How to tell if a water pump is bad?

[conway]

Besides the obvious overheating, how can i pinpoint that the water pump is on it's way out.

[egebhardt]

Hard to say.
I just removed one from my car. It was an OEM BMW plastic impeller pump with 65,000 miles on it. It had no leaks of any kind and spun freely. The impeller was all intact. It looked like new. I replaced it with one with a metal impeller to be safe.

[DLite]

There's no simple way to tell.

You might be able to determine what temperature rise accross the engine is, by shooting metal temps with a IR temperature gun, thermocouple or RTD. My guess that a normal temperature rise from inlet to oulet is going to be 15 to 20 degF.

[Hova]

Besides the obvious overheating, how can i pinpoint that the water pump is on it's way out.

Its just a shaft on a bearing, and an impeller...

Sometimes the bearing fails, sometimes the impeller cracks/breaks. There really is no way to know if its about to die or not. If you are at 75k on the water pump, its probably a good idea to change it.

[conway]

If i'm overheating at speed, is that a sign of the water pump can't keep up. I've never over heated on the highway before. Outside temps were only 73 degrees.

[khaos]

How can one tell if the water pump has been replaced? Is there an obvious visual difference between the stock one and the metal impeller one?

[corruptshin]

oh yea you can tell. stock one's impeller is made of plastic and it's black. I had just replaced mine with a metal impeller and it's color is....well metallic colored.

[mmark.]

To clarify.
There are two waterpumps on the market at this time that have non metallic impellers.

The first are the discontinued ones that are still in aftermarket stock. these have true plastic impellers.
The second are the units with composite impellers that are currently being sold by BMW factory parts dealers.

If your car overheats in motion, replace the water pump.
If it continues to overheat and the cooling system has been bled, then you'll be looking at a headgasket leak or remotely, a clogged radiator.

m

[Moron95M3]

if the bearing is going out, the water pump will (sometimes) start to leak from that area.

also, when it gets really bad...the fan/fanclutch will wobble pretty bad...to the point that it will break the fan blades off (did this twice).

However, mine was not overheating, just showing those symptoms.


I just picked up a 325 that is overheating -but I'm guessing it's the Tstat (no leaks/fan is tight).

However, might aswell do both while I'm in there.



as for your issue, it may need a bleed? or you tstat is sticking.

[hokie36]

don't know...
I had mine replaced when I changed the radiator, Tstat and those stuff in cooling system, cuz I was using a mechanic and trying to save on labor then. ps, I did the cooling system at ~137k mi

[Hova]

If i'm overheating at speed, is that a sign of the water pump can't keep up. I've never over heated on the highway before. Outside temps were only 73 degrees.

That is not good.

You probably have air in the system, or your waterpump is shot, there is a clog, or your thermostat is stuck, something is very wrong.

[sak335]

There are a couple of tell-tale signs.

1. If you pull the belt off and grab hold of the pulley, try and wiggle the pulley to see if there is play in the bearings. If the bearings are worn you will notice definite play and you should replace the pump. "Play"
means you can feel movement.
2. When the pump is really worn out you will see fluid leaking out the weep hole.

There is no way to tell if you have plastic vs. metal. If you know the mileage since the last pump was replaced and it is more than 75k miles, it's a good idea to replace it. If you don't know the mileage and there are more than 75k on the car, and the pump isn't nice and shiny, then replace it.

[stupenal]

if the bearing is going out, the water pump will (sometimes) start to leak from that area.

also, when it gets really bad...the fan/fanclutch will wobble pretty bad...to the point that it will break the fan blades off (did this twice).

However, mine was not overheating, just showing those symptoms.


I just picked up a 325 that is overheating -but I'm guessing it's the Tstat (no leaks/fan is tight).

However, might aswell do both while I'm in there.



as for your issue, it may need a bleed? or you tstat is sticking.

Had the WP go out on my old e36 325i, and recently on my 97 M3. Both times they went out, different symptons

325i: Driving to work, heard a couple of clunks as i ran over what I thought was road debris. By the time I pulled into the parking lot, the car died and wouldnt start. Radiator fan broke to bits, pump completely seized.

M3: heard random squeals from the engine, saw a check coolant message. Next day, random squeals again, noticed coolant had all drained out. Pulled the pump and it had a metal impellar, looked visually fine. Noticed a tiny bit of wobble in the bearings and figured that's what caused the somewhat slow coolant leak and random squeals. New pump was composite (not metal) as the reviews seemed more favorable.

Hope this helps

[zohaibrose]

You sir have the best signature I've seen in a while

[TostitoBandito]

Easy answer. If it's never been replaced in your car, go buy a Stewart pump and install it (and do belts at the same time because why not).

PS - nice thread necromancy

[ugeeks]

There's no simple way to tell.

You might be able to determine what temperature rise accross the engine is, by shooting metal temps with a IR temperature gun, thermocouple or RTD. My guess that a normal temperature rise from inlet to oulet is going to be 15 to 20 degF.

If the pump is running, there should be very small difference across the pump. Like less than one or two degrees.
If pump is not running, then there will be a larger temp delta...could be 10 degrees plus. Not much natural circulation occurs (where the cool water from radiator- higher density- pushes the higher temp water (lower density).

Bottom line is when the water pump is working, the temperature across it should be nil.

[realjones]

Bottom line is when the water pump is working, the temperature across it should be nil.

Thank you for making your fourth post in three years a correction of a seven year old post.

[tjm3]

If i'm overheating at speed, is that a sign of the water pump can't keep up. I've never over heated on the highway before. Outside temps were only 73 degrees.

If the radiator is not plugged up or blocked of airflow and assuming a plastic impellor hasn't come apart, you may just have a thermostat that no longer opens as much as it should as the engine heats up. Even a leaky water pump will still pump coolant. Also, make sure you're tensioner is still tensioning.

[M3X3X5]

I have some very slight play in the pumps pulley but with the thermostat off I may just do the pump too while I am in there. I have 35k miles on the pump. I hear so much talk metal impellers are better but at Napa they went from metal to plastic and the plastic costs more. With all these various schools of thought on impeller material I am tempted to just leave the pump in but I sometimes like to really wind up the car for a while on some hills and I hear if you lost a pump it could be too late to save the head once you noticed the gauge rising. Does anyone use some kind of overheat alarm that would alert you right away in case of a temp increase?

[TostitoBandito]

Just put a Stewart pump in and don't worry about it anymore.

[Bm6w]

I have some very slight play in the pumps pulley but with the thermostat off I may just do the pump too while I am in there. I have 35k miles on the pump. I hear so much talk metal impellers are better but at Napa they went from metal to plastic and the plastic costs more. With all these various schools of thought on impeller material I am tempted to just leave the pump in but I sometimes like to really wind up the car for a while on some hills and I hear if you lost a pump it could be too late to save the head once you noticed the gauge rising. Does anyone use some kind of overheat alarm that would alert you right away in case of a temp increase?

Yes, buy a digital gauge that plugs into your obd port