loud bang sound driver's side near feet

[Lazerskull]

I was driving downhill about 30 min drive. Don't notice anything out of the ordinary. Then, as I am decelerating and getting off the freeway, I hear a "bang" sound
and it's like once every 20 seconds. I get off the freeway stop at a light, then I drive residential streets lower speeds and I don't hear it anymore. But I make a mental note of it.

The next day I drive to do a shopping errand. The noise comes back and it's more frequent. I'm like "oh ****." So I park and plan to do my shopping and then drive to the transmission shop.

I get back in the truck and I try to drive in just 2nd gear. I still hear the noise. I try just 1st gear only. Still noise. I get to the intersection and the banging is so loud and repeating now and it like alternates from a banging to like a grinding. I drive thru the intersection and park and I have it towed to the transmission shop.

The transmission mechanic is going thru surgery and got really back logged. So he hasn't had a chance to put it in the rack. But he suspects it is the transfer case.

My question is. Is the transfer case toast?

Could it be low t-case fluid or a shift motor or GEM module?

What would other symptoms be of a GEM module failure causing t-case malfunctions?



I have been able to find a same 1997 V6 SOHC 4.0 in the junkyard with lower miles. And it looks like it wasn't driven off road at all. I am hoping maybe to pull the t-case and swap it in mine. It'll run me about 200 bucks for the t case plus all the fees to install it, find someone to help me pull it also.

Am I screwed?

_Justin

Background - my engine and transmission were recently rebuilt. The engine starts and idles / runs fine. The transmission was running smooth like I said this all happened suddenly. Also the transmission has had appropriate fluid no leaks.

 

[Mbrooks420]

It could technically be a few things, including the front driveshaft (for a member more familiar with 97s, are they double cardan, or cv at the t case?) front differential, or the transfer case.

How many miles?

 

[Wrath]

I've had some loud backfires on deceleration when I had an exhaust leak. Is this an explosive bang or a collision bang?

 

[Mbrooks420]

If it was exhaust related where would the related grinding come from?

 

[Lazerskull]

I've had some loud backfires on deceleration when I had an exhaust leak. Is this an explosive bang or a collision bang?

it's not an exhaust leak it's more front left sounding, also it sounds even if you aren't going fast and right before i shut it down it was getting wayyy worse.

 

[Mbrooks420]

Check to see if the cv axle on that side has a torn boot. If so it’ll have flung out it’s grease.

 

[RangerX]

Remove the front driveshaft and then drive a bit and see if the noise is gone.
Is your 97 tcase full time or is it 2wd 4hi 4lo?

 

[Ryanca]

It could technically be a few things, including the front driveshaft (for a member more familiar with 97s, are they double cardan, or cv at the t case?) front differential, or the transfer case.

How many miles?

Had same pb. Replaced transfer case. Grinding and sudden bang under drivers side feet gone. Expensive. V8 98 Mountaineer.

 

[Mbrooks420]

My guess was your chain was stretched or broken. These are different animals. His should only add power to the front when there’s slippage between the driveshafts, yours puts power to the front no matter what.

 

[Lazerskull]

It turned out to be the transfer case blew up. I did not realize one of my tires had a leak and running on lower PSI. I think the AWD was overworking. Also the tcase fluid was black (my own fault). I swapped in one from the junkyard and it runs now but doesn't go over 40mph.

 

[Mbrooks420]

It turned out to be the transfer case blew up. I did not realize one of my tires had a leak and running on lower PSI. I think the AWD was overworking. Also the tcase fluid was black (my own fault). I swapped in one from the junkyard and it runs now but doesn't go over 40mph.

Che k engine lights

 

[wollimann]

I swapped in one from the junkyard and it runs now but doesn't go over 40mph.

Maybe the Borg Warner 4405 runs in 4low now. Could you swith between Automatic/high/low? Did you hear any sound while switching?
The transfer case from the junkyard had a shift motor installed or did you change them?
Unfortunately the 4405 could get many issues with high mileage. (chain, shift fork, bearing case, range slider, ...)

 

[Lazerskull]

Maybe the Borg Warner 4405 runs in 4low now. Could you swith between Automatic/high/low? Did you hear any sound while switching?
The transfer case from the junkyard had a shift motor installed or did you change them?
Unfortunately the 4405 could get many issues with high mileage. (chain, shift fork, bearing case, range slider, ...)

I was going to try and swap in the speed sensor from my old case into the one I just installed... but I had to work too much and it's been too damn hot outside to work in the garage.

On top of that I hadn't driven it around in over three months and it stopped wanting to start. I thought maybe it was the battery but threw in a new battery still cranks doesn't start. used to start and run fine maybe the gas is bad or filter clogged.

I have a question would the Transfer Case from a stock 1997 V8 Eddie Bauer 5.0 work on my 1997 XLT 4.0 ?

[One thing I remember. When it was running on the "new" salvage transfer case... it would switch back and forth from 4 wheel to 2 wheel just fine. Going on a slow, hard left turn like a U turn though... it would suddenly engage the Control Trac 4x4 and I'd hear that banging sound. I think the tires are bad.]

 

[wollimann]

would the Transfer Case from a stock 1997 V8 Eddie Bauer 5.0 work on my 1997 XLT 4.0 ?

The 5.0 has AWD if i am right, so it's TC is not compatible to 4.0.

I am not shure if your TC produce that banging sound, sometimes the splines of the rear drive shaft are dry,
so they canted and go free again with a loud metallic bang.

On the other side, the BW4405 TC and the control trac system are not very sensible and comfortable.
If there is spin the system engages sometimes very hard in my opinion.