Bender9406

Or so I thought ... Noise came back! That hellacious hammering, knocking, noise. It did go away with new thermostat, but after a day it returned. The good thing is, the knocking after the engine is shut off is gone. So maybe it did need a new thermostat, but that didnt rid my problem entirely. You can feel the surging going on and out of the block in the lines that go to the heater core. You can also see the surging on the bottom and top radiator hoses. Water pump is new. Is there a special bleed procedure? Will a bad surge tank cause the surge/knock Im experiencing? Maybe air getting into the lines? Oil looks OK so I dont suspect head gasket.

https://drive.google.com/file/d/1KoqKtUDVdsJEYxBm7jxRX3q82TtU4r3y/view?usp=drivesdk

So. The answer was …. Thermostat! Faulty thermostat. That knocking and tapping only started when thermostat got to temp - and continued to make noise after engine was off. $50 from Auto Zone and you get the thermostat and housing unit in 1.

Truck is back at dealership so I will let you know what the verdict is… it actually hasn’t made this sound in a week since I took the video.

You might be onto something- when I was under the other day I saw the inspection plug missing from the housing. And also the side plastic coverings on the sides of transmission were loose. So maybe transmission work was done and there is a bolt in there tapping or knocking around…. Idk Next time I hear it I’m going under and seeing what I can see with it running still. Vaccum pump and something with belt or pulley could also still be an issue. But only once it warms up. I do have a rather stiff break peddle too now that you mention it.

I have a scanner and can see what it says when I plug it in. I’ve never seen a CEL come on but maybe something is stored? I do only hear it once it’s warmed up. if it’s misfire and unburnt fuel I assume a coil and/or spark plugs should take care of that?

https://drive.google.com/file/d/1vO8ojl2bpotXkoedAmKTQt5VHnkNbJas/view?usp=drivesdk here is an mp4. ^^

https://drive.google.com/file/d/1_7mOY251Z7tJBQeOSBZDkZMjNCdfNOKL here is a link to the video … does that help? Thanks Jim for being so kind. And I’m unsure about rpm’s. I’ve always been at idle/park when noticed.

I’m so sorry … I uploaded from my iPhone. I will try and get something better uploaded.

I just picked up a 14 Sierra 5.3, and it only makes this noise once it’s warmed up? Has anyone heard this before?? It does not sound good. FullSizeRender.mov