signs and symptoms of a bad water pump...
Senior Member
Joined: Aug 2004
Posts: 285
Likes: 0
From: Richmond, Va.
1991 300E
Get your car up to operating temperature, run the A/C. Once the temp is about 80-85 deg. Park it and let it sit idling with the A/c on for about 5 minutes, then turn the car off. let the car sit for about 5 minutes with the engine off. Then turn the ignition so that the temp gauge registers. You will probably see it spike to over 100 because the car has been sitting with a hot engine and no coolant flowing through to take away the heat. Note the temp, then start the engine. If the temp doesn't come down to normal within about a minute, then you probably have a bad pump. When functioning properly, as soon as the car is cranked the pump will move enough coolant through the head to drop the temp very quickly.
Super Member
Joined: May 2003
Posts: 560
Likes: 1
From: Walnut, CA
MB 1990 300E
Originally Posted by mhorn
Get your car up to operating temperature, run the A/C. Once the temp is about 80-85 deg. Park it and let it sit idling with the A/c on for about 5 minutes, then turn the car off. let the car sit for about 5 minutes with the engine off. Then turn the ignition so that the temp gauge registers. You will probably see it spike to over 100 because the car has been sitting with a hot engine and no coolant flowing through to take away the heat. Note the temp, then start the engine. If the temp doesn't come down to normal within about a minute, then you probably have a bad pump. When functioning properly, as soon as the car is cranked the pump will move enough coolant through the head to drop the temp very quickly.
my car will do this everytime i turn on and off the car. even when i dont have the A/C turned on. If i just drive and do some errands, turn off the car and come back later the temp will be in the 90's and the fan will go off until i start the engine and give it some gas, then the temp will drop down to normal. Is this still normal because I've never noticed it doing this before. It would always stay in the normal temp range when just doing errands and stuff, but it seems like it runs really hot when i drive and after i turn it off.
Senior Member
Joined: Aug 2004
Posts: 285
Likes: 0
From: Richmond, Va.
1991 300E
It is perfectly normal for your temp to spike after you turn the car off. Think about it. When you turn off your car the coolant stops circulating around the engine. But the engine is still hot and will stay hot for a good while. So it just sits there and has only the stagnant coolant that is in the engine and the outside air to remove the heat that the engine has built up. This will take a while. However, as soon as you crank the engine up again and start pumping coolant through it, that will take all the built up heat away fairly quickly, Unless you have a bad water pump. So in short, don't worry if you run some errands, turn off your car, then come back a little later and find the temp is in the 100 range right when you start it.
This was a big problems with early turbos that were cooled by oil from the engine. When the car was turned off, the oil that cooled the trubo stop flowing to it, but the turbo was still spinning at about 7000 rpm and was still very hot. They didn't last very long and most manuf. started making seperate oil and coolant systems (intercooler)for the turbocharger.
This was a big problems with early turbos that were cooled by oil from the engine. When the car was turned off, the oil that cooled the trubo stop flowing to it, but the turbo was still spinning at about 7000 rpm and was still very hot. They didn't last very long and most manuf. started making seperate oil and coolant systems (intercooler)for the turbocharger.
Thread Starter
Super Member
Joined: Jul 2004
Posts: 842
Likes: 2
2001 c320 - 2002 ml55 - 2011 c300 - 2014 slk350 - 2015 cla45
...
well heres what my car is doing...
during acceleration i hear this funny whinning noise....
and lately ive noticed my engine temperature getting pretty warm... ive had this car since new.. and have never seen it run this hot.
during highway its at approx 100.. but once i get of the highway and in normal stop and go traffic it gets almost up to 120. this is with the a/c running full blast and the weather here in kc has been around 95 consistently.
i recently had my radiator changed from the original to the updated behr with the reienforced neck. does anyone know if this new one tends to run warmer than the original.
any thoughts or suggestions?
-thanks
carino
during acceleration i hear this funny whinning noise....
and lately ive noticed my engine temperature getting pretty warm... ive had this car since new.. and have never seen it run this hot.
during highway its at approx 100.. but once i get of the highway and in normal stop and go traffic it gets almost up to 120. this is with the a/c running full blast and the weather here in kc has been around 95 consistently.
i recently had my radiator changed from the original to the updated behr with the reienforced neck. does anyone know if this new one tends to run warmer than the original.
any thoughts or suggestions?
-thanks
carino
Last edited by ML55CLA45; Mar 19, 2019 at 05:54 AM.
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Thread Starter
Super Member
Joined: Jul 2004
Posts: 842
Likes: 2
2001 c320 - 2002 ml55 - 2011 c300 - 2014 slk350 - 2015 cla45
....
im assuming that when the dealer but the new radiator in they flushed it... but im not sure... i had it installed a few months back... march or april.. i cant remember. the therm is the original and yes the aux fans come one.. they turn on at about 100ish or so. i dont seem to be loosing any fluid from anywhere except small (very small) puddles of water every once and awhile that im assuming is comming from the AC.
-carino
-carino
Newbie
Joined: Aug 2012
Posts: 1
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Mazda 626
Car Overheating
I am having the exact same problem. When I drive my car for about 15-20 min my car will start to run hot. It tends to go up faster with the A/C on. It will constantly go up unless I either drive at a higher speed or put the car in park and put my foot on the pedal. I have done evrything. My mechanic has changed the thermostat 3 times, changed the radiator, flushed the coolant, changed the overflow box. What else is there left to try. Im all out of luck right now.
MBWorld Fanatic!
Joined: Dec 2003
Posts: 1,016
Likes: 0
Temperature creeping up at stopped/ low/ slow speeds and cooling down at freeway speeds is a classic sign of needing a new waterpump.
The pump is not pushing enough coolant through the cooling system when stopped. The higher rpm and increased airflow past the radiator assist in cooling at higher speeds.
The pump is not pushing enough coolant through the cooling system when stopped. The higher rpm and increased airflow past the radiator assist in cooling at higher speeds.
Senior Member
Joined: Jul 2004
Posts: 462
Likes: 3
From: Boulder, CO
86 W124
The heat build up is because of a bad fan clutch. The radiator can handle a lot of heat dissipation but if the fan works properly, it will be able to supply cooler coolant.
It gets worse as it wears out. First it's really warm restarts, then just getting off the freeway and because of reduced air flow, temps rise into the top third. Running AC, forget it.
30mph cruising speed is when you could drive without a fan all together. So when stopped temps rise with a fan that doesn't actually create flow. Also the engine works harder at freeway speed, which when you stop, goes through a major heat soak.
It gets worse as it wears out. First it's really warm restarts, then just getting off the freeway and because of reduced air flow, temps rise into the top third. Running AC, forget it.
30mph cruising speed is when you could drive without a fan all together. So when stopped temps rise with a fan that doesn't actually create flow. Also the engine works harder at freeway speed, which when you stop, goes through a major heat soak.
Super Member
Joined: Nov 2002
Posts: 977
Likes: 0
From: San Jose
300TE / 300E / 300CE
I replaced water pump's in both my M103 & M104. The M103 sprung a leak so I let the car sit for a year. I tried to start it recently and the bearing froze. I immediately stopped the engine when I heard the belt squeal. This happened once in my other M103 on a smog pump pulley. The M104 on the other hand began to make a clunking noise which I isolated with a mechanics stethoscope. The engine ran fine and only occasionally heated slowly over 100 so I didn't drive it on long trips and always watched the temps. I noticed the temp would go down quickly if I turned the heater on which added cooling capacity.
If you get any of these symptoms it's time to replace the water pump, belt tensioner & shock, belt, idler pulley, MB equivalent coolant, and thermostat. Flush or replace the radiator. Somewhat costly but much less than a head rebuild and gasket replacement...
If you get any of these symptoms it's time to replace the water pump, belt tensioner & shock, belt, idler pulley, MB equivalent coolant, and thermostat. Flush or replace the radiator. Somewhat costly but much less than a head rebuild and gasket replacement...
MBWorld Fanatic!
Joined: Jul 2011
Posts: 1,890
Likes: 6
From: Northeast PA-Poconos
2014 E350, 2006 C350 Sport(made it to 280k, loved it!), 1990 300E
:::Bump:::
I read through this thread since I am having a problem w/ my AC. I had it charged today because it was blowing out lukewarm air. It was empty so it needed it. So the AC works but my car was running hot when idle. I turned the AC off and the temp went down to 80 F. I installed a new thermostat and radiator a few months ago so I am good in that regard. What could be the culprit of me running hot when AC is engaged?
I read through this thread since I am having a problem w/ my AC. I had it charged today because it was blowing out lukewarm air. It was empty so it needed it. So the AC works but my car was running hot when idle. I turned the AC off and the temp went down to 80 F. I installed a new thermostat and radiator a few months ago so I am good in that regard. What could be the culprit of me running hot when AC is engaged?
Super Member
Joined: Aug 2005
Posts: 801
Likes: 1
From: Mercerville New Jersey
1991 560SEC Teal 1989 420SEL Ice Blue 1984 500SEC White
Viscious fan clutch.
The fan clutch engages and disengages the fan according to temperature, when the clutch fan goes bad the fan does not engage fully.
The fan clutch engages and disengages the fan according to temperature, when the clutch fan goes bad the fan does not engage fully.
:::Bump:::
I read through this thread since I am having a problem w/ my AC. I had it charged today because it was blowing out lukewarm air. It was empty so it needed it. So the AC works but my car was running hot when idle. I turned the AC off and the temp went down to 80 F. I installed a new thermostat and radiator a few months ago so I am good in that regard. What could be the culprit of me running hot when AC is engaged?
I read through this thread since I am having a problem w/ my AC. I had it charged today because it was blowing out lukewarm air. It was empty so it needed it. So the AC works but my car was running hot when idle. I turned the AC off and the temp went down to 80 F. I installed a new thermostat and radiator a few months ago so I am good in that regard. What could be the culprit of me running hot when AC is engaged?
Member
Joined: May 2009
Posts: 110
Likes: 2
2000 clk320
Having this problem, slow leak dripping from the lower radiator hose, no overheating. Looking at water pumps there is one with oil cooler and one without, is there a way to tell which one I have without taking it off?
Thanks
Thanks
Newbie
Joined: Jul 2019
Posts: 1
Likes: 0
CLA 250
Help
I recently purchased a used 2014 CLA 250 from a dealership in Miami. I was told it only needed an oil change so I drive it home to Jacksonville and then took it to a local Tires Plus to do an oil change. I was then told it needed a tune up with spark plugs and an ac recharge (AC is ice cold.) I told them to go ahead and do the spark plugs and ever since they put their hands on it the car is not functioning properly. Tires Plus said they fixed it as there was something in the fuel line and it needed an injector cleaning...I don't buy it as it still has issues. Now there is brand new oil all over the engine, there are over 16 codes in the computer active, including an engine 1 misfire, the car is running rough/shaking VERY bad, the car turns off while driving, and the needle indicating the car is hot is spiking ONLY when the car is idle or at a redlight/stopped. Mercedes dealership is saying that the thermostat and water pump needs to be replaced but the car is not running hot and is not leaking any coolant. I thought maybe the wiring was hit from the oil spilling everywhere from Tires Plus lack of workmanship. Has anyone else had this problem? Like I said I just bought this car and had no issues driving it all the up from Miami now as soon as Tires Plus handles it then all of these issues start occurring.
I am going after Tires Plus for the other issues but if anyone would have any idea how they messed it up any information would be great! Thanks!
I am going after Tires Plus for the other issues but if anyone would have any idea how they messed it up any information would be great! Thanks!
Junior Member
Joined: Jun 2006
Posts: 40
Likes: 3
From: San Diego, California
1998 E320 Wagon 253K miles
Wanting to confirm.....can a water pump with bad bearings throw off the path of the serpentine belt?
I'm not sure which happened first: my belt tensioner was pretty chewed up and my serpentine belt shredded.
My neighbor mechanic took off the belt and had me run the engine. He said listen -- bad bearings in the water pump.
He put on a new belt and it didn't sound right at all; the water pump started to leak.
Few days later I gave him a new water pump to install.
So far no leaks, belt is rotating like it should, no weird noises.
Anyone else experience this?
I'm not sure which happened first: my belt tensioner was pretty chewed up and my serpentine belt shredded.
My neighbor mechanic took off the belt and had me run the engine. He said listen -- bad bearings in the water pump.
He put on a new belt and it didn't sound right at all; the water pump started to leak.
Few days later I gave him a new water pump to install.
So far no leaks, belt is rotating like it should, no weird noises.
Anyone else experience this?
Junior Member
Joined: Jan 2008
Posts: 36
Likes: 1
From: Pretoria
W202 C200 1998, W123 200 1982, W123 230E 1982
Wanting to confirm.....can a water pump with bad bearings throw off the path of the serpentine belt?
I'm not sure which happened first: my belt tensioner was pretty chewed up and my serpentine belt shredded.
My neighbor mechanic took off the belt and had me run the engine. He said listen -- bad bearings in the water pump.
He put on a new belt and it didn't sound right at all; the water pump started to leak.
Few days later I gave him a new water pump to install.
So far no leaks, belt is rotating like it should, no weird noises.
Anyone else experience this?
I'm not sure which happened first: my belt tensioner was pretty chewed up and my serpentine belt shredded.
My neighbor mechanic took off the belt and had me run the engine. He said listen -- bad bearings in the water pump.
He put on a new belt and it didn't sound right at all; the water pump started to leak.
Few days later I gave him a new water pump to install.
So far no leaks, belt is rotating like it should, no weird noises.
Anyone else experience this?
Newbie
Joined: Apr 2021
Posts: 4
Likes: 1
w176 a250
Overheating a250 2014 help appreciated
W176 a250 50k miles
I was driving home when my serpentine belt snapped, I only noticed when the temp was getting to 120 so I pulled over and noticed it was snapped, after the car was recovered home I fitted a new belt and went for a drive, after 5 minutes the temp gauge inside was shaking around going from 90 to 120 in under 2 seconds then back down to 100 and all over the place. I have no codes logged and have flushed the coolant to see if it was a blocked coolant hose or airlock but now it’s only taking 3 1/2 litres of coolant in so I’m thinking it’s the pump seizing which has caused the belt to snap? But I did check the pulley before replacing the belt and it was fine.
Any ideas what could be the cause? I think I’m going to replace the pump myself which is a big job but want to see if anyone els has any ideas to save me some time and money. I have a new thermostat and coolant sensor I can fit but don’t want to change them if I don’t have too.
Thanks for reading any help much appreciated!
I was driving home when my serpentine belt snapped, I only noticed when the temp was getting to 120 so I pulled over and noticed it was snapped, after the car was recovered home I fitted a new belt and went for a drive, after 5 minutes the temp gauge inside was shaking around going from 90 to 120 in under 2 seconds then back down to 100 and all over the place. I have no codes logged and have flushed the coolant to see if it was a blocked coolant hose or airlock but now it’s only taking 3 1/2 litres of coolant in so I’m thinking it’s the pump seizing which has caused the belt to snap? But I did check the pulley before replacing the belt and it was fine.
Any ideas what could be the cause? I think I’m going to replace the pump myself which is a big job but want to see if anyone els has any ideas to save me some time and money. I have a new thermostat and coolant sensor I can fit but don’t want to change them if I don’t have too.
Thanks for reading any help much appreciated!
