Hard to start when warm - below operating temp (misfire code)

[transcendtient]

I have a '00 3.0 4x4 and its pretty cold around here now and in the morning my truck starts great with the only thing of note being:

My oil pressure gauge in the morning gives me a nil reading until the engine is approaching operating temperature. I haven't seen a depreciation in pressure from this reading, meaning once it does pop up its always in the same place and stable.

I'll get to work and it warms outside and start to I head out my truck won't start unless I gas it, and its misfiring on cylinder 4.

Have replaced plugs, wires, coil, injector 4, flushed fluids.

What diagnostics do I need to run to figure this out?

 

[transcendtient]

Just found out compression is low in cylinder 4 and exhaust smells like gas. Am I correct in assuming its most likely an exhaust valve and I need the heads refurbed?

Receding exhaust valve seats are apparently common in this engines cylinder head so I'm rolling out some dough to grab 2 heads and go to town unless anyone thinks I should look elsewhere.

Now I'm wondering what the cylinder bore tolerances are and if I should check anything else while I'm at it.

 

[Rearanger]

Just found out compression is low in cylinder 4

How low?

 

[transcendtient]

12%, its had a MIL on for misfire on cylinder 4 for a couple months now while I was trying to figure what was wrong.

 

[Rearanger]

12%

Doesn't look good. I'd think you'd also get a run rich code as well on that bank??? Raw fuel is not good for the CAT either. Reading here does show bad valve(s) the cause of many misfire codes and a weakness of Ford 3L. Maybe if you talk to the dealer Ford might chip in from hidden warranty program, but I've not seen Ford to have Christmas spirit on design flaws out of warranty. If valve seat I'd replace them all while you're in there.

 

[transcendtient]

Apparently my head gasket was working on blowing out, had water seeping from the jacket into the cylinder head on cylinder 6 and worse at 4. There was white corrosion built up on the outside edge of the pistons and the intake valves were minimally burned, but the spark plugs that I replaced around 1500 miles ago were burned to points already in those cylinders so I opted to replace those two.

The upper radiator hose needs to be replaced and the clamp I put back on leaked a little yesterday and I had to replace fluid. Until the thermostat opened there was a squeaking chirp I'm pretty sure was the water pump. I collected some of the fluid from the system from the drain petcock and there was a small amount of blackish debris that settled at the bottom of the cup that could be crap from the rebuild or could be dirty shavings.

Should I flush the cooling system and risk further wear on the water pump or just replace the hose and anticipate replacing a pump sometime soon?