So....I fill everything up with water. Fill the res tank and also (using a hose nozzle) fill the radiator from the top of the radiator bleeder screw hole.
Start the car and let it idle for a while with everything tightened u (bleeder screws closed and res cap on).
Bleed the bottom (8mm) bleed screw, bleed the top of radiator bleeder.....water seems to be flowing, no air.
Car heats up to about 194...dont see any leaks from the res cap.
Close the hood, go for a drive, drive starts out 20 to 30 mph max, then I get to a road where I can speed up to about 50.....
OBDII reader and gauge match, temp starts to climb, gets to 220 and I make it to the gas station, shut it down....top off res tank with water....
On the way home, car creeps back up to 220, then I turned the heat on and full defrost and the temperature did drop back down to about 208 and stayed there till I got home. Heat seemed to stay hot and didn't all of a sudden go to cool air)

At a loss as to where to go from here as I have basically replaced the whole damn coolant system. ANY help would be greatly appreciated.


Items I have changed:
Radiator
Water Pump and O-ring
Water pump flange and O-ring
Res tank and cap
Thermostat (verified this works by putting it in hot water and it opened up)
Low / High Speed fan assembly and relay (used part, but can now verify the low and high speed fans work)

Pics attached so you can help me focus my displeasure onto this machine

 

when it gets hot is the low speed fan turning on?

 

Temps will be higher with just water in the system. Mix 50/50 with blue coolant and try again.

 

not true, water will cool better than coolant.
OP, are you losing coolant? Might be your head gasket.
also a new OEM thermostat may be needed. My t-stat would open but not correctly until I replaced it.

 

It's fairly easy to install the thermostat backwards. Have you checked?

 

Honestly If I am losing it anywhere it seems to always boil out of the rest tank. I did replace the thermostat, then removed it again to test it in hot water (it passed)
I also checked compression on all 4 cylinders and they were all at 120.......
I have a borescope camera, Do i run the car, then take the plugs out to check for moisture?

 

that would do it.


OP you won't see coolant on plugs. You may see milkshake oil especially on the oil fill cap.

 

When cold, there should only be one inch or so of coolant in the expansion tank - it's not a header tank.
You appear to be filling & bleeding the engine & radiator correctly, though it can be difficult to get all the air out.
120 lbs psi is pretty low for compression but I expect the throttle was not held wide open - I'd hope for 150 or so. As long as they are all even it's most likely OK.
220F is OK for a running temperature in a pressurized system.
I'd siphon off the excess coolant.

 

Sorry to jack the thread if i am, but its funny as I’m reading this post and having the exact same issues, what is the easiest best and most for sure way to bleed this w11 engine , let make sure I’m on the same page as everyone

jack it up
open front screw
Take cap off , fill until thermo screw leaks out and front screw comes out,
tighten thermo screw
start car , heat on lo bleed until air pockets out .

that’s it right ? After so i Go for a spirited drive and then for me all of a sudden tank boils over and front bleed screw has nothing but air

 

Your CAT or exhaust might be plugging up. Creating back pressure and overheating the engine.

 

i figured out the problem, thought I’d post my results because almost 99% threads never end with a solution,

Puddle of water in cyl 1, ^note this is a new head gasket too^

Plug #1, plug #2


Note to self, send head to machine shop no matter how broke you wanna be doing this work so you don’t have to do it twice .

 

and what was the problem?

 

I'll take a wild guess: he said he replaced the head gasket and still had coolant intrusion into one of the cylinders. He then lamented not sending the head to the machine shop during the head repair.

It sounds like the engine overheated and warped the cylinder head. Since the head wasn't machined back to flat, the coolant intrusion to the cylinder persists.

 

I just came in to say its probably the head. Mine was the exact same. Replaced EVERYTHING and it refused to stay cool. Head kept pushing the water out and creating air pockets in the coolant system. Had head decked, new gasket, no more overheating problems.

To anyone searching this later, go to Autozone or Oreilly or Advanced and get and head gasket leak detection kit. Its just a rubber stopper on a graduated cylinder with a little hand pump. You add blue fluid to it. Follow the instructions. If the fluid changes colors to green or yellow (can't remember) you have hydrocarbons in your coolant which means the head is bad. Then you can attack the problem. If it stays blue, then you know its not the head and can look elsewhere.

Also, I couldn't get a very expensive and supposedly top of the line aftermarket aluminum coolant tank to work with the OE cap. So, my suggestion is to keep the OE style tank.

 

you are correct

 

Ouch. Good luck getting it sorted.

Have overheated several times and was always scared of this happening. Read somewhere on here that the head was relatively strong and it was difficult for this to actually happen?

 

went thru 3 heads, aluminum heads are strong but jcw heads have a slight prone to crack near cyl 1 where the 10mm bolt holds the head and timing guides

 

What year is your JCW?

 

2002