I bought a 2003 5.4L SuperCrew last month. The coolant looked really old so i flushed it. Afterward I started hearing gurgling under the dash.

Thinking it was air trapped in the system, I spent the money and got a tool to fill the coolant under vacuum. The cooling system holds vacuum. Drained and filled with the vacuum tool. Still gurgles.

Noticed wetness in the wheel well and around the degas bottle. Replaced thermostat, degas bottle cap, and water pump. Still gurgles and pukes coolant. After driving a short distance the rad hoses are very hard.

I don't get the impression it's a head gasket since I changed the plugs when I got it and they all looked normal. The cooling system also holds vacuum. It runs good and the temp gauge never gets above normal.

What else could it be?

EDIT: The tstat and rad cap are Motorcraft parts, the water pump I got from oreilly's

 

Might be that you heater core is showing signs of age??
I too get the occasional gurgle, usually that is when I haven't driven it up to full operating temp. But I haven't had or noticed and wetness on the degas bottle or anywhere else. I got it to greatly reduce when I did much like you did by replacing the water pump and T-Stat. Only I did have a sight leak on the intake manifold, so I replace it as well and the radiator at that time. The radiator was because the transmission cooler in it was plugged up. SO with miles on it I just replaced it as well rather then trying to flush it.

To really rule out a head gasket issue I would test the coolant for signs of exhaust gases, ( hydrocarbon test).

I truly hope you have good luck with that water pump....many years ago I ended up replace 3 in our minivan, in the course of a year, before I got a good one.

 

If the tank pukes out antifreeze and the hoses are hard, then NORMALLY the engine will overheat as seen on the gauge... If it is not overheating, then you don't have a circulation problem, you have a PRESSURE problem. I would also check for exhaust gas in the radiator. You don't necessarily have to burn water... the head can leak into the water jacket, but not necessarily water into the combustion chamber.


I would guess there was a problem and the owner added a bottle of sealer. You washed that out with the "FLUSH" and now it has a small pin hole leak in the head gasket.. I would try to prove that first... THen I would add a bottle of Bars Leak Copper Gasket Sealer.... I think the number is #1109.

 

Thank you for the replies. The heater core was replaced by a previous owner last year. Saw it in the stack of receipts that came with the truck.

I performed a block test on it and the test fluid did not turn yellow. The reservoir overflowed before the tstat opened and there were bubbles coming up through the coolant but the test fluid stayed blue.

What next?

EDIT: I see there is a TSB out for "COOLANT DEGAS BOTTLE OVERFLOW". TSB # 051713, NHTSA #10018062. Anyone able to look it up and see more than just a summary?

 

I had my brother look up TSB's and there was nothing related.

I removed the radiator and it's not clogged. I drilled two holes in the old thermostat and installed it. It doesn't puke coolant as often now but there is always gurgling in the heater core on startup. All that air in the system has to be coming from somewhere. Exhaust gases are the only source that makes sense.

I'm 90% sure it's a head gasket now. Going to begin tear down tonight after work.

Anyone got any tips for head gasket replacement? Are there any better gaskets than OEM?

 

I completed the head gasket replacement yesterday. The passenger side head was leaking from at least 3 cylinders. Also had a blown out timing chain tensioner that rattled a little on startup which I had thought was the starter, and 6 seized valve lash adjusters. This was a very labor intensive endeavor. I've driven it about 70 miles now after the new head gasket and no issues or leaks so far. Oh, and the gurgling behind the dash is gone.

here's pics:
https://photos.app.goo.gl/z439Tu6DCg0DG5dn2

Interesting note:
In the pics, you can see the head internals on the passenger side are a lot darker color. Also, the exhaust collectors had white ash on the passenger side, but sooty on the driver side. Passenger side head was definitely running a lot hotter!

 

Yeah any time you tear an engine down to the block while it's still in the vehicle it's a lot of work. Good job solving all of those issues.

 

I replaced the heater core on my 1999 F-150 this past winter. Similar symptoms. Expensive, but worth it.