np203/th350 problems - The 1947 - Present Chevrolet & GMC Truck Message Board Network

special70gmc · 06-16-2004, 09:00 PM

ok ive got an 81cab with an 85 framw and this setup behind a 350 its been sitting for at least 3 years and i got the motor running, then when you put it in gear to go (truck has no drive shafts) the front and rear yokes spin normal even if ypu rev it up it will respond like it should. so then all of a sudden they stop spinnig out of no where? but if you cut the motor and start it back up it will work again for about another minute then cuts out again. it makes no sence to me? the modulater is hooked up and it has good fliud thats nice and red,the np203 has good gesr oil in it too. do i need a new trans? transfer case? both? personally im just helplesly confused. please help me out. thanks - kyle

bouncytruck · 06-16-2004, 11:07 PM

Does it make any noise? Is the NP203 popping out of gear? Make sure your shifter is adjusted properly. They can be tricky. A lot of guys go twin stick on the 203. Does is have a part time kit?

1969 GMC · 06-16-2004, 11:12 PM

maybe the chain is bad?

stan79chevy · 06-17-2004, 12:12 AM

Quote:

Originally Posted by 1969 GMC

maybe the chain is bad?

or broken in half. thats what happened to mine. but if your chain is broken you will know it will lots of noises that dont sound good.

stan

**JIMs70GMC** · 06-17-2004, 06:39 AM

I would make sure the 203 is in gear. Also does it have a part time kit? When you say both out puts stop turning can you stop them with your hand?

special70gmc · 06-17-2004, 05:24 PM

i just bought the wholer truck in peices for $500 with another body and like i said its been sitting for 3 years at least it makes a weired popping oize but if i put my had in the trans or tcase i cant feel where its coming from also the truck has no exaust so itr makes it hard on hearing, it very well might not be shiftin into gear cause the shifter binds up all through its through and gests stuck all the way either folwad or back. sometimes its even difficuld to get it into any of the out side gears. thanks -kyle

special70gmc · 06-17-2004, 05:26 PM

o and i can only stop it with my hand after the first 30 sec- minute but when i first start it up it works perfictly as far as i can tell it responds to rpm where as 30 seconds later it just wont. -kyle

Grim Reaper · 06-23-2004, 10:54 AM

Shift it all the way back and that will make sure it's fully in High AND the case it Locked. If the drive shafts are off then a borken chain is not going to spin the front.

If it still happens then the problem is either the conection between the case and the tranny is stripped or the transmission in bad. I'm leaning towards bad transmission.
It's prboably driving on parisitic drag till the fluid this out then dying. The converter could do that. Hell it michg just be low on fluid have you checked the fluid level when its running? Fluid drains back into the pan out of the converter when they sit so not running your probably showing fluid on the stick but once started it's running dry. The banging might be it shifting gears with no load.

updatelee · 06-27-2004, 03:20 AM

this probably wont answer your problem, but I beleive the np203 is supposed to have 10w30 in there not gear oil.

06-16-2004, 09:00 PM	#1
special70gmc Registered User Join Date: Sep 2002 Location: long island, new york Posts: 1,333	np203/th350 problems ok ive got an 81cab with an 85 framw and this setup behind a 350 its been sitting for at least 3 years and i got the motor running, then when you put it in gear to go (truck has no drive shafts) the front and rear yokes spin normal even if ypu rev it up it will respond like it should. so then all of a sudden they stop spinnig out of no where? but if you cut the motor and start it back up it will work again for about another minute then cuts out again. it makes no sence to me? the modulater is hooked up and it has good fliud thats nice and red,the np203 has good gesr oil in it too. do i need a new trans? transfer case? both? personally im just helplesly confused. please help me out. thanks - kyle Attached Images __________________ 1986 c-10 swb 5/7 drop 20'' coys 1958 belair 2door

06-16-2004, 11:07 PM	#2
bouncytruck SKINNY TIRES RULE! Join Date: Sep 2001 Location: Bothell, WA Posts: 11,038	Does it make any noise? Is the NP203 popping out of gear? Make sure your shifter is adjusted properly. They can be tricky. A lot of guys go twin stick on the 203. Does is have a part time kit? __________________ bouncytruck 1972 K5 The Hauler 1994 K1500 Suburban The Daily2010 Kia Soul Wife's Ride2014 Fiat 500L

06-16-2004, 11:12 PM	#3
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	maybe the chain is bad? __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

06-17-2004, 06:39 AM	#5
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	I would make sure the 203 is in gear. Also does it have a part time kit? When you say both out puts stop turning can you stop them with your hand? __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

06-17-2004, 05:24 PM	#6
special70gmc Registered User Join Date: Sep 2002 Location: long island, new york Posts: 1,333	i just bought the wholer truck in peices for $500 with another body and like i said its been sitting for 3 years at least it makes a weired popping oize but if i put my had in the trans or tcase i cant feel where its coming from also the truck has no exaust so itr makes it hard on hearing, it very well might not be shiftin into gear cause the shifter binds up all through its through and gests stuck all the way either folwad or back. sometimes its even difficuld to get it into any of the out side gears. thanks -kyle __________________ 1986 c-10 swb 5/7 drop 20'' coys 1958 belair 2door

06-17-2004, 05:26 PM	#7
special70gmc Registered User Join Date: Sep 2002 Location: long island, new york Posts: 1,333	o and i can only stop it with my hand after the first 30 sec- minute but when i first start it up it works perfictly as far as i can tell it responds to rpm where as 30 seconds later it just wont. -kyle __________________ 1986 c-10 swb 5/7 drop 20'' coys 1958 belair 2door

06-23-2004, 10:54 AM	#8
Grim Reaper Registered User Join Date: Jul 2001 Location: Atlanta GA Posts: 1,704	Shift it all the way back and that will make sure it's fully in High AND the case it Locked. If the drive shafts are off then a borken chain is not going to spin the front. If it still happens then the problem is either the conection between the case and the tranny is stripped or the transmission in bad. I'm leaning towards bad transmission. It's prboably driving on parisitic drag till the fluid this out then dying. The converter could do that. Hell it michg just be low on fluid have you checked the fluid level when its running? Fluid drains back into the pan out of the converter when they sit so not running your probably showing fluid on the stick but once started it's running dry. The banging might be it shifting gears with no load. __________________ Grim-Reaper 70 Pontiac LeMans Sport Convertible, worlds longest resto in progress Looking for 71-72 2wd Blazer or Jimmy Project

06-27-2004, 03:20 AM	#9
updatelee Registered User Join Date: Feb 2004 Location: Lancaster Park, AB Posts: 38	this probably wont answer your problem, but I beleive the np203 is supposed to have 10w30 in there not gear oil.



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