# 78 chevy 4x4 turbo 400 loud bang now won't move



## turfpro (Dec 19, 2019)

I own a 78 chevy 4x4 turbo 400 & np203.I was pushing up a berm with heavy snow and it made a loud bang and just stopped moving.
I assumed it came out of gear as it sounded like that but louder.
It had popped out of 4 wheel drive from my dog putting weight on it a few times and I really thought it just popped out of gear. 
So, I shut it off and pulled it back out of 4 low but if I remember correctly, the 4x4 shifter seemed to move freely. 
I then started it and nothing in and gear or any gear transfer case.
I went under assuming broken ujoint and again everything seemed find.
Transmission fluid was find and no noise at all when I start it and shift gears or and 4x4 position.
It feels like it's shifting onto forward and reverse but won't move.
I had a local auto shop put a used transfer case in it and it's exactly the same.
I can start it and put in any gear and no abnormal noise.
What the heck is wrong.
I don't have anymore extra money right now to waste. 
Shops around here just want to sell you a full bullet proof tranny and transfer case. 

Help Please. 
Jerry


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## Wickedmainah (Dec 10, 2019)

Check your bolts on the torque converter, may have sheared them off. But sounds like you destroyed the transmission if you already replaced transfer case. You should beable to find a used 400 or 350 for pretty reasonable.


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## turfpro (Dec 19, 2019)

Wickedmainah said:


> Check your bolts on the torque converter, may have sheared them off. But sounds like you destroyed the transmission if you already replaced transfer case. You should beable to find a used 400 or 350 for pretty reasonable.


Would it feel like going into gear?reverse to 2nd or 1st you feel it and kinda hear it.
It made a pretty loud band, like if you're under power when it pops out of 4 wheel drive.
I already look the bottom cover off bell housing and it was fine.

Something had to have broke.
I'm not a tranny guy but good repair mechanic.
I repair most all my equipment.

Never really got into tranny repair though.

Thanks and much appreciated response.

Anyone else.


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## turfpro (Dec 19, 2019)

There's a guy close that has a 77 Chevy with turbo 350 and I think 205 transfer case.
He only wants 500 for it all.
He bought it to put tranny and transfer case in his suburban and he said it was too short etc.
Also the yoke on the 350 and 400 I heard are different.
I was thinking about buying that truck and using the turbo 350 and transfer case as they are already out of it.
But what about the swap in my 78 chevy with turbo 400 and 203 transfer?

Appreciate the tips and help...
Jerry


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## Randall Ave (Oct 29, 2014)

Did you drain some fluid from the transfer case to see if any metal is in it? Drop the pan on the tranny and check that. My money is on the transfer case. There's no noise at all?


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## Mr.Markus (Jan 7, 2010)

I once blew a turbo boost hose accelating down the highway. Was a major bang, and total loss of power. Check the upper and lower hoses to your turbo and connections


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## SHAWZER (Feb 29, 2012)

Loud bang , 9 times out of 10 it is the transfer case .


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## leolkfrm (Mar 11, 2010)

broke the chain in transfer case???


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## FredG (Oct 15, 2012)

Yup ditto, I know that noise, even argued about it. I was wrong,


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## FredG (Oct 15, 2012)

I would of bet dollars to donuts was not the transfer case when happened to me. Especially when it just had one over the GM rub factor. Suppose to give you some kind of indentation. Shimmy etc, did not notice and kept on wailing. 

My bad according to my tranny guy.


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## LapeerLandscape (Dec 29, 2012)

turfpro said:


> I own a 78 chevy 4x4 turbo 400 & np203.I was pushing up a berm with heavy snow and it made a loud bang and just stopped moving.
> I assumed it came out of gear as it sounded like that but louder.
> It had popped out of 4 wheel drive from my dog putting weight on it a few times and I really thought it just popped out of gear.
> So, I shut it off and pulled it back out of 4 low but if I remember correctly, the 4x4 shifter seemed to move freely.
> ...


You had a local auto shop put a used transfer case in it? Did you have them check your transfer case when they took it out? Were they sure the new/used transfer case was good? I would go back to the shop and ask if they can take look at your old one to see if that was the problem. Too many people just replacing parts and not diagnosing the problem.


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## fireball (Jan 9, 2000)

Had this happen many years ago Brake lining separated from shoe spun around in drum and the loud bang was the lining jamming under the shoe against drum. Truck wouldn’t budge


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## leigh (Jan 2, 2009)

My only thought is what mine did 20 years ago,the main shaft in the tranny broke clean,no noises,just wouldn't move. Spinning in place.


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## LapeerLandscape (Dec 29, 2012)

If it's a turbo 400 trans or any older trans like that if you put it in drive wouldn't the speedo move if the trans was good?


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## Randall Ave (Oct 29, 2014)

Back then, I think the speedo was a cable. Would have been at the rear of the transfer case.


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## Mudly (Feb 6, 2019)

Nobody checked the rear/front end pumpkins?


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## Hydromaster (Jun 11, 2018)

leigh said:


> My only thought is what mine did 20 years ago,the main shaft in the tranny broke clean,no noises,just wouldn't move. Spinning in place.


I snapped a output shaft on a furd when I wuz a kid .

Bang then noth'en. No noise, no visual damage.


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## Mr.Markus (Jan 7, 2010)

Day 3 of speculation...i really hope the OP comes back and lets us know whT happened....


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## LapeerLandscape (Dec 29, 2012)

Randall Ave said:


> Back then, I think the speedo was a cable. Would have been at the rear of the transfer case.


Was it at the transfer case? I cant remember.


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## LapeerLandscape (Dec 29, 2012)

Hydromaster said:


> I snapped a output shaft on a furd when I wuz a kid .
> 
> Bang then noth'en. No noise, no visual damage.


That was a ford they always break. This is a cheby so we need a committee and debate about for days.


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## Randall Ave (Oct 29, 2014)

LapeerLandscape said:


> Was it at the transfer case? I cant remember.


Hmmm, 1978, I was out of high school for two years, the things that I remember. It would have been at the rear of the transfer case.


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## leigh (Jan 2, 2009)

I had a 78 GMC back in the 80's ,that was 6 trucks ago !Won' t the truck still drive without the transfer case working ?


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## Aerospace Eng (Mar 3, 2015)

leigh said:


> I had a 78 GMC back in the 80's ,that was 6 trucks ago !Won' t the truck still drive without the transfer case working ?


Nope.

Something needs to connect the input and output.


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## leigh (Jan 2, 2009)

Aerospace Eng said:


> Nope.
> 
> Something needs to connect the input and output.


 I was always weak in ancient history ! Thanks


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## Mr.Markus (Jan 7, 2010)

Aerospace Eng said:


> Nope.
> 
> Something needs to connect the input and output.


Also needs lube....
Just saying.


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## turfpro (Dec 19, 2019)

leigh said:


> I had a 78 GMC back in the 80's ,that was 6 trucks ago !Won' t the truck still drive without the transfer case working ?


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## turfpro (Dec 19, 2019)

I don't Believe so as what I've been told there's a differential in the center of the transfer case so if it doesn't connect from the back to the front meaning from the transfer case to the transmission you have no gears just like if you have the transfer case in neutral you will not move I had a profaessional repair shops a(Integrity Auto Repair) swap out one of their used transfer cases for mine and found out he's a con after I went to pickup my my transfer case out of that truck and he hesitated, I tested it and it locked up fine and gears shifted and were solid. So you gotta be careful with Repair shops guys and I'm a home self repair type person and a Chevy guy all my stuff Chevy I just haven't messed with transmissions and transfer cases much other that swapping out! 
But I'm just pulling the tranny and transfer case out of my 77 4x4 with a stroker motor and was building into a mud play toy and I didn't want to but although short on bucks,so taking it out now.
I feel it broke something in the transmission but I can't believe it did in that Turbo 400 plus no noise in it also fluid never had a smell I'm very careful and cautious on how I run things hard!
I honestly felt it was the transfer case.

When I went to pick up my truck it was 3 quarts low on fluid, I filled it, started it and I could feel it connect in reverse and 2nd and 1st, but wouldn't move.
I didn't feel the solid connection in 3rd.
So assuming tranny.

Any masterminds with a thought.

Merry Christmas everyone from Coeur d'Alene Idaho


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## turfpro (Dec 19, 2019)

The transfer case is out I had them put it in the back of the shop and believe it or not the do the try to con me put a if decent used transfer case in the truck but pulled a good one out so he could sell it wanted to charge me for taking out the transfer case in my truck! Considering posting about this on Facebook but I'm not that type of guy! 
I still felt it was the transfer case because it made the same noise like one I've knocked it out of gear with my dog falls on the for a drive shifter a Bang noise but a lot louder and then just nothing but no noise I figured the chain broke in the transfer case but as I said I tested it and it's solid so that means of chains good is there some in the tranny simple wall it's just that instead of pulling this whole unit out of my other truck? To Turbo 400 and I used it all last winner work flawlessly at the end of the winner I was pushing a berm up higher my friend my neighbor's place to if you get out of his gate and that's when this happens when I wasn't going fast but I was put a lot of power to it ends compound low


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## Mr.Markus (Jan 7, 2010)

...repost


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## Randall Ave (Oct 29, 2014)

I am trying to make sense of this. You heard a bang, truck will not move, I got that. Now you had the transfer case replaced and the truck somewhat moves? Also as far as I know, you may have a diff in the transfer case if the truck is full time four wheel drive, if that's what you have.


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## Mudly (Feb 6, 2019)

UH


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