C6 Problem

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Jan 31, 2009 | 02:03 AM

pcwb

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From: Eckert, CO

C6 Problem

I bought a rebuilt C6 (no warranty) and installed it with a 460 in my '70 crewcab. When I start it up it will go into reverse right away, but will not go into drive until it warms up - 10 to 15 minutes and only if you leave it in drive while it warms up.
Anybody have an idea what is wrong with it?
I have the old tranny that I can get rebuilt, but would like to fix this one if it is something simple, do not relish the idea of replacing this one again this soon......

Thanks Guys

Jan 31, 2009 | 02:53 AM

icrman

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Likely a bad / broke seal ring.

Jan 31, 2009 | 03:06 AM

pcwb

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From: Eckert, CO

icrman,
Thanks for the reply!
Is this a tear down on the tranny? or is it in the valve body? I have never tried to work on the auto trans, so admitting ignorance here.

Jan 31, 2009 | 12:01 PM

Lazy K

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Quote:

Originally Posted by icrman

Likely a bad / broke seal ring.

I think he means the seal on the forward clutch servo and he could well be right. However are you confident that the manual shift linkage is properly adjusted? Does it do the same thing if you shift into 1 or Low?

Jan 31, 2009 | 12:37 PM

pcwb

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From: Eckert, CO

Lazy K,

It does the same thing in 1 -2- D, and it does not seem to matter which forward gear you warm it up in.
I am fairly handy mechanically but I have not worked on a auto trans before. I am wondreing if I can fix this tranny or get the old one rebuilt by someone who knows what they are doing. I spent a fair amount of time replacing the C-6 and really don't need to practice over and over if the rebuild should not be done by a rookie (me).
Your description sounds like it means a complete disassembly, I was hoping it was in the valve body so I could fix it in the truck.

Thanks for your response

Jan 31, 2009 | 02:38 PM

Lazy K

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I am not a transmission expert, you would need Mark Kovalsky or jk080 for that, but here is what I would do. Make sure the manual linkage is shifting properly. Make sure you have vacuum to the modulation valve at the trans.. Pull the vacuum pipe off at the trans and see if there are any traces of fluid in the pipe, if there are replace the modulator.

Jan 31, 2009 | 06:26 PM

pcwb

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From: Eckert, CO

Lazy K,

Thanks for the info, I will look at it tomorrow. I did not think to check the modulator, would that cause the tranny to not go into a forward gear? I am sure the shift linkage is correct, when I originally put the 460/C6 combo in I put a Hurst floor mounted shifter in. When I replaced the tranny I pulled the old instructions and followed them like the original install. When the transmission warms up and starts working, it will function OK all day and you can shift it from low to drive. The past couple of days it has taken longer than 15 -20 minutes for it to engage, which leads me to beleive that the seal, valve or whatever is wrong is getting worse.

I appreciate your input.

Paul