C6 Auto transmission issues
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Cross-Country
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C6 Auto transmission issues
Hello!
I have a 1978 F-250 4x4 with a 351M C6 Np205 and it makes some really weird noises and is acting funny when I drive it.
When I fire it up it's fine no noises no issues in park no movement. But when I put it in reverse I hear a loud sudden Whir noise and it's really hard to describe and when I get on the gas in reverse it gets very loud with RPM. But when I put it in drive Its silent but then as I get moving with 1st gear it is loud. 2nd gear its quieter but I still hear it. 3rd gear is silent and recently its been cold out but when its in drive I refuses to come out of 1st gear unless I manually shift it to another gear. I have checked the fluid it is topped off and I have put Lucus stop slip in it because when it started making the noise I hoped that would help it a bit, but I don't know if it made it worse or better. And when I checked the fluid it was dark brown and had some black on it even though the gears feel strong and shift nicely. I'm just wondering what you guys think went wrong in it. Don't know how I managed to wreck a C6.
I have a 1978 F-250 4x4 with a 351M C6 Np205 and it makes some really weird noises and is acting funny when I drive it.
When I fire it up it's fine no noises no issues in park no movement. But when I put it in reverse I hear a loud sudden Whir noise and it's really hard to describe and when I get on the gas in reverse it gets very loud with RPM. But when I put it in drive Its silent but then as I get moving with 1st gear it is loud. 2nd gear its quieter but I still hear it. 3rd gear is silent and recently its been cold out but when its in drive I refuses to come out of 1st gear unless I manually shift it to another gear. I have checked the fluid it is topped off and I have put Lucus stop slip in it because when it started making the noise I hoped that would help it a bit, but I don't know if it made it worse or better. And when I checked the fluid it was dark brown and had some black on it even though the gears feel strong and shift nicely. I'm just wondering what you guys think went wrong in it. Don't know how I managed to wreck a C6.
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Joined: Feb 2007
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From: S/W Missouri, Polk county
Maybe a clogged filter, if the fluid is dark brown and not RED, sounds like it is burnt up. Have you check the modulator line?
" Check the vacuum modulator and the line that goes to it. Check the line for kinks or other problems, make sure it hasn't come off. If the line checks out, take the line off where it connects to the modulator. If trans fluid leaks out, its bad. If no fluid, it still could be bad. They're simple to replace, disconnect the vacuum line, remove one bolt that holds the clamp in place and the modulator comes out. It has an o-ring seal.Modulators are identified by the color of the stripe. Pretty much the "go to" one is the black stripe. If they don't show that one in the catalog, go with the green stripe. Avoid the pink stripe. That one is a dual diaphragm version that has two vacuum line going to it. If by chance you have one of these, replace it with one of the other two and use the vacuum line that goes to direct manifold vacuum, cap the other line. When you pull the modulator out, be careful. There is a pin that goes in the modulator. Sometimes it comes out with the modulator, sometimes it stays in the tranny. If it comes out, don't lose it."
Still with all the noise and it acting up likeit is, it sounds like it is professionial rebuild time.
" Check the vacuum modulator and the line that goes to it. Check the line for kinks or other problems, make sure it hasn't come off. If the line checks out, take the line off where it connects to the modulator. If trans fluid leaks out, its bad. If no fluid, it still could be bad. They're simple to replace, disconnect the vacuum line, remove one bolt that holds the clamp in place and the modulator comes out. It has an o-ring seal.Modulators are identified by the color of the stripe. Pretty much the "go to" one is the black stripe. If they don't show that one in the catalog, go with the green stripe. Avoid the pink stripe. That one is a dual diaphragm version that has two vacuum line going to it. If by chance you have one of these, replace it with one of the other two and use the vacuum line that goes to direct manifold vacuum, cap the other line. When you pull the modulator out, be careful. There is a pin that goes in the modulator. Sometimes it comes out with the modulator, sometimes it stays in the tranny. If it comes out, don't lose it."
Still with all the noise and it acting up likeit is, it sounds like it is professionial rebuild time.
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