Topic: crawl box runs hot, then something went BOOM!!

[slander]

My trucks a DD with a 4.7:1 crawl box in it, and it runs hot. It heats up the shifters and i can feel it under the shift boot. Oil looks okay, not burnt or anything. Case does not leak, and it does not have an internal leak. It doesnt spew out of the vents either. I cant really get a pattern down, and cant tell if its just heat coming off the cat that right next to it or what. It gets hot about 5miles into my 30mile commute and stays at a constant temp, from what i can tell by touch. I have had it in for about a year now, and has done this since i put it in. How normal is this? My commute is mostly highway, 55-65mph.

[Pat]

I would think that if you have been driving it for a year with these conditions it might be normal..  I know mine gets warm too. 

[blackdiamond]

Do you have duals?  I have an inchworm crawl box and a marlin 4.7 rear case and  I notice quite a bit of heat coming though the shifter.  If I crack a window it really pulls the heat.  I think in my case it related to not having the floorboard completely sealed back up.  I think there can be a lot more heat than most people notice, but I think you should be able to touch it without burning a finger at normal operating temperature.  Compare it to other components like the transmission and differentials to feel what's normal.

When a previous crawl box locked up from a bad bearing it was so hot that when I got within a few inches of the case and realized I'd melt something if I made contact.  When I pulled the shifter off it smoked a bit from the inside.  In that case, I could touch everything but the crawlbox.

[slander [OP]]

Funny i posted this, leaving work today i let the clutch out making a right turn and BAM, truck stops moving and i hear all kinds of grinding.  Truck got towed to my parents house and i started to take it apart but its late and i am sick so i stopped.  I did take the shifter off the crawler and evreything spins and i dont see any breakage and didnt see any metal in the oil.  It makes a horrible grinding sound in the box tho.  How common are stripped out couplers, and or blown up tcase inputs?  The input to the crawler i think is okay because its getting power from the tranny, and plus how likely is a 23total spline input failure in 2wd accelerating through 10mph on the street in the rain with no wheel spin.  Im going to tear it down tomrrow and find out whats up.  If its the tcase input, any links as to how to swap out the shafs?  This is a 2002 taco.

[Cheesemaker]

Marlin just introduced the "NEW" 4.7 gears that help with lubrication of the bearings.  Because there was a lack of lubrication to a bearing.
http://www.marlincrawler.com/transfer-case/low-range-gears/new-4701-xd-gear-kit

[slander [OP]]

Got it torn apart today.  The stock tcase coupler : Stripped.  The marlin coupler (crawl box main shaft): Stripped.  SO heres the good news, i have a spare coupler, and a line on a tcase.  Now how do we prevent the stripage?  The crawl box had a vibe since the day i put it in, this i blamed on drievshaft angles.  The vibe was only noticed when you would touch the shifter or if change was on the boot.  This happend almost 1 year to the day since installation.  My trucks a DD (put about 10-15k miles on the crawler) and i went on 4 wheeling trips with it.  Probibly had it in double low for less than a half hour.  Im on ifs and 33s so nothing hardcore lol!!  I will call marlin when i get a chance, just to give them some info on some product breakage for their own knowledge.  Not blaming marlin, just that crappy 3/4" of spline engagement on the stock taco tcase input.  Is my only option a lefty in the future?