How do you get stuck in 4WD? and other questions (1 Viewer)

[wildheffalump]

Hey guys, I've been lurking and trying to learn for a while now. Finally had to register and ask
1991 fj80 3FE. I blew the motor, threw a rod and knocked a hole in the block (more about that later).I got a replacement motor out of a wreck. I had a mechanic put that motor in, but ever since...she's stuck in 4WD! loud cranking clacking noises when making tight turns etc. No indicator lights present, center diff lock button changes nothing at the moment.
Any clues on where to start?
As for the motor...what would you do? try to repair/rebuild, or scrap it for parts to sell?

thanks in advance.

 

[ZackR]

Welcome! Wow that's quite the intro. Search the forum for CDL is stuck and report back.

 

[Tanner H]

Not sure what you mean by stuck in 4wd since all the 80's here in the US are full time. Are you saying its stuck in 4-low? That would change how the truck drives on pavement. If so, thats not an engine issue but a transfer case issue.

 

[iptman]

Warn birfs.

 

[lp2k]

Sounds like U joints need to be replaced and Birf rebuilt like above

 

[wildheffalump]

Not sure what you mean by stuck in 4wd since all the 80's here in the US are full time. Are you saying its stuck in 4-low? That would change how the truck drives on pavement. If so, thats not an engine issue but a transfer case issue.

I agree, that it's not an engine issue. That's why I'm asking, because nothing that was purposely done should have caused this condition.
I'm decent with a motor, but I'm a complete newb with 4WD. The gear shift is in high. But after the first week of the new motor none of the lights about 4WD come on, no CDL, nothing. The truck does drive odd on pavement turning is super tight, and you hear a clanking noise and tires squealing from tight turn.
I'll be working on figuring it out. Thanks for anything you guys can provide.
and if you know someone with ideas on where i can offload the motor, let me know.

 

[Chris Wilcox]

Can you just keep the motor for parts or did you just buy a short block and really nothing of use for spares.

Regarding the 4WD issue. Mine always shifts in and out of locked center diff so I have never had to get into it. Why don't you pull the front driveshaft to see what is happening. Driving around that way for a bit won't be an issue but for months or years it will probably fret the gear teeth and ruin the center diff. best guess anyway.

 

[Box Rocket]

Sounds to me like the center diff is locked. If you have a center diff lock switch have you confirmed that it's plugged in correctly? It's possible that it was somehow locked prior to, or during the motor swap and then unplugged. Would explain why you seem unable to get it unlock.

It's also possible that the solenoid for the center diff lock is stuck. I had a solenoid go bad on my last 80. It would not unlock when shifted back into high range.

 

[wildheffalump]

I'd like to keep the motor for parts but the reality is that I don't have the space. The block has a hole in it that appears to be repairable. Still has the head, crank etc that can be parted out.

 

[wildheffalump]

Sounds to me like the center diff is locked. If you have a center diff lock switch have you confirmed that it's plugged in correctly? It's possible that it was somehow locked prior to, or during the motor swap and then unplugged. Would explain why you seem unable to get it unlock.

It's also possible that the solenoid for the center diff lock is stuck. I had a solenoid go bad on my last 80. It would not unlock when shifted back into high range.

That's pretty close to what I'm experiencing driving. As I mentioned... Total newb to 4wd. Pressing the CDL doesn't light up anything. Once it's moving fast I don't notice any problems, but low speed and parking are difficult and it's noisy. It didn't drive like this before and the mechanic I had do the swap wasn't able to figure it.
Given that I knocked a hole between the last 2 cylinders any chance engine oil gummed up or messed something you think?

 

[Desert Dino]

If your center differential is locked, then Do Not Drive on the pavement!!!

 

[Box Rocket]

That's pretty close to what I'm experiencing driving. As I mentioned... Total newb to 4wd. Pressing the CDL doesn't light up anything. Once it's moving fast I don't notice any problems, but low speed and parking are difficult and it's noisy. It didn't drive like this before and the mechanic I had do the swap wasn't able to figure it.
Given that I knocked a hole between the last 2 cylinders any chance engine oil gummed up or messed something you think?

Highly doubt oil lost when the engine blew would cause the issues.

I’m still betting on a center diff that’s locked and won’t unlock. As was mentioned, driving it in dry pavement with the center diff locked can put a lot of stress on the drivetrain and cause damage.

 

[KennyBob]

Agree with the above. CDL is activated somehow. I wouldn't drive it until you can unlock it.

 

[MoJ]

It’s never this simple but check the diff lock fuse.

 

[wildheffalump]

Noobsauce activated. Anyone got a guide to the diff lock fuse handy?

 

[MoJ]

From memory there are two related fuses. A 10amp in the interior fuse panel labeled “gauge” and a 30amp? in the engine bay fuse block. Also, check the wiring and connector running to the transfer case. Just wondering if some got pinched or not connected during the engine swap.

 

[ppc]

Instead of the CDL being activated the viscous coupler may be seized giving the same symptoms.

 

[shocktower]

Warn birfs.

Warn makes Birlfs I live close and follow their products, maybe Worn birfields

 

[MoJ]

Not sure 91-92 has a VC

 

[shocktower]

Instead of the CDL being activated the viscous coupler may be seized giving the same symptoms.

It is a 91 no VC