Merry Christmas y’all!

I took the blazer out for some light off-road action yesterday and was met with a nice grinding/dragging sound coming from what sounds like my transfer case. I’m hoping someone can shed a little light on this for me, if I gotta replace it I’ll just go with a junkyard swap since the holidays got me a little drained but willing to do what it takes!


The noise gets pretty good around 30 seconds:

 

I looked to see if the frequency of the noise was proportional to the wheel speed and it seems as if it is. This would mean it is likely "downstream" of the transmission.

As for the quality of the sound, on the video it sounds kind of tinny, as if a loose piece of metal is rubbing against a drive-shaft or u-joint.

Have you got under it to inspect it?

Did this noise start all at once?

 

Hard to say for certain by sound, but I wonder it almost sounds if the chain in the transfer case is skipping. You might be able to tell by removing the fill plug and if damaged internally you may be able to just see excessive sloppiness in the chain (as well as metal fragments in the oil). Go to this video and start watching around minute 40:00.

 

I agree it sounds small, I got under there briefly and nothing was dangling and didnt see any signs of damage such as oil leaks or anything.

Its fine just out of a turn and then once you let off the gas for a second thats when the scraping/grinding sound starts and just keeps going, it does chill at higher speeds (45 mph) which i discovered while crossing my fingers on the drive home.

It happened after I was going down a dirt road with a few small bumps, nothing major, in 4hi between 20-30mpx approximately. I stopped and turned around and the noise was very obvious, no history of it prior. So long as I can trust the 4x4 lights on the switch, it went back to 2hi. I just replaced my accuator, tcase switch and all hoses so I dont suspect any issues there.

 

Im goinna check that out now, thank you! Ive seen a few awesome diagnostics from this guy on s10/blazer and hes super thorough.

I actually just got a hex set this morning so I can pop that open and check, really hoping if there is a lack of fluid I can fill it up and get a few more miles before I have to swap it out, doesnt really seem working it to tear the thing open and get super involved given a salvaged one is like $300, but hey, if anyones got an extra one laying around I might be in the market! hahaha

 

Quick update - I opened my fill plug and fluid started shooting out with pretty good pressure. The obvious high level answer is that the trasnfer case is overfull but I saw someone saying that sometimes I believe its the input seal that goes bad and collects fuild from the trans. The overfull part I definetly get because obviously I covered my hand in fluid but fluid leaking from the trans into the tcase sounds a little iffy, either way that things gotta be drained down but I dont see it fixing the problem necessarily, maybe ill get lucky.

 

How did the fluid look? Any sparkliness from ground-up metal?

 

From what I could tell it didnt look brown and burnt too bad, couldnt tell too much as far as metal shavings go on account of most of it being a puddle on the asphalt since I wasnt expecting that haha.

I hosed everything down though and Im gonna pop the plug back out after work once everythings dried up from hosing it down.

Do you know if its even possible for fluid to leak from the trans to the tcase? Does that sound like it could happen?

 

Absolutely. Very common for the seal to go bad. Also results in fluid getting sucked up in the vacuum lines at the t-Case switch and puts fluid all thru the lines, the 4wd diaphragm, the reservoir and can even go into the vac lines at your HVAC controller. I've heard of folks finding fluid in their ash tray.

 

Oh man, that might be what it is then I havent noticed fluid in the lines but ill have to take a look again. It would also make sense if it was a seal seeing as how that transfercase was packed with fluid and the noise just started at once which would make me think the seal just blew out.

The fact that those lines were burned straight through and the diaphram was trash makes me think this 4x4 hasnt been used in years so that would also support the seal theory.

I dont have a lot of working knowledge on transfer cases. Assuming that is it though, I wouldnt think replacing the seal at this point would fix my issue. I would assume that grinding is in fact the chain which leads me to believe play in the gears, etc etc. I found one from a salvage yard so if i go that route I assume I would just be replacing the seals and changing the fluid with swapping it out, is that correct?

I plan on doing a little more diagnosis before jumping the gun, I’ll probably do u-joints while im at it.

Also I was able to finish draining my fluid and it looked a little burnt but I didn’t see any metali shavings. I didn’t feel much from the fill hole but I was able to get my finger in the drain just enough to make my girlfriend jealous and didn’t feel any play in the chain. That being said obviously something is rattling and I can’t imagine being over filled would like weigh the chain down but idk maybe with it having that much pressure that’s what was happening