Shifting poorly and bad shudder

[HardCorps79]

So, just when I got the IP replaced and was enjoying the M1009 immensely, something else had to get weird, right?

I searched this and read a good 30 threads and saw similar things, but nothing just like what I'm experiencing. So, here's the deal:

The truck is driving like a tank. 1st gear is great and shifts smoothly to 2nd. But my shift point into 3rd went up from around 35-40 to 45-55mph. And between 40-55 the engine shakes and shudders like I'm driving with the brakes on. It will barely pull itself up a hill. Once I get over 60mph and up through 70mph, everything's peachy again (except going up hill- shudders slightly which it didn't do before). Then when decelerating, it shakes and shudders and feels almost like it's jake-braking down through the 50's to the 40's. Once it's in 2nd, things are cool again. What gives?

The tranny fluid was a little low (right at the fill line) when I noticed the problem, so I put a pint in and it measured right at the top line. Seemed to shudder a little less for about 100 miles, then it started dragging again even though I'm not leaking fluid.

Also checked that the vac-modulator on the IP hadn't loosened and moved. Was right where I put it on the last adjustment which had been fine for my shift points.

I just changed the vac lines from the IP to the Vac-pump a couple months ago. So I'm pretty sure those should be good, but could there be a leak somewhere else?

It's still driving fine to and from work, as I don't get over 25 mph, but I don't really want to take this out in town and blow it up.

Could this be the vac-pump itself (didn't I see somebody had them NIB on here a few months ago)?

In order from simple/cheap fixes to complicated/expensive, what are your recommendations to check and replace?

 

[4bogginchevys]

the problem does not seem to be vaccuum to me......maybe a partially clogged filter, it's a cheap try......if you replace filter, make sure that you re-use as much of the origanol fluid as possible. Nothing will make a old, almost ready to fail transmission go to it's grave quicker than 8 new quarts of fluid. Good luck!!

 

[HardCorps79]

So this tranny is gonna go out with 50k miles on it? (Realizing it's 23 years old, but still!) I'll have to dig in and replace the filter this weekend, I guess. Any other ideas floating around out there? Was hoping the tranny would last at least until Jan/Feb...

 

[Westech]

mine was doing the same thing! I found a cooler line that was crushed and not flowing much. I replaced the cooler line and added a 20K transmission cooler and never had a problem after that.
I would look for that and a good filter kit and some new fluid never hurts.

 

[derby]

Are you shure it is not 150.000 miles? I had a high milage GM trans that I thought should have some service done to it, bad idea! I ended up replacing the filter five more times. My neighbor told me to re-use the old fluid but to strain it through a nylon stocking. I thought what a dumb idea! well 15 miles down the road there I sat with a trans with 5 neutrals. it would move about a quater mile at a time then time for a break. seems the new fluid will flush all the crud to the pan and plug the filter,as mentioned above. pull the vac line off the shift modulator and see if there is any trans fluid getting past the diaphram. also check the kick down cable, make shure it is not frayed and works smoothe.

 

[flewbyu]

All that "old crud" flushed out by new fluid is friction material from old discs. New fluid has very high detergeant content and will clean your clutch packs of stuff that should be there. Creates slipping, which creates heat, which is the number one tranny killer in the world. And regardless of how few miles are on these trucks, never kid yourself they were all down hill with a tail wind and no load...LOL!

 

[tm america]

if your filter is getting clogged you have something coming apart in the trans from the sound of it you ran it low and burned up the direct clutches brake torque it in rev see if it slips if so you fried third and trans has to come out to fix it putting a new filter in a bad trans is like putting a 20dollar bandaid on a broken dam. i agree with not changing the fuild on a high milage vehicle that hasnt had its fuild changed regularly since aft is a detergent and will free up any sediment in the cooler and could make the gov stick but sediment comes from worn out parts which means you have something coming apart either way

 

[HardCorps79]

With the ridiculously unworn condition of most of the truck, and being a ARNG HQ CO vehicle, 50k miles doesn't seem unbelievable. The tranny and diff fluids appear to have been pretty well maintained and regularly serviced. There's paint marker on the covers/pan says "changed xxxxx 2007" (don't remember the date, but it was late '07). I bought it early '08. Tranny fluid looks good and clean- not a ton of sediment, nice clear red. (Course, who knows what's settled to the bottom).

So, Westy- tell me more about this cooler line and filter kit...

 

[HardCorps79]

*bump*

 

[aebiv]

I'd certainly do the filter, and my guess is yours is like mine, and does have low miles... If you drain the fluid, try blowing through the cooler lines, it should push out any of the old fluid, if not use an air compressor to make sure there is no blockage... Also, a good shop has a tool that plugs into the cooler lines to flush the whole tranny, which also helps remove blockages and is what I'd recommend.

Otherwise, of course check the filter.

 

[HardCorps79]

Wow- okay. So it's apparently a gremlin. *praying* I think running it hot while low on fluid may have locked up a clutch or something (I probably have no idea what I'm talking about, but it sounds good, right?). It just never felt like when I put it into gear with the shift lever that it was locking all the way in. After filling it to the right level and running it around town in 1st and 2nd, last night when I moved the shift indicator it kind of popped solid the way it should and lo & behold, it's running great again. Any chance the new ATF I topped it off with unfroze a clutch or something?

Another possibility is that I had run 2 full minis of Howe's through the fuel system. It had been a little weak since I put in the swapped Injector Pump. Any chance that the Howe's loosened up some debris that maybe clogged an injector or a line, and then after the second bottle, cleared that too?

About 3 days after running the second bottle of Howe's through and topping off the tranny fluid it seems to run better than ever: quieter running even when cold, smooth solid shifts and great acceleration. I have yet to take it out on the freeway, but in town it hit 50 with no shuddering to speak of and got there quicker than it ever has before. Weird.

Is there maybe something I need to check between the shift indicator and the transmission? Not sure what I'd be looking for as to why it wasn't going into gear all the way.

 

[ssgtwright-usmc]

Had a similar problem but it was a easy fix after about 2 months of trying to find the problem.
Mine was the rubber vacuum line from the transmission modulator to the metal vacuum line to engine.
The rubber vacuum line, about 4-6 inches in length had dry rotted and was sucking in air which made it not want to shift or even give me speed.
I replaced the hose with a HD fuel line and that seemed to fix my problem.

 

[The Janiter]

Ford autos have a problem with shudder also - most shops tell you "Replace" $$$$$$ - the one I use just told me to bring it in every year and they change fluid and filter plus an additive - cost me $125.00 and no more shudder. could be just the same nature of the beast (car has 114500 miles) same trans. Down time is hard on a auto.