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I just got my newly bought Longchamp engine to run, so I now discovered issues with my C6.

I've changed the oil on the C6. I did it by unplugging a hose to the radiator, and with engine running the oil came out. This is the first time I've changed autotrans oil like this, so I'm not sure how much more oil I actually got out than the usual oilpan-off method. I also changed the oil filter which is an external spin-on filter. I then added 4-5 quarts, and that's about right on the oilstick (idling in Park).

When idling there was no gear, only after 1500rpm for almost a minute there suddenly was Reverse gear, the tires squealed, good thing I was sitting in the car with my foot on the brake...

Stopped engine, spent a few hours fixing something else, started engine, no gear again. In my previous experience (GM cars) this means too little oil and 4-5 quarts sounds too little, depending on how much I got out of course. But the stick showed oil level 1" above where it should be. However, I added 2 quarts, and now I got gears, after 1-2 seconds. I added another quart.

Status after the 8 quarts added is:
-I have gears
-When moving gear lever to Reverse or Drive the gear comes in quite hard, especially Reverse
-When driving very softly it shifts perfectly into 2nd and 3rd
-When accelerating at half throttle, I get no 2nd gear until I release the throttle, same with 2nd to 3rd
-The oil level according to the oil stick is 4 inches(!) above where it should be

Any ideas? I'm tempted to add more oil. There's no foaming of the oil, which on GM cars is a sign to take oil out. I've checked the vacuum from the engine to the transmission, seems fine. And the kick down rod is only actuated when the throttle is a lot more open.
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It sounds like there is devris internally. The point of droping the pan is to be able to clean out the dbris in the pan and screen.

I think that you will still have to do this anyway. It may be much more complicated now to get it cleaned out.

Open the valve body and clean the passages. If it is contaminated with debris, just pull the entire trannie apart and clean it part by part, it will be the only way for sure to know it is clean.

If you are lucky there is no debris and it is just the balls in the valve body are sticking from varnish. It doesn't sound like the bands are slipping or the pump is hurt, just debris blocking valve body passages.

Good luck.
Are you sure that the filter you changed was for the trans, Most automatic of that vintage have the filter in the pan attached to the underside of the Trans, It sounds like your filter is plugged, I would drop the pan and look at this, also there is ussally a rubber grommet on the filter to the spiggot it attach's to to seal the top side so the tranny pump is able to pull threw the filter off the bottom of the pan, its really a good idea non the less to clean it out.

good luck, Mark
I'm NO expert by no means! That said, on one of my Lincolns, I think it was a 1978 model. When I serviced the trans. they dropped the pan to clean or change the filter it also had a plug in the torque converter.(some years have them some don't?)They pulled the plug and drained another 3/5 qts. When back back together the trans. took about around 10/12 qts of trans. fluid.
Good Luck
Sick Cat, yes the filter I've changed is the transmission filter. It's the first time I've seen it externally, but the hoses go to the auto trans/oil cooler in the radiator, and it's also in my Longchamp parts book, so I think they all have it.

But there may be a filter in the trans itself of course. What I'll do is take a good long drive tomorrow, probably the first time this transmission get warmed through in 5-10 years. If that doesn't miraculously fix it, I'll drop the pan and change filter if it's in there. Taking the valvebody apart is probably beyond me, then I need a professional's help.
The C6 I had in my old Bronco and every other Ford transmission of the era has a filter inside the pan. This needs to be changed. If the pan is off the valve body is right there. It should be taken a part and soaked, cleaned and rebuilt with a kit. The only easy good way to get all of the fluid out of the trans is to flush it with a specialized machine.
Ron, bad news is OK if it's the facts. We have to deal with reality...

I hope you're wrong, I just used the procedure found on a few professional looking websites like:
. Look in "3."

Besides, the transmission was the same before changing the oil, I did do a 2-3 mile drive before starting to fix the car.
Last edited by noquarter
That tranny is DONE ... you can't run an automatic trans with it down 4-5 quarts of fluid ?? it burns it up .

I had this same thought.

But, inasmuch as the car was not driven, and no load was put on the tranny, I kind of think it may not have done any harm.

BUT, I surely do not advise this method!!

As for dropping the pan and cleaning the valve body. This is basic mechanics 101. Not too scary if:

you have a good manual with good diagrams

you realize there are many small parts than can fall out - you need to know where they go back!!

you keep things clean and have a large, secure work area

Years ago I did a Trans-Go valve body performance kit on a C-4. I pulled it off with no problems, and man did that sucker shift! First time out, it grabbed into second so hard that it literally sheared off the splines on the inside of the torque converter. That was the end of the cheapo parts house brand. Wink

If you are going to pull the valve body, you may want to consider a shift-imporovement kit such as that.

Originally posted by LF - TP 2511:
That tranny is DONE ... you can't run an automatic trans with it down 4-5 quarts of fluid ?? it burns it up .

I had this same thought.

But, inasmuch as the car was not driven, and no load was put on the tranny, I kind of think it may not have done any harm.

BUT, I surely do not advise this method!!



I believe that since you were using the transmissions pump to pump the fluid out you also inadvertantly pumped fluid out of the torque converter. This won't get filled back up by simply filled the transmission hence the reason you only put acouple quarts of ne fluid in.

I would suggest you start back from scratch and do it the right way meaning the messy tranny fluid all down the driveaway way Big Grin Drop the pan, replace that filter, drain the torque converter (hopefully you have the drain plug other wise unbolt the driveshaft, drop the tranny, etc etc) and the button everything back up and fill.

Since the car is new and of unknown mechanical history I would do this before I drove it anywhere to pevent more damage.
Miles, one question. If I take out the fluid from the converter by removing a plug, and you say it doesn't fill up automatically, then how does the new fluid get in there (w/o dropping the trans to the garage floor)?

I still refuse to believe I did anything wrong because the tranny was like this even before I changed the fluid (denial Wink)

By the way, owning a powerboat as well, I have oil suction device to change engine oil. I use that to suck up transmission oil as well before lowering the oil pan. Just a tip to avoid too much mess.
Larry or anybody, assuming I try to clean the valvebody and take pictures, it must be possible to get back together...

Does anybody have a PDF of what I need for this procedure on the C6?

I don't want to get firmer shifts. The car is supposed to be a gentle daily driver, with the power and handling for the occasional stop light grand prix, in Italian gentleman style... Cool
Last edited by noquarter
Finally got the TCI Sizzler trans from across the Atlantic. I forgot how much "fun" it is to switch gearbox from beneath, especially on a Longchamp where the crossmemeber is welded in, not bolted. And when I uploaded the new trans, I tightened the trans oil cooler fitting too much so it broke off in the trans Mad. So I had to lower the trans again, then it was easy to get the broken fitting out fortunately.

I went for a short drive around the block today (no license plates) and the trans appeared to shift perfectly. Smiler

Moving the gear lever from one trans to the other, I had to open the old trans, and I think I found (at least one of) the reason(s) why it killed itself. There was no spring to ensure the detents, so if the gear lever was not adjusted exactly right, the trans could have been between gears...
Just as a comment, waiting for the trans to cross the Atlantic I started looking at rust. It's quite OK, rust 3 places on the body. BUT the rocker panels! Rust all over, had to replace most of them. Man, was it thin, never seen so thin rocker panels on any of my US-cars.

Took the time to rust-proof the entire bottom, wheel arches and inside the rocker panels. The plan is to drive the car this winter, see what rust pops up, fix it, and then paint the car (same colour)
I've just had my C6 rebuilt. It was a casualty of top gear red line incident, when the rear extension housing blew of the back of the tranny. To replace the whole C6 my mechanic had to remove the brand new motor which has just gone in before he could get the tranny out of the car. As you say the mount is welded not bolted and the advice was not to modify it to bolted mount as the car might not be the same again after removing the structural welded brace under the trans. This cost me 3 days labour in total engine out/ tanny out/ tranny in/ engine in. It sounds like you tried everything first before needing to take the transmission out of the car....
Hi dovf

In case you get in that situation again, here's how to get it out w/o removing the engine.
1. From inside the cabin, remove the gear selector and the approx 5"x10" black plate, that gives room for the rear of the trans.
2. Drop the front of the trans approx 2", push it as far back as you can, that gives 2" space, then remove the flywheel

Then you can lower it, despite the crossmember. And he's right, it shouldn't be converted to bolt on, the car has to be stiff...
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