More 3.0 coolant problems

[plasticsguy]

Where to start?
parts replaced, intake gaskets (small leak), Thermostat, Radiator, radiator cap. Flushed several times. Truck will idle for hours without building up a lot of pressure in the system, can even remove the radiator cap slowly without losing any fluid, but drive it for five miles and the pressure will force antifreeze into the overflow tank and the hoses get rock hard. Idling with the radiator cap off allows the antifreeze to surge and splash out of the radiator. Heater works intermittently. Suspected a head gasket failure but No smoke in the exhaust, no anti freeze in the oil. Pulled spark plugs and the plugs and cylinders were dry. Pressure tested radiator with 14 psi and only lost 2 lbs in two hours. Tried using a block tester and the blue fluid remained blue.
Does anyone have any ideas?

 

[cp2295]

Have you performed a compression test? You might have a head gasket starting to go and only leaks off pressure once a load is placed on the engine. Look for white spark plug electrodes too. I had a cracked head on my 4.0 that kept fouling the #6 plug took me forever to figure out what it was until it got really bad and started mixing with the oil, never overheated somehow lol.


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[plasticsguy]

3.0

Had a shop tell me that they checked the compression and it was good. But then again they told me that they had replaced the thermostat and when I checked it I found that they didn't. I did notice one plug had had white residue while the others looked normal. Going from the possibility of a bad head gasket to a cracked head just doesn't brighten my day.
I will do a compression check myself to see what I get.
Thanks.

 

[cp2295]

Had a shop tell me that they checked the compression and it was good. But then again they told me that they had replaced the thermostat and when I checked it I found that they didn't. I did notice one plug had had white residue while the others looked normal. Going from the possibility of a bad head gasket to a cracked head just doesn't brighten my day.

I will do a compression check myself to see what I get.

Thanks.

That’s unfortunate, but at least it seems you are on the right track. You can also get those little strips that check for combustion gases in the coolant to help you verify the issue. It seems that coupled with the fact that your coolant system gets over pressurized leans towards a bad head/gasket

I also want to point out that a white plug doesn’t necessarily mean coolant, could also be a lean condition, there should be some photos somewhere on google that you can compare your plugs to.


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[fr7]

Did you figure out the problem? I know you said you replaced the thermostat but I've had similar problems and didn't suspect about the thermostat till it blew the radiator, put new radiator in, worked for a week then it started blowing the reservoir cap, I figured sometimes it wasn't opening, building too much back pressure and blowing the reservoir cap open. Replacing the thermostat seemed to have fixed the problem.
Just a suggestion, thermostats ain't that expensive nor hard to replace.