Transfer case trouble or transmission

[b26j]

I'm hoping someone on here can help me out, I have a 1984 Chevy k10 suburban and I am having trouble with the transmission, last couple times I drove it it acts like the transmission is out but if I shift it to 4high then back in drive i can drive a short distance then it will act like the transmission is out again, if I put it back in 2high then once again I can drive a short distance, I checked the transmission fluid and it is at the correct level

 

[1987 GMC Jimmy]

I'm no transmission/t-case expert, but that sounds like a transfer case issue more than a transmission one. It sounds like your transfer case is going into neutral somehow, and messing with it will reengage it and give you a little more distance. Let me get a better suited individual to diagnoses this on the line. Please hold. @Honky Kong jr

 

[crazy4offroad]

I'm not familiar with NP208s but it sounds like the linkage may be out of adjustment.

 

[b26j]

I will look into the linkage, now when driving down the road it seems like something is holding it back and at 55mph the motor kind of revs up and down

 

[MtBraun]

I will look into the linkage, now when driving down the road it seems like something is holding it back and at 55mph the motor kind of revs up and down

That sounds like transmission slippage. You said the fluid is at the correct level. How does it look? How does it smell?

 

[b26j]

The fluid is pink and doesn't smell burnt, the transmission itself only has less then 8,000 miles on it, but it only seems to rev up and down around 55 but going 60 mph or more it stops revving up and down

 

[1987 GMC Jimmy]

Is it a 700R4? I don’t think the revving is related to the disengagement issue, but I could be wrong. I’d try to drive it at those same speeds but in third gear to see if it does it. If it’s a TH350C, then the same test but in second. This is to see if the issue is related to the lockup of the torque converter clutch.

 

[b26j]

It has a th400 in it now, but I will give that a try, I appreciate the replies I have gotten so far, i want to get it sorted out soon so I can drive it again

 

[Snoots]

Is it a 700R4? I don’t think the revving is related to the disengagement issue, but I could be wrong. I’d try to drive it at those same speeds but in third gear to see if it does it. If it’s a TH350C, then the same test but in second. This is to see if the issue is related to the lockup of the torque converter clutch.

Isn't there a lock-up solenoid for the TCC? They do have a tendency to crap out at the worst possible moment.

 

[rpcraft]

How many miles and are you checking the trans fluid with the trans warm and while running? Just making sure, the TH400 is pretty durable but they do wear like anything... Then again so does the Tcase, especially if it is high miles and your selector pads are worn down from high mileage.

 

[crazy4offroad]

Th400 wasnt an option in 84 for half ton trucks. You sure it aint a th350C? It could be the lockup kicking in and out.

 

[Honky Kong jr]

I’m gonna go with out of adjustment, the linkage that is, do to a trans swap if it is a 400. Which caused shift fork pad wear and the transfer case is jumping to neutral and when you put it in 4 hi it semi resets it then works back to neutral. This is based on your info thus far.

 

[rpcraft]

I was thinking the TH400 was an option on the Burb 4 x 4's around that time???

 

[1987 GMC Jimmy]

Isn't there a lock-up solenoid for the TCC? They do have a tendency to crap out at the worst possible moment.

Yes, there is. Those seem to be more failure prone than the clutches, but the clutch will fail to. The solenoid symptoms are either it won’t lock up or it stays locked up and the engine tries to or does stall. Typically. The clutch will chatter, make the car lurch back and forth, and it feels a lot like an ignition advance issue in my experience. The 700R4 in my car has a failed clutch, but I put three tubes of that Instant Shudder Fixx, and it works almost perfect now. That tranny’s got like 258,000 miles, and it’s never been rebuilt so when it dies, which it will sooner rather than later, I’ll put a new converter in it.

 

[1987 GMC Jimmy]

I was thinking the TH400 was an option on the Burb 4 x 4's around that time???

I thought 3/4 ton Burbs got them, and the halves did not.