Author Topic: Transmission Trouble  (Read 697 times)

Offline 1974ChevyC20

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Transmission Trouble
« on: November 15, 2018, 12:11:14 PM »
I have a 1974 C20 that doesnt want to move when I first put it in gear. It moves a little and then stops and eventually will move after 5 minutes of revving the engine. I changed the transmission fluid and filter. After it gets moving its fine. Could it be the torque converter? Thanks! 


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Offline MIKE S

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Re: Transmission Trouble
« Reply #1 on: November 15, 2018, 12:22:49 PM »
If your saying it moves and shifts normally when warmed up, more than likely you have hard seals and or sticky valves in valve body. I would try some additive like trans x. Its a seal softener and varnish dissolver. If your saying it always has trouble taking off from a stop then you may have a burnt clutch. Does the fluid smell or look burnt? 

Offline 1974ChevyC20

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Re: Transmission Trouble
« Reply #2 on: November 15, 2018, 12:36:13 PM »
It takes off from stops fine. Its just when I first start and move it after its set a day.


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Offline JohnnyPopper

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Re: Transmission Trouble
« Reply #3 on: November 15, 2018, 01:20:19 PM »
Sounds like stuck valves, try Seafoam Transmission product. Works good.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Online VileZambonie

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Re: Transmission Trouble
« Reply #4 on: November 15, 2018, 03:41:04 PM »
Are you checking the fluid level with it running at operating temp?
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Offline MIKE S

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Re: Transmission Trouble
« Reply #5 on: November 15, 2018, 04:06:46 PM »
If when you start it cold and it takes like 10 seconds or so to move and its not slamming into gear once it catches and your fluid level is good then you probably are suffering from converter drain back. In other words as it sets the fluid in the converter is draining down into the pan and it takes 10 seconds or so to pump up the converter. The cause is usually worn bushing in pump and converter drive hub. tear down would be necessary. 

Offline 1974ChevyC20

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Re: Transmission Trouble
« Reply #6 on: November 16, 2018, 02:27:56 PM »
Yes. I am checking it running at operating temperature. It takes a lot longer than 10 seconds to go and keep moving though. It moves about 2 inches as soon as I put it in gear.


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