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Pelican Technical Article:

Replacing the Water Pump

Mike Holloway

Time:

1.5 hours

Tab:

$100 to $600

Talent:

**

Tools:

13mm wrench, 27mm socket wrench, 6-inch extension, needle nose pliers, slot face screwdriver, drain pan

Applicable Models:

Mercedes-Benz R107 (1972-89)

Parts Required:

Water pump, Gasket, coolant.

Hot Tip:

Wash the engine compartment down

Performance Gain:

Better performing engine from thermo-management

Complementary Modification:

Replace hose, fan clutch, thermostat, flush the cooling system

If your car starting to run hot or it is overheating while sitting at idle, it's possible you may need to replace the seals or the water pump. Typically, the seals and bearings are the first items to fail. An easy way to check your water pump is to look underneath the car and check for water seepage out of the pump. This means that water is leaking past the bearing and seals, indicating the pump is on its way out. If the seals have failed there will be coolant leaking behind the drive pulley. You may not need a new pump but new seals are in order. If the bearings have failed you may hear a squealing or there will be too much play in them when you move the drive pulley back and forth. Another way to check to see if it is pump failure is to squeeze and hold the upper radiator hose for a few seconds (CAUTION: the hose may be hot) while the car is running. If you feel no pressure building up, it is a sign that water is not circulating and the pump may be bad.

When a water pump begins to fail, you'll notice that the car tends to overheat at low engine speed, such as sitting at a stoplight. When you accelerate, the engine temperature will drop. Now, this is not always indicative of a water pump, but a good starting point. You may also want to try squeezing the top radiator hose with the engine warmed up and running. You should feel pressure build up on the back of the hose and surge once it is released. If you feel no pressure, it's a fair bet that the water pump is failing. Sometimes, you can also see a slight drip coming from the water pump housing itself. These weep holes are cast into the pump housing and allow excess coolant to drain out if it has leaked past the various seals in the pump. One is located on top. The other one is below.

Make sure that the car is cool before you begin working on it. You will drain the coolant from the radiator. To drain the coolant, locate the drain plug on the bottom of the lower front passenger side of the radiator. Place your drain bucket under the hole and turn the plug and empty the contents into a proper drain pan. Coolant will begin to come out but will not drain rapidly because of the vacuum caused by the sealed system. To get all the fluid out, go up to the coolant reservoir and undo the cap, this will break the vacuum and allow the coolant to flow freely. Be careful not to spill any coolant on the ground. If you have pets, they may lick it up and die.

In order to get at the water pump you will have to remove the air filter. After the air filter has been removed, the power steering pump adjusting and pivot bolts have to be loosened. You need to do this in order to remove the water pump drive belts. After the drive belts are removed, the fan shroud has to be removed. There are clips that hold it in place. If you require step-by-step instructions, refer to the articles already written for air filter removal, power steering pump position, belt removal, and radiator shroud removal.

With a slotted screwdriver, loosen the hose clamps connecting the water pump to the engine.
Figure 1

With a slotted screwdriver, loosen the hose clamps connecting the water pump to the engine. 

There will be a total of two tubes on the pump that have to be loosened and removed.
Figure 2

There will be a total of two tubes on the pump that have to be loosened and removed. Some coolant will leak out. Make sure you have a drain pan to catch it.  

As the fluid is draining out of the hose, you can now begin to remove the water pump fan blade and clutch.
Figure 3

As the fluid is draining out of the hose, you can now begin to remove the water pump fan blade and clutch. With a 10mm open-end wrench or 10mm socket, loosen and remove the bolts that hold the clutch in place.

After the bolts have been removed, you may need to use a rubber hammer to pop off the fan blade set-up.
Figure 4

After the bolts have been removed, you may need to use a rubber hammer to pop off the fan blade set-up.

Using a 13mm socket and a six-inch extension, loosen and remove the bolts that hold the water pump.
Figure 5

Using a 13mm socket and a six-inch extension, loosen and remove the bolts that hold the water pump. You may have to turn the engine crank (clockwise) in order to get a clear path to the bolts.

If you have to turn the crank, use a 27mm socket and move it clockwise until the slot is lined up with the bolt.
Figure 6

If you have to turn the crank, use a 27mm socket and move it clockwise until the slot is lined up with the bolt.

This is what the bolt looks like that you will have to turn.
Figure 7

This is what the bolt looks like that you will have to turn.

There are two bolts that can only be accessed by turning the crank in order to provide the pathway for the socket and six-inch extension to fit through.
Figure 8

There are two bolts that can only be accessed by turning the crank in order to provide the pathway for the socket and six-inch extension to fit through.

Some bolts will not require an extension to be used.
Figure 9

Some bolts will not require an extension to be used.

When you loosen each bolt, make sure not to let it slip out of the socket and end up in the drain pan.
Figure 10

When you loosen each bolt, make sure not to let it slip out of the socket and end up in the drain pan. Once the bolt is free, keep it in place and use needle nose pliers to remove it. This is a far better option than fishing through the drain pan for a bolt.

Examine the bolts as you remove them.
Figure 11

Examine the bolts as you remove them. In certain cases there may be corrosion.

As you loosen the bolts, you will notice the coolant left in the pump will drain.
Figure 12

As you loosen the bolts, you will notice the coolant left in the pump will drain.

Make sure you have a drain pan to collect the coolant.
Figure 13

Make sure you have a drain pan to collect the coolant.

The water pump can now be removed.
Figure 14

The water pump can now be removed.

After the water pump has been removed, check the case for any signs of rust.
Figure 15

After the water pump has been removed, check the case for any signs of rust. The pattern pictured shows rust and may be due to the fact that this car sat idle for almost two decades. 

Examine the pump as well.
Figure 16

Examine the pump as well. Here you will notice residue from the coolant. This is a indication that the coolant sat in the pump for an extended period of time and began to breakdown. Notice the residue and corrosion.

Further examination of the pump indicates severe rust has occurred.
Figure 17

Further examination of the pump indicates severe rust has occurred. Depending upon how severe the rust is depends on if the pump can be rebuilt. It is not clear if this pump can be saved. Installation is the reverse of removal. If your water pump looks as bad as this one, you need to flush and bleed the coolant.

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Comments and Suggestions:
Armandworks Comments: What are the touque anounts when replacing the parts ?
January 25, 2016
  Followup from the Pelican Staff: I don’t have that info.


I would grab a repair manual. It will have the procedure, special tools and torque specs.

Give our parts specialists a call at 1-888-280-7799. - Nick at Pelican Parts
 

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