Could my tranny be causing a loss of power? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

cmyc5575 · 05-29-2013, 06:09 PM

Hello, 83 gmc short box. 350ci backed by 350 tranny with 2500 stall.

This truck is about to drive me crazy, I have no take off power, It seems like I have a 4 cyclinder underneat the hood, its that bad. High revs before it will finally shift into second. Weird experience here lately has been when im crusining @ 60 mph the truck will all of a sudden start reving really high and seems like someone has put the truck into nutral. So, I even tried putting into first gear at the bottom so i know for sure it would be the right gear to take off in and it seems to help once in awhile, or not at all. Im thinking that Im either about to replace the torque converter or i may be losing the tranny in it. Thanks for all help upfront guys!!!

Billy81 · 05-29-2013, 06:51 PM

With a stall that high unless your engine has a pretty radical cam in it that is probably your problem right there. Without more info on your engine it's hard to give advice on what stall you should be running.

cmyc5575 · 05-29-2013, 07:07 PM

Quote:

Originally Posted by Billy81

With a stall that high unless your engine has a pretty radical cam in it that is probably your problem right there. Without more info on your engine it's hard to give advice on what stall you should be running.

Im seriously thinking that its only a stock 350 bc the stall that is in it is kinda retarded imo and doesnt suite my needs. I just bought the truck like that. Im also thinking that im starting to lose 3rd gear. BUT, lets say its a stock 350, what then should I do?

bigwheel15 · 05-29-2013, 08:38 PM

Quote:

Originally Posted by cmyc5575

Im seriously thinking that its only a stock 350 bc the stall that is in it is kinda retarded imo and doesnt suite my needs. I just bought the truck like that. Im also thinking that im starting to lose 3rd gear. BUT, lets say its a stock 350, what then should I do?

Put a stock torque converter in place of the stall, no need to have a bigger stall on a stock/mild 350.

66skylarkpost · 05-29-2013, 09:50 PM

2500 is not high at all, thats just over stock . i'd be looking into your transmission, something doesnt seem right

cmyc5575 · 05-29-2013, 10:04 PM

Quote:

Originally Posted by 66skylarkpost

2500 is not high at all, thats just over stock . i'd be looking into your transmission, something doesnt seem right

Yeah i have decided im going to tear into it this next weekend when i have some vacay and a paycheck to play with.

INSIDIOUS '86 · 05-30-2013, 01:10 AM

Should go from the back behind the carb and run down the passenger side to the back of the trans at the rear of the pan.
You could have internal leaks on the seals and prong inside that comes with higher mileage transmissions. So it could be slipping in an out of gear as your driving. 2500stall is high but not overkill. High stalls also create a lot of heat. Possible that your trans is cooking itself

Take out your dipstick and smell it. It smell burnt or fishy?
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cmyc5575 · 05-30-2013, 02:07 AM

Quote:

Originally Posted by INSIDIOUS '86

Should go from the back behind the carb and run down the passenger side to the back of the trans at the rear of the pan.
You could have internal leaks on the seals and prong inside that comes with higher mileage transmissions. So it could be slipping in an out of gear as your driving. 2500stall is high but not overkill. High stalls also create a lot of heat. Possible that your trans is cooking itself

Take out your dipstick and smell it. It smell burnt or fishy?
Posted via Mobile Device

Yes and it's causing the cab floor to get extremely hot!
Posted via Mobile Device

cmyc5575 · 05-30-2013, 08:52 PM

What is the purpose of the shifting module?

chris989 · 05-30-2013, 11:18 PM

Quote:

Originally Posted by cmyc5575

What is the purpose of the shifting module?

It is a device that senses the manifold vacuum to determine when the transmission needs to shift. At idle you most likely have15-20 inch of vacuum. As you increase the throttle and load the vacuum decreases.

Less vacuum= higher shift rpm
more vacuum= lower shift rpm

cmyc5575 · 05-30-2013, 11:29 PM

Quote:

Originally Posted by chris989

It is a device that senses the manifold vacuum to determine when the transmission needs to shift. At idle you most likely have15-20 inch of vacuum. As you increase the throttle and load the vacuum decreases.

Less vacuum= higher shift rpm
more vacuum= lower shift rpm

Ok so i have some serious vaccum issues if all i have is reverse and does not even go into drive? So i put the truck back into reverse and back up another 20 feet and then into drive and it works.

INSIDIOUS '86 · 05-31-2013, 01:04 AM

Pump may be going out as well. You shouldn't be getting more than a warm floor from the trans. If its hot then the tans has to have something wrong
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cmyc5575 · 05-31-2013, 02:46 AM

Quote:

Originally Posted by INSIDIOUS '86

Pump may be going out as well. You shouldn't be getting more than a warm floor from the trans. If its hot then the tans has to have something wrong
Posted via Mobile Device

What pump are u referring to?
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meatwagon83 · 05-31-2013, 01:42 AM

sounds to me like its not starting in first, and a 2500 stall is very small!

meatwagon83 · 05-31-2013, 08:08 AM

trans pump, behind the torque converter

05-29-2013, 06:09 PM	#1
cmyc5575 Registered User Join Date: Jun 2012 Location: okc, OKlahoma Posts: 483	Could my tranny be causing a loss of power? Hello, 83 gmc short box. 350ci backed by 350 tranny with 2500 stall. This truck is about to drive me crazy, I have no take off power, It seems like I have a 4 cyclinder underneat the hood, its that bad. High revs before it will finally shift into second. Weird experience here lately has been when im crusining @ 60 mph the truck will all of a sudden start reving really high and seems like someone has put the truck into nutral. So, I even tried putting into first gear at the bottom so i know for sure it would be the right gear to take off in and it seems to help once in awhile, or not at all. Im thinking that Im either about to replace the torque converter or i may be losing the tranny in it. Thanks for all help upfront guys!!!

05-29-2013, 06:51 PM	#2
Billy81 Registered User Join Date: Jun 2004 Location: Medford,Oregon Posts: 390	Re: Could my tranny be causing a loss of power? With a stall that high unless your engine has a pretty radical cam in it that is probably your problem right there. Without more info on your engine it's hard to give advice on what stall you should be running. __________________

05-29-2013, 09:50 PM	#5
66skylarkpost Registered User Join Date: Mar 2006 Location: kearney,nebraska Posts: 443	Re: Could my tranny be causing a loss of power? 2500 is not high at all, thats just over stock . i'd be looking into your transmission, something doesnt seem right __________________ '70 k-10 longbox- mid 70's drivetrain 350/350 487x heads 10.1:1 flowmasters ,35's 3.73's auburn posi ,rear shackle flip. '72 short stepside U.S. forestry truck, '73 455 buick,400 turbo,dropped 2"-4 1/4" ,3.07 posi,:'89 silverado 1500 ,OK truck ,5.7 holley tbi ,trick 700r4 3.07 auburn posi ,and my '66 skylark ,'73 centurion and my '84 monte carlo imca stock car

05-30-2013, 01:10 AM	#7
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Could my tranny be causing a loss of power? Should go from the back behind the carb and run down the passenger side to the back of the trans at the rear of the pan. You could have internal leaks on the seals and prong inside that comes with higher mileage transmissions. So it could be slipping in an out of gear as your driving. 2500stall is high but not overkill. High stalls also create a lot of heat. Possible that your trans is cooking itself Take out your dipstick and smell it. It smell burnt or fishy? Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

05-30-2013, 08:52 PM	#9
cmyc5575 Registered User Join Date: Jun 2012 Location: okc, OKlahoma Posts: 483	Re: Could my tranny be causing a loss of power? What is the purpose of the shifting module?

05-31-2013, 01:04 AM	#12
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Could my tranny be causing a loss of power? Pump may be going out as well. You shouldn't be getting more than a warm floor from the trans. If its hot then the tans has to have something wrong Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

05-31-2013, 01:42 AM	#14
meatwagon83 Registered User Join Date: Dec 2012 Location: Preble county ohio Posts: 1,914	Re: Could my tranny be causing a loss of power? sounds to me like its not starting in first, and a 2500 stall is very small! __________________ "DON'T TOUCH THE TRIM!!"-Early Kyler

05-31-2013, 08:08 AM	#15
meatwagon83 Registered User Join Date: Dec 2012 Location: Preble county ohio Posts: 1,914	Re: Could my tranny be causing a loss of power? trans pump, behind the torque converter __________________ "DON'T TOUCH THE TRIM!!"-Early Kyler



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