DIY C240 WATERPUMP CHANGE
07-08-2009, 10:49 PM
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2003 C240 automatic
DIY C240 WATERPUMP CHANGE
After driving around with a noisy waterpump, I decided to change it and make pictures for you all, together with a little how to.
First of all as a disclaimer: Don't be stupid and don't break your car while being stupid if you choose to be so... So wear safety glasses, don't drain coolant when it's hot etc etc etc. I take no responsibility for anything whatsoever so proceed at own risk!
Tools needed:
- Car jack (optional but easier)
- T50 torx key (for idler pulley)
- external torx / deep star sockets # 10, 12, 14 (#14 is for alternator)
- Metric socket set really helps (# 8 for skid plate under engine)
(#17 for serpentine belt tensioner)
- Drain pan, at least 8 qt's / 2 gallon capacity, bigger = better.
- New coolant, the system takes about 8 qt's / 2 gallon which is diluted
50/50 with water, so you need 4 qt's coolant from MB.
- Flathead screwdriver (to release coolant hoses / uncap idler pulley)
In bolt print i have included links to pictures that may help you.
First things first:
1) Jack up your car, with the parking brake set, transmission in park, support it etc. And remove engine top cover, only the front side of this is needed, pull the 2 airhoses towards the front of the car, they will come off. Now pull the front part of the engine cover up and backwards (no screws here....)
Now the "real" stuff:
2) loosen the 6 screw's that hold the skid-plate under the engine. (#8 socket)
3) remove skid plate.
4) Uncap the coolant reservoir cap. (helps draining coolant)
5) On the passenger side of the car, bottom side of the radiator, the radiator hose is held in place by a spring-clip. I used my flat-head screwdriver to get the spring out of it's socket. When you have removed this spring you can remove the lower radiator hose. BE CAREFUL THE COOLANT WILL RUN OUT RATHER QUICKLY NOW BE SURE TO HAVE YOUR DRAIN PAN UNDER THE RADIATOR AT THIS POINT!
-> Link to "the clip holding radiator hose" http://tinypic.com/view.php?pic=24b55ea&s=3
6) remove serpentine belt, before you do so make a drawing with the layout of how the belt runs over all pulleys! Done by getting your largest wrench that fits a # 17 metric socket. Place socket on belt tensioner pulley bolt, that is left and below the pulley. Turn counter clockwise and remove belt. See picture.
-> Link to "belt tensioner - release bolt" http://tinypic.com/view.php?pic=10ymgwz&s=3
7) Now remove the waterpump-belt-pulley, held in place by 4 bolts, each metric # 10 socket. A second person holding the pulley still for you may help losening it, on mine I had no problems doing this though.
-> Link to " remove bolts waterpump pulley" http://tinypic.com/view.php?pic=eu11jp&s=3
8) Loosen alternator TOP bolt, External Torx / Deep star socket # 14.
It's a long bolt, after a lot of turning you need to pull it out, may
require some force.
-> Link to " remove alternator bolt" http://tinypic.com/view.php?pic=rvy4d2&s=3
9) Now remove the 2 radiator hoses connected to the waterpump, you will need to loosen the hose clamps and might even need to pry the hose off afterwards using your flathead screwdriver.
-> Link to " removing 2 radiator hoses from pump" http://tinypic.com/view.php?pic=r0bjvp&s=3
10) Remove upper clamp holding electrical thingy on waterpump, don't know what it is (someone please fill in): Use the external torx # 10 for this.
-> link to "removing clamp holding thingy onto pump" http://tinypic.com/view.php?pic=2ci7joy&s=3
11) Pry off the plastic cap on the idler pulley, and remove the torx bolt holding the idler pulley. (torx T50).
-> link to "remove cap from idler pulley" http://tinypic.com/view.php?pic=15hobnt&s=3
12) Now remove all screws from the pump, sizes are external torx #10 and #12, see picture:
-> link to "remove all bolts from pump" http://tinypic.com/view.php?pic=s2wo45&s=3
13) Now the pump should be free to come off, if it doesn't double-double check that you actually removed all hoses and bolts! Then try to pull a little harder....... Mine came of really easy though.
14) Clean up all gasket and dirt residue on the engine block where the new pump has to go, You can use a paint scraper or similar to remove gasket residue that is sticking to the block, don't scratch this area though!
After this clean with a degreaser and wipe.
-> link to "Cleaned waterpump area on engine block" http://tinypic.com/view.php?pic=1pxiky&s=3
15) Use a couple of the shorter bolts and put those in the new pump, now put the new gasket on the backside of the new pump, the couple screws that you've put in the new pump should hold the gasket in place while you put the new pump in place.
16) With the gasket held onto the new pump by a couple of the shorter screws put in the pump guide it into place and hand-tighten the bolts. If the gasket is correctly positioned you should be able to put all other bolts back in. Don't over-torque any bolts, you may damage components or threads!
17) Assembly is like haynes workshop manuals would say: "all above in reverse order" Always wise: double-double check every bolt and connection!
Bassically when you've put everything back together, fill the coolant reservoir with coolant mix, check for leaks, check that everything has been removed from the engine bay, start engine turn off immediately, check if belt has been running correctly (still on there
) and no leaks. 
Now leave the engine running, go back up front, keep filling the coolant reservoir, also have the heater in the car turned on since that works on coolant as well.
Put coolant cap back on, skid plates, engine covers etc. Let engine warm up check for leaks....
GOOD LUCK ON YOUR PUMP CHANGE!
First of all as a disclaimer: Don't be stupid and don't break your car while being stupid if you choose to be so... So wear safety glasses, don't drain coolant when it's hot etc etc etc. I take no responsibility for anything whatsoever so proceed at own risk!
Tools needed:
- Car jack (optional but easier)
- T50 torx key (for idler pulley)
- external torx / deep star sockets # 10, 12, 14 (#14 is for alternator)
- Metric socket set really helps (# 8 for skid plate under engine)
(#17 for serpentine belt tensioner)
- Drain pan, at least 8 qt's / 2 gallon capacity, bigger = better.
- New coolant, the system takes about 8 qt's / 2 gallon which is diluted
50/50 with water, so you need 4 qt's coolant from MB.
- Flathead screwdriver (to release coolant hoses / uncap idler pulley)
In bolt print i have included links to pictures that may help you.
First things first:
1) Jack up your car, with the parking brake set, transmission in park, support it etc. And remove engine top cover, only the front side of this is needed, pull the 2 airhoses towards the front of the car, they will come off. Now pull the front part of the engine cover up and backwards (no screws here....)
Now the "real" stuff:
2) loosen the 6 screw's that hold the skid-plate under the engine. (#8 socket)
3) remove skid plate.
4) Uncap the coolant reservoir cap. (helps draining coolant)
5) On the passenger side of the car, bottom side of the radiator, the radiator hose is held in place by a spring-clip. I used my flat-head screwdriver to get the spring out of it's socket. When you have removed this spring you can remove the lower radiator hose. BE CAREFUL THE COOLANT WILL RUN OUT RATHER QUICKLY NOW BE SURE TO HAVE YOUR DRAIN PAN UNDER THE RADIATOR AT THIS POINT!
-> Link to "the clip holding radiator hose" http://tinypic.com/view.php?pic=24b55ea&s=3
6) remove serpentine belt, before you do so make a drawing with the layout of how the belt runs over all pulleys! Done by getting your largest wrench that fits a # 17 metric socket. Place socket on belt tensioner pulley bolt, that is left and below the pulley. Turn counter clockwise and remove belt. See picture.
-> Link to "belt tensioner - release bolt" http://tinypic.com/view.php?pic=10ymgwz&s=3
7) Now remove the waterpump-belt-pulley, held in place by 4 bolts, each metric # 10 socket. A second person holding the pulley still for you may help losening it, on mine I had no problems doing this though.
-> Link to " remove bolts waterpump pulley" http://tinypic.com/view.php?pic=eu11jp&s=3
8) Loosen alternator TOP bolt, External Torx / Deep star socket # 14.
It's a long bolt, after a lot of turning you need to pull it out, may
require some force.
-> Link to " remove alternator bolt" http://tinypic.com/view.php?pic=rvy4d2&s=3
9) Now remove the 2 radiator hoses connected to the waterpump, you will need to loosen the hose clamps and might even need to pry the hose off afterwards using your flathead screwdriver.
-> Link to " removing 2 radiator hoses from pump" http://tinypic.com/view.php?pic=r0bjvp&s=3
10) Remove upper clamp holding electrical thingy on waterpump, don't know what it is (someone please fill in): Use the external torx # 10 for this.
-> link to "removing clamp holding thingy onto pump" http://tinypic.com/view.php?pic=2ci7joy&s=3
11) Pry off the plastic cap on the idler pulley, and remove the torx bolt holding the idler pulley. (torx T50).
-> link to "remove cap from idler pulley" http://tinypic.com/view.php?pic=15hobnt&s=3
12) Now remove all screws from the pump, sizes are external torx #10 and #12, see picture:
-> link to "remove all bolts from pump" http://tinypic.com/view.php?pic=s2wo45&s=3
13) Now the pump should be free to come off, if it doesn't double-double check that you actually removed all hoses and bolts! Then try to pull a little harder....... Mine came of really easy though.
14) Clean up all gasket and dirt residue on the engine block where the new pump has to go, You can use a paint scraper or similar to remove gasket residue that is sticking to the block, don't scratch this area though!
After this clean with a degreaser and wipe.
-> link to "Cleaned waterpump area on engine block" http://tinypic.com/view.php?pic=1pxiky&s=3
15) Use a couple of the shorter bolts and put those in the new pump, now put the new gasket on the backside of the new pump, the couple screws that you've put in the new pump should hold the gasket in place while you put the new pump in place.
16) With the gasket held onto the new pump by a couple of the shorter screws put in the pump guide it into place and hand-tighten the bolts. If the gasket is correctly positioned you should be able to put all other bolts back in. Don't over-torque any bolts, you may damage components or threads!
17) Assembly is like haynes workshop manuals would say: "all above in reverse order" Always wise: double-double check every bolt and connection!
Bassically when you've put everything back together, fill the coolant reservoir with coolant mix, check for leaks, check that everything has been removed from the engine bay, start engine turn off immediately, check if belt has been running correctly (still on there
) and no leaks. Now leave the engine running, go back up front, keep filling the coolant reservoir, also have the heater in the car turned on since that works on coolant as well.
Put coolant cap back on, skid plates, engine covers etc. Let engine warm up check for leaks....
GOOD LUCK ON YOUR PUMP CHANGE!
Last edited by hollik; 07-08-2009 at 10:56 PM.
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jvakos (07-13-2019)
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07-11-2009, 01:43 PM
#9
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2003 C240 automatic
there were 90.000 miles on the car when the pump started making a slight whining noise when cold, no leaks though... I got the pump from shuck's www.cskauto.com who sells it for 110 dollars, it's a remanufactured original and seems to be holding up fine...
02-07-2011, 07:51 AM
#11
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2003 C230K Coupe Orion Blue
Nice writeup, but may I suggest changing your post such that the links show up as actual photos in the thread? 
Just requires a minor tweak to your coding.
Just requires a minor tweak to your coding.
02-23-2011, 11:12 PM
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c240
so i replaced the water pump and replaced the coolant with Prestone, i then tried the car it worked but i had a check engine light come on and the fan was running high. just wondering if any one has suggestions.
02-24-2011, 05:19 AM
#14
Super Moderator
Prestone is not a MB approved coolant. Suggest you try Valvoline Zerex G 05 - it's the cheapest approved product available in the US.
Have you squeezed all the hoses & evacuated all air from the system?
Suggest you get your hands on an OBDII scanner & read codes that have caused the CEL. Plug is under a rectangular flap under the steering column. Autozone will do this for you free
Have you squeezed all the hoses & evacuated all air from the system?
Suggest you get your hands on an OBDII scanner & read codes that have caused the CEL. Plug is under a rectangular flap under the steering column. Autozone will do this for you free
02-24-2011, 08:26 AM
#15
MBWorld Fanatic!
As Glyn suggested above, you need to have the diagnostic codes to diagnose further.
My guess is that you've accidentally disconnected/knocked a connector while replacing the water pump. Look around the water pump, there may be loose wires/connectors.
My guess is that you've accidentally disconnected/knocked a connector while replacing the water pump. Look around the water pump, there may be loose wires/connectors.
02-24-2011, 04:22 PM
#18
MBWorld Fanatic!
I highly doubt new coolant causing the check engine light and P0117 code.
05-10-2011, 09:25 PM
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2003 c240 4matic wagon
did you have to remove the cooling fan and fan shroud? my manuals says i have to (haynes and alldata)
hopefully not as it looks like alot of work on my 03 4matic wagon
hopefully not as it looks like alot of work on my 03 4matic wagon
Last edited by contact148; 05-10-2011 at 09:41 PM.
05-11-2011, 06:43 PM
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2003 c240 4matic wagon
temp sensor ive done you dont need to remove anything
the water pump looks like i can get it out with the fan and shroud in place but every manual says to remove them.......
the water pump looks like i can get it out with the fan and shroud in place but every manual says to remove them.......
05-18-2011, 12:23 PM
#23
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2021 GLC300 4Matic
After driving around with a noisy waterpump, I decided to change it and make pictures for you all, together with a little how to.
First of all as a disclaimer: Don't be stupid and don't break your car while being stupid if you choose to be so... So wear safety glasses, don't drain coolant when it's hot etc etc etc. I take no responsibility for anything whatsoever so proceed at own risk!
Tools needed:
- Car jack (optional but easier)
- T50 torx key (for idler pulley)
- external torx / deep star sockets # 10, 12, 14 (#14 is for alternator)
- Metric socket set really helps (# 8 for skid plate under engine)
(#17 for serpentine belt tensioner)
- Drain pan, at least 8 qt's / 2 gallon capacity, bigger = better.
- New coolant, the system takes about 8 qt's / 2 gallon which is diluted
50/50 with water, so you need 4 qt's coolant from MB.
- Flathead screwdriver (to release coolant hoses / uncap idler pulley)
In bolt print i have included links to pictures that may help you.
First things first:
1) Jack up your car, with the parking brake set, transmission in park, support it etc. And remove engine top cover, only the front side of this is needed, pull the 2 airhoses towards the front of the car, they will come off. Now pull the front part of the engine cover up and backwards (no screws here....)
Now the "real" stuff:
2) loosen the 6 screw's that hold the skid-plate under the engine. (#8 socket)
3) remove skid plate.
4) Uncap the coolant reservoir cap. (helps draining coolant)
5) On the passenger side of the car, bottom side of the radiator, the radiator hose is held in place by a spring-clip. I used my flat-head screwdriver to get the spring out of it's socket. When you have removed this spring you can remove the lower radiator hose. BE CAREFUL THE COOLANT WILL RUN OUT RATHER QUICKLY NOW BE SURE TO HAVE YOUR DRAIN PAN UNDER THE RADIATOR AT THIS POINT!
6) remove serpentine belt, before you do so make a drawing with the layout of how the belt runs over all pulleys! Done by getting your largest wrench that fits a # 17 metric socket. Place socket on belt tensioner pulley bolt, that is left and below the pulley. Turn counter clockwise and remove belt. See picture.
7) Now remove the waterpump-belt-pulley, held in place by 4 bolts, each metric # 10 socket. A second person holding the pulley still for you may help losening it, on mine I had no problems doing this though.
8) Loosen alternator TOP bolt, External Torx / Deep star socket # 14.
It's a long bolt, after a lot of turning you need to pull it out, may
require some force.
9) Now remove the 2 radiator hoses connected to the waterpump, you will need to loosen the hose clamps and might even need to pry the hose off afterwards using your flathead screwdriver.
10) Remove upper clamp holding electrical thingy on waterpump, don't know what it is (someone please fill in): Use the external torx # 10 for this.
11) Pry off the plastic cap on the idler pulley, and remove the torx bolt holding the idler pulley. (torx T50).
12) Now remove all screws from the pump, sizes are external torx #10 and #12, see picture:
13) Now the pump should be free to come off, if it doesn't double-double check that you actually removed all hoses and bolts! Then try to pull a little harder....... Mine came of really easy though.
14) Clean up all gasket and dirt residue on the engine block where the new pump has to go, You can use a paint scraper or similar to remove gasket residue that is sticking to the block, don't scratch this area though!
After this clean with a degreaser and wipe.
-> link to "Cleaned waterpump area on engine block" http://tinypic.com/view.php?pic=1pxiky&s=3
15) Use a couple of the shorter bolts and put those in the new pump, now put the new gasket on the backside of the new pump, the couple screws that you've put in the new pump should hold the gasket in place while you put the new pump in place.
16) With the gasket held onto the new pump by a couple of the shorter screws put in the pump guide it into place and hand-tighten the bolts. If the gasket is correctly positioned you should be able to put all other bolts back in. Don't over-torque any bolts, you may damage components or threads!
17) Assembly is like haynes workshop manuals would say: "all above in reverse order" Always wise: double-double check every bolt and connection!
Bassically when you've put everything back together, fill the coolant reservoir with coolant mix, check for leaks, check that everything has been removed from the engine bay, start engine turn off immediately, check if belt has been running correctly (still on there ) and no leaks.
Now leave the engine running, go back up front, keep filling the coolant reservoir, also have the heater in the car turned on since that works on coolant as well.
Put coolant cap back on, skid plates, engine covers etc. Let engine warm up check for leaks....
GOOD LUCK ON YOUR PUMP CHANGE!
First of all as a disclaimer: Don't be stupid and don't break your car while being stupid if you choose to be so... So wear safety glasses, don't drain coolant when it's hot etc etc etc. I take no responsibility for anything whatsoever so proceed at own risk!
Tools needed:
- Car jack (optional but easier)
- T50 torx key (for idler pulley)
- external torx / deep star sockets # 10, 12, 14 (#14 is for alternator)
- Metric socket set really helps (# 8 for skid plate under engine)
(#17 for serpentine belt tensioner)
- Drain pan, at least 8 qt's / 2 gallon capacity, bigger = better.
- New coolant, the system takes about 8 qt's / 2 gallon which is diluted
50/50 with water, so you need 4 qt's coolant from MB.
- Flathead screwdriver (to release coolant hoses / uncap idler pulley)
In bolt print i have included links to pictures that may help you.
First things first:
1) Jack up your car, with the parking brake set, transmission in park, support it etc. And remove engine top cover, only the front side of this is needed, pull the 2 airhoses towards the front of the car, they will come off. Now pull the front part of the engine cover up and backwards (no screws here....)
Now the "real" stuff:
2) loosen the 6 screw's that hold the skid-plate under the engine. (#8 socket)
3) remove skid plate.
4) Uncap the coolant reservoir cap. (helps draining coolant)
5) On the passenger side of the car, bottom side of the radiator, the radiator hose is held in place by a spring-clip. I used my flat-head screwdriver to get the spring out of it's socket. When you have removed this spring you can remove the lower radiator hose. BE CAREFUL THE COOLANT WILL RUN OUT RATHER QUICKLY NOW BE SURE TO HAVE YOUR DRAIN PAN UNDER THE RADIATOR AT THIS POINT!
6) remove serpentine belt, before you do so make a drawing with the layout of how the belt runs over all pulleys! Done by getting your largest wrench that fits a # 17 metric socket. Place socket on belt tensioner pulley bolt, that is left and below the pulley. Turn counter clockwise and remove belt. See picture.
7) Now remove the waterpump-belt-pulley, held in place by 4 bolts, each metric # 10 socket. A second person holding the pulley still for you may help losening it, on mine I had no problems doing this though.
8) Loosen alternator TOP bolt, External Torx / Deep star socket # 14.
It's a long bolt, after a lot of turning you need to pull it out, may
require some force.
9) Now remove the 2 radiator hoses connected to the waterpump, you will need to loosen the hose clamps and might even need to pry the hose off afterwards using your flathead screwdriver.
10) Remove upper clamp holding electrical thingy on waterpump, don't know what it is (someone please fill in): Use the external torx # 10 for this.
11) Pry off the plastic cap on the idler pulley, and remove the torx bolt holding the idler pulley. (torx T50).
12) Now remove all screws from the pump, sizes are external torx #10 and #12, see picture:
13) Now the pump should be free to come off, if it doesn't double-double check that you actually removed all hoses and bolts! Then try to pull a little harder....... Mine came of really easy though.
14) Clean up all gasket and dirt residue on the engine block where the new pump has to go, You can use a paint scraper or similar to remove gasket residue that is sticking to the block, don't scratch this area though!
After this clean with a degreaser and wipe.
-> link to "Cleaned waterpump area on engine block" http://tinypic.com/view.php?pic=1pxiky&s=3
15) Use a couple of the shorter bolts and put those in the new pump, now put the new gasket on the backside of the new pump, the couple screws that you've put in the new pump should hold the gasket in place while you put the new pump in place.
16) With the gasket held onto the new pump by a couple of the shorter screws put in the pump guide it into place and hand-tighten the bolts. If the gasket is correctly positioned you should be able to put all other bolts back in. Don't over-torque any bolts, you may damage components or threads!
17) Assembly is like haynes workshop manuals would say: "all above in reverse order" Always wise: double-double check every bolt and connection!
Bassically when you've put everything back together, fill the coolant reservoir with coolant mix, check for leaks, check that everything has been removed from the engine bay, start engine turn off immediately, check if belt has been running correctly (still on there
) and no leaks. Now leave the engine running, go back up front, keep filling the coolant reservoir, also have the heater in the car turned on since that works on coolant as well.
Put coolant cap back on, skid plates, engine covers etc. Let engine warm up check for leaks....
GOOD LUCK ON YOUR PUMP CHANGE!
Just wanted to say thank you for the instructions and the detail steps. and No you don't have to remove the fan and shroud.
05-18-2011, 12:36 PM
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Nowhere ...Fast
alot of f$$$ng bolts i tell ya! Great stuff! But 90K miles isnt that a bit premature? I am at 195K now with all original parts, except for the alternator which i did couple of months back...hmm
05-18-2011, 12:48 PM
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2021 GLC300 4Matic
my alternator just went out this week and so I am replacing it with a rebuilt one and I am putting a brand new (fresh) battery since the original from 2003 was still there.
all of this was diagnosed after putting the car in Dyno Mode and checked the voltage drop every 5 seconds with no sign of charging.
I could not believe the alt went out so soon since the car only has 65000 miles but these cars are so dependent of a good battery and a full working charging unit.
