Yeah I can, I'll do that on my spare one though I did just throw a brand new one in there. I grabbed a leakdown tester last night. I'll try both today

 

Edit: I found a weird leak that isn't detectable with my decay tester. The bleed port on the drivers side has some sort of hairline crack in it because I see some steam coming from it. I was able to drive a few miles without overheating today. Replacing the plastic bleed port should do it. Time will tell. So that's 2x soft lines that were pushed off of their barbs, and 2 leaks caused by the freezing. Could be way worse...


Leakdown checked out OK. I did a regular test to get numbers then ramped up the pressure to each cylinder to check for bubbles in the radiator. No bubbles at 75 psi in any cylinder.
​​​​​​
Engine was cold, so numbers are high. All of the leakage was into the crankcase from what I could tell.
Percentages:
Cyl1:27.5
Cyl2:29.5
Cyl3:28.5
Cyl4:32
Cyl5: 25
Cyl6:25

This is good and bad news. Not sure what the culprit is here. Not much to work off of yet.

​​​​​​I'll bleed it out, heat working fine, then drive down the road. 1/8 mile down the road then the heat stops working and there's a bunch of air in the coolant system again along with a pegged temp needle but nothing comes out of the overflow tank and the system seems to be at about 8 psi instead of ~19 per the cap.

​​​​​Oil cap is super milky, could be from short runs.

Might try a coolant system leak test with the engine warm, though the pressure would drop due to cooling at the same time.

If it were broken water pump vanes it would be boiling out of the radiator cap. The system fails to build pressure which causes localized boiling yet passes pressure testing. ¯\_(ツ)_/¯

 

I'm tired ... it may be in the above post ... but,

are in the in & out hoses different temps while you're over heating? Meaning the top hose is hot but the bottom hose is cold? or are both congruent with each other?

also, if you wanna throw parts at it, it may be smart to replaced the water pump. When I overheated back in the day I believe I messed up my water pump seals. I think a new OEM-equivilent was $40 or so and it's something that'll need replaced at some point in time.

just a thought...

 

Water pump is a big job! I could try the method through the inspection cover if need be.

But, I think I'm good for now... I edited the above post (first paragraph). I think that leak is where the water is expanding through. Hopefully that's all there is to it. It drove fine yesterday but I think it was a matter of time until the coolant stopped expanding and it overheated. I have some parts coming in from Z1 sometime this week

 

Yea, water pump is a two hour job via the inspection covers! If I was smarter I'd have done it when I did my headgaskets.

Cool - keep us posted