Re-Assembling Oil Cooler - 2001 Pathfinder

[krustykanuck]

Hello Everyone,

I had an oil leak around the oil cooler of my 2001 Nissan Pathfinder so I decided to look up the remedy and started what should have been a basic repair.
After reading on various forums that the culprit is usually the two O-rings (one attached to the bolt and one attached to the cooler itself) I ordered spares from Nissan and proceeded to remove the cooler and repair it myself.

I drained the oil, replaced the oil filter and then loosened the single bolt that secures the oil cooler. It took a little effort to actually remove the bolt from the cooler assembly though.

I then cleaned the bolt and replaced the small o-ring for that part.
I also cleaned the oil cooler and replaced the larger O-ring making sure it fit snuggly in the cooler.
I then proceeded to put the bolt back into the cooler... and this is where my problem begins.
As hard as I try I can't put the bolt all the way through the cooler assembly.
I could see the threaded end of the bolt stick out by about 1/3 inch from the cooler, but not enough to thread into the engine mount.
The bolt would seem to have some kind of resistance when the bolt would thread through up to the holes on top of the bolt.
I tried rotating the bolt around a little to see if there was some give and even tapped it with a mallet.

However, if I were to stick the bolt through the opposite side of the cooler it would pass through with ease not matter how I rotated it.

What gives? I can't finish the assembly until I can secure that bolt..... and yes my oil cooler is oriented such that the metal tooth on the mount is between the notch in the oil cooler.

THanks for any input!

[krustykanuck]

Anyways. I finally managed to get the bolt back into the Oil Cooler. After two days of trying to insert thebolt it went straight through today without much effort. I cleaned the bolt one more time and then lightly oiled the top half of the bolt. I also clamped the coolant feed lines as I was about to remove the lines to better look at the cooler.

All is fine now and my cooler is working great without a leak so far.