1996 xlt 2wd 3.0 auto trans.
Engine got new heads and a re ring kit about 400 miles ago. Had to remove trans after engine install because i bent the flexplate. So replaced that too. Runs great except a cooling issue (or heating I should say.) Can't get the truck to operating temp and heater wont blow hot. Probably an air bubble im assuming, the tstat is new. But on cold starts (intermittently) one of if not a couple of the lifters make a rediculous tapping noise. Probably the worst lifter on cold start noise I have ever heard. Last about 5 seconds. Sometimes lasts 30 seconds. Sometimes it only taps twice and it's gone. Sometimes it can sit for 8+ hours and make zero noise on start up cold. I replaced the lifters when I had the engine out for the re ring kit. Soaked the new ones in oil before installing. Truck is throwing code p0351 ignition coil A. The coil, plugs, and wires are all new. Connections are all good as far as I can tell and like I said other then the cold start tapping the engine runs smooth and quiet. I just changed the oil and went a little thicker and used a Motorcraft filter but after the last cold start it still tapped for a second or 2. According to the gauge the oil pressure is great, I'm not sure where to go from here. I got some hours in this truck the last week or 2 losing interest in working on it at this point.

 

Reads like the oil is draining out of one of the new lifters when engine is off long enough, outside of the noise it makes its not a sign of anything bad coming, if it kept making the noise that would be a sign of a problem

You can do "Clear Flooded Engine" mode before each cold start
Turn key on
Press gas pedal down to the floor and hold it down
Crank engine over, it should NOT start(clear flooded engine mode turns OFF fuel injectors)
Count to 3 or 4(while cranking engine) and release gas pedal
Engine should start with no "ticks" as oil has been pump up thru the system
I do this every morning on my high mile 4.0l, just to pre-oil it

P0351 Ignition Coil A Primary/Secondary Circuit Malfunction
This is the coil in the coil pack that does #1 and #5 cylinders

Do you feel a misfire?
Check #1 and #5 spark plug wires to make sure they are pushed all the way down in coil pack and at the spark plugs
The computer expects a voltage surge when it grounds and ungrounds each coil in the coil pack, coil A(1/5), B(2/6) and C(3/4)
Its not getting that every time from coil A

Put the old coil pack back in, "new" just means NEVER EVER tested, not "it works"
You can swap #1 and #5 spark plugs with other cylinders

Cold engine
Remove rad cap
Remove either heater hose at the firewall
Add fluid to radiator until it comes out the hose and heater core port
Put hose back on
There is now NO AIR in the engine side of the cooling system

Start engine
Feel upper rad hose and heater hose at the firewall, both COLD of course
Wait 2 minutes idling
Feel them again
Heater hose should be warming up
Upper rad hose should still be stone cold, if upper rad hose is warming up then thermostat is open and it should be closed, replace it


Ford temp gauge has 200degF as 1/2
Engine coolant should warm up to 185-190degF, so should show just below 1/2 on the gauge after 5 to 8 min of run time