No pressure so removed pump. What is milky yellow substance leaking from openings in engine and pump when I pulled pump off?

So sorry to hear of this Problem, But You have either A head Gasket that has Acquired a Crack or A crack in the Engine Block somewhere between the Cylinders and an Oil port. this is what will cause Milky Oil in the Coolant reservoir/overflow tank, if the color is More Brown then it is Definitely engine Oil if it is Reddish then it is a trans coolant leak But since You say you replaced the Radiator then My money goes to and Engine Problem, You nee to See a Professional Mechanic shop to have the System Pressure Checked, And The Oil Dipstick checked, if You have Milky foam on that stick then You will have narrowed down the Problem

that sounds as if your engine breather system requires cleaning, the substance is emulsified oil, normally caused by poor oil, lack of oil changes, or possibly head gasket problems, clean out all the breather hoses, filter etc, run engine until warm, drain engine oil and refill with a good quality oil, renew oil filter and then run and check again after a few miles

The "milky solution" could be oil that's been contaminated with water. You may have a bad seal within the pump, allowing water to mix with the oil...

no that is cause dby oil and coolant mixing together

Milky substance on your dip stick indicates contamination in your engine oil, most likely coolant and that is an indication of head gasket, or intake gasket gone bad and coolant leaking into your oil system. Note that coolant in your engine oil is bad, coolant will corrode the internal engine's bearing causing you to replace or overhaul the engine. The engine not starting is most likely the result of being blown and will need to be replaced.
Thank you for using Fixya and god luck

change the oil and put in some lucus oil treatment this should take care of your problem!!!!!!!

not sure if i understand everything, the ac,will drain condensation water under the car,that a sure sighn that its working properly,the air conditioning system has almost nothing to do with the engine and the coolant system,directly,it runs off a belt powered by the engine,if you overheated your engine ,bad enough,meaning that the second you noticed the car was hot you didnt immeaditly pull over and shut it down,or even if you did.it may not have been soon enough,remove the oil fill cap look at the bottom of it for sighns of antifreeze or water,brown milky substance looks like choclate milk,

There are a fw possibilities.

1. you have a cracked block and the oil is going in to the water system. To check this open the water cap ,When cold , and see if there is a milky substance in the water.

2. Look to see if there are any oily leaks around the valve pan areas.

3.Your oil pump may be failing.

White smoke out of the exhaust; blown head gasket.

check for coolant in the oil. remove the oil fill cap and look for a white milky substance. most likely engine damage has already occured because to have that low if oil pressure there is too much "clearance" between the bearings and the components they work with-(crankshaft,camshaft,connectiong rods). that vehicle came with dexacool coolant and it would shorten the life of the intake gaskets. they then would leak into the engine ruining the bearings over time. the skip can happen from lifters hydrolocked with the oil/coolant solution. take it to a reputable mechanic for an analysis......Good luck.......Scott