Automatic transmission woes

[Snatch Napkin]

My work truck, 1997 Chevrolet 1500, has decided to quit pulling. I check my fluid routinely, and it has always been level, excellent color, and proper smell.

Last Wednesday, I was heading to the gym when it suddenly quit pulling. I was driving normally (grandpa slow) and the transmission lost all ability to move the vehicle as I was going through an intersection. After getting into a parking lot, I check linkage, drive shaft, and then fluid level. It now appears to be overfilled, but I haven't had to add any since I took ownership of the truck over a year ago. It still looks good and smells good, though.

I get back in the truck and go through all the gears to see if maybe it was just an odd fluke and notice that it goes into reverse and drive as it always did. I start to drive it back home and it starts slipping again. At this point I get it towed home.

I don't know much about automatic transmissions. I'm hoping that maybe some trash has blocked a pickup passage and a simple filter and fluid change could fix it. I can do that myself. Has anyone had a backflush for their transmission? My dad made this recommendation, but my lack of knowledge on the subject has me paranoid.

Does this sound like a pump has quit pumping? Modulator valve?

Any help will be greatly appreciated. I assume the transmission is a 4l60e as the motor is a 350.

[91CoupeMike]

I've had one do that in a 96 with a 305. Never had a problem and then one day it just shit the bed going down the highway, we were acually exiting the freeway and it wouldn't move from the stop sign, clutches were fried and the trans was rebuilt.

[Lone Sailor]

The only times I've had that happen to me, and this was all in Mustangs, either the fluid was too low, the front pump was going out, the line pressure was not within proper spec(cable), OD band was toast, had a sticking valve, clutches were completely worn out, or the cooler/lines were restricted and limited fluid flow as well as cooling effect on the fluid that able to get through. Again, these were all Ford AOD problems.

[Snatch Napkin]

I feel like it's a pump issue or a clogged passage, but I have very limited experience with autos.

I can't decide if I want to have it back flushed or if I want to replace the filter and fluid myself to see if there is any trash build up.

[Lone Sailor]

All you're going to see is dark fluid and possibly some metal shavings, but depending on how fine they are you will probably have trouble seeing them unless you use a screen and sift the fluid after you drain it. Up to this point had you been keeping up maintaining the transmission with fluid and filter changes at recommended intervals?

[Snatch Napkin]

Yeah, this truck has 172,000 miles. I drive it like an old man. I maintain it so it will last as long as possible. I fully intend to drive the wheels off this thing.

I finally found something of substance, so I'll go through this list after work.

http://www.gmtruckhq.com/?q=node/93

Common failures on 4L60E, symptom < cause > any possible repair:
1. Slow, slipping or no reverse: “lo-reverse” clutches are worn out, fluid leak in the reverse apply circuit, or broken sunshell. It is possible to remedy a fluid problem by removing the checkball from its cage in the case in the rear of the trans may help (must remove valvebody), or adding a high-viscosity additive such as Lucas Transmission additive or other seal restorer product. May also have worn boost valve (can replace in the pan).
2. 1-2 shift does not happen at WOT until you let off the gas: Best case: try replacing the TPS. Middle case: leak in the 2nd gear apply circuit (servo assembly or 1-2 accumulator). Doublecheck by using the pressure gauge and watch for a big drop when the PCM commands 2nd gear. Worst case: poor line pressure rise (see below).
3. 1-2 Shift shudder at WOT; delayed or abnormal 1-2 shift; There's a problem ONLY on the 1-2 shift: 1-2 accumulator piston cracked or stuck cocked in the bore. Check the yellow spring inside the accum housing for breakage. Also, if the accumulator housing walls are scored, the housing must be replaced. Easy fix in the pan.
4. 1-2 shift is delayed and harsh, may not shift into OD: Check TPS for smooth and linear electrical response over the entire range of motion. If not, replace.
5. Trans does not upshift out of first, speedometer reads zero at all times: VSS failure. Easy fix on rear of transmission, but xmember must come out to access VSS.
6. No 3rd or 4th gear: “3-4” clutches are worn out. R&R. The car is safe to drive (in 2) until you can get it fixed.
7. Sudden grinding noise with no prior warning primarily in 2nd gear, behavior in reverse may be abnormal; sunshell is fractured. R&R. Try not to run or drive the car or further damage could result.
8. 1st and 3rd only, no 2,4 or R; sunshell is fractured or splines are sheared off. R&R. Try not to run or drive the car or further damage could result.
9. No 2nd or 4th gear. 2-4 band is slipping. Servo seals may be damaged (can be fixed without removing trans. Otherwise, 2-4 band is worn out. R&R.
10. Trans shifts into gear harshly, car feels sluggish off the line, No 1st, 4th or TCC lockup available, Manual 2nd, 3rd and Reverse are only available gears, CEL is on: Transmision is either in limp-home mode or has lost electrical power. If there are lots of error codes in the PCM, check the underhood fuse that powers the transmission, and if it pops again, look for a short in that circuit like an O2 sensor harness touching exhaust. Otherwise, check PCM codes for a particular fault in the transmission causing the PCM to put it in limp-home mode.
11. No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD and locks the converter : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
12. Car goes into gear but feels very sluggish like the brakes are dragging, but it will roll easily (starts out in 4th gear), you manually shift to 2 to get it moving, once it's moving you put it back in OD and the car shifts 3rd to 4th on its own and locks the converter at the appropriate time: ShiftB solenoid failed: Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.
13. No TCC lockup: Brake pedal switches improperly adjusted (always on), TCC solenoid failed (easy fix in the pan), TCC clutch worn out (must remove trans and replace TC).
14. TCC always locked: TCC apply solenoid circuit shorted to ground, TCC solenoid blockage (easy fix in pan), or TC broken (must remove trans and replace TC).
15. Horrible noise in 4th and feels like the brakes are on: overrun clutches are applying due to a cracked or leaking forward piston. Overrun clutches will be worn out after 30 seconds of this behavior. Car can be safely driven in D. R&R.
16. Soft shifting, gradual performance degradation: Poor line pressure rise due to leaking boost valve, clogged EPC filter screen, failing EPC solenoid, or worst case: leaky seals throughout. Transgo HD2-C kit fixes first two without removing trans. Seal restorer may fix last problem, but probably R&R. Also try a transmission flush with BG brand products (Firestone stocks it).
17. No forward movement in OD or D, but L2, L1 and R work: Forward sprag is broken. R&R. Try not to run or drive the car or further damage could result.
18. Extremely harsh shifts from P or N, normal shifts at WOT: EPC (Electronic Pressure Control) solenoid failed. Easy fix in pan. Fix as soon as possible or hard parts will eventually break.
19. Loud bang, grinding sound, loss of all gears, and a binding driveshaft: snapped output shaft. Try to wiggle driveshaft - if more than 0.020" play, that's the sign. R&R.
20. Trans seems noisy when moving in 1st and Reverse, noise goes away instantly if you shift to N or the trans goes into 3rd gear: Reaction planetary is worn out due to high miles or insufficient lubrication. Not a critical failure, but not a good sign either. R&R sooner rather than later.
21. No movement in any gear: pump failure, or total loss of fluid. R&R, or refill pan and find the leak. If out of fluid, avoid running the engine until the trans is refilled to avoid pump damage. To check for pump failure, check fluid level with the engine off, then start the engine and recheck fluid level. If level does not go down when engine is running, the pump is broken.
22. Transmission does not shift automatically, only manually. Swap in a known-good PCM, check wiring, check other sensors such as VSS and TPS.
23. 3rd gear starts, can manually shift through all gears. When car has been turned off for a bit, then back on it will run normally.: VSS dropoff w/ Hi-stall converter. The rpms are too high, but VSS is showing no movement. Happens after a tire burning take-off. Doesn't store a code, will not throw a CEL (I've heard that it will store a code if it happens 3 or more times). Cure: Reprogram PCM for VSS dropoff -- PCMforLess knows about it.
24. Fluid leak out of the front of trans where the converter connects; partial or full loss of movement: Front pump bushing walked out. R&R. May have to replace converter also if hub is scored. Note that a leaking front seal usually means the bushing is walking out (i.e. call your local trans shop and schedule an appt.).
25. Torque converter shudder in 4th while lockup is engaged; problem goes away when the brake pedal is pressed slightly to unlock converter. Have a shop verify line pressure, and provided no valves in the TCC hydraulic circuit are worn, replace the torque converter. Also, Lubegard Shudder Fix will at least fix this for awhile. Or try a transmission flush by a shop that uses BG brand products.
26. Shift suddenly become very hard. When going from park to either reverse or drive it slams into gear. 1-2 and 2-3 shifts are also harsh. All gears seems to work. Problem may be intermittent: Check TPS for smooth electrical response. If the response is jumpy or erratic at all, replace TPS.
27. All fluid pumped out through the vent tube: Plugged cooler line. Flush the transmission cooler and cooler lines. Also could be overfiled transmission.
28. Car acts like it's in OD in neutral, car is locked stationary in R, engine feels loaded in P, all four forward positions work fine: R&R: Internal crossleak feeding the forward clutches all the time. Most likely a cracked input housing, or cracked forward piston means forward clutches are fused together. Car can safely be driven gently in forward gears until the repair.
29. Needle bearings in the pan, first gear and/or reverse may be noisy: Either a torrington bearing or a planetary bearing is on its way out. Trans will eventually die a loud, catastrophic death. Cheaper to rebuild now (saves further damage to hard parts), but requires R&R. It is drivable until it breaks.
30. 1-2 or 2-3 shift is slow/soft above part throttle: Trans is on its way out. R&R.

[Lone Sailor]

Any updates?

[Snatch Napkin]

I've been too busy, then the rain happened last night.

I'm hoping to look into it in the next couple days.

[JimD]

Since we don't have a backflush machine at work, we replace filter, clean pan, yank off 1 line going to the cooler. fill it back up. Start motor, continue to pour fresh fluid in till comes out clean at the line. Worth a shot, but ill bet the trans is fucted.

[shumpertdavid]

my guess would be trans will need a build. 4l60's have proven to be junk for the most part. It's the most common build transmission by my buddy in that business. If it's not had regular routine filter/fluid changes then it's had a good run/life to have made 172k. You can gamble the fluid\filter change, but in my experience (auto tech for last 15 years, damn that makes me feel old) changing the fluid/filter only escalates the problem.

Worst case scenario for us was one that was slipping, customer wanted to do fluid\filter service against our better judgement. Performed service and vehicle literally would not pull itself out of the bay.

[JimD]

Worst case scenario for us was one that was slipping, customer wanted to do fluid\filter service against our better judgement. Performed service and vehicle literally would not pull itself out of the bay.

Yep, then they think you did something to it.

[JC316]

170K is about the life span of a 4L60-E in a truck. It was about the same for the 700R4. My guess is that it's shot.

[03shadow4v]

What did the fluid smell like ?

[Snatch Napkin]

Just got a chance to look at my truck.
The fluid has gotten thinner, there's even more than the last time I checked it, and it is darker than before.

Also, it makes noise that it didn't make before.

I would say its toast.
What are my chances at getting it rebuilt and it lasting?
Should I just look for a good 4l80e instead of spending money on this 60?

[bobs94formula]

When you get it rebuilt make sure to put on an auxillary cooler along with the stock cooler. That will help it live a lot longer.