Hi. My transmission (auto c6 in N/A 7.3) has had a strange issue sense I purchased the truck. I figured now that I've got it to "daily driver" status, I could go ahead and start diagnosing the tranny.
Starting out, it stays in first good and strong, then drops off when it should shift to second and slips pretty badly. The motor will keep revving with no power. You have to decrease throttle then it will jump into second. When it does get into second, everything is fine. Shift points seem to be fine, downshifts fine, everything is good except the slip. The PO said it was a new transmission.
----All I can tell you so far is that there is fluid in it... However, in the gauge cluster, the gear "indicator" (orange tab that sits over the selected gear) is stuck in between "1" and "2", and, as said by PO, has been that way sense the new transmission was installed. It does not move with the gear shifter, it always stays in that position.
----In addition, the tachometer only works for a few minutes when the truck is started, and at this time, the shifts are firm with no slips or defects. However, when the tach. dies, the transmission starts to slip again.
----If I manually put the truck into second gear, it usually starts strong in second, but sometimes will also slip, and you must release throttle to get it to shift fully into second.

I know these are mechanical motors, I was just wondering to what extent. Will the transmission not shift properly because of a bad tach. sensor? Could it be the "gear indicator" that may cause this? I just felt a red flag when the tranny seems to be fine only when the tach. works which is only for a few minutes after startup. I was just wondering if this sounded familiar to any f you know it all's (i mean that in a good way)..

As always, thank you guys for your input and help.

 

Are you positive it's a c6? The tach signal will affect a E4OD, but will not affect a c6. If it is a c6, I would drain the fluid and change the filter, and see how much stuff is laying in the pan, and what the fluid looks like.

 

The C6 transmission doesn't rely on the tach sensor at all, so the two problems are unrelated.

Slipping in manual 2 is a little concerning though. In manual "2", it should grab quickly and hold on.

Its possible that the shifter is not aligned properly, but it doesn't really explain why 2nd gear is the only one that slips.

Having a transmission problem that is temperature related tells me that it could be a sticking valve. I had similar problems with my E4OD transmission. The good news is the valve body can be removed or even replaced without having to remove the transmission. You will have to drop the pan and drain the fluid though.

At least thats my theory. Stick around in case some one has another idea....

 

maybe it mojo is off dave lol

 

LOL, I'll never live that one down!


Franklin, I looked in his profile and the year of his truck is 1988. 1989 was the first year for the E4OD.... Officially at least.

 

Well, it is a 3spd automatic, which I thought was all a c6 could be. 88 f250 7.3. I'm pretty sure it is. e40d's are 4 speed right? Yea, I figured it was more than likely a coincidence with the tach./slipping. Perhaps the amount of time it takes for the tach to crap out is just how long it takes before the tranny warms up a bit and starts missing. I really wish I knew more about transmissions because I forsee myself dropping it off to a shop and leaving with my tale between my legs. I'm still open to all opinions so atleast I can pretend like I know what Im talking about to a specialist, and increase my chances to 'not' get screwed.

I will pull the pan this weekend if I get a break and change the filter, fluid, modulator valve (just incase) and ad a drain orphice. God I wish this thing had another gear. Anyone know of a good online source for transmission parts? I hate getting butt raped by stealerships.

Thanks for the responses!

 

probley not iam watching wrestle right now but i think ur right about it being an e4od that y i drive stick

 

My 88 has a C6, so I bet yours is too, and like yours when I bought mine it slipped in 2nd.

The first thing I would do is drop the pan and put a new filter in it, it did mine wonders., not to mention its like 10 bucks. Don't get scared though, it is very very very easy to do, just pull the bolts out of the pan, then there is the filter (it is more like a screen actually), pull the bolts out of it, then reverse the steps and your done. Just droppin the pan takes about 5-6 quarts to fill it back up, but if I had the time I would go ahead and drain the TC as well and if I were you I would invest in a bottle of Lucas tranny fixer stuff, I've heard tons of good things about that stuff.

 

Good deal. I actually have a new filter, rubber gasket, mod. valve, and some piece to put together a nice, controlled drain valve (why in the name of the lord would ford not have put a drain on the pan?!?! If nothing else, to lessen the mess) I suppose ill get in there and do my part, take a look, maybe some pictures, and see what it looks like. DEAN88, what was the verdict of your slippage? Mine is actually very tolerable, I just want to not think about it every time i speed up.

 

I also recommend going and getting some of those paint filters (the funnels with the tight gauze screen) and then pour your tranny fluid through it just to make sure there isn't any particles floating.

 

Good call, I've got a few of those left over from my last paint job.

 

hope it works out for u

 

i alos have a c6 in my 88. One more thing while your under there I would check the vaccuum modulator. It's on the passenger side, with the vaccuum line on it. Pull the vaccuum line off. If you see fluid you need to replace it. Part is like 10 dollars.

 

As far as your ger selecter it runs on a string in the steering column, and is probably broken. Mine moves slow. A mechanic at work told me about it, but I've never messed with it. Hope this helps

 

I agree with all these guys. And yes drain the TC while you are there. You will probably need around 12qts of Dexron3 to fill it afterwards. Also check the vacuum line and mod. as suggested. Good luck.