C6 no shift

SkylabTech86IDI

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1986 F250 with 1989 7.3 n/a & C6 from an 89 E350 swapped in. Standard sized transmission pan.

Just did a fluid and filter change. I Rowed through all of the gears, drained the oil, put new pan gasket and filter in, Put 8 quarts of MECRON in.

I row through each gear and sit in it for a good 10 seconds & then I’m pulling my dipstick to check my fluid while hot idling in park.

Problem #1: 8 quarts of input is showing that I’m extremely overfilled. I filled the trans from the dipstick tube. I waited about 3-4 days and I guess the tube either has ATF still coating the walls, or there really is more than 12+ quarts of fluid in the C6. I’m going to drain the fluid and measure it out to see what’s really in there. And maybe run compressed air down the full tube to push any residual fluid off of the inner wall…


Problem #2: Shifting into drive and accelerating does not get me into third gear. And it struggles to get into 2nd. From a stoplight, I’ll have to rev the motor out in 1st and then take my foot off the “throttle” so that the engine falls down to idle while I’m rolling along at 17+ mph and it falls down into 2nd. It does not do that for third. I can’t get third gear.

am I low on fluid and the tube is giving me a false reading? I know I used 2 full gallons of ATF fluid. Just not trying to add a bunch of fluid and blow the transmission up. I just need to drain to oil and measure how much comes out.

Here’s my configuration. The red box circling the hookup causes the accelerator pedal to bind up and be real stiff
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My vacuum pump is pulling suction.
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Cubey

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Did you drain the torque converter? If not, the pan only holds 5-7qts (can't seem to find the exact). If the stick shows you are overfilled then you are. Fix that first, and then see how it acts. The tube can't give you a false reading. It's just a metal straw that leads to the pan for the dipstick to dip into. Are you checking both sides of the dipstick or one side? It can drag some up and you have to check several times on both sides of the stick to see where the true level is.
 

SkylabTech86IDI

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Did you drain the torque converter? If not, the pan only holds 5-7qts (can't seem to find the exact). If the stick shows you are overfilled then you are. Fix that first, and then see how it acts. The tube can't give you a false reading. It's just a metal straw that leads to the pan for the dipstick to dip into. Are you checking both sides of the dipstick or one side? It can drag some up and you have to check several times on both sides of the stick to see where the true level is.
No I didn’t drain the torque converter. To be honest I didn’t know that and I had to look up how you do that. Either way, Rookie mistake & lesson learned. Thank you
I was checking both sides and inserted and wiped about 20 times just today. I’m overfilled. I’ll drain the pan and start over.
 

Jim993

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Got vacuum? It won't shift normally if the belt driving the vacuum pump breaks, the vacuum pump dies, the vacuum adjusting valve up by the IP is defective, a vacuum line gets interrupted or the vacuum modulator on the transmission goes bad.
 

Cubey

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Got vacuum? It won't shift normally if the belt driving the vacuum pump breaks, the vacuum pump dies, the vacuum adjusting valve up by the IP is defective, a vacuum line gets interrupted or the vacuum modulator on the transmission goes bad.

It will still go up to 3rd by centrifugal means if the vacuum hose is totally undone from the modulator, so the C6 doesn't "NEED" vacuum to operate in all gears. I know because that happened to mine. It'll upshift later and it'll downshift to 2nd when slowing down below 20mph. Since OP can't even get 3rd gear at all, it's not that.
 

franklin2

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It may shift without vacuum but it's very stubborn about it.

The trans holds around 13 quarts if you drain the torque converter.

With it over filled, it really messes things up. The spinning parts in the tranny get in the fluid and stir it up making it foam. All that air in the fluid messes up the valve body.
 

Cubey

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It may shift without vacuum but it's very stubborn about it.

The trans holds around 13 quarts if you drain the torque converter.

With it over filled, it really messes things up. The spinning parts in the tranny get in the fluid and stir it up making it foam. All that air in the fluid messes up the valve body.

It's not stubborn, just late. Without any vacuum, it'll go to third constantly around 35-40 with my 4:10, if i remember right. Vacuum should make it go sooner, depending how you have it adjusted.
 

XOLATEM

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I am sorry to hear about your trouble but it looks like a good time to learn about a fine old transmission that I never once ever heard about it ever breaking any hard parts internally.

Back in the 80's there was a monster truck with a big block engine that was capable of turning 7's in the quarter mile in a race car. This truck ran a C-6. No broken hard parts, ever. Gotta love that "Built Ford Tough" engineering.

Ok...with that outta the way... I am looking suspiciously at your throttle cable...and the kickdown lever and rod. Can't make out if everything is good there because your vacuum hoses to the VRV are in the way...but...if the pedal is hard to push...something is in a bind or otherwise outta kilter. Do you have cruise control? And... if you do, is it working..? Is something wrong with your throttle cable..?
 

Cubey

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Oh and looking closer at your kickdown adjustor screw, it's WAY too far in. it should only contact the throttle lever thing at a bit over 3/4 of the way wide open, or there abouts.

This is how it should be roughly:
xc_hide_links_from_guests_guests_error_hide_media

That's on my 85 E350. The kickdown sits angled much different on my 87 F250 for some reason and it barely needs thread poking out towards the throttle. So you'll just have to try to adjust it until it's about like the video shows.

You might still have to fine tune it if it's kicking down too much. Too much thread out towards the front of the vehicle, the more it'll be in kickdown at less pedal travel, which you don't want.

(edit: Removed a redundant and erroneous sentence, and made the rest less confusing)
 
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IDIBRONCO

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Here’s my configuration. The red box circling the hookup causes the accelerator pedal to bind up and be real stiff
The problem is probably your throttle cable. Part of the red housing is broken and may be what is causing the binding.
or there really is more than 12+ quarts of fluid in the C6.
From what I can remember, a C6 takes about 12 quarts of ATF when you install a new (rebuilt) one. That means that both the convertor and the transmission are completely dry.
PS in my view, every diesel should have a vacuum gauge in the cockpit.
I second that.
 

SkylabTech86IDI

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Got vacuum? It won't shift normally if the belt driving the vacuum pump breaks, the vacuum pump dies, the vacuum adjusting valve up by the IP is defective, a vacuum line gets interrupted or the vacuum modulator on the transmission goes bad.
I pulled the vacuum line out of the brake booster and it had good suction.

I found this online about the VAV. https://www.nickpisca.com/diesel/fuel-system/proper-idi-vrv-adjustment-and-calibration/ it reads like it assumes that you have a known good working valve.

Haven’t yet checked the lines going to the transmission yet.

Drained the oil and I’ve got the fluid back to the right level on the stick.Still no third gear.


The problem is probably your throttle cable. Part of the red housing is broken and may be what is causing the binding.
Oh and looking closer at your kickdown adjustor screw, it's WAY too far in. it should only contact the throttle lever thing at a bit over 3/4 of the way wide open, or there abouts.

This is how it should be roughly:
xc_hide_links_from_guests_guests_error_hide_media

That's on my 85 E350. The kickdown sits angled much different on my 87 F250 for some reason and it barely needs thread poking out towards the throttle. So you'll just have to try to adjust it until it's about like the video shows.

You might still have to fine tune it if it's kicking down too much. Too much thread out towards the front of the vehicle, the more it'll be in kickdown at less pedal travel, which you don't want.

(edit: Removed a redundant and erroneous sentence, and made the rest less confusing)

I second that IDI. I’ve got a 3D printer. Maybe I can model and print a replacement plastic retainer.

thanks Cubey I’ll back it out to where it’s supposed to be. I drove it all the way in because I, A: wanted to see if it would do anything & B: I don’t know what I’m doing.
 
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