Overheated engine Help with Mechanic in Northern CA

[Rabbit on Roids]

sounds like the cracks between your valves might be just a BIT too DEEP...

[Baron VonZeppelin]

Theres nothing IN the cooling system that can emulate an air compressor ( when cold)

True.
Not easy to work with problems over webnet.
Sometimes some engines have probo on refill with air pockets, due to tstat location. Normally they work themselves out sooner or later. While present - they form steam and excess pressure etc...

Leaving out tstat would eliminate that condition on a troubleshoot.

RoR probably has your diagnosis.
A compression test would be real good info.
Harbor Freight has the Diesel Comp Tester on sale right now for $17-18. Usually $25. A lot of us have that exact tool - its a good tool.

[Rabbit on Roids]

HF diesel compression gauge <3

[745 turbogreasel]

sounds like the cracks between your valves might be just a BIT too DEEP...

IMO  a head gasket  leak to coolant passage is way more likely, by at least 20-1 odds in my experience.

[Vincent Waldon]

  Interesting that there is no water in oil or out the exhaust..

Here's one way to look at it:

Water pressure (when cold) = 0 psi
Oil pressure = 50 psi or so
Compression pressure = 400 psi

Guess which system wins the battle of the pressures when there's a head gasket leak between the cylinder and the water jacket?  Between the oil gallery and the water jacket?

Hence, easy for the water jacket to get pressurized with no sign of water in the exhaust.  Same rational as to why you almost always see oil in the water but not the other way round.

[Rabbit on Roids]

sounds like the cracks between your valves might be just a BIT too DEEP...

IMO  a head gasket  leak to coolant passage is way more likely, by at least 20-1 odds in my experience.

if it got over heated, my bet is on the cracks opening up.. diesels DO NOT LIKE HEAT..

[745 turbogreasel]

They don't like it, but I've fixed probably more than 20 from overheating and headgasket failure...all warped and or leaking, but the only one which went into water was a bad injector which burned the burned a hole through the prechamber

I'm of the opinion inter valve cracks grow over time regardless of operating temps.