1998 Dodge Grand Caravan radiator fan?
This is the easiest way--Really!
From the top. Remove the windshield wiper "tub." It's not as imposing as you might think. First, you have to remove the wiper arms. Lift up the plastic cover at the end of the wiper arm and remove the nut. Then, use a battery terminal puller to remove the arm from the stud. Once the arms are off, use a torx screwdriver to remove the torx screws holding the plastic cowling to the wiper "tub". Also remove the nuts at the front of the cowling. With the cowling off, remove the 14mm bolts holding the tub in place to the firewall. Disconnect the electrical connection to the wiper motor. Remove the brackets holding the tub to the upper firewall and then lift the entire tub out of the vehicle. You can easily reach the rear plugs and wires now. I can do the whole tub removal in 20 mins now. It will probably take you 1 hour the first time you do it. But it's a heck of a lot easier than removing the upper intake manifold (there are fasteners on the rear of the manifold that are very difficult to remove), and you won't bruise yourself like you will if you go in from the bottom.
With great difficulty. I have changed 5 of 6 total, the back 3 are truly a bear. After doing this myself, the only thing I can think of that could give a dealer or pro mechanic an edge would be a very small air ratchet to overcome the difficulty of turning a manual one once you have actually gotten a socket on a plug.
First, give up trying to do this from the topside. You have to get the car up, on jackstands was enough for me. I then put a flex joint on the spark plug socket (this is important). Laying under the vehicle (supported fully by 4 jackstands) I reached up with my right arm and with great difficultly removed just the spark plug boot.
I had to use a combination of a short, medium, and flex extenders on my 3/8" drive (in different combinations for each plug). Movement is minimal once you finally get a combo that works; you have to do this a few degrees at a time. The plugs coming out were rusted, overheated, and in one case, obviously not seated 100% (OEM install at that!). The center back plug requires a very thin socket and preferably one with a good taper at the end. If not, you will have problems extracting the socket once the plug is seated - it will bind at the tip.
I looked into removal of the heat shield (which is of course in the way), and other impediments to access, but the only one that may help at all would be the complete removal of the alternator and trying this from up top.
With great perseverance I managed to get the plugs and wires changed, I would love to know how anyone could do this more easily, as even on a lift the only edge I can see is removal of a lot of parts that just does not seem practical.
That said, it can be done - it's just very, very difficult with the average home shop tool set and no lift.
After about 2 hours of frustrations, scratches, and cuts I found that the only "easy" way of doing this is to remove the intake manifold. The manifold doesn't come all the way out, but moves enough to allow access to all the rear plugs.
I just did this from the top of the car.
First slack the serpentine belt by taking a 15mm wrench to the tensioner and pulling the belt off the idler.
The alternator has this two part bracket. Take the top part off (3 bolts) and the top alternator bolt. Loosen the bottom alternator bold and shove the alternator all the way back.
Then remove the ignition coil thing from the passenger's side of the intake manifold (4 10mm bolts). You don't need to disconnect the plug wires. Just move it out of the way.
Now you can get to the 1 plug. After you do the 1 plug don't put all that stuff back; you will need the room for the rest of the job.
Then remove the intake manifold resonator (that thing in the front that says "remove me to get to the air cleaner") by removing two bolts (10 mm) and loosening up two air duct strap clamps. Take out of the car. The air duct to the throttle body comes out two.
Disconnect the throttle cables by pulling the throttle all the way wide open and then flipping the cable back and sliding it out. Then remove the bracket from the side of the throttle body (2 10mm bolts). There's also two of the four vacuum hoses on this 'tree' on the side of the intake manifold; take off the ones that point toward the front (remember which one's which).
Finally, I removed (didn't just loosen) that little strut that goes from the head to the frame. Once you have it loosened, it is trivial to get it off. So just remove it.
Now you have it opened up. This is where the unique hints are: 1) don't bother with shorty ratchets. You can't get enough torque working like that.
2) cylinder 1 is pretty easy once you have the alternator out of the way. Cylinder 3 I used a 1 1/2" extension and I had the ratchet behind the engine compartment and sort of pointing downward and I unfortunately had to push.
3) (big hint) Cylinder 5 I could bring the ratchet across the head to the passenger's side and reach in from both sides (hug the intake manifold with your head on the windshield) and then you can pull the ratchet. I used a very short extension with this one.
Or you can take it to the dealer.
I think it easier to do from beneath unless you have thick arms. You should have a fair amount of experience because you must work by touch. It is impossible to see what you are doing.
My most important suggestion is to buy really good long life replacement plug. You won't want to do this again. You will need a good selection of extensions and universal joints. Various combination will be needed. The van must be cool as you will be putting your hand and arm on the exhaust manifold.
Put the van on stands just high enough to get under and flex your arm. Two of the three rear plugs require you to reach up and around. Replace one plug at a time. Take a good look at where your arm is while removing so that you can fing the hole again with your finger when inserting the new plug. As others have mentioned, you will get just one click on the ratchet. Think calm blue ocean to maintain your composer.
This is the easiest way--Really! REVISED a little
See previous post to get tub off... Then, I just moved the tub and set it on the engine. The back 3 are still still tough to get to from the top! I jacked the van up, put in jack stands and crawled underneath. You can reach the spark plug cables if you follow the exhaust manifold, there is enough room to get to them. Once you pop the cable off, you need to apply the socket and extensions from below, then go to the top and ratchet out. Then go under to insert the new plug, add the extension, go back up top and tighten. Be sure to use a good platinum plug and gap correctly, you don't want to do this process again.
I agree with the person that said to remove the tub covering the windshield wipers, this clears a lot of room for maneuvering and is easier than it looks. The only plug that is really difficult is the rear one on the passenger side and the above method makes a wee bit easier. I found the removing of the manifold cover and alternator bracket and belt a little overwhelming for my skills. I can take anything apart, it's getting it back together that stinks.