C6, super hard shift
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Senior User
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From: Rappahannock County,VA
C6, super hard shift
Hey guys, my c6 started shifting really hard this evening. I noticed this morning when it was warming up a little fluid coming out of the hose right at the oil cooler. I figured no big deal, tightened the clamp up through the grille and went on with my business figuring I'd check the fluid when it was good and hot. This evening it started shifting really hard and have to really rev it up to get it to shift. Im not so sure about the fluid on the dipstick. This is the first auto I've ever owned. I know with universal hydraulic fluid its hard to see on the dipstick and you have to put it on a paper towel or something to really see it. I have fluid on the stick but its pinkish and just barely there. It seems to me like its low. I added about a quart but I cant really tell if the level went up or not. It was in the dark and about half went on the valve covers and exhaust manifold, YUCK! It will shift well manually from first to second but not so from second the drive. I'll check the fluid tomorrow when its daylight but it seems odd that it started doing this like the turn of a switch not little by little and seems that added fluid should've helped out somewhat. What could be the case. Im sure numerous things. Now I know why my dad has always hated autos lol
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Senior User
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From: Rappahannock County,VA
I was thinking that myself. One before when replacing a valve cover gasket I left a vacuum line under the valve cover and had practically the same problem, actually it wouldnt shift into drive at all. The modulators themselves go bad?
Elder User
Joined: Dec 2007
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Modulators will go bad over time. But before you rush out and buy a new one? Check the rubber hose at both ends of the steel line.. Had an older chevy (I know..evil word) van that had dry rotted the hose off at the modulator. Shifted extremely hard and late. Replaced both rubber lines? And she was all good.
Quick and dirty check on the modulator valve. If the hose is attached to it? Remove it and see if any transmission fluid comes out where the vac. hose was. When the internals fail? It will actually allow the engine vacuum to pull transmission fluid right up the tube into the intake.
And of course the usual, check and make sure the fluid level is correct.
S-
Quick and dirty check on the modulator valve. If the hose is attached to it? Remove it and see if any transmission fluid comes out where the vac. hose was. When the internals fail? It will actually allow the engine vacuum to pull transmission fluid right up the tube into the intake.
And of course the usual, check and make sure the fluid level is correct.
S-
Laughing Gas
Joined: Sep 2006
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From: Backwoods of western Pa
Also make sure you check the engine oil. If it is overfilled, that means that the modulator is shot and it has started to fill the engine with tranny fluid. You'll have to change the engine oil when you fix the modulator. Had this happen on my Bronco. Put about 8 extra quarts in the motor.
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Senior User
Joined: Jul 2007
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From: Rappahannock County,VA
I had just checked the oil yesterday and it was a little bit low but not by much. Checked the tranny fluid and it is pretty normal. I replaced one hose that goes down to the transmission to a metal line a while back when I had the tranny out. Anyone have a pic of the modulator so I know what im looking for?
Elder User
Joined: Dec 2007
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Follow the yellow brick road....hummm...nope...
Follow the vacuum line from the intake manifold to the steel 'tube', and it will connect to a small vacuum rubber hose that connects to the modulator valve. Just do a parts search at any of the online auto parts houses and it will show the pictures.
S-
Follow the vacuum line from the intake manifold to the steel 'tube', and it will connect to a small vacuum rubber hose that connects to the modulator valve. Just do a parts search at any of the online auto parts houses and it will show the pictures.
S-
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Senior User
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From: Rappahannock County,VA
Okay figured it out before I got the time to look on here again but gotta give my thanks to you guys anyhow. Replaced the modulator and boy the was a pita for a simple job. Getting it back in was hard, like it was spring loaded. Anywho took it for a spin and still the same thing! Both the vacuum lines are in good shape, the longer one I replaced a while back. Pulled the vacuum line off at the modulator and put my finger on it to see it had vacuum. In theory this should suck on my finger a little right? It didnt a bit and it didnt make the engine sound any different. I noticed the big line from the engine to the brake booster was a little cracked so im gonna get another one of those this evening maybe. What else could it be except internal damage?
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Senior User
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From: Rappahannock County,VA
How much vacuum should I have? Should it be able to suck my finger at idle cuz like I said it didnt and I would imagine it should. I mean no suction at all. What kind of problems could it be on the upper side? I mean that line was cracked but it didnt look like all the way through and it seems like me pulling that vacuum line off the modulator should make it idle rough if it was drawing accurate vacuum. Im sure it does have a leak somewhere cuz it lopes at idle some.
Elder User
Joined: Dec 2007
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You should have some vacuum at that line. If you follow that line up I believe it goes into the "vacuum tree" thingie at the rear of the intake manifold. Just disconnecting that one line won't be enough to cause the engine to stumble. Yeah it's vacuum--but the hose is got a small diameter so it won't cause to much of a headache.
Just a random idea---but how is the steel line itself? Should be rubber hose from the engine to a steel line down next to the valve....back to a rubber hose to the modulator. If the steel line is rusted out or damaged? Just thinking outloud about this.
S-
Just a random idea---but how is the steel line itself? Should be rubber hose from the engine to a steel line down next to the valve....back to a rubber hose to the modulator. If the steel line is rusted out or damaged? Just thinking outloud about this.
S-
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Senior User
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From: Rappahannock County,VA
Im thinking the steel line is in good shape, I pulled the tranny a couple months back or so to put a flexplate in it. I replaced the long hose back then. I got one to replace the shorter section today. The parts man just cut me off a short section for free but it wasnt long enough. Im gonna pull the floor pan outta it tomorrow and get a better look at the steel line and the long vacuum line down low. I guess its a possibility that it got pinched somewhere. I havnt had the time I wanted to deal with it today. I really hope it isnt something serious cuz its my daily driver and I really need the truck to feed cattle with. I got my dads old 20 year old hay unroller/mover out of the bushes and spent 200 bucks to get it fixed and shes been very useful to me. This is the first pickup I've ever had. The tree on the intake was a little bit loose. It was turned more parrallel to then engine than turned upwards. As in if it was a bolt it was 1/4 turn loose, I tightened it but havnt dealt with it since yet. Im still sure its something vacuum like you guys say though cuz it acts just like the time when I pintched the modulator line under a valve cover. It seems like I should get the smallest of vacuum on that line. Maybe I'll try putting a piece of paper on it tomorrow.
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From: Rappahannock County,VA
Okay, was tinkering around with it this morning, pulled the floor pan and was super excited to see the vacuum line to the steel line was loose. This is it i was thinking and got some new line while I was in town delivering hay today. Replaced both lines again and replaced the brake booster line. Started it up and the first thing I noticed was how much quieter it was with the choke on. Im super excited so take off in just a couple minutes of warm up and was again happy to see she runs pretty decent now even when cold. All the hype and I still have the same problem! I put my finger over the line again and I now I have vacuum down to the modulator. How delicate are the modulators cuz I did use a punch and a hammer to drive it in a little bit cuz it was being a PITA to stay in the whole and trying to put the hold down on by myself. Anywho I have her in 1st gear right now on flat with the parking brake on and chokes under the wheels. Im going to go check the fluid and if thats good then im clueless what else I can do. This is really bugging me but its an excuse to put the 4 speed in I have lying around I guess.