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Old 12-13-2006, 04:51 PM
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700R4 quick diagnosis?

So my 700R4 in my 89 Suburban started acting up as soon as I got the engine running great again. It is a remanufactured unit that was put in somewhere between 50,000 and 80,000 miles ago. Pulls real hard, but all of the sudden has problems shifting. I can barely get it to shift, and it's at extremely high rpm's in first gear. I really have to gun it to get it to shift, sometimes backing off throttle. I don't know if it will even go into overdrive on the highway, but it seems to be at least going into third.
I also noticed that many times during city driving, it won't downshift into first, as I realized a few times that I was taking off in second gear. When it takes off in second gear from a stop light, I can very easily get it to kick back down into first gear when I put my foot in it.

I had noticed a really stiff gas pedal at times in the last several months, and a few weeks ago, I sprayed some lubricant in both ends of the cable. However, I did notice it doing the same thing a time or two since then. I thought maybe it was the TV cable sticking as I was reading up on it last night, but upon quick external inspection of the TV cable just now, it seems to be moving freely.

Any clues on where to look? Is this mainline pressure tap that is spoken of on here located on the driver's side of the trans case near the middle? I think I have a compression test gauge, I'll see if that will work on it at all, or if possibly I can hook up a regular air pressure gauge to it.
Hoping it's not a severe internal problem. I haven't spent much time educating myself on automatics (manuals only in my project cars!), so I don't have any advanced repair knowledge.
If it was just a cable adjustment or replacing some simple parts, I may tackle it myself. If it involves the valve body very much, I think I may leave that to a pro. Money is tight at the moment due to house rehabs, so I'm hoping I can figure this one out on my own.

Does this sound like a time bomb if I drive it more before I repair it?

Also if someone could explain to me exactly what the TV cable does as far as shifting goes, that would be helpful. As far as I can imagine, I would guess it just triggers downshifts upon harder accelleration, correct? If under light accelleration at higher speeds, does it also trigger upshifts when letting off the gas? Maybe my problem lies more in the governor or valve body?
It seems to shift a little better from second to third than it does first to second, but still not normal by any means. It seems to do the same thing hot or cold. That is the only thing that gives me hope of not having to do an entire rebuild. Could the TV cable have slipped where it attaches in the trans? I have never even taken the cover off of a 200/700R4 to see what it looks like. It's been a good 12 or more years since my last minor auto trans work, and that was a TH350.

Thanks,

Chuck

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Old 12-13-2006, 06:25 PM
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UPDATED SYMPTOMS:
Now it seems that when I try to force it to upshift from first by quickly letting off the gas at high rpm's and then stabbing the gas again, it now skips 2nd and jumps into third! And it won't downshift at all unless I manually downshift it. When I let up off the gas in 2nd and 3rd, it seems to upshift normally. It will not upshift out of first unless doing as described above. I only got it to downshift from second to first once or twice on the 10 minute drive, and that was at lower speeds. No other gears will downshift.
Also, if I try to force it to downshift manually from 3rd to 1st gear, it seems to dump it in second, and only will go into first if I hit the gas. Normally it always would just drop through the gears straight to 1st when I would put it in L1.

Still sound like a sticking throttle valve, or is this a more serious issue? How difficult is it to install a Transgo Jr. shift kit, and would this fix the problem? If so, can I install a shift improver kit like the Jr and skip a part or two and keep the originals so that I can maintain the same smoothness of shifts as from the factory? I'm afraid it would just tear up my truck, as I am not racing it at all, just used for transportation and hauling.

Thanks.
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Old 12-13-2006, 07:21 PM
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govenor

i really dont know much about the 700r4's but as i have one i would like to know the solution to your problem. i have heard that these trannys have a plastic govenor gear and they tend to get eaten up. i would think if your govenor wasn't working properly it would make the tanny act weird. i had a simular problem with my tranny and when i took it to the tranny shop it turned out to be a mis-adjusted tv cable. but as i dought you have messed with your tv cable, i think it would be the govenor. try reading some the the posts about this tranny on here, there is a lot of good information here!
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Old 12-13-2006, 09:07 PM
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If you have a sticky governor and TV valve in the v-body... this worries me after a recent engine replacement.

Is it possible the converter was not fully engaged when the engine was bolted back in?

Has the TV cable been readjusted since the engine install? Full cable pull at WOT is the correct setting to start at.




If the tranny is generating metal to stick valves and related items , something is wrong. A shift improver kit will not repair it.

The TV cable tells the tranny everything. It raises line pressure and shift points in relation to the engine load. That is why the adjustment & operation of the TV cable is sooo important on the 700/4L60 tranny.


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Old 12-13-2006, 09:22 PM
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Engine is running GREAT with almost 250,000 miles, never rebuilt. I just mentioned that I had gotten it running great again (tuneup and new fuel filter/plug wires really helped!), and the tranny took a dump the day after...

I have never touched the TV cable adjustment. Never changed the tranny filter since I've had it (3 years/40,000 mi).

I'll check to see that the cable has full pull at WOT. I didn't want to attempt to use my compression gauge for the tranny, so I will use a spare air pressure gauge, but I need to reduce it to a smaller pipe thread size with a few fittings, maybe Thursday I will check that out.
Is the main line pressure tap on the driver's side near the middle of the trans?

Is there anything else electronically controlled in the trans besides the torque converter lockup? Wondered if there could be a bad connection?
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Old 12-14-2006, 02:04 AM
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i would drop the pan, change filter and fluid and see if there is anything is getting eaten up in your tranny. i was driving a friends truck and the truck started to act weird, wouldn't shift and holding gears to long. i know that it had a completely different tranny, but when i cracked the pan to change the filter and fluid i found a pile of aluminum shavings in the bottom of the pan. not a good sign. when i asked her how long ago she service the tranny, "dont they do it with the tune up". lets just put it this way, 2000 dollars later the truck was on the road again.
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Old 12-14-2006, 06:03 AM
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700R4 quick diagnosis?

This won't be an electrical thing,ie bad connection because it is an 89 unit,no shift solenoids,etc. The mainline tap is on drivers side,near linkage.

Have you pulled the dipstick out to check condition of fluid? Look at the stick in sunlight,you should not see anything sparkling in the fluid on the stick.

Of course if you do see glittering,this would explain why things[valves] seem to be hanging up. While the prognosis is not good,based on symptoms,if the fluid is void of metal the tv cable may still be the culprit. Good luck with this.
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Old 12-14-2006, 03:57 PM
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WOW, not sure how accurate my 160psi air pressure gauge is, but it clocked in at around 130PSI in park on fast idle!!!!! Could my throttle valve stuck on full throttle????? Might drop the pan in a minute.

UPDATE:
Automotive engineers in recent years seem to really have their head up their *****, who would design a vehicle to have the transmission crossmember directly underneath all of the rear bolts that hold the transmission pan on!!!!!! THANKS! Now I have to deal with 8 really rusty nuts and bolts that hold that on, and put a jack under the trans once I torch those off and slide the crossmember back, JUST TO REMOVE THE STINKING PAN!!!! No way to really get to those bolts otherwise!

Anyway, daylight is scarce these days, so I held the dipstick under a shop light, and I may have seen some really really fine metallic sparkles in the fluid... If that's what I was seeing, they are so small that they are barely visible. Is this a really bad sign? Or is this somewhat normal for a high mileage tranny? I was hoping to drop the pan to see if there were any large fragments or debris in it, but I'll have to wait until tomorrow after work to get the air impact out at a decent hour.

Please enlighten me more on whether or not these type of symptoms could be easily fixed with this:


Also, does the full on Transgo 700R4 shift kit include all parts in the Jr. kit?

Last edited by Chuck78; 12-14-2006 at 06:28 PM. Reason: update
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Old 12-15-2006, 07:57 AM
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700R4 quick diagnosis?

Putting a pressure gauge on mainline tap,and checking it in park,pressure over 90psi usually indicates a sticking tv valve. For those that have a gauge or will spend the relatively small amount of money,to purchase a gauge,the readings obtained can be a huge help with diagnosis.

The factory pressure regulator spring is calibrated to run about 65-70 psi.

When the tv valve sticks,it introduces a greater influence on the pressure system. Since governor pressure is already trying to overcome the spring tension on the shift valves,this pressure will push,or stroke the valve so that fluid can travel to the necessary component.

For example,the 1-2 shift valve strokes,fluid travels to the 1-2 shift check ball,seats the ball,travels thru the 1-2 shift passage[hole in separator plate] travels to 1-2 accumulator piston,travels to converter clutch valve,3-4 relay valve,and to the 2-4 servo,to apply the band,giving you a nice 1-2 shift.

In addition to the spring pressure on the 1-2 shift valve,there is also M.T.V. up oil[fluid] which is the resulting pressure from the tv valve,which is also producing a force on the 1-2 shift valve. This fluid pressure,and spring pressure, is what the governor is pushing against,trying to stroke the valve.

You can see by this explanation that,a sticking valve that raises pressure in the system,will produce a much greater force for the governor to overcome [to stroke the valve] ,since governor pressure increases with road speed,this is why the shift points increase so much when the tv valve sticks.

The governor will usually build up enough pressure to overcome these forces,and the trans will shift,eventually!

OK. The gauge tells you the tv valve is sticking,the stuff you see on the dipstick tells you maybe something is not so good. when you pull the pan,then you will know the rest of the story.

If the pan has got metal in it,a very little may be alright,but too much means something is very wrong.

If not much going on in the pan,put the transgo kit in,if the tv valve was sticking,this will fix it. If you don't want to install the entire kit,thats ok,only use the tv valve setup. A high mileage unit will have some stuff in,fine metal is not ok.

The performance kit does have this redesigned tv valve.

Best of luck to you Chuck,post back if we can be of further assistance. Dana.
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Old 12-15-2006, 06:44 PM
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just a short comment from me tonight;

engineers have been putting cross members under or in the way of the tranny pan for many , many years. Or the exhaust pipes are in the way too.

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Last edited by Crosley; 12-15-2006 at 06:51 PM.
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Old 12-17-2006, 11:28 AM
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Dropped the pan, no debris in pan, but the fluid probably could have used changed 40,000 miles ago! Looking at where the TV cable goes into the trans, the linkage that it comes in contact with has a bit of movement before it even touches what I would call a plunger in the valve body. Down the line just a little from that "plunger," I see a small opening on the other side of the plunger that I can see a spring in the bore of. I can move the "plunger" in and out by hand, and I can also put a flat head screwdriver on the spring and move that back and forth with some obvious slop/free play back and forth. I'll have to buy a 700R4 Haynes manual and see what part it is exactly that is sticking. In my picture of the Jr. kit above, what I am calling the plunger looks to be what is clearly visible on the bottom right of that picture. So is there something else that is stuck inside the valve body? a ball check or something?
Or is that plunger all there is to it that would be sticking, and is that spring that I can see in that small opening just seated up against something solid, to provide as a return spring for the TV plunger piece? If so, the spring must be worn our or broken in two somewhere, as it does not push plunger backto return to come in contact with the cable linkage. I'm afraid to take it apart without any further understanding of the assembly, and without the TransGo kit.

I can take a picture if that will help, but I'll see what the Haynes manual has to educate me on, and post again.

Any suggestions would be great! Trying to locate the SK700Jr kit locally, no luck yet.

Last edited by Chuck78; 12-17-2006 at 03:27 PM. Reason: additional questions
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Old 12-17-2006, 02:46 PM
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Well, I leafed through the Haynes manual for all the 3 and 4 speed GM automatics for RWD vehicles, and it doesn't go into detail at all about the 700R4. It just has disassembly and re-assembly instructions. The Chevy Truck Haynes manual doesn't have much at all for the trans either, just TV cable adjustment procedure, replacement, filter change, and maybe one other minor repair. No in depth info at all. Maybe Chilton's has a better manual that I can reference?

So I still could use a lot of advice!
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Old 12-18-2006, 08:45 AM
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700R4 quick diagnosis

Chuck, the tv valve that sticks, is further in the vb bore than you can see.

You must have the valve body off the transmission to install the transgo tv valve.

The picture you posted,the valve right above where it says step 3,this is the redesigned tv valve.

When you do get the kit,you will find very good instructions,along with good pictures that will assist you with installation.

Don't freak out on us here,you can do this. But prepare to get messy.

If the transgo kit does not answer all of your questions please post back. Good luck!
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Old 12-18-2006, 05:10 PM
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Got the complete SK700 kit from TransGo at a local wholesale trans part distributor for $54.99! The packaging is quite a trip, the "NoYoYoİ SysKoKalİ Kit" as the cartoon head drawing of Gil "Mr. Shiftİ" Younger calls it on the package!!!
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Old 12-18-2006, 11:43 PM
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wow, the instructions for the full SK700 kit show a heck of a lot of stuff! I think this one may take me quite a while!
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