Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.
Diagnosing a Failed Water Pump Can Be Tricky
Diagnosing a water pump failure is one of those dreadful repair tasks most car drivers don't like to find themselves in.
First, taking your car to the shop isn't going to be cheap, and trying to find out on your own if your water pump has failed isn't much fun either. And that's because potential clues can lead you astray. You start replacing components that don't fix anything.
However, your real problem here is that applying the wrong fixes can get real expensive pretty soon. And dangerous.
Give it a chance, and a bad water pump will overheat and destroy your engine in no time.
But things don't have to get to that point. A failed water pump will give you specific clues that something is amiss, if you know how to look for them.
This guide outlines, in a step-by-step way, three different but related methods you can use now to help you check and confirm that your water pump in your car has failed. Most of the time you won't need any tools unless you must remove components to gain access to your pump. Sometimes, though, a special tool will prove valuable in certain situations (we'll get to it later), but often it is not needed.
Before getting into the steps, let's take a look at the configuration and operation of a common car water pump. This will help in diagnosing yours.
I. How a Water Pump Works
Five Main Reasons Your Water Pump Fails
What You Should Know About Bad Water Pump Symptoms
II. Testing a Bad Water Pump
Diagnosing Water Pump Operation
Diagnosing Bearing Failure
Diagnosing Seal Failure
What If Your Water Pump Is OK but The Engine Still Overheats?
Top 5 Tips to Increase Water Pump Service Life
I. How a Water Pump Works
Your car water pump has a simple but efficient design. The pump uses an impeller, mounted on one end of a centered shaft, to push coolant throughout your engine, cylinder head, radiator, heater core, intake manifold, connecting hoses and lines.
The centered shaft has a pulley on the other end and is supported by one or two bearings to transfer rotating force to the impeller.
Depending on your particular vehicle make and model, your engine may use a serpentine belt, drive belt, or timing belt to run your water pump.
Although a shaft seal isolates coolant from the bearing assembly, your water pump silver housing has a weep hole (or relief port) to one side or at the bottom to allow coolant to exit if your pump develops a leak.
Five Main Reasons Your Water Pump Fails
A water pump may fail in more than one way. For example:
- An old, worn out seal starts leaking coolant.
- An over-tensed belt puts extra pressure on the shaft and bearing, which may lead to a broken shaft or bearing, and a leak.
- A worn out or damaged bearing prevents your pump from properly rotating or at all, causing your engine to overheat.
- Old coolant and rust buildup destroy your water pump.
- An old gasket gives in and leaks.
What You Should Know About Bad Water Pump Symptoms
A failed water pump shares some symptoms with other bad components in your vehicle:
- Coolant leak. A bad hose, gasket or radiator may also leak coolant. But the water pump glossy, green leak will usually show up on the floor right under the water pump.
- Engine overheating. Also, a stuck thermostat or clogged radiator will cause your engine to overheat.
- A whining, sometimes a grinding, noise coming from the front of your engine. A bad accessory pulley, slipping or misaligned belt can become noisy, as well.
Since these symptoms may appear when other components go bad as well, you still need to confirm the failure of your pump.
II. Testing a Bad Water Pump
When testing for a bad water pump becomes difficult, you can divide your diagnostic into three simple procedures that give you a better chance of revealing the fault and the type of failure you are facing.
The advantage with this approach is that your diagnostic can make it easier to tell whether other components played a role in your water pump failure, which you must correct before installing a new pump.
So first, we'll check the operation of your water pump, followed by a diagnostic of the bearing, and signs of a potential water pump seal failure. You can combine one or more of these methods until you can verify the failure and possibly pinpoint the cause.
Diagnosing Water Pump Operation
The purpose of this type of diagnostic is to check whether your water pump is working.
- Place your transmission in Park (automatic) or Neutral (manual) and apply the parking brakes.
- Remove the radiator cap and start the engine.
- Let your engine idle for about 15 to 20 minutes to let it reach operating temperature.
- At operating temperature, you should see through the radiator opening how the coolant begins to circulate; otherwise, either your thermostat has failed to open, the radiator is clogged, or your water pump isn't working.
- If you suspect the water pump isn't working, replace the radiator cap and, using a shop rag to prevent burning your hand, squeeze the upper radiator hose (the one going from the radiator to the engine).
- With a working water pump, you should feel the surge of coolant as you release the radiator hose.
- When you don't feel the surge of coolant, squeeze the upper radiator hose again, and while an assistant depresses the accelerator to increase engine speed, release the radiator hose.
- If you still don't feel the surge of coolant through the upper radiator hose, most likely coolant is not circulating. Get inside the passenger compartment.
- With the engine still idling, turn on the heater to Max.
- If you feel very little heat or no heat coming out, and you've noticed your engine overheating, you'll need to locate the fault among a stuck-closed thermostat, a clogged radiator, and a failed water pump. Go on to the next procedure.
Diagnosing Water Pump Bearing Failure
One way to check for worn out or failed pump bearing is to check for water pump shaft movement.
1. With a faulty bearing, you can often hear a squealing, howling, or sometimes a grinding noise coming from the front of the engine. Even if you don't hear any noises, apply the next steps.
- To isolate the source of the noise, you can use a large screwdriver or a length of rubber hose to isolate the source.
- Start your engine. Keep your hands and screwdriver or hose away from moving parts.
- Touch the front of your water pump housing with the tip of the screwdriver shaft or one end of the hose.
- Put the other end of the screwdriver or hose against your ear. If the bearings are worn out or damaged, you'll clearly hear the noise coming from your water pump as the bearing causes a rough rotation of the pump shaft.
Be aware that a loose or slipping drive belt, an AC compressor, alternator, steering pump, belt tensioner, or another accessory driven by the belt may also cause a squealing noise.
2. Check the water pump shaft and pulley for signs of damage or movement.
On vehicle models where a serpentine, drive or timing belt runs the water pump, you may need to remove the belt to manually check the water pump pulley.
- Wiggle your pump pulley with your hand. If you notice damage or movement, replace the water pump.
- Rotate the pulley by hand. It should turn freely but not feel loose or rough; otherwise, replace the pump.
- On vehicles where the radiator fan attaches to the water pump assembly, you can grab the fan and carefully wiggle the fan. If you notice movement, most likely the water pump will need replacing, but check that all mounting bolts are tight. And carefully examine the fan as well. With enough time, a loose or damaged fan will cause the water pump to fail.
Diagnosing Water Pump Seal Failure
A bad seal will cause the water pump to fail, allowing coolant to leak. Often, a simple visual inspection of the water pump itself can reveal the leak of a seal or even a gasket.
- On some vehicle models, you have easy access to the pump for inspection. On other models, you may need to remove an engine front cover to gain access and even raise the vehicle and supporting it on jack stands.
- Once you gain access to your pump, use a flashlight to inspect the pump. Check the pump weep or relief port (at the bottom, to one side, or under the pulley), around the shaft or pulley and mounting area (where the pump comes in contact with the engine block)
- Also, look where the radiator hose attaches to the water pump.
- Look for traces of coolant residue or tracks of dried coolant. If your water pump is driven by a drive or serpentine belt and you find traces of coolant, make sure the leak is not coming from an over-head hose or another source above the water pump.
A slightly wet weep hole isn't cause for concern. However, a dripping weep hole means a failed shaft seal.
I Found Traces of a Leak But Don't Know the Source
If you find traces of a coolant leak around your water pump but aren't sure of its source, pressure test the cooling system:
- Get a hand pressure tester. You may loan a tester from your local auto parts store. This is a simple hand-operated air pump.
- With the engine off, install the tester cap in place of your radiator cap and start pressurizing the system by squeezing the pump handle.
- The pump comes with a gauge so you know how much pressure you're applying. Do not exceed the pressure your cooling system is rated for—about 14 or 15 psi (check your radiator cap or your vehicle repair manual, if necessary).
- With your system pressurized, make a visual inspection of the water pump. Look around the weep hole, shaft, pulley, mounting surface and hoses above the water pump.
If you discover a small leak at the pump, don't try to fix it with an after market sealer. Most likely the problem will come back or you won't be able to repair it successfully.
What If My Water Pump Is OK but The Engine Still Overheats?
Other than a failed water pump, you can find several reasons behind an overheating engine you might want to check:
- Make sure the cooling system has enough coolant. Check coolant level at the coolant overflow tank.
- If your water pump is run by a belt, check that your drive belt or serpentine belt is not loose; a loose belt will not allow the water pump impeller to push coolant at the proper rate, causing your engine to overheat.
- Check for a stuck-closed thermostat. A failed thermostat in the closed position will not allow coolant to flow into the radiator.
- Make sure your radiator is not clogged. A clogged radiator will prevent coolant circulation.
- Bad radiator fan. There won't be enough airflow through the radiator to remove heat from hot coolant.
- Bad radiator cap, worn out or damaged seal. A failed cap will lower coolant boiling point.
- Air in the cooling system. Air may form pockets (bubbles) that prevent coolant from removing heat away from the engine.
Top 5 Tips to Increase Water Pump Service Life
A water pump often fails prematurely. You can avoid this by following some simple guidelines:
- Replace old coolant at the recommended car manufacturer service interval. Old, worn out coolant allows rust to build up causing your water pump and other cooling system parts to fail.
- When replacing a belt that runs the water pump, install the belt with the appropriate tension and replace belts at the recommended car manufacturer schedule (including belt tensioner), and verify the belt aligns with all the pulleys it runs. A loose, misaligned, or over tensed belt will prevent proper operation of the water pump and other accessories and can damage the pump shaft, bearing and seal.
- Fix engine overheating problems as soon as possible. Overheating will damage the seal and impeller inside the water pump.
- Use a quality water pump to keep your cooling system working at optimal condition for a longer period.
- When replacing a water pump run by a timing belt, always replace the timing belt at the same time, especially if the water pump was leaking. A coolant contaminated timing belt will have a reduced service life. On the other hand, a worn out timing belt may break and damage your new water pump. In most applications, the water pump and timing belt have about the same service life period (50,000 miles or more), so you'll save time and money by doing both at the same time.
You should begin diagnosing a water pump failure as soon as you suspect something is wrong. Apply the three methods outlined in this simple guide. An early diagnostic can save you thousands of dollars in repairs. Remember that driving a car with a failed water pump can leave you stranded in the middle of the road, with an overheated engine and a much more expensive repair.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: My car doesn't start getting hot immediately, but the temperature goes up after driving for a while. Would this be the thermostat sticking?
Answer: This is the most common reason. Check also the cooling make sure it's not constantly running. If necessary, check the temperature sensor.
Question: I've already replaced the cap and thermostat of my water pump. It still builds up so much pressure that most of the coolant is pushed out of the radiator and into the overflow tank. Before driving, I have to take off cap to release pressure and let coolant drain back into the radiator. Would a clogged radiator most likely be the issue?
Answer: There are three things you might want to check. Make sure you have the correct cap for your application, see your vehicle repair manual, if necessary. Also, make sure the cap is sealing correctly. Closely inspect the radiator neck for damage or anything in there not allowing the cap to seal properly. Then, check for a blown head gasket leaking hydrocarbons into the cooling system. This will require a leak down test.
Question: If my coolant leaks out almost completely when I fill the reservoir how do I know for sure it's the water pump and not something else before paying for the part? I'm not a mechanic, but I changed the reservoir and hoses. Also replaced the AC fan assembly. Now I have this problem. Please help.
Answer: Take a close look at the pump. If the pump is leaking, you should be able to see traces of coolant around the pump. You can try listening to the pump with the engine at idle (be very careful with moving components) using a piece of hose. Put one end of the hose against the pump and the other end at your ear. You may be able to hear a whirring noise if the pump bearings are worn or have failed. If not, look around the cooling system for the leak. You shouldn't replace components until you know what is causing the leak. Small leaks are hard to find sometimes.
Question: After turning a water pump on, the engine check light came on, and it misfired. Why is this?
Answer: Make sure that you purged the system correctly. You need to get rid of all the air pockets in there. Otherwise, that could cause overheat, misfire and hence the CEL. Download the codes and see what they say.
Question: can coolant leak from the radiator hose cause water pump failure?
Answer: Not really, the water pump is sealed. These pumps have a weep hole where coolant leaks through when the bearing or seal fail.
Question: Why does my car's fan run on high at times?
Answer: If your vehicle uses a clutch fan, check the clutch; otherwise, there could be a problem with an AC compressor pressure switch.
Question: The water pump gave up on my ‘05 Toyota Sienna, and I have noticed that the upper front timing cover was cracked. Also found out that half of the timing belt is off the top sprocket and will not move at all. Is that normal for a car when that happens to the water pump?
Answer: If the water pump sprocket seized, it probably affected the timing belt and caused a misalignment. When changing the water pump, have the mechanic check the sprockets, idler and adjuster and install a new belt. Install a new timing belt kit would be the best way to go.
Question: My car overheats but runs well. It doesn't overheat until the coolant runs out, which happens every time after going about 3 or 4 miles (6.44 km) if that. What would cause my car's coolant to be gone so fast? The heat does work. It may get 1 out of 7 drives/rides.
Answer: There's a leak in the system you need to find. If you don't see any signs of leakage on the ground where you park your car, it could be an internal leak. This other post may help:
Question: I have a 2007 Nissan Pathfinder. The temperature rises the faster you drive unless I run the heat at full blast. But I can put the vehicle in park, run the AC, and it never overheats. What would cause that?
Answer: There are several problems that could cause this. Debris and bugs can cause insufficient air flow through the radiator. Also, the radiator may be partially restricted. If the cooling fan isn't working properly, this may cause the same problem. Take a look at the lower and upper radiator hoses. If a hose is collapsing when engine speed increases, it will restrict coolant flow. Running the AC at full blast help to lower the coolant temperature.
Question: Why is my water pump getting hot?
Answer: If the temperature gauge indicates the engine is overheating, the water pump bearing may be faulty and not allowing coolant to circulate properly. Another possibility is the thermostat is not functioning right. Depending on your particular model, you can try to listen to the pump with a length of hose. Put one end against the water pump and the other end at your ear and see if you hear noise coming from the pump. This other post can help you check your thermostat.
Question: Does it sound normal or appropriate for the water pump inside the intake to be a 13 hour job, and cost around $1330?
Answer: A repair job for a particular component can vary by hundreds of dollars, depending on your particular model and the cost for the part for the particular model. But you can get an estimate through several online sites like this:
There are other ones. You can check more than one. Just search for "car repair estimate" and you'll get a list of several sites. Hope this helps.
Question: My car's water leaks more when the engine is hot. Could this be caused by a damaged water pump or are the seals out?
Answer: It could be the water pump or another cooling system component. Sometimes, exterior leaks are easy to find. If possible, follow the leak marks left on the engine. You may need to raise your vehicle and support it on jack stands. This other post has some common parts that may eventually leak:
Jared Kloth on August 25, 2020:
Yes this was SUPER SUPER helpful. It's good to have clarity into this. sometimes it's inevitable but this will help me prepare more for when it is necessary.
THIS IS THE BEST AUTO BLOG – will be revisiting this for all future questions. YOU ROCK DAN!
Dan Ferrell (author) on August 18, 2020:
You may not necessarily cause severe damage in the short term. Of course, you'll be wasting fuel. It's been calculated that about two idle minutes equals one driven mile.
But you may wan to to consider this:
* Your battery's lifespan will be reduced. A battery can't be charged properly at idle and it puts a stress on it.
* You'll need to keep an eye on oil level and condition: It'll degrade and burn up faster.
* Key components wear like piston rings and head gasket will accelerate.
If you're going to idle your vehicle for long periods of time, trying to park in a well ventilated area, and take it for a long ride on the highway at leas once a week. Hope this helps.
Jared Kloth on August 16, 2020:
Wow that was extremely clear and significantly helpful. I wasn't sure if there was a better way to respond, but for anyone else who finds this blog....this is a great resource with a very insightful response team. Thanks Dan, this really put my fears to rest – and while I assumed most of that, it still puts me at ease having just put in $1700 over 2 months into a POS 2008 Subaru that I bought used at 125K miles (now 175K miles) and that I was really hoping to not pump too much money into......it sounds like these fixes were critical to making the car last longer so let's pray they're somehow the last major fixes before I replace her. sometimes car repairs can be simple and sometimes they can waterfall....the latter is never fun to deal with.
While I have you and while you happen too be quite insightful....I'm curious about the act of running the car in idle, i.e. sitting in my car and not driving it but having the engine on (air on and off) for extended periods of time. I've asked many mechanics and car people about whether I'm damaging my car by doing so – at the moment, my car is my only sense of privacy from my home life and I often like to hang out in there, i can get internet down there so sometimes I'll just work from there and will have the car on sometimes for 1-4 hours.......the resources I've asked all say that I can't damage a car by running it idle/not driving like that, but of course there are always those who say otherwise.....in your opinion, how much damage am I/can I do to my car by doing so? For context assume I sit there a few days a week (not every week) and on average the car will run for 1-2 hours before I turn it off for a 30 min break before either running it again or just going back inside.
THANKS IN ADVANCE!!
Dan Ferrell (author) on August 12, 2020:
If you'd never replaced the water pump before in this vehicle, I think it was way overdue in relative terms. You may expect a water pump to last between 70 to 100,000 miles. It depends on how good you are at taking care of the cooling system. Sometimes, a soon-to-fail pump can become a little noisy or it may start to leak a bit. However, unless you open the hood and take a look around and listen carefully, you may not catch any potential issues, specially if you don't have much experience under the hood. Using a mechanic's stethoscope or piece or rubber hose to listen to components at regular intervals and mileage, can help the experience DIYer or technician to spot problem. Other than that, you would've needed to gain access to the water pump and check pulley play to realize something was not right. Also, a water pump may fail internally and not give you an apparent clue as to what is gong to happen. Changing the radiator didn't have an adverse effect on the pump. And checking a radiator for leaks or restrictions is relatively easier than checking a water pump. In most vehicles, the pump is hidden under a cover and, sometimes, you need to remove accessories to gain access to it. So probably you actually needed to replace the radiator; otherwise, you would've noticed the same problem with the cooling system soon after the radiator was replaced. Hope this helps and clarifies some of your concerns.
Jared Kloth on August 12, 2020:
I just replaced my radiator mid-June 2020 – I was making a drive PA to CT, about 2 hours from CT my temperature gauge started spiking, luckily I made it with breaks to CT, got it fixed, all was fine for a bit.
Context: subaru outback 2008, 173K-ish miles at that time (bought car Jan 2018 @ 126K miles – has needed work here and there, nothing incredibly significant outside of old car stuff and subaru stuff, oxygen sensors, tire crap, leaks here and there)
Over next 6-8 weeks, I didn't drive much – partial employment due to COVID still and try to avoid public things while people are so crazy these days, so not driving a lot. I regularly check liquids, sometimes more than once a week, sometimes once a week...some weeks I forget when the car is fine and I'm not driving much.
About two weeks ago, I checked my liquids (power steering, oil, antifreeze) and noticed they are all low, filled them with new stuff except antifreeze, found an old one in my basement so I thought I'd save some money. It was bright green and i'm still pretty positive it was meant for any and all cars makes etc, but it was an old bottle didn't have EXP date (do they?) and didn't have the most clear marketing/instructions (i've seen the brand, but possibly just old marketing tactics).
Over the next week I barely drove, two days work (30 min away) and aside from market here there nothing. I do sit in my car while it runs sometimes, just for peace and solitude. One night I did such a thing, 2 hours in the car, no problems. Next morn woke up brought my roommate to work then went back to sleep, went to walmart 3-4 hours later, got out walked away only for a nice stranger to point out my car was leaking, rapidly. Bright green liquid dripping like a faucet – I had just filled it to fill, but after this 30 min trip i was below the LOW fill line. WTF right? this sucked since I know I just replaced the radiator, not for a cheap one, not the most expensive either.
Long story short, just brought it in yesterday (my mechanic is a real nice honest guy) and he took me lifted the car and showed me the problem – needed a new Water Pump & Timing Belt.
My last service (mentioned above, mid-June) was through a family friend who gets me discounts on parts – and that was $750 (radiator, something in a tire was cracked, oil change, labor, maybe something else small).....now i'm looking at $800-1000.....WTF right.
My question is: how do you know whether its the radiator or water pump? It seems that the symptom overheating can indicate either or (I'm not a car guy YET but def gonna be moving forward).....do you have to replace the radiator first to find out whether the water pump is bad instead/also? is a water pump breaking at 175Kish miles good, bad, whatever? Does me replacing the radiator in mid June mean anything? Did that first guy mis-diagnose the problem? Any help/clarity would be helpful – i'm hella broke and this will push me to $0 all over...and while there's nothing I can do, this is a significant fix that I can't avoid, I am curious what happened and if it was avoidable, possibly for future reference as well. If overheating can mean bad radiator and/or bad water pump, how do you know which to fix if you are mechanic and diagnosing? does the radiator always come first as a fix? thanks and sorry for the length (i tried to type briefly but clearly)
Dan Ferrell (author) on May 09, 2020:
First, have the radiator cap checked. It should hold pressure as stated on the cap itself. Make sure it's the correct for your applciation. The cap's gasket should be in good condition. Also, there could be a problem in the cooling system, a faulty thermostat, water pump, radiator or even a damaged head or block. If necessary, check the cooling system. Hope this helps.
Vincent on May 09, 2020:
I have this problem for my Honda radiator revers the liquid back into reservoir tank fully and radiator becomes empty, fill it, drive about 3 to 4 km and start heating up again, what could be a problem?
Dan Ferrell (author) on December 23, 2019:
If you can see water dripping close to the cabin, it's probably one of the heater hoses that is leaking. Open the hood and look for two hoses that connect through the firewall, on the passenger side. You may see one of the hoses wet. Also, look inside the cabin, passenger side, under the carpet. if it is wet, the heater is leaking. If water is dripping where the engine is, passenger side, probably the water pump is leaking or the radiator hose connected to it. Hope this helps.
Tee park on December 23, 2019:
When I let my car run in park til it idles out the temperature gauge remains even. But as soon as I drive it for no more than a block the temperature rises and coolant runs out from bottom of engine. Most noticeable on the passenger side and when I turn the car off I can hear the hissing noise. Is it the pump?
Dan Ferrell (author) on December 18, 2019:
Make sure it's at the water pump. Trace the leak, if necessary. There could be a loose hose or connection, specially if the leak starter right after you fixed the heater.
Derrick clayton on December 17, 2019:
I fixed my heater now I leak coolant from water pump I believe
Dan Ferrell (author) on December 14, 2019:
The weep hole is there to alert you when the seals have gone bad. So it's better to replace the water pump as soon as possible.
Sam Genaro on December 14, 2019:
Had to replace leaking thermostat gasket and put new thermostat in,now antifreeze is leaking from pressure port on water pump,water pump only 2yrs old.any recommendation what could be wrong.
Dan Ferrell (author) on November 09, 2019:
Not necessarily. There could be several reasons why the engine is overheating. This other post can help you diagnose the problem. Start with the most simple things:
Cheyenne Anderson on November 09, 2019:
My engine was over heating. Its 2001 subaru outback. I got a new thermostat and seal changed it all out the car was fine for a week and it started over heating again. Ive squeezed the radiator hose to see if coolant is getting through and it is does that means its clogged somewhere? If so how do i fix it. God forbid its my pump.
Dan Ferrell (author) on September 28, 2019:
Most likely the seal is leaking. It can get worst, and you may get stranded. Plan for it, if you can. Keep an eye on the temp. You don't want to end up replacing an engine instead of a pump.
Dave on September 28, 2019:
My water pump is leaking slowly. If it helps to answer my question, my car is a 2009 VW Tiguan. The indicator light that coolant is low comes on about every four days and then I add coolant. I have a plan to take the car in to a mechanic in three days but need to make a 100 mile drive before then. If I keep coolant with me to add, can I drive the 100 miles?
Dan Ferrell (author) on August 19, 2019:
Check the source for the drip; a gasket may be blown and causing the overheat.
Heather on August 18, 2019:
I have a 2002 chevy s10 4wd and last week otw home i heard a loud noise and luckily i was less than a mile from home and when i cut truck off steam was rolling out from under hood but oddly gauge wasnt reafing too hot. I had it checked out and apparently my fan was dry rotted and broke off and went through radiator so i replaced fan, radiator, and trough(i think is what its called), then drove it amd still overheated so replaced thermostat and drove it yesterday and its still overheating...not immediately bit maybe 10-15 min down the road. My water pump was replaced at beginning of this year but could the mishap with fan cause water pump to go bad? And there is a slow drip under hood of water/coolant too
Dan Ferrell (author) on June 25, 2019:
You may be write but, it can be the connection to the water pump as well. If it is dripping, raise the car after parking and trace down the leak. You need to make sure where it's coming from before buying and installing components. Hope this helps.
Joe on June 25, 2019:
My car only leaks antifreeze after I drive and then turn it off. It seems to be leaking in the center of the front (driver side), and my best guess is the water pump. I can hear liquid circulating back to the radiator/reservoir, and then i look under the front and see a steady drip. I went to fill up the radiator (after driving it only one day after filling it up the day before), and the radiator itself was still full, but the reservoir was short liquid.
As mentioned, the car doesn't leak antifreeze when it's parked, only after I ride it and park. (It drips for a couple minutes and then stops.)
The radiator is relatively new, I had new hoses put in a few years ago, and the cap is on properly... my best guess is the water pump?
Dan Ferrell (author) on February 23, 2019:
You need to find out where that coolant is going. Check for leaks around the system. Also, check the radiator cap's seal. This can also leak and upset system pressure.
Dan Ferrell (author) on August 16, 2018:
If the fans don't come on when they should, there may be a problem with E (ECT). The coolant you find under the car may come from the overflwoing tank but overheating may have caused a leak. If it keeps overheating, other serious problems may develop.
Anonymous on August 16, 2018:
I have a 2008 Honda CRV and its overheating and the AC does not work. Some symptoms I have noticed...
1. Steam from the engine when the car over heats while on the road.
2. Found coolant liquid pooled up under the car.
3. Both the radiator fan and AC fan do not come on when they should.
4. Coolant reservoir tank constantly goes low and having to refill.
A. Bad Water Pump
B. Bad Thermostat
C. Bad Radiator Fan / Bad AC Fan Motor
D. Bad Head Gasket / Combustion Gas getting into the cooling system
E. Bad ECT (engine coolant temp) sensor / Radiator Fan Switch
F. Bad Radiator Fan and AC Fan Fuse / Relay
G. Bad Radiator Cap
Dan Ferrell (author) on July 12, 2018:
The message it's usually related to a bad water pump, and sometimes a problem with the radiator fan/circuit, coolant sensor may cause this message to appear. Also, there might be some problems with the evaporator system causing trouble to the AC. If possible, have it diagnosed before doing any repairs on it.
Hope this helps, good luck.
AlexanderNevrmind on July 11, 2018:
I need a new water pump. After reading your article I have no doubt in my mind that I need to replace it, thank you.
One thing that I was hoping to understand better and I presume is related to the water pump in general is that every time I turn the AC on it triggers a "coolant visit workshop" message on the instrument cluster. This message appears eventually if I do not use the AC but will trigger immediately if I turn the AC on. It is not the same as the "Coolant check Level" which is more serious and indicates noticeable loss of fluid. I have checked the fluid level and if the fan engages when i turn the AC on; fluid is OK, fan engages. Also not surprising is that my AC will sometimes work sometimes wont and most of the time will work only after I have driven the car 10 - 15 minutes. This is more pronounced when the car sits in the heat, when this happens the AC wont kick in for a considerable amount of time if ever it does. This is not because the car itself is hot and the AC has to cool down an already hot cabin interior or air passage ways etc. It simply blows hot air for 10-15 minutes depending on how hot it is outside and then as if someone reminds it that i turned it on 15 minutes ago it wakes up and blows in cool air. When it does work it works well and it isn't long before the temperature inside the cabin is lowered. Final note: I do not have the problem where the rear vents blow hot while the front vents blow cold nor does one side blow hot vs the other side cold. Not too long ago I had the AC refrigerant level checked and filled if necessary.
What I really would like to know is why turning the AC on triggers the Coolant Visit Workshop message and why there is such a long delay before the AC decides to wake up.
If it helps, I drive an 05 E500 MBZ
Do you think replacing the water pump will remedy the intermittent AC or am I looking at two separate problems?
Dan Ferrell (author) on May 17, 2018:
There could be several possibilities, but that whining sound could be the clue. Try to find the source of the sound with the engine at idle or someone revving up the engine while trying to find the source. Check the water pump pulley.
Make sure the AC is working correctly and the radiator is not clogging.
This other post might help you too:
nelson cruz on May 16, 2018:
very impormative, i learn a lot.but it doesn't answer my problem right now. i experience overheat, and when i check the radiator the water is still full. I just close the ac and the fan of the aircon and the temp. goes back to a normal state. I'm hearing a whining sound and i don't know where is it coming from. When we got home I open the radiator cap and rev the engine, i noticed that the water overflow when we step on the gas pedal, why is that so?