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700R4 no upshift - again

7K views 23 replies 6 participants last post by  camarodriver67 
#1 ·
I did 4 complete overhauls in the past year.
400 miles everything was running great, few days ago no upshift again - only first and reverse.
I checked line pressure with TV cable pulled and released
Looks like the TV valve is stuck on full open.
Last time I open the valve body (400 miles ago) the TV valve was moving freely.


Tv cable released
started the engine (cold) pressure at P was at 70psi and then 20 sec later jumped to 125-130 psi and stays there.
P - 125psi
R - 190psi
N - 140psi
OD - 130psi
D - 130psi
2nd - 140psi


with the cable fully pulled
P - 140
R - 190
OD - 140
D - 140
2nd - 140


How do I fix it?
The Tv valve has the little aiding spring.
 
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#10 ·
There are no new valve body's here in israel, it's either order a new from the states (and wait 4-6 weeks) or get used one.
I chose the used one.
Yesterday after a week of cleaning the "new" used VB I finally put it in the truck.
NO CHANGE!


Transmission still shifts only in very high RPM, and the pressure reading I took were around 70psi in both TV valve positions.
Pressure not rising when TV valve is pulled out - that's a new symptom.


When setting the TV valve I took some pictures to see what is the relation between the throttle and the valve.
This TV valve does not have the helping spring (at the back) so there is a little slack in the valve till the main spring starts to engage.
When throttle is at WOT the TV is out of its bore by 0.2" when throttle is at idle the TV valve touches the "cable" only if I pull the valve all the way out.
Both pictures here are at the same idle position.
One is when I pull the valve all the way out
second is when I push it all the way in till it touches the spring.
I'm starting to think my throttle lever is not correct.


After unable to fix the problem with the valve body, I moved to the governor.
I could not see anything wrong with it's movment, so I opened it up and only then I saw a little nick.
This nick was not doing anything when the valve was in, but when I took the valve out of it's bore and then tried to put it back in - it hits.
Here is a short clip I took.


https://youtu.be/_yGiGHPfANs

I filed the nick a little, the valve was still hitting on it, but it look a little better.
Put the governor back in the truck and went for a test drive.


Truck was shifting from 1st to 2nd at a little high rpm (just 500 more than usual, maybe wrong tv adjustment) I had my part throttle shift again, I was happy and than I found it does not shift to 3rd.
Not even in high rpm, I could drive 65mph in second with the torque locked and unlocked but no 3rd.
 

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#15 ·
I've done some more reading, they say if you can shift from 1st to 2nd in part throttle at low rpm then the governor is fine.
(I can)


Nevertheless, I sourced a "new" used governor and went for a test drive - same same.
only 1st and 2nd, no 3rd.
I will replace my valve body again to the one I had before it all started.



Maybe this VB has problem with the 2-3 shift valve - I have no more new ideas...
 
#17 ·
Just got back from a test drive.
I got all my gears back.

But (why there is always have to be a but)

Transmission is getting hot very fast, 2-3 miles and temp is at 175, a few extra miles and temp is at 200, before it never went more than 170.

Feels like slipping, didn't push it too much so i'm not 100% sure.
Before I start to cry and take the transmission out for a complete rebuild, could it be related to TV adjustment?
I set the TV a bit tighter than before.
 
#18 · (Edited)
I think the key to your issue lies in the line pressure and no line rise with TV valve depressed. 70psi isn't terrible for base line pressure at idle in park on a stock unit. However, you should see an immediate rise in pressure as you begin to pull the TV cable. As far as setting the TV, basic rule of thumb is, when the TV cable is at full pull, which it needs to be at full throttle, the valve plunger should be flush with the TV plunger sleeve. In other words, the TV valve linkage cam should depress the plunger in as far as it can go so that the cam itself touches the TV plunger sleeve. Also, the fact that you are having to pull the valve back out to touch the cam tells me that the TV plunger spring is too weak, or the TV valve is stuck.

If it were my trans, the first thing I would do at this point is pull the TV plunger and sleeve out of the VB. Check that spring to see if it is collapsed. If necessary, find a stiffer TV valve spring. This spring along with the pressure regulator valve spring set base line pressure and have a big affect on line rise.

Check the plunger sleeve for wear, the plunger for sticking in the sleeve. The sleeve is aluminum and the plunger is steel, which tends to wear on the aluminum sleeve. It is a basic upgrade also to install an anti stick spring on the TV valve itself. For clues on this, do a google search for 700R4 performance mods. Look for the Transgo video, on their website, of the 2-3 shift kit install. While there are things there you don't need to worry about, they do touch on installation of the no stick spring. These springs are used by most any trans shop and shouldn't be too hard to find. You can service the TV valve plunger, sleeve and spring without removing the VB. Installing the no stick spring will require dropping the VB to remove the TV valve itself.
You may end up wanting something like the the Transgo or Sonnax TV valve spring. In fact Sonnax sells a complete line boost kit that includes a stiffer plunger spring, stiffer pressure regulator valve spring, and large ratio boost valve. They also sell a very well made billet TV plunger sleeve with new large bore plunger.

Once you have the TV valve working right. With the trans in park, check line rise with a 400psi gauge in the line pressure test port. You should get at least about 70-80psi at idle in park with no TV pull. Pulling the TV cable to full travel, you should get 150psi at idle in park. At 2,500 rpm, the pressure should reach about 200+psi at full TV. A little less should still work okay on a stock trans. A minimum I suppose would be about 180 at 2,500 in park. Others who know more than me, which is alot of people, may say different.

Shifting into reverse, the pressure should jump to 200 at idle. If you are still not getting line rise after addressing the TV valve, you need to move to the PR valve and boost valves. I hope you have a good service manual for the unit. It is critical that you assemble the boost valves correctly and that they move freely in their sleeves. The Transgo video also touches on assembly of the boost valves. Check the PR valve spring for being collapsed. Make sure the valve moves freely through its full travel. Mainly check that it isn't getting stuck in the decrease position, about 1/4 inch or so from the top of its travel.

Once you have verified the TV valve, PR and boost valves are working correctly. If you still don't have line rise, you will need to tear down the unit to check the pump for damage or a missing slide spring, check the unit for cross leaks.

The governor will cause a no up shift, but unless it is completely missing from its bore, it doesn't explain no line rise.
 
#19 ·
Sorry Rob. I didn't catch your later posts, that you got your gears back. Apparently, you are also aware of the TV valve sticking issue.

The heating up and slipping are most likely caused by the same problem. Slipping clutches due to low line pressure will cause the fluid to heat up. One more time, you need to connect your pressure gauge. Once you verify line pressure and line rise are normal in all gear ranges, you can also use the gauge to check the individual clutch apply circuits by connecting at those test ports. This may give you a clue to an internal leak.

I know it's a pita to do, but on any overhaul each valvetrain in the VB should be removed, the bore and valve cleaned. You can use a scotchbrite pad to gently deburr the valves and then as you reinstall each one, make sure it moves freely. These VBs are cast iron with steel valves. Rust can be an issue on a VB that sits out for any time.

When you had the trans out last time, did you flush the cooler lines? Have you done the PR valve mod, removing the second land to increase cooler flow? You may have a later unit with flats on the PR valve second land.
 
#21 ·
Trans was getting hot, I figured it's because some clutches are slipping, I found some clutch debris in the oil pan (again).
And for icing on the cake - trans did not always shift, sometime it did other time I had to rev it very high.
I gave up and decided to take the truck to a local trans shop.
They rebuild the trans in 3 days (it would have taken me just 2 weeks to get the trans out of the truck)
Went there to take the truck and found that it overheats fast and line pressure is not high enough.
It's been almost 2 weeks now, and the truck is still there...
 
#22 ·
That stinks. It's one thing if we fix it ourselves and have an issue. It's another thing to pay a professional to fix it and have an issue. I hope first that someone at the shop is actually familiar with the 700R4 and can find the problem. I further hope that they care enough to get it right.

If you have any kind of material in the fluid, it ends up in the cooler. At the very least, the cooler has to be flushed anytime a trans makes crud, whether it's metal or friction material. Otherwise the crud just ends up right back in the newly rebuilt trans. If the cooler has enough junk in it, it may not flow at all. The factory style cooler installed in the radiator may not flush clean, once it's contaminated with material. Often best to just bypass it with a good external cooler. In addition, it's important to have a regulator valve installed that increases cooler flow, like was installed in the later units.
 
#24 ·
I hope from the first time you found clutch material in the pan you remove the trans cooler and clean it out really good and replaced the torque converter unless you have a way to flush it. After you flushed the trans cooler and installed new converter you need to take it to a shop to have the transmission flushed, then change the filter and add new fluid. This should remove and clutch material in the system.
 
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