Truck overheating, also spraying gear oil, need help/ideas, '02 MT

[jaymzinsa]

Hello all, I posted this in a FB R50 group and hope to get more eyes on here to take a look. I am just gonna copy/paste my FB post. 

 

This is a text message I sent to my mechanic about my truck. I put it on here to see if anyone has any thoughts/recommendations as to what might be the problem or better, come up with a solution. It seems to be almost a lost cause; sad situation because I love my beast but if I cant depend on it, I probably have to put it out to pasture. Quick synopsis, i recently completed a second build and swapped to xterra diffs with a lokka, swapped 3rd member with packed lsd, swapped out the tranny, installed a new exedy clutch, and replaced my AC system. Also had the radiator cleaned and flushed. This was to be my first real test of the recent work. The truck has never had an overheating issue before this shake down trip. Was going to go to lake havasu, about 150 miles from scottsdale, and run a bunch of trails along the lake. Had made the trip many times in the past and the truck was awesome on the trails. With the new gears the plan was to run even rougher stuff but that fell through. Please give me any feedback you feel is relevant, I want to save my buddy. Here is a synopsis of what happened.
Looks like the text makes the post too long. I will place it in the comments.

 

I took the truck out for a trip to havasu yesterday. We were very lucky to make it back. I’ll give you bullet points.
- left early morning, got to the turn off on I-10 without any issues.
- stopped to get a drink, left the truck idling as the boys were asleep and didnt want to turn off the ac, (which works great)
- got back in the truck and the temp gage is almost at overheat temp. Didnt notice until i started driving.
- once i drove for maybe 15-20s the temp immediately dropped down to normal, i literally watched the needle drop to normal temp in 1-2s. Also had a strange smell which I’ll get to later
- thought maybe stuck thermostat.
- spent the day without any issues although i did not want to take any chances and did not let the truck idle.
- left at dark and drove at 70mph 3k rpm ac on without any issues for awhile
- after ~1hr i saw the temp needle start to rise. It got to about 3/4 of the way up and i pull over at the next exit.
- waited 15-20 min, started the truck, the temp was still at 3/4 and decided to try to get to a station a couple miles up the highway to run some water on the radiator.
- as soon as i got over 15-20mph the needle immediately dropped to normal temp. Wish i had thought to take a video.
- it stayed at normal temp until the gas station. Checked the coolant reserve and it was fine. Since it was normal temp i decided to see how far we could go.
- ran for another 45min without the ac then hit a bad dust storm. Once we slowed down, the temp needle started to go up, at 3/4 temp i pulled over again.
- waited out the dust ~15min, started the truck, temp was a little more than halfway.
- as soon as we got some speed the needle again dropped to normal temp but the gearshift area and console between the seats was very hot.
- hit a huge rain storm and the drop in outside temp kept the truck temp at normal for the next 30min.
- hit construction outside phoenix and as we slowed down the needle climbed almost to overheat temp.
- i drove on the shoulder, (pissing off the stopped traffic) at 35-40mph and that dropped the temp to almost normal. Again wish i had video to show the temp needle going up and down.
- pulled into a station after getting off the highway.
- after 15-20 min drove the last 45min home with the needle staying at normal temp.
- Was a very nervous trip home but somehow we made it and in the driveway the temp was normal and the hood didnt feel hot. i let the truck idle for 5-10min to see what would happen and it ran as if everything was fine. Turned it off and there wasnt even any coolant bubbling into the overflow reservoir.
I have no idea what happened but am ready to get rid of the truck as i feel i cant trust it.
I will bring it in at some point to see if you can come up with a diagnosis. Also. At some point on the trip home, the check engine light turned off after on of our stops. Crazy.

As for the strong smell from the morning stop. There is gear oil all over the back of the truck. The pics show it even came up around the bumper and sprayed onto the liftback and rear tire mount. Gasket failure?

 

I'll try to post some pics through tapatalk to show the extent to which the gear oil was splattered over the back of the truck. I have no idea how much oil leaked, how much is left, etc. I certainly don't want to ruin the diff or cause future issues if I'm able to salvage the truck.

Any help as to the cause and/or solution for either issue is greatly appreciated.