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Old 11-21-2012, 08:38 AM   #1
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Water pump tapping?

I have a 72 350 and when the engine is cold, it sounds like there is tapping noise coming from the water pump, has anyone ever heard that. I dont have any overheating isues at all and if anything, Tthe car definitely runs cold which i dont mind at all but i was curious if thats what it is.

Any thoughts as to how to test the pump, again having no issues except that sound.

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Old 11-21-2012, 10:34 AM   #2
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Hi Dan
There isn't much in a waterpump other then the bearing,shaft,seal,and impellar. Typically the bearings go bad and the shaft is wobbling around and then it starts to leak.
See if you can move the fan by hand laterally it should be tight then listen with a long rod or screwdriver for a bearing noise while the engine is running.
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Old 11-21-2012, 10:36 AM   #3
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There really isn't much in a water pump to knock. A shaft that spins in a cylindrical bushing with an impeller on the end. I suppose if the belts were out of alignment it might cause some noise. You might check that.

I would venture a guess and say that it is more likely to be timing chain related and coming from behind the pump.

See if you can locate one of the cheap auto stethoscopes and use it to listen around and positively locate the knock. I believe Harbor Freight has them........

My $.02
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Old 11-21-2012, 07:32 PM   #4
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If the knock is relative to engine speed, (RPM), I'll bet on the fuel pump. I've heard them knock so bad it sounded like a rod bearing had spun.
A long rod of some type or a stethoscope will pin it down.
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Old 11-21-2012, 07:41 PM   #5
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Yes Harborfreight sells the stethoscope, I think I paid less than $10 for mine, works great
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Old 11-23-2012, 09:12 AM   #6
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Originally Posted by TimAT View Post
If the knock is relative to engine speed, (RPM), I'll bet on the fuel pump. I've heard them knock so bad it sounded like a rod bearing had spun.
A long rod of some type or a stethoscope will pin it down.

Water pumps is an unlikely source of the tapping. Fuel pump is a good place to start.

I'm also thinking a stuck lifter at the front might also generate a similar and misleading noise. Maybe some gunk or trash has clogged a lifter.

If the fuel pump option doesn't pan out, buy a can of Seafoam. Read the instructions, and use it as an oil system cleaner. Be aware though, it's meant to be done before a fluid change. Read the directions on the can. Also, even if if it's not a lifter, it can't hurt anything and might be a good thing to do anyway after years of sludge and varnish buildup.
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Old 11-23-2012, 02:01 PM   #7
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Sometimes you can rest your hand on the fuel pump or use a socket extension and touch the pump while its running and feel the knock. Obviously where it knocks the hardest is usually the source.
I agree with others that the fuel pump is a more common source. Lifters usually make a tick sound more than a knock. Just a thought has your oil pressure dropped a few pounds? A rod bearing on the 1st journal might sound like its coming from the water pump.

Sent from my Razr Maxx
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I'm not saying let's go kill all the stupid people...I'm just saying let's remove all the warning labels and let the problem sort itself out.
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