How do get at 7.3 started after changing the oil cooler?

Did you use barbed fittings? You can do whatever you want its your car.

Check your transmission oil the trany cooler is located in the radiator itself so the transmission oil is mix with prestone 2 solution change the radiator or cheaper solution bye a transmission cooler that you gonna intall in front of the radiator remove the trany cooling line that goes to the radiator and intall them on the trany cooler you just bought it come with rubber line clamp everything you need to do the job

The problem is NOT your oil cooler, You have a blown gasket. Which is really bad, very expensive to fix. usually means replacing the engine. I REPEAT, IT IS NOT THE OIL COOLER!!!

Disconnect the hose (s) from the oil cooler line ( some oil might drip from the hose ) change the fitting, reconnect the hose, start the car and check the fitting and hose connection ( clamp ) for leaks ( tight as necessary ) move the transmission shifter thru all the gears and check the transmission oil level.

if it started after changing the oil the oil cooler loosend up have to pull the filter back off and tighten the oil cooler back down

??? Sounds purely coincidental... You may want to look at where the oil is coming from and fix that issue. Oil pan, Oil filter, oil cooler, oil sending unit, intake manifold, valve covers, rear seal....

The oil is most likely leaking from the oil cooler seal. The oil cooler is the square aluminum piece that the oil filter screws onto. To replace the seal, remove the filter, remove both coolant hoses that attach to the cooler, remove the nut that secures the cooler to the block and slide the cooler off the tube. Replace the rubber o-ring seal which is available at the VW dealer. It's inexpensive. Replace everything in reverse order. Good luck

hi did you get a solution for this? the same thing happened to me too.I had my oil change yesterday and today I saw the engine oil pressure lights come off and the oil started leaking very bad and the mechanic told me that the oil filter housing cracked.

its more than likely either your head gasket or intake gasket. You either have the 3.4 or 3.8 engine and they are well known for these to leak.

There are two items that can be leaking oil there. There is a gasket between the oiler cooler flange (the item attached to the engine), and the rubber gasket/seal that goes between the cooler and the flange. (the latter is the one that leaks most often as most oil change shops over tighten the oil filter).
I just replaced the gasket between the cooler and flange recently. I chose to do it quick and dirty: 1. remove oil filter 2. remove oil filter nipple (the portion you screw the filter onto) 2a. you'll need a deep well socket to get the bolt that holds the cooler tight (I believe 27mm)
2b. pull down the cooler, Grab the nipple with a pair of pliers between the flange and cooler and loosen/remove
3. remove old gasket/seal and clean surface 4. put new seal/gasket in place 5. re-seat the nipple back in. use the pliers method, just make sure you don't scar the threads where you NEED them( you don't need all of them). 6. put some gasket sealer (oil friendly) on the gasket and make sure its in place 7. tighten oil cooler onto flange with large nut and socket 8. replace oil filter and add oil as needed.
it is a tight working area, expect some scrapped knuckles, but it isn't too difficult.
good luck