DODGE CARAVAN ALTERNATOR REPLACEMENT
This applies to a 1994 vehicle with the 3.3L engine. (Some aspects may be the same for the 3.8L version, and for the 1996-onward installation but it may be worse.)
You need a service manual, though I may include brief pointers from it to make this advice more cohesive. Study the manual, including Fig. 5 showing the terminal to wiring block you have to move to the replacement alternator.
Changing the alternator on the Chrysler 3.3/3.8 litre engine is very awkward. Be prepared to go under the vehicle, to work down the back of the engine, and to take off more than you expect.
So you want to be sure of the diagnosis before you start. The alternator is controlled by the engine computer, which will set a fault code. In my case rapping the side of the alternator with a wrench restored function every time. I was alerted to alternator problems by the Check Engine light, reflecting a code 41 which points to the charging system. I then checked the voltage gage in the instrument panel, but had to check with a hand-held meter as the gage is difficult to decipher (you think that it is 2 volts between marks, but count the marks between 8 and 18!) and not consistent in scaling (seeming to have at least .25 volt hysterisis). It does seem that the marks you'd expect to be 12 (battery close to charged) and 14 (approx charging voltage of typical system) are roughly that.
Prepare yourself with lighting, 18mm deep socket, 15mm deep and shallow sockets (preferably extra shallow to fit between nuts and other pieces), 8 and 10 mm sockets, 3/8" ratchet wrench with short extenders and adapter to 1/4" for the small sockets, desireably a 1/2" ratchet wrench for leverage on some bolts/nuts, and belt tension relief tools. If your 15mm socket is not shallow enough you may find a cranked closed-end 15mm ratcheting wrench helpful for the tensioner nut.
You will of course have to remove and reinstall the serpentine drive belt - go to my main Caravan page to see my advice on that, and needed tools.
You might consider replacing the tensioner for the serpentine drive belt though it is another $80. or more cost. If you have time/alternate transportation to go get one if needed, you might examine it - I found the old one had taken a set relative to the new one (the mechanism and pointer were significantly CW from the new one which appeared to be at fully extended position). I purchased a new one because in reinstalling the belt previously the old one had stuck in a retracted position so the belt was loose, until I whacked it with a wrench. It was more difficult to get the belt back on with the new one, given the limited tool travel I describe in my page on the belt.
Looking at the service manual instructions, I make these recommendations:
- instead of loosening the cranked heavy metal bracket that runs horizontally off a manifold bolt, you may want to remove it to access the bottom alternator attach bolt and get it out. (Not difficult, but see later suggestions. At the manifold, you'll need a deep socket.)
- the forward-most of three bolts (top) attaching the tall "generator support bracket" to the engine goes through an angle bracket to an engine mount. Remove that bracket (which requires a deep 18mm socket). There is a spacer between it and the "generator support bracket", to fall out and get lost - the bolt is long.
- You have to undo three bolts to move the power steering fluid reservoir, counting a hose clamp lower down. (8 mm socket.)
- The "generator support bracket" only holds the top of the alternator, whereas the bottom long bolt goes into a cast metal structure. So you should be able to get the bracket out by removing its attachments plus the top alternator mounting bolt (a medium length one). Then you can get good access to the bottom bolt of the alternator, the very long bolt. At that point, I suggest removing the terminal block from the alternator while it is still supported (8 and 10mm sockets). (Going back together, you can put the bolt in place but not fully tight until the "generator support bracket" is installed - at which point it is awkward to work on to tighten, as you have to have a socket wrench on both ends (deep socket on outboard end where the nut is).
- Note that the bolt does not squeeze the two alternator lugs together - there is a press-fit spacer that slides in one lug to take up slack (the replacement alternator should have the spacer backed out somewhat to accommodate tolerances).
- The wiring diagram in the factory manual shows the terminal block flipped upside down. Not essential to understand geometry as you don't need to work on it until you have a good view with other pieces out of the way, unless you need to diagnose where the fault actually is before undertaking this painful job. (The wires off the studs of course actually come out of the back of the terminal block as the wiring harness). Examine the alternator internal diagram to understand what the wires are for (hot stud A11 includes a filter capacitor to ground). The wiring harness comes from forward on the engine somewhere to the terminal block, with branches to a 4-contact square connector near the firewall (probably the heated oxgen sensor which gets ground from the alternator) and a rectanglular connector TBD near the firewall.
- The forward lower hole in the "generator support bracket" is oversize to ensure the tensioner mounting stud clears it. Note the "generator support bracket" goes on the inboard side of the cast structure there whereas at the three mounting bolts it is on the outboard end of the engine, with one bolt location between the engine and the L-bracket discussed above.
- The tensioner has a projection from its mounting face that goes into a slot in the cast structure to position it in rotation. I suggest jamming something between the tensioner and the frame once you get it rotated correctly, to ensure it stays there while you go underneath to put the nut on.
Yes, you'll need to go under the vehicle to get at the tensioner stud retaining nut. You can reach past the sharp manifold-exhaust joint, under the alternator, using a 3/8" ratchet with shallow 15mm socket, handle aft. Relatively speaking that is far easier than trying to get your arm far enough down the back of the engine past the junk there (if you can tilt the engine forward, going down the back might be feasible - to tilt the engine in my 1994 vehicle would require removing parts from engine/radiator to get clearance).
- If you could move the A/C lines on top of the shock tower that would really help work on the side to remove the "generator support bracket". Perhaps you can get an A/C shop to do that next time your A/C is serviced, in case bending them causes leaks.
- To improve access down the back of the engine, disconnect the square alternator connector, the connector to the MAP sensor (that sharp-cornered plastic box on the back of the manifold), the vacuum line to the PCV valve, and the ground strap to the firewall
- You may be able to pry the engine forward a bit and put a block between it and the firewall.
- 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 and other proximities. There's something in that claim about parking brake and Park transmission selector position but it is garbled. 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.
© Keith Sketchley Page version 2012.10.30 (1950PST)
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