SPARK PLUG REPLACEMENT
(plus valve cover bolts - DODGE CARAVAN)


I presume you have a service manual, though I may include brief pointers from it to make this advice more cohesive.
All directions are as viewed from the driver's seat.

An alternative way to get at rear plugs if you are removing the intake manifold which allows access to rear injectors and rear valve cover.


Do not attempt this job unless you are experienced at changing spark plugs - this work requires a feel for threading plugs in correctly to avoid damaging heads by cross-threading, and getting the socket off the plug without cracking the insulator - for sure, as you cannot see it to inspect it afterward.

Suggested tools:
- For spark plugs:
> 3/8" drive ratchet wrench
> standard spark plug socket (regular size 13/16", no swivel, rubber retention insert in good condition but not too tight, preferably a longer than normal socket to be able to pull it off of installed plug, perhaps modify standard socket with holes to a pull wire)
> medium extension bar (clearance to firewall for wrench is a bit tight, normal medium extension is 3"
- air supply with nozzle (to blow junk out of spark plug well)
> desirably a photo of the area of the right rear spark plug, especially one looking down showing the stud of the brace bracket and the plug.
> the "Oxygen Sensor - 3.3L Engine" illustration from the Chrysler service manual, to help you visualize where the plugs are relative to bigger pieces, though it may not show all interfering parts.
> long skinny arms ;-)
> and protection for them, you'll be rubbing against oily engine parts as you reach far up or down.
> lights, mirrors, and perhaps a video inspection camera of wand type.
Let the engine cool down before working on the rear plugs and bolts, as you'll be touching the exhaust manifold.
> You may want a good wire puller, preferably that locks onto the plug wire below the bend in it and has very good grips for your hand as the tight space makes gripping difficult and there is little room to pull, though I have pulled the wires off with my bare hands - the aft RH plug is especially difficult with bare hands. And you have to get the wires back on - see below.
> thumb turn wheel that fits in place of ratchet wrench, for feel installing plugs and for quicker turning
> an experienced touch to start threading the replacement plug in correctly.

- For valve cover bolts:
> 10mm wrench with open and closed ends (closed end vertically offset, see photo of offset closed ends:)
* Craftsman offset end with slight angle (short, open-closed ends)
* Craftsman offset end with slight angle (long, dual ended)
* Craftsman offset end with arch (long, dual ended)
(Those samples have progressively thinner surround of the bolt head in order listed.)
* 'DOWIDAT No. 2' offset end with step (long, dual ended)
(I've seen the offset on MasterCraft (Canadian Tire brand) but it seems to vary with batch. Princess Auto sells a set of wrenches with the step. The step will be better if the valve cover flange is high or close to the bolt. Short may have an advantage in the tight space.)
> low profile ratchet (1/4" drive)
> 10mm short socket
> long extension bar for the ratchet
> swivel extension for the 1/4" ratchet (separate from socket), try to limit its movement with rubber in the mechanism

Parts
I have good success with RN14MC5 plugs, which are specified for my US-emissions 1994 and my Canadian-emissions early 1993. (The 1993 has an alternative of RN16YC5 listed on the underhood emisssions label, that is a higher eat range and a longer nose projection.) 5 is 0.050" gap, C is Copper.
There is an RN14MCC5 plug (two C characters for 'Double Copper' in electrodes.)
I suggest a very small amount of anti-seize compound on plug threads.

Beware of 'platinum' plugs, those with a fine wire centre electrode are not suitable as the 'DIS' ignition system's reversing spark polarity will erode it quickly.

I'll emphasize the rear plugs and cover bolts as they are a challenge, but do the front ones first so you learn something of the geometry of the parts, which are reversed for the rear head.

SPARK PLUGS

Changing rear spark plugs on the Chrysler 3.3/3.8 litre engine in early 90s Caravans is very awkward.

You can do the aft leftmost two by working from underneath on the back side of the engine (it does not take much lift of the vehicle for appropriate reach when crawling under on your back, to reach standing up would take a high lift), using a non-swivel socket with medium extension bar and preferably a 3/8" ratchet drive.
The rightmost is a long reach from either below or above, I prefer working from above while visualizing geometry.

(You'll be working almost blind thus it is difficult to judge the angle of the plug and your wrench. After you've spent five hours and/or done the job five times that month you'll do better at it.) Memorize orientation relative to the adjacent higher one of the two manifold runner bolts (strut stud for middle rear plug). Refer to photo of middle rear plug, relative to a strut, looking down from front of vehicle, access to right rear plug is from forward of the strut. Your socket extender bar will be roughly near the stud but the plug hole is to the right because of its angle in the manifold.

I recommend blowing air into the well around the plug to remove sand and pebbles that would fall into the cylinder once you've removed the plug.)

The aft plugs are angled opposite to the front ones, as if the same head casting was used, with a bend & tab in the wire as the front ones have. Aft plugs angled to left, front ones angled to right. Looking at the front ones you can also see how far they are recessed beside exhaust manifold legs, and orientation relative to manifold bolts.

For the centre aft one you can get both hands in, one each side of exhaust take-down pipe.

CLEARING JUNK OUT OF THE WAY TO WORK FROM ABOVE
- remove MAP sensor (use a wrench on the pseudo bolt head aft side, note orientation with connector to right, sensor is marked UP)
- detach ground strap terminal from firewall
- detach hose to PCV valve (tuck it under the TCM)
- tuck/tie up any loose wires out of the way
- the fitting securing the oxygen sensor harness to the intake manifold is a scratch point, it should be moved to the firewall.
You can then reach the two aft left plugs with your left hand. (On vehicles without ABS you may be able to reach around with your right hand under the throttle body, or detach the vacuum unit for the EGR valve and put it out of the way to reach over the TB (but be careful with those thin plastic vacuum lines).

To thread the plug in I feel where the plug points relative to the manifold bolts (using the fwd side of the engine to learn), as I can feel them (different on each side of plug, points closer to the higher bolt).

SPARK PLUG WIRES
They are changeble if you use the access from above method after removing pieces.
One problem when changing plugs is feeling if the wires are fully on the plugs, first check that the contact sleeve has not been pushed back in the outer casing, test the fit of it to plug terminal with a spare or old plug to ensure diameter is correct (adjust with pliers or screwdriver as needed), then expect to push hard. (Experiment with a front one to get a feel for rigidity of a properly mated wire, there should be a click - before that you are pushing the wire shround over the ribbed spark plug insulator.) The right rear one will be especially difficult to get on due limited finger room.
Do inspect the metal contact clip in each end of the wire, if it has not been properly pushed on the plug it will corrode. And the distributor end has to be seated fully, you are pushing the shroud over the boss on the coil (the design at both ends is to keep moisture out but it makes seating more difficult).
Checking resistance of plug wires is a good idea, from memory they should be between 5 and 15 kohms depending on length (that's resistance type wires of course).

VALVE COVER BOLTS
While you have access to the back side of the engine, whether from above after removing pieces or from below, tighten the centre aft bolts of the rear valve cover. As your tool choose either a 10mm wrench of medium length with open and closed ends, one angled with a bit of offset as is common on closed-end wrenches (as the cover has a lip around the edge), or a 10mm socket with very low profile ratchet.
OTOH, if you want to buy tools, Snap-On has a combination of closed end wrench with swivelled socket on the other end (no ratchet). Otherwise the offset closed-end wrench is best as the left end and next to right end bolts are obscured from above/right by things, go at them from the left.

The lip on the valve cover prevents use of an integral ratchet closed end wrench, proximity to the cover prevents use of a normal ratchet wrench. The valve cover is above the spark plug area of course, and the intake manifold hangs well over the back of the engine so you cannot reach over from the front.
Possible wrenches (10mm): > a closed end wrench whose end is a bit offset from the shank, as some are (see Tools at beginning of this page).
> perhaps a 10mm socket on a swivelling right angle bar>BR> > SnapOn sell a bar with socket integral, with a bit of swivel

You should be able to reach the middle two from the back side (they are approximately in line with the exhaust manifold legs), the RH one is especially difficult for people with short wide arms: using wrench with left hand though not much swing room, perhaps getting the wrench in the cover edge groove then sliding the wrench to the right until it hits the head, then lifing it up on top of the head and rotating plus wiggling until it sits down over the head (don't laugh, I've succeeded with that).

(You may be able to use a socket wrench with right hand but that is awkward if wiring is lying over the bolt head and because space between exhaust manifold joint and PS pump tubing is narrow.

The corner ones are reachable from under the hood, though the left one might be just as easy from underneath where you will be anyway.

(For trying to curb oil leaks in general, note there is a grommet toward the right end of the aft valve cover where the PCV valve hose, it may need replacement, best done before it gets very hard. check that, which valve cover?)

- Back around the front of the engine (well, start there first so you know which ones are left to do from the rear), you can reach these valve cover bolts:
> with a 1/4" swivel and very long extension on a 10mm socket, the right most aft bolt of the rear valve cover (through the cutout in the alternator bracket), the left-most aft bolt of the rear valve cover (with care), and with even more tricky maneuvering the front RH bolt of the aft valve cover (or try a 10mm closed end wrench with a bit of offset as exists on some of those wrenches - see ; otherwise you can take the coil pack off: 4 bolts, the underneath ones on more of a pedestal than the top ones).
> with a long extension on a 10mm socket all other [front?] valve cover bolts.

- Chrysler could have done several small things to improve access to the RH side and back of the engine, such as hose clamp location, manifold pressure tap location, ground strap location/length, sensor orientation, and computer location. Kurmudgeon Keith thinks that all designers and managers should work in a vehicle maintenance shop on awkward unfamiliar vehicles for a week every two years. :-)
As well, they could have put locking devices on the valve cover bolts. They loosen, just like those on the Pontiac 4-cylinder engine that sometimes caught fire in the Fiero car. (It may be good practice to have loose fit of engine fasteners, but surely designers could have added a friction locking method.)

POSSSIBLE ADDITIONAL FACILITATION
An article on AllPar web site advises to take out the front engine mount bolt by the radiator, and let the engine rotate forward - but it looks to me as though there is little clearance from engine to radiator fan shround, and other proximities. There's something in that claim about parking brake and Park transmission selector position but it is garbled. And there's the matter of the RIH engine mount being high up so how can the engine rotate? Sounds tricky, as there is more than one bolt and multiple pieces in the service manual's instructions - perhaps the mount can simply be dropped from the front crossmember. The service manual cautions to support the engine to prevent rolling forward, and advises the RH mount is adjustable by about 2/3 inch but that seems tricky. I've concluded it is far from a practical approach.

- Or maybe remove intake manifold, then you can change the rear valve cover gasket too. That's the time to check rear fuel injectors if you want to. Take a week and do everything. ;-)


© Keith Sketchley Page version 2019.07.07

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