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cavitating water pump?

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Old Jun 18, 2013 | 09:38 PM
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tygerof2's Avatar
tygerof2
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cavitating water pump?

So, I finally got my 78 F250 back in working order after having to rebuild the heads. I went ahead and replaced the water pump, thermostat, fuel pump, timing set while I was in there. After starting the engine (400), I have a noise that starts in the water pump area when the thermostat starts to open. The engine temp. gets up to normal temp. and never goes too high. I though I had to get the air out of the cooling system but its been 2 days I've been trying to work it out. I put a new radiator cap and overflow tank to catch excess coolant. Wondering if anyone thinks the water pump may be cavitating? How to remedy this condition? Any thoughts?
 
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Old Jun 18, 2013 | 10:19 PM
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HIO Silver
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I highly doubt that the water pump is cavitating. The impeller design is good for the typical operating range running unless you've decreased the pulley diameter to a lil teensy wheel.

Please describe the noise. Is it a gurgling, grinding, ticking, or what??? Is "starts" in the water pump area but where does it end up? Could there be a foreign object in the cooling system??? Hmmmmm.
 
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Old Jun 19, 2013 | 04:14 PM
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Its clicking and popping (rapidly) so loud you can hear it while your 10 feet away. Its almost as if its boiling inside the engine/hoses because the heater hoses will twitch. Another way to describe it is like water hammer but on smaller scale. Like I said, I bought a new 13# cap and I'm not getting any leaks anywhere. My overflow can gets a 1/3 full after driving around town a little. The noise is definitely related to when the t-stat opens cuz that's when it starts making noise.(after it gets up to operating temp.) I can squeeze the lower hose and it changes frequency too.
 
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Old Jun 19, 2013 | 08:08 PM
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bronco kenny
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how did you try to get the air out did you take the cap off and fill a funnel with coolant till you reached operating temperature and turned on heater
 
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Old Jun 21, 2013 | 06:04 PM
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Yes, pulled the cap off the radiator and allowed it to warm up to operating temp. The level in the upper tank rose so I placed a funnel in the filler hole. It gurgled and acted like it was trying to expel the air. I did have heater on high. I was told it may be my heads need retorqued too. The thought was that gases could be leaking past the head gaskets and entering the water side, thus the popping noise. Any thoughts?
 
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Old Jun 21, 2013 | 07:29 PM
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From: Lexington. Mi.
Originally Posted by tygerof2
Its clicking and popping (rapidly) so loud you can hear it while your 10 feet away. Its almost as if its boiling inside the engine/hoses because the heater hoses will twitch. Another way to describe it is like water hammer but on smaller scale. Like I said, I bought a new 13# cap and I'm not getting any leaks anywhere. My overflow can gets a 1/3 full after driving around town a little. The noise is definitely related to when the t-stat opens cuz that's when it starts making noise.(after it gets up to operating temp.) I can squeeze the lower hose and it changes frequency too.
by any chance is the thermostat in backwards, thats what it sound like to me (imo) if not i would replace the new stat with another new stat
 
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Old Jun 23, 2013 | 07:37 PM
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When you installed the head gaskets, are you certain they were installed correctly?
 
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Old Jun 23, 2013 | 07:43 PM
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Originally Posted by tygerof2
I can squeeze the lower hose and it changes frequency too.
You shouldn't be able to do that... there should be an internal spring, or a thick walled hose that's not easily squeezed, otherwise the hose can collapse under high rpm's.
 
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Old Jun 24, 2013 | 03:23 PM
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Head gaskets had stamped on them "front". Thats how I put them in.
Yes, maybe I will get a new lower hose. thanks.
 
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