ever built. I laugh to myself every time I look at people driveing their "Caravan", because they think it is such a great van, till they find out you can hardly get 150,000 miles out of them. The Aerostar, when properly maintained is good for twice that. Out Aerostar has 180,000 miles on it, and runs like a champ, and can easily out accelerate a Caravan.

 

Well, now, we've also got a Plymouth Voyager with 3.0 SOHC that has 200,000 miles on it, and shows no signs of giving up. This Mitsubishi-built engine is quite good (it did require a crank seal at 120K), and coupling it with the reliable 3-speed automatic (vs. the trouble-prone 4-speed/OD) has made for a pretty reliable vehicle. Doesn't hold as much, but it is more car-like. And the plugs are three times easier to get at....
Oh, and I suspect that the fully optioned Aero 4.0 AWD has a lot less room than the 3.0 RWD, especially if lightly optioned. But then again, maybe I'm just bitter about your "15 minutes" statement....

 

I have a socket with Hex head on it. Then I put my wrench on the socket and turn. Easy as pie. I use a 18" Wobble extension for the center ones from outside the van. Takes me .30mins to do the whole van.

 

15 MINUTES!!!! [grumbles as he soothes cut and busted knuckles]

 

actually thought I was doing well with changing plugs and wires in just over an hour. lol