Can a water pump make a knocking noise? [Archive] - FSB Forums

: Can a water pump make a knocking noise?


jesse_h97
12-11-2009, 06:22 PM
My heater doesn't work and I hear a knocking noise when the motor gets warm, it sounds like its in the front of the motor. I felt the heater core hoses and there cold, the radiator fluid is flowing like the thermostat is working. Does the water pump make noise when it dies? Ive never seen one. And what kind of damage can i do driving it like that?

jesse_h97
12-11-2009, 07:29 PM
Nutn?

KYBOSH
12-13-2009, 01:33 AM
I would say no.
There is nothing really to knock in a water pump.

Look around the front of the engine to see if a bolt/bracket has come loose and is causing this sound.

Knocking sounds are NEVER good.
Sure its not your engine itself knocking?

Good Luck

waltman
12-13-2009, 02:29 AM
I doubt a water pump would knock without pissing out water. I would suspect a bearing.

eXcali
12-13-2009, 03:18 AM
You could possibly be getting a knocking sound from trapped air, you could also get a knocking sound if your radiator froze over. I suppose even a large build up of steam would cause a knock as it popped your radiator cap pressure valve or even a build up of steam and the thermo opening and snapping shut once pressure relieves.

Does your top radiator hose get hot?

I'd pull the top radiator hose loose and check to see if the fluid is coming out under pressure. My guess is you either have a dead water pump or lots of air trapped in the line. To test it, back fill the fluid into the block at the thermo, then reassemble.

waltman
12-13-2009, 03:35 AM
You could possibly be getting a knocking sound from trapped air, you could also get a knocking sound if your radiator froze over. I suppose even a large build up of steam would cause a knock as it popped your radiator cap pressure valve or even a build up of steam and the thermo opening and snapping shut once pressure relieves.

Does your top radiator hose get hot?

I'd pull the top radiator hose loose and check to see if the fluid is coming out under pressure. My guess is you either have a dead water pump or lots of air trapped in the line. To test it, back fill the fluid into the block at the thermo, then reassemble.

Why would trapped air cause a knocking noise and wouldn't coolant with not enough antifreeze freezing, cause either the rad to burst or a frost plug to be pushed out, or both? As for the steam scenario, how could steam cause knocking? Your description of what could be happening would also have water pouring into the overflow and not with an associated knocking noise but a steady stream of coolant until pressure is relieved then the cap would quietly seal...no knock.

As for a dead water pump, even when the bearings go, they still pump water but they also piss out coolant.

Sorry man, I just don't buy it.

eXcali
12-13-2009, 03:45 AM
Why would trapped air cause a knocking noise and wouldn't coolant with not enough antifreeze freezing, cause either the rad to burst or a frost plug to be pushed out, or both? As for the steam scenario, how could steam cause knocking? Your description of what could be happening would also have water pouring into the overflow and not with an associated knocking noise but a steady stream of coolant until pressure is relieved then the cap would quietly seal...no knock.

As for a dead water pump, even when the bearings go, they still pump water but they also piss out coolant.

Sorry man, I just don't buy it.

Sorry man, didn't know I have to break things down 1st grade style.


If he's got an air pocket and the block is only partially filled with water/coolant with the pump shot it's going to boil the water in the block. Pressure builds, trips the thermo. The thermo is a mechanical part and with no liquid to dampen the noise will cause a knocking sound. *side note* If he's running water in his system and it were to freeze the water in the overflow will also be frozen.

I mention this because I had to deal with a friend who ran water in her rad and of course it froze in the 5degree cold the other day. Her water pump was frozen as well and the water in the block boiled causing a knocking sound coming from the expanding rad and the thermo popping. And no freeze plugs popped.

waltman
12-13-2009, 04:04 AM
Sorry man, didn't know I have to break things down 1st grade style.


If he's got an air pocket and the block is only partially filled with water/coolant with the pump shot it's going to boil the water in the block. Pressure builds, trips the thermo. The thermo is a mechanical part and with no liquid to dampen the noise will cause a knocking sound. *side note* If he's running water in his system and it were to freeze the water in the overflow will also be frozen.

I mention this because I had to deal with a friend who ran water in her rad and of course it froze in the 5degree cold the other day. Her water pump was frozen as well and the water in the block boiled causing a knocking sound coming from the expanding rad and the thermo popping. And no freeze plugs popped.

I guess I just don't see how a rad cap can knock especially when it is rubber against brass. I can believe the sound of water boiling making a gurgling sound, but not a knocking sound. Is it possible that your grade one definition of knocking is different from mine?

But I guess we will have to wait for the OP to say whether or not he is running antifreeze to eliminate your theory

eXcali
12-13-2009, 05:20 PM
I guess I just don't see how a rad cap can knock especially when it is rubber against brass. I can believe the sound of water boiling making a gurgling sound, but not a knocking sound. Is it possible that your grade one definition of knocking is different from mine?

But I guess we will have to wait for the OP to say whether or not he is running antifreeze to eliminate your theory

I take it you have never heard steam pipes knocking and pinging from an old boiler. I'm offering the OP up some possibilities and theorizing why they would hear knocking. I guess I could kindly just sit back and not contribute to these forums, or I could pick apart other peoples responses to bump my post count....

waltman
12-13-2009, 06:08 PM
I take it you have never heard steam pipes knocking and pinging from an old boiler. I'm offering the OP up some possibilities and theorizing why they would hear knocking. I guess I could kindly just sit back and not contribute to these forums, or I could pick apart other peoples responses to bump my post count....

:histerica you're not going to cry are you?
Hey, you made an opinion and then so did I, if you want to knock everything I ever say, then please feel free, i am a grown up and can take criticism. :thumbup

...last I checked, a boiler and a water cooled internal combustion engine are two different animals.

I was also thinking about how you mentioned your friends water pump was frozen. If that was the case then the belt would have been screaming like a banshee so I gotta ask, why would you not tell your friend to shut it down instead of allowing the belt to squeal while the motor got hot enough to boil the water?

Daves 88'
12-13-2009, 10:15 PM
the weep hole in the water pump tells me when my water pump is bad. I think coolant lubricates the water pump to keep it from freezing. As far as a knock is concerned, I use a stethoscope.

El Kabong
12-13-2009, 10:49 PM
Does an 83 still have V belts?

I was telling an old mechanic friend that I thought that the 351w in our 69 Mustang had a knock. He asked to be sure that it was a 351w. He told me that those engines had something odd that would make a knocking sound related to the belts, & to try some belt dressing to see if that was the issue. I thought he was nuts, but it was a cheap test, so I tried it. The knock disappeared immediately. Belt dressing was only a short term fix, the belts were swapped eventually. It might not be the issue, but it's worth a check.

jesse_h97
12-14-2009, 08:49 AM
Will the heater core receive water whether or not the thermostat is working? I have no hot water flowing to the core from the send hose, thats why I was thinking water pump. Funny you should say that about the belt I had an old mechanic tell me to look at the belt on the harmonic pulley cause it was wobbling a bit and i disregarded that info because it didn't knock till it got hot.

bigblueford
12-14-2009, 09:40 AM
My F250 diesel water pump sucked the spring wire out of the bottom radiator hose. So I'd say that it COULD make a ticking or grinding sound. That bottom hose could collapse as a result and cause restricted flow to the pump.

Robs79BBbronco
12-14-2009, 10:08 AM
a failing water pump squeals like a pig.....it doesn't knock.make sure your harmonic balancer isn't about to fly off.

waltman
12-14-2009, 11:20 AM
Will the heater core receive water whether or not the thermostat is working? I have no hot water flowing to the core from the send hose, thats why I was thinking water pump. Funny you should say that about the belt I had an old mechanic tell me to look at the belt on the harmonic pulley cause it was wobbling a bit and i disregarded that info because it didn't knock till it got hot.

Plugged heater core would be my guess for that.

Brochoncho
12-14-2009, 12:33 PM
The fan clutch will make somewhat of a knocking noise when it is going bad or wore out. With engine off, grab the fan to see if it can move. Pay attention to what is moving, if the whole pully is moving then the water pump is junk. Once again do this with the engine off.