Strange water knocking sound.

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Dutch Rutter

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Joshua
Truck Year
1984
Truck Model
K20
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5.7
Recently I replaced my water pump, and clutch fan with new severe duty units, I also replaced my radiator with a new unit. Have been driving it just fine without any heat/cooling issues what so ever. Except after I shut the engine off I hear a knocking type of sound. I opened the hood to see my upper radiator hose bounce along with the knock.

First I thought an air bubble so I did the burp process, no difference. Then thought air bubble trapped under the t-stat, so I pulled the 195 out and drilled a single 1/8" hole in the flange and put it back, re did the burp process. Still getting the knock sound along with a "boiling feeling" from the upper hose if I squeeze it a little when its cooling down.

Temps are all still fine, coolant seems to be flowing like it should, overflow bottle works like it should, heater is fine, no visible leaks.

Today I ordered two new t-stats a regular flow 195, and a high flow 195 without bypass holes as a shot in the dark but I have no idea if they'll help any. Any thoughts on this?
 

Charlie

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Try a new radiator cap. I have had issues with some.
 

Dutch Rutter

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Independence, Or
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Joshua
Truck Year
1984
Truck Model
K20
Engine Size
5.7
Try a new radiator cap. I have had issues with some.

Thanks for the recommendation but I forgot to mention, I did get a new cap and it seems to be working well. I'll grab one of those pressure tester setups and give things a go over as well just to make sure things check out.
 

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