C6 Problems!!
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Senior User
Joined: Sep 2009
Posts: 174
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From: Goldsboro Nc
C6 Problems!!
I got a 78 ford f150 4x4 351m/c6 np205. I've been having some issues putting it in drive and the rpm wont drop down to 600 or so and i'll hit the gas and i wont move. i haft to rev it some to get it to drop into gear. what could be causing this??? also in drive, its like its in 3rd gear all the time.
Transmission Rebuilder
Joined: Jul 2008
Posts: 1,569
Likes: 62
From: North Georgia
The delay into gear can be caused by low fluid or old worn seals in the forward drum.
The third gears starts most likely due to a sticky governor. Governors tend to stick due to excess debris in the fluid.
It sounds like you are headed for a rebuild to keep this thing on the road.
The third gears starts most likely due to a sticky governor. Governors tend to stick due to excess debris in the fluid.
It sounds like you are headed for a rebuild to keep this thing on the road.
Senior User
Joined: Dec 2008
Posts: 226
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Here is an article with several tests to check the health of your C6 and to narrow down problem areas. I thought it was a good read and learned a lot from it.
http://mustangtek.com/Library2/PDF/ShopTips3-8.pdf
http://mustangtek.com/Library2/PDF/ShopTips3-8.pdf
Tuned
Joined: May 2009
Posts: 435
Likes: 1
Not to hijack a thread, but I'm having the same delay problem on mine. I'm building a 76 F350 and had the c6 tranny out, drained the fluid, put a B&M shift kit in, put it back in and filled it with fluid. Reverse works great, but when I put it in drive, 1st, or 2nd I have to rev it up to get it to "engage". Once it engages it seems to work fine. I haven't driven it down the road yet, just around the driveway, what are the chances I just need to get it out and run it and it will work?? Is there a possibility the thing has air in it or the fluid hasnt circulated enough? I know nothing about trannies and REALLY don't want to have to have it rebuilt. Oh......and I couldnt get the link above to work.
Senior User
Joined: Dec 2008
Posts: 226
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,696
Likes: 2,618
From: SE Florida
The seals in your forward clutch drum are bad. The trans needs a rebuild to fix this.
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Senior User
Joined: Feb 2011
Posts: 252
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From: Moore, OK
I had this caused by leak back from my torque converter I believe. It would take a while to go in gear then take a minute to shift to 2nd once I started going. After that it was fine. I assume the TC would fill by then and be fine.
Now, this is not a "fix" and I may get flamed, but I tried the Lucas Stop Slip. The trans was on its way to a rebuild anyways, and still is... 7 months later. It doesnt do that anymore on morning start-ups, but its still slow to 2nd the first time if it is really cold.
Like I said, I dont consider this "fixed" but it was a band aid that happens to have worked very well. Im hoping it will make it to my vacation in May when I will pull it and rebuild it. Im sure it will. It seems ok, the whole thing is just tired.
So try it or dont, but I say if you are looking at a rebuild or replace anyways its worth a $6 bottle of this stuff even if it buys you a month. If you can do the rebuild now, just do it though.
Now, this is not a "fix" and I may get flamed, but I tried the Lucas Stop Slip. The trans was on its way to a rebuild anyways, and still is... 7 months later. It doesnt do that anymore on morning start-ups, but its still slow to 2nd the first time if it is really cold.
Like I said, I dont consider this "fixed" but it was a band aid that happens to have worked very well. Im hoping it will make it to my vacation in May when I will pull it and rebuild it. Im sure it will. It seems ok, the whole thing is just tired.
So try it or dont, but I say if you are looking at a rebuild or replace anyways its worth a $6 bottle of this stuff even if it buys you a month. If you can do the rebuild now, just do it though.
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