the problem with only going to 210 is the temps at the stat could still be lower thus not getting a full open. If your gasket blows at 220 it's on its last leg anyway. I've had my truck to 240's way more than once or twice. You have to cycle it and let it go through the motions.

or

just keep having issues resulting in changing your stat again with some stat made on the same assembly line of the one you just took out and said was bad, yea it was the stat...not.

 

 

Ok. Pressure tested the system having taken #8 plug out.
Pumped it up to 19 psi, and low and behold every junction attached to the ridged Y below the t-stat was dripping.
I installed all new hoses & ridged connectors when I replaced my water pump. I double checked all the connections for tightness before installing them. Ran the truck fro 20 miles, and re tightened them. Seems stupid that there leaking now after 6 months of driving.
Took off the fan and shrouds, RE tightened those connections. Re tested. Now just the 180 deg hose attached to the 45 deg neck at top of t-stat is dripping. I pulled up the spring type hose clamp, and worked the hose down as far as I could, and re secured the spring clamp ensuring that the clamp was below the neck Ridge... Still leaks. Should I just replace the spring clamp w/ a screw on type? Or do I have to drain the sys and dry out the connection adding oil at the neck for a proper seal?
Thanks.

 

 

OK, so I replaced all the spring type hose clamps in the cooling system with screw type that included a hose collar in between the hose and the worm gear clamp...all connections are firm and hold dry under 18psi pressure testing.
as for the pressure testing, w/ plugs 7 & 8 out I would pressurize the system to 18 psi, and within a few minutes, the pressure would drop by 1 psi, then hold steady for hours... I don't know if this loss is due to the variances in the tool, or what.
reinstalled the plugs...had the chase the threads on #8 as the plug would not hand screw in more than a few turns...all good after chasing once w/ the wrench, and going in and out by hand several times with plenty of grease in the chaser to remove all the little bits of metal.
started the truck, brought it up to temp. drove around the block twice, and again the temps started to spike right there at the end. pulled into the driveway and cut the engine at 217.
incidentally, there was no waterfall sound. I performed RAVE bleeding several times during the pressure testing procedure including squeezing hoses etc to work out any air.
the truck is cooling down now. will bleed again in the AM.
thoughts?

 

 

Ok, so I blead that thing 6 or 8 times to no avail.
I replaced or tightened down All the coolant connection clamps.
There is no leaking that I can see in the engine or on the ground.
Still temps spike and coolant boils over after warmup.
Pulled the heads this weekend.
I'm no gasket whisperer, but they didn't look obviously blown to me.
The 2 impossible lower rear head bolts were not Nearly as hard to break as the rest, for whatever that's worth.
No obvious steaming in the combustion chambers... Piston 5 looks quite clean though.
Also, no obvious signs of sleeve slippage.
Any thoughts... Should I flush the rad and heater core while it's all opened up to make sure that flow is good?
What else can I look for if the heads don't seem to be problematic. Taking the heads today for hot tanking and pressure testing and surfacing... Should I have them fluxed to see if there is a crack, or will the pressure test reveal this?
Pics below.
Thanks much!

 

Left bank looks weird to me...can you post pics of the intake gasket & ports?

 

The 3rd cylinder from the front left side is way too clean compare to the rest. My bet is that is where your problem was/is

 

Yeah, thought it was strange that #5 was so clean, but the combustion chamber shows plenty of buildup... Although the valve heads look a bit clean as well.
Additional pics attached as requested.