cavitating water pump?
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5th Wheeling
Joined: Apr 2013
Posts: 30
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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?
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 82
From: NorCal
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.
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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5th Wheeling
Joined: Apr 2013
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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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5th Wheeling
Joined: Apr 2013
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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?
Senior User
Joined: Jul 2007
Posts: 276
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From: Lexington. Mi.
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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Joined: Oct 2012
Posts: 67
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From: Ontario Canada
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Post Fiend
Joined: Apr 2008
Posts: 8,261
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From: Big Sky Country
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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