Help with diagnosis and repair

[Freddie11]

Looking for a little help. I'm posting here cause there are some helpful smart people here. If needs to be deleted because it's not chevelle I understand.

87 Chevy truck. 305 Trucks. Sat for 15 years. Has new radiator. New heater core, New hoses.
I've flushed the system out Five or six times. And I still get Grungy Grimy. Dirty water coming out.not rusty color.
It also has Small fizzy Bubbles in my burpping funnel.
Compression Tested engine All cylinders good 180 185 pounds Per cylinder. No signs of water in any cylinder, no smoke out of tail pipe.

I'm thinking headgasket is bad or cracked head or block because of Bubbles? What do thinking?
but why does the water get so Grungy?
No smoke from tailpipe.
I tried to add video but couldn't

 

[YakkoWarner]

What does your dipstick look like when you pull it? Could be cross-contaminating coolant and oil, which could come from either lower intake or head gasket... If you pull the oil stick and have something that looks like brown mud, or notice any kind of whitish foamy looking stuff on the inside of the oil fill cap, that is likely what you have.

 

[Freddie11]

What does your dipstick look like when you pull it? Could be cross-contaminating coolant and oil, which could come from either lower intake or head gasket... If you pull the oil stick and have something that looks like brown mud, or notice any kind of whitish foamy looking stuff on the inside of the oil fill cap, that is likely what you have.

No water in oil. Oil still looks good. No whitish foam on oil cap

 

[YakkoWarner]

No water in oil. Oil still looks good. No whitish foam on oil cap

Weirder and weirder.....

I'd almost bet you have some kind of small leak that is allowing exhaust into the coolant. It would have to be happening at a location where the exhaust pressure is higher than the coolant pressure because otherwise you would be seeing steam in the exhaust.

I'd consider doing a cylinder leak-down test - like the reverse of a compression test but you're putting compressed air into a cylinder and seeing if it holds the pressure. Take the radiator cap off (with the engine cold in this case) and watch for bubbles as you pressurize each cylinder. If you find one not (or more) not holding pressure - you know which side of the engine needs to be gotten into. Otherwise its pulling both heads.

 

[fast 99]

If automatic, power braking many times will help with diagnosis. Load engine to 1/8th - 1/4 throttle, watch for bubbles in radiator. In the shop we use a pressure tester and watch for pressure increase. Can't give exact numbers it's one of those experience tests but I have seen 5 psi increase in 10-15 seconds or less.