Water pump replacement on older 107's
The replacement of the water pump is not the easiest of jobs, but it is a job that can be done by someone with a bit of mechanical experience. You need a few tools (metric, of course), but it is doable at home.
You will need a couple of specialty tools for this job, a timing light, a dwell meter if your car is older than 1976, a 1/2" drive 27mm socket, with a 3-4 inch extension, and a "breaker bar" about 18-24 inches long. This is in addition to the regular 3/8" drive metric socket set, and a set of metric combination wrenches (open on one end and closed or "box" on the other). If you want to do more than occasional minor work on your car, a set of combination wrenches with the ratcheting box ends would be very handy.
If you are going to be working on your car, a manual is pretty much a necessity. The most desired is a paper factory service manual, the second would be a CD-ROM of the scanned service manual, while the third would be an "aftermarket" manual. The first are fairly rare, but obtainable occasionally on E-Bay. CD-ROMS are available at places like Mercedes Benz Manual - Mercedes Repair Manuals - Mercedes-Benz Service Manuels and occasionally on line, but you sometimes only get poor copies of copies of the real CD-ROM, be careful. The aftermarket manuals such as Haynes or Chilton will be of some value, but they are sometimes lacking in some areas, because they generally try to cover as much as possible in as little space as possible. An often overlooked resource is your local Public Library. Many subscrice to online services such as Alldata or Mitchell Online, and you can print off sections for the job you need to do. Some libraries also let you access these through their systems from your home computer.
Before you start, you need to decide what you are going to replace. Are the hoses and belts, thermostat, and radiator cap due? What sort of shape are the clamps in? Be sure to check for ALL the pieces you are going to need. There is a short hose about 3 inches long from the back of the pump that is often forgotten. Parts runs during a project that make you put everything away tend to be frustrating.
Remember to have some new coolant ready for when you're through. Mercedes has a lot of aluminum in the cooling system, so you need to get the right type. The Green Stuff is known to have issues with not inhibiting corrosion in aluminum, should be avoided. It is good for all cast iron systems, but isn't formulated for aluminum.
Determine whether or not you are going to remove the radiator. The plus is that it will give you a lot more room to work, and if you're going to replace all the hoses, you'll have most of the job done. The minus is that you have to tale the transmission cooler lines off, and they leak ATF until you're done. If you do take the radiator out, check the condition of these hoses, too. There are newer replacement hoses that are protected by a spring wound around the outside. Be careful when removing and replacing these hoses, as cross-threading is possible, and will ruin your day because you will have to replace the radiator. There are also rubber mounts on the radiator that should be checked and replaced if too old.
The general procedure for the older 107's is to first drive the front end up on ramps. This will serve 3 purposes. First; it will be a lot easier on your lower back. Second; you will have to get under there to drain the coolant and pick up dropped tools, bolts, etc... Third; You will have the car in the correct position to burp after you're done. I would do this the night before you are going to do the job. Working on the cooling system of a hot engine is not recommended. There is potential for damage to the engine and you. Let's just try to avoid the pain, if possible.
Drain the coolant into a container that will hold all of it, there are about 3 gallons of fluid involved, and it will splash around from various places as you open connections. Do not leave coolant out in the open. The sweet smell and taste attract animals including cats and dogs, it it VERY toxic to them.
Remove the air cleaner and set it aside, out of the way. It's the first thing that come off, and the last thing that goes back on.
Loosen the 4 bolts that hold the fan and clutch onto the water pump itself. Those ratcheting box-end wrenches are heaven-sent for use in this job, your knuckles will thank you. Note that I haven't said anything about loosening the belts yet. The tension of the belts will help keep the water pump from turning while you're on these bolts, just loosen them.
Next, remove the 2 belts on the water pump by loosening the power steering pump and pushing it inward toward the center of the car. Finish backing out the bolts from the pulley of the pump. After you get them out, the fan and clutch assembly should be loose. Be gentle with this, so you don't bang up the fins on the radiator.
Remove the top hoses from the radiator to get them out of the way, then remove the two bolts at the top corners of the fan shroud. You should now be able to pull the shroud and the fan / clutch assembly straight up, again being careful of the radiator fins.
If you are removing the radiator, you can now remove the transmission cooler hoses and lower coolant hoses. If not, just the lower coolant hoses. To remove the radiator, there are metal keepers on the body at the top of the radiator that just need to be moved clear of the radiator. It should then be able to come straight up. At this point, you may want to have the radiator cleaned inside and out. This is usually done by a commercial shop by dipping it into a solvent tank. If necessary, they may be able to repair the brass or replace failed plastic or aluminum parts. My local shop charged me $99.00 to take a brass radiator apart, run cleaning rods through the fin assembly, repair a couple of dings and cracks, clean in a solvent tank, reassemble and repaint. In about a day. Your mileage may vary.
Edit:
NOTE: On 107's with K-Jet injection systems, it is not necessary to remove the distributor. This makes the job a LOT less scary.
The next step is to rotate the engine to #1 TDC. This is done by taking a 27mm 1/2" drive socket onto the bolt at the front of the crankshaft and turning the engine CLOCKWISE as you are facing the engine from the front. THIS IS IMPORTANT: ALWAYS rotate the engine in the direction of normal running. You may need an 18 or 24 inch breaker bar to get enough leverage to turn the engine, not everyone has arms like a gorilla, don't worry. You can tell this by making sure that the marks on the harmonic balancer line up with the pointer attached to the engine, and checking through the oil fill cap and looking toward the front of the engine. The cam lobes for #1 cylinder should be pointing up, like rabbit ears.
Now you have to get the distributor out of the way, this is why we have to take care to get the engine in a specific place. The distributor cap comes off by turning the hold down screws 1/2 turn, and lifting straight up. The rotor should be pointing to a mark on the edge of the base of the distributor. This is an indicator mark just for this type of job. There is a green wire going to a box just behind the left headlight, and a black cable with a large connector on it coming out of the distributor. find the connectors and pull them apart, noting the routing of the wires. Then find the screw or bolt at the point where the distributor goes into the engine, and remove it. This will let you pull the distributor straight out, getting out from in front of the right side of the water pump.
You should now be able to take all but the bottom two bolts out of the water pump. Start by taking off the inlet connector from the top, and the thermostat housing from the side. Then all but one top bolt from around the water pump, just loosen this. In order to get to the bottom two bolts, the notch in the harmonic balancer has to be aligned in turn to allow access to the bolt, to remove them. When this is done, the remaining top bolt can be removed and the pump removed. Clean all mating surfaces and install new pump in reverse order.
When you have the pump back on, the bolts tightened, the inloet connector and thermostat and housing can be replaced. Be sure that the small bleeder valve on the thermostat is at the top, and the longer, or 'action' section of the thermostat goes toward the body of the pump.
With the pump back on and its' attachments back on, it's time to put the distributor back. Make sure that the engine is at #1 TDC, checking as before, if necessary. Remember that the distributor gears are helical, and that you have to have the rotor a bit 'ahead' of the index mark when you insert it into the engine, so it will line up to the mark when it fully seats. Replace the distributor hold down screw and line up the rotor with the index mark before snugging it down. The timing will have to be adjusted to final specs later, with a timing light and the specs for the particular engine.
Reassemble everything in the reverse order as it was taken apart, making sure that bolts are torqued correctly, the clamps tight, and there are no "leftover" parts.
Fill the radiator from the reservoir, until the coolant level comes up to the level mark. Start the engine with the pressure cap off, and let it run, adding coolant as necessary, until the small hose from the top of the radiator to the reservoir feels hot, then put the cap on.
Now, you can set the timing per the specs for your engine. This varies by engine and year, on some, vacuum hoses have to be removed and plugged. This is where the manuals come in.
With any luck, the air has been burped out of the cooling system, and going for a drive will be without incident. Keep an eye on the temp gauge to make sure. You may have to repeat the "burp" procedure; Front on ramps, start cold engine with pressure cap off, and run until the little hose gets hot, filling as needed. It may be necessary to repeat a couple of times.
If anyone sees anything that needs correction or expansion, please tell me. I'll fix it.
The replacement of the water pump is not the easiest of jobs, but it is a job that can be done by someone with a bit of mechanical experience. You need a few tools (metric, of course), but it is doable at home.
You will need a couple of specialty tools for this job, a timing light, a dwell meter if your car is older than 1976, a 1/2" drive 27mm socket, with a 3-4 inch extension, and a "breaker bar" about 18-24 inches long. This is in addition to the regular 3/8" drive metric socket set, and a set of metric combination wrenches (open on one end and closed or "box" on the other). If you want to do more than occasional minor work on your car, a set of combination wrenches with the ratcheting box ends would be very handy.
If you are going to be working on your car, a manual is pretty much a necessity. The most desired is a paper factory service manual, the second would be a CD-ROM of the scanned service manual, while the third would be an "aftermarket" manual. The first are fairly rare, but obtainable occasionally on E-Bay. CD-ROMS are available at places like Mercedes Benz Manual - Mercedes Repair Manuals - Mercedes-Benz Service Manuels and occasionally on line, but you sometimes only get poor copies of copies of the real CD-ROM, be careful. The aftermarket manuals such as Haynes or Chilton will be of some value, but they are sometimes lacking in some areas, because they generally try to cover as much as possible in as little space as possible. An often overlooked resource is your local Public Library. Many subscrice to online services such as Alldata or Mitchell Online, and you can print off sections for the job you need to do. Some libraries also let you access these through their systems from your home computer.
Before you start, you need to decide what you are going to replace. Are the hoses and belts, thermostat, and radiator cap due? What sort of shape are the clamps in? Be sure to check for ALL the pieces you are going to need. There is a short hose about 3 inches long from the back of the pump that is often forgotten. Parts runs during a project that make you put everything away tend to be frustrating.
Remember to have some new coolant ready for when you're through. Mercedes has a lot of aluminum in the cooling system, so you need to get the right type. The Green Stuff is known to have issues with not inhibiting corrosion in aluminum, should be avoided. It is good for all cast iron systems, but isn't formulated for aluminum.Determine whether or not you are going to remove the radiator. The plus is that it will give you a lot more room to work, and if you're going to replace all the hoses, you'll have most of the job done. The minus is that you have to tale the transmission cooler lines off, and they leak ATF until you're done. If you do take the radiator out, check the condition of these hoses, too. There are newer replacement hoses that are protected by a spring wound around the outside. Be careful when removing and replacing these hoses, as cross-threading is possible, and will ruin your day because you will have to replace the radiator. There are also rubber mounts on the radiator that should be checked and replaced if too old.
The general procedure for the older 107's is to first drive the front end up on ramps. This will serve 3 purposes. First; it will be a lot easier on your lower back. Second; you will have to get under there to drain the coolant and pick up dropped tools, bolts, etc... Third; You will have the car in the correct position to burp after you're done. I would do this the night before you are going to do the job. Working on the cooling system of a hot engine is not recommended. There is potential for damage to the engine and you. Let's just try to avoid the pain, if possible.
Drain the coolant into a container that will hold all of it, there are about 3 gallons of fluid involved, and it will splash around from various places as you open connections. Do not leave coolant out in the open. The sweet smell and taste attract animals including cats and dogs, it it VERY toxic to them.
Remove the air cleaner and set it aside, out of the way. It's the first thing that come off, and the last thing that goes back on.
Loosen the 4 bolts that hold the fan and clutch onto the water pump itself. Those ratcheting box-end wrenches are heaven-sent for use in this job, your knuckles will thank you. Note that I haven't said anything about loosening the belts yet. The tension of the belts will help keep the water pump from turning while you're on these bolts, just loosen them.
Next, remove the 2 belts on the water pump by loosening the power steering pump and pushing it inward toward the center of the car. Finish backing out the bolts from the pulley of the pump. After you get them out, the fan and clutch assembly should be loose. Be gentle with this, so you don't bang up the fins on the radiator.
Remove the top hoses from the radiator to get them out of the way, then remove the two bolts at the top corners of the fan shroud. You should now be able to pull the shroud and the fan / clutch assembly straight up, again being careful of the radiator fins.
If you are removing the radiator, you can now remove the transmission cooler hoses and lower coolant hoses. If not, just the lower coolant hoses. To remove the radiator, there are metal keepers on the body at the top of the radiator that just need to be moved clear of the radiator. It should then be able to come straight up. At this point, you may want to have the radiator cleaned inside and out. This is usually done by a commercial shop by dipping it into a solvent tank. If necessary, they may be able to repair the brass or replace failed plastic or aluminum parts. My local shop charged me $99.00 to take a brass radiator apart, run cleaning rods through the fin assembly, repair a couple of dings and cracks, clean in a solvent tank, reassemble and repaint. In about a day. Your mileage may vary.
Edit:
NOTE: On 107's with K-Jet injection systems, it is not necessary to remove the distributor. This makes the job a LOT less scary.
The next step is to rotate the engine to #1 TDC. This is done by taking a 27mm 1/2" drive socket onto the bolt at the front of the crankshaft and turning the engine CLOCKWISE as you are facing the engine from the front. THIS IS IMPORTANT: ALWAYS rotate the engine in the direction of normal running. You may need an 18 or 24 inch breaker bar to get enough leverage to turn the engine, not everyone has arms like a gorilla, don't worry. You can tell this by making sure that the marks on the harmonic balancer line up with the pointer attached to the engine, and checking through the oil fill cap and looking toward the front of the engine. The cam lobes for #1 cylinder should be pointing up, like rabbit ears.
Now you have to get the distributor out of the way, this is why we have to take care to get the engine in a specific place. The distributor cap comes off by turning the hold down screws 1/2 turn, and lifting straight up. The rotor should be pointing to a mark on the edge of the base of the distributor. This is an indicator mark just for this type of job. There is a green wire going to a box just behind the left headlight, and a black cable with a large connector on it coming out of the distributor. find the connectors and pull them apart, noting the routing of the wires. Then find the screw or bolt at the point where the distributor goes into the engine, and remove it. This will let you pull the distributor straight out, getting out from in front of the right side of the water pump.
You should now be able to take all but the bottom two bolts out of the water pump. Start by taking off the inlet connector from the top, and the thermostat housing from the side. Then all but one top bolt from around the water pump, just loosen this. In order to get to the bottom two bolts, the notch in the harmonic balancer has to be aligned in turn to allow access to the bolt, to remove them. When this is done, the remaining top bolt can be removed and the pump removed. Clean all mating surfaces and install new pump in reverse order.
When you have the pump back on, the bolts tightened, the inloet connector and thermostat and housing can be replaced. Be sure that the small bleeder valve on the thermostat is at the top, and the longer, or 'action' section of the thermostat goes toward the body of the pump.
With the pump back on and its' attachments back on, it's time to put the distributor back. Make sure that the engine is at #1 TDC, checking as before, if necessary. Remember that the distributor gears are helical, and that you have to have the rotor a bit 'ahead' of the index mark when you insert it into the engine, so it will line up to the mark when it fully seats. Replace the distributor hold down screw and line up the rotor with the index mark before snugging it down. The timing will have to be adjusted to final specs later, with a timing light and the specs for the particular engine.
Reassemble everything in the reverse order as it was taken apart, making sure that bolts are torqued correctly, the clamps tight, and there are no "leftover" parts.
Fill the radiator from the reservoir, until the coolant level comes up to the level mark. Start the engine with the pressure cap off, and let it run, adding coolant as necessary, until the small hose from the top of the radiator to the reservoir feels hot, then put the cap on.
Now, you can set the timing per the specs for your engine. This varies by engine and year, on some, vacuum hoses have to be removed and plugged. This is where the manuals come in.
With any luck, the air has been burped out of the cooling system, and going for a drive will be without incident. Keep an eye on the temp gauge to make sure. You may have to repeat the "burp" procedure; Front on ramps, start cold engine with pressure cap off, and run until the little hose gets hot, filling as needed. It may be necessary to repeat a couple of times.
If anyone sees anything that needs correction or expansion, please tell me. I'll fix it.
