I have a 2002 f 250 lariat 7.3 diesel engine w/oil puking out the dipstick. What would cause so much pressure that it would cause this?

 

How many miles on the truck, and how has it been operated and maintained?

My first thought is that's the result of some crazy blow by. Take the oil fill cap off with the engine running and describe what you see.

 

Make sure you dont have a mixture of coolant and oil too!

 

As Justin03PSD mentioned, whats the history? Is there any engine knock? Loss of power? When did you notice this issue etc.

Yep.. thorough inspection needed here.

Couple things to the already mentioned Check Degas for signs of contamination (oil). Flip oil cap and check for excessive blowby and report back.

Check your crankcase ventilation box on the drivers side valve cover is not clogged (unlikely but there have been reports). Note: once you remove it have replacement orings on hand. The originals will swell and not be reusable. 4 Viton O-rings to reseal the Crank Case Vent cover

Pull your valve covers off and inspect push rods and check torque on rocker arms. Torque injectors and glow plugs. If you can do a Buzz and or Contribution test it could give you a clue before diving in.

 

Have you checked to see if your crankcase ventilation is obstructed or plugged? If it is, any crankcase pressure is going to find it's way out elsewhere, and the dipstick would be one of those places.

It could also be excessive blowby from mechanical failure or excess wear.

Do the easy test first. Take your oil fill cap off, flip it upside down on the opening with the motor running. If it stays there, or simply slides or vibrates off, then your blowby is normal. If it pops up and off from pressure, then you have excessive blowby. Normally, you'll get a puffing smoke from the fill tube. But if there's pressure behind it, you have too much combustion pressure getting past a failed or worn part.