It Leaked Everywhere!! How To Replace The Water Pump 1978 Dodge B200 Camper Van
September 12, 2020
We bought a van but its water pump is leaking. Let’s replace the entire cooling system! When your water pump starts leaking, it is only a matter of time until it lets go and you find yourself stranded on the side of the road with no coolant. It is best to just replace it and in our case, we are going to replace the entire cooling system while we are at it. We are putting in a new radiator, water pump, thermostat, heater core and all of the hoses. Upper and lower radiator hoses, coolant bypass hose, and both heater core hoses. Let’s see if we can ger this all done in an afternoon.
The first thing to do is get the coolant drained out of the system. Now, most radiators including this one have a drain on the bottom that you can typically use to drain the system. However, this radiator looks like the original one that came with the van, and its drain is completely seized. The next best thing is to drain the coolant by pulling the lower radiator hose. However, with this van … the hose is stuck to the outlet and refuses to come loose.
Not a problem, I am just going to use a large plain screwdriver and push it in between the hose and barb, releasing the fluid that way. I could have also just cut the hose, but I am trying to minimize the mess that I am making and do not want to get a bunch of coolant on the ground. Animals will sometimes drink coolant as is it sweet, and it will kill them. Be a responsible backyard mechanic, and make sure to collect all of your fluids and dispose of them properly. Your local parts store will typically recycle them for you for free, so make sure that it gets there.
Once you have as much fluid drained out of the system as you can get, it is time to start disassembly. In some ways, the fact that we are removing everything makes replacing the water pump easier as it is directly behind the radiator. First up is removing the grille. There are usually five screws along the top holding it in, but in our B200 they are missing so all that is left is the five screws along the bottom. It helps to use a magnetic tipped screwdriver here, as you have to sneak in between the grille and the bumper and it can be easy to drop the screws into the bumper itself. They should come out fairly easily, and once all of the screws are out you can almost remove the grille. See those blinkers? Well, you need to unplug them from their wiring harnesses, they are located in the engine bay directly behind the lights. Once those are disconnected, you can feed the wire harness thru and carefully pull the grill away from the van. Set it someplace safe, you don’t want to break this thing accidentally.
Next up is getting the coolant reservoir out of the way. Ours sits right on top of the radiator, and has a single hose connecting it to right below the radiator cap. There is a single clamp on the radiator side that needs to be removed, and then two bolts that go into the front crossmember. Once those are removed, you can lift the reservoir up and out of the way. Be careful with this though! The reservoir will still have anywhere from a little to a lot of coolant in it, so make sure you are ready to drain it into your bucket once it is out.
Now we move on to the hoses. The upper radiator hose is first, there is a clamp on the radiator side, and another one on top of the engine where it connects to the thermostat housing. You can typically grab the hose with your hand and twist it loose, but if that doesn’t work a pair of alligator pliers will work wonders. Once that hose was off, I moved on to the heater core hoses. When removing the hoses from the heater core side, have a rag ready as some coolant may leak out. Mine did not, but it can happen. Once that side is off, it is time to get them pulled from the motor side. On the Dodge 318, one comes off of the water pump, and the other is on top near the thermostat. They should pull off pretty easily, and if you have a bracket holding them out of the way make sure to remove that as well so that you can get them out.
Not all engines will have a small coolant bypass hose like this one, but we are replacing it as well. One side is on the water pump, the other goes in under the thermostat. I had to use pliers on that one, but it came off without much of a fight. Now that all of the upper hoses are out, it is time to move under the motor.
The clamp on the radiator side was already loosened as this is where I drained the system, but if you look up into the engine bay you can see where the other one connects to the bottom of the water pump. This hose absolutely did not want to come loose, and once I got it off I could see why, the lower barb on the radiator was mangled. Good thing we are replacing it!
Next up is disconnecting the fan shroud from the radiator. I forgot to record loosening the nuts, but there are two on each side that will need to be removed. Once they are off, you can pull the shroud back towards the motor, over the fan blades, and set it there out of the way.
Now it is time to remove the radiator. It has four bolts holding it in typically, but a previous owner installed this transmission cooler that connects thru a couple of holes in the radiator flanges. Removing them threw me for a bit of a loop as he used 10mm nuts, when everything else on this van is imperial, but eventually I figured it out and removed the three nuts that held the cooler in place, leaving it hanging by its top strap. I also decided to unhook the window washing fluid reservoir and shift it out of the way, as it is mounted right next to the radiator. Once that is done, I removed the two top bolts that were holding the radiator in place. On this vehicle, and most others, you do not need to remove the bottom bolts, just loosen them as the radiator flange has tabs that sit on top of the bolts.
Once I had that down, I decided to remove the bolt holding the oil fill tube in place, to give me extra room to move the radiator as we will need to pull it upwards before setting it down. Which is exactly what happens next. Pull the radiator straight up, then tilt the bottom of the radiator towards the motor, then just set it down on the ground. There isn’t quite enough room at this point to tip the radiator out from under the van, but that is all right as the next step will make it work.
With the radiator sitting on the ground, that now gives you easy access to the four bolts that are holding the fan blades, spacer and pulley onto the water pump. They should come out fairly easily, but make sure to leave the top one in there to remove last so that you can hold onto the fan blades so they don’t fall on the ground. After that you can remove the pulley from the water pump and set it aside as well. Now that the fan blades are out of the way, the radiator can be tipped over and pulled out from right under the front of the van.
Getting the radiator out of the way makes this entire process a lot easier. I also disconnected the last strap holding the transmission cooler in place and set it over to the side to completely open up the front of the engine bay. As you can see, in this 1978 Dodge B200 they used several of the water pump bolts to hold both the power steering pump on the right and the alternator on the left in place. I removed the bolts for the power steering pump first, and even though I was expecting it the heavy little bugger fell down and hung by its hoses. Make sure not to do that, also make sure to have a catch pan under this area as liquid will come out from various places during this process. Carefully set the power steering pump back on top of the steering linkage, out of the way. Next up is the alternator brackets. First, disconnect your battery cables. No need to fry the system accidentally. Then I just removed the lower bracket entirely, and once unbolted was able to swing the top one up and out of the way. After that I loosened and removed all of the water pump bolts, making sure to know which lengths went to each hole. The shortest bolt is in the top center, the bottom two are the next longest and the two outer bolts on either side are the longest ones.
While holding onto the lower hose barb, I hit the shaft of the water pump with a rubber mallet, breaking its gasket seal with the motor. This leaves a lot of the gasket in place on the motor, and it all needs to be removed before putting the new water pump on, or you will end up with another leak, which was the whole reason for doing this in the first place. I use a razor blade to scrape it all off, but if you try this be super careful to not gouge the metal … as again that can lead to a leak.
Once I had that whole area cleaned up, It was time to remove and replace the thermostat. It is held in by two bolts, which on my motor are pretty obviously not original. Once you are able to remove the housing, pull out the old thermostat and clean the gasket off of both surfaces. Once they are cleaned up, it is time to put the new thermostat in. Grab the housing, and put the new thermostat in there point first, followed by the new gasket. Set it back in place, put both of the bolts back in and tighten them up evenly.
We can finally do what triggered this whole process, install a new water pump. Take the water pump and its gasket and put the top bolt thru its hole. Slide the whole assembly loosely onto the motor, using the top bolt to hold them in place. You can put the rest of the bolts in place, carefully putting them thru the pump and the gasket making sure to not tear anything. Once it is all fit back together, you can snug up the top bolt and the bottom left bolt, but not too tight you are just holding it in place while you get the alternator and power steering pump remounted.
I did the alternator first, hooking the upper bracket back into the two bolts on the side of the water pump along with adding the adjustment bracket back in place. After that I bolted the power steering pump back in place, but you will notice that I completely forgot to put the double bolt mounting bracket back in. Don’t worry, I notice it later when I find the bracket sitting in the parts pile.
All of the water pump bolts are snugged down in place now, but not tightened as that is one of the last things we want to do once we know that everything is in place. I am moving on to the hoses, starting with the coolant bypass hose and then getting the two heater core hoses attached. I moved the sheathing from the old hoses to the new ones as they do help protect them from vibrations, and then secured them both up and out of the way with the bracket they were in before.
Next, I discover that I completely forgot to install the bracket on the power steering pump, so I got that installed. It can be a bit of a pain to do this, the bolts and spacer have to go in a very specific place and it really made me work for it. Then again, at least I wasn’t replacing it in the snow in a Portland parking lot, which is what I ended up doing when we brought the van home. I finally got it all bolted up and set both belts in place. The alternator and water pump belt goes in first, just set it back there and then put on the power steering pump belt. Once it is in place, grab a ½” drive ratchet and put it in the square hole in the bracket, it will fit right in there. That allows you to put pressure on the whole assembly and get the belt nice and taut. Snug everything down tight, except for the two bolts going thru the water pump as we will be doing those later.
Now grab the water pump pulley and set it in place, then put the belt on over the main pulley, alternator and water pump pulley. At this point you should grab the fan shroud and set it in place over the pump and pulleys, I forgot and will have to carefully work it in place afterward which is a pain in the butt. Grab the radiator, and tip it back up into place before the next step, otherwise you won’t have enough room to do it. Put the fan back in place with he spacer and tighten down those four bolts. After that it is time to take the slack out of the belt using the alternator. Either pull on it from the top, or if you are careful you can use a screwdriver to pry between the bracket and alternator housing to get it tight, then snug down all of the bolts.
At this point you are going to need access to a torque wrench. Set it to 30 pounds of torque, and stat tightening all of the water pump bolts. Snug them down in an alternating pattern starting at the top as the first bolt, then do the third, then the fifth, then the second, then the fourth, then back to the first. Work that alternating pattern gradually tightening them until you hit 30 pounds of torque, which is all you need. Once that is done, you can move on to the next part.
Carefully pull the radiator up into place and set the bottom tabs onto the lower bolts that you left in place earlier, then put the top bolts back in and tighten them down. Once those are secured head back underneath, and tighten down the lower bolts as well, which finishes securing the radiator in place. Move the fan shroud back where it goes onto the radiator and tighten it down as well.
Next up I needed to get the transmission cooler mounted, however this radiator did not have the same holes in its flange that the older one had. After double checking to make sure there was nothing behind the hole I was about to drill, I put two more holes in the flange of the radiator so that I could get the transmission cooler remounted. With that in place, it was time to move on to the upper and lower radiator hoses. They will each get two clamps, one on each end.
Now it is time for the heater core. On most cars, this can be a nightmare. Heater cores are typically buried inside under the dash, but in the 1978 Dodge B200 they kept it in the engine bay in this large plastic box. There are ten small screws around the top holding the lid on, and they will all need to be removed. There are also two nuts on the air box on the left, and then two more on the heater fan box that will need to be removed so that you can shift the entire assembly slightly to the right so that you can get the lid open.
Once the lid is off, you can see the heater core. It has two screws on the bottom holding it in place, remove those and you can pull the heater cool up and out of the way. Be careful as it is still full of coolant and will need to be emptied. Now, the heater in this van has never worked right, and I can see why. The adjustment flap is half rusted away, at some point in the past the heater core had leaked for a long time, and the liquid had done a number on the flap. Unfortunately, this is not a part that you can just go out and get, so I am just going to have to try to rebuild the one that I pulled out of there. For now though, I am just going to remove it, and reassemble everything without the flap.
Set the new heater core in place, and secure it to the bottom of the box with the two screws. Put the lid back in place, put all ten screws back in, shift the box over and tighten down the four nuts that let you move it out of the way. Attach the hoses to the heater core and tighten down the clamps. My camera died at that point, so we will just move over to security camera footage for the rest. I got the coolant reservoir reinstalled and put a new radiator cap in place. At this point, go back over all of your clamp connections and make sure they are tight. This is where you are most likely to get a leak from, once the van warms up and the system pressurizes it is easy for water to get pushed by a loose clamp and you do not want that.
Once you are sure that everything is tight, go ahead and fill the system back up. I am only using water right now, as I plan to flush the system once I have leak tested it so I will put in antifreeze later. Once the system was full, I hooked the battery up, and then put the grille back in place before starting the van and letting it warm up. Keep an eye on everything, specifically the fluid level in the overflow. While the van is cold you can open up the radiator cap to see if you need to add a little more, but once it starts to warm up you are going to want to have that cap closed and in place. Eventually your thermostat will open up, and you will be able to feel the hot coolant running thru the upper radiator hose. It is entirely normal and expected to have air bubbles coming up thru the fluid and into the overflow tank, this is actually what you want to see as you want all of the air to make its way out of the system. Keep an eye on your temperature gauge, if there is air around the water pump it can cause no fluid being circulated which in a worst-case scenario can lead to a blown head gasket. Once the van is warmed up and it looks like things have stabilized, go ahead and take it for a test drive. Stop occasionally to check the fluid levels. Get it home, shut it off and watch underneath for any drips. This is when you will definitely be able to tell if your clamps are tight enough or not.