Torque Convertor going out?

[Andrew1990]

Well I have been having some issues with my trany the past coouple of days that I thought may be a simple overheating issue but it isnt.

When I drive for lets say over an hour, off and on, my transmission starts freaking out. For example,

I stop at a red light. The oil pressure will drop quite a bit and then when I give it gas, the rpm goes up to 3000 and the car barely goes. I have to let off the gas and give it gas multiple times to get it to go.

After 1st gear, there is no problem with the transmission. It will shift from 2nd to 3rd to 4th perfectly fine. It is only when I stop at a stop sign or red light this will happen.


I was then thinking it may be by torque converter, or could it be something as simple as getting my transmission flushed or something?


The transmission is a GM 4L60E.

 

[Bignate603]

What's your coolant level and what what does it look like? Is it clean? Brown? Black?

 

[deadken]

Honestly, I haven't been repairing cars for a living for over 15 years, but I doubt much has changed for torque converters.

Torque converters don't usually fail. Perhaps the 'lock-up' clutch will fail, but even those usually hold up unless something else went wrong (causing engagement at the wrong time, etc..).

Simply put: A torque converter is there to let the Engine RPM vary from the Transmission RPM. It replaces the clutch assembly on a Manual transmission. The easiest way for me to describe its operation is like this: Imagine one fan facing another fan (just picture a pair of those little 12" desk fans). If you turn on one fan, the air thrown from its blades will hit the second fans blades and cause them to turn. There is no mechanical connection. Now, imagine a set of fan blades attached to the crankshaft (output) of your engine while another set is attached to your transmission (input). Instead of air, you 'sling' fluid from one to the other. You could physically hold the input blades in place and nothing would wear or get damaged. The only downside is that with a viscous coupling (using fluid, not a mechanical connection) you will NEVER get a 1:1 input / output ratio. So, if you want to eek out that last bit of loss you add a clutch to 'lock' the input / output as 1:1 and engage it with a solenoid so that it only comes on in certain conditions (cruising in higher gears with low throttle opening).

Ok, now that we have basic theory of how a Torque Converter works, I can tell you that yours is not bad.

What your problem sounds like is a slipping set of clutches. There are more then one set in an automatic transmission. The 'clutch pack' that control first gear in your transmission are the ones that are at fault. Now, here is a simple way to test what I am saying: put the car in Reverse and hold the brakes while applying throttle. Look for excessive RPM's on the tach. Most (of the older) transmissions operate similarly where the 1st clutch pack and what was the highest clutch pack (3rd or 4th) would both be applied in order to obtain reverse. The important thing is, since it's ALSO used in reverse, any slippage in the first clutch pack will show up in both places (first and reverse gears). Now, please realize that the front pump output pressure is increased dramatically in reverse (250PSI instead of 100PSI, IIRC) so a slipping clutch wouldn't necessarily slip as much in reverse as in first gear. That is why I suggested you 'power brake' it a little bit. If your engine revs much higher then normal in reverse then it usually would (similar, but not exactly the same as it acts in first gear) then your problem is verified to be in the first clutch pack (or in its circuit: solenoid, piston seal, valve body, etc...).

Unfortunately, most likely you will need a transmission rebuild. There is a possibility of the the control circuit being defective (what used to be the 'Valve Body' (mechanical) was replaced by 'Solenoids' (electrical)). If the problem is in the solenoids or valve body a repair can (most likely) be made without removing the entire transmission. Unfortunately, even if the problem is in the application of the fluid to the first clutch pack (control circuit) since you have been driving the car around, it has likely become worn. Think of it this way, slipping a clutch (whether in an automatic trans or manual trans) will cause excessive wear.

Sorry for being so long winded but I was trying to be simple since there are a lot of people who don't understand basic theory (principle) of how automatic transmissions work. Frankly, there are a lot of people who don't know basic engine theory also, but I don't want to get started with that.

-Ken

 

[Iron Woode]

TCs go bad fairly often, at least back in the day. I suspect its caused by quality control issues.

happened on 3 different cars of mine.

2 had the impeller fail and caused fluid overheating. Eventually turning the fluid a nasty black colour. The trans still shifted ok. Nothing stinks worse than seriously burnt trans fluid.

The other was a failure of the TQ neck or collar. The TQ wedged itself into my bellhousing. It took a crowbar to get it out. Otherwise the trans was fine. I had it rebuilt anyway and the replacement TQ started making strange noises. I had it replaced under warranty.

 

[HarryLui]

What was the maintenance history??

Do the test deadken says.

 

[Gillbot]

Check the fluid level first, after that it's brobably worn out bands or the like. Just replace the trans.

 

[TonyH]

Actually torques converter failure has become quite common these days. I think it would be great if they didn't because we could probably save a thousand or more a week in torque converter rebuilding at our shop. I remember the days before the lock ups when a simple converter flush was all that was need during a tranny rebuild. But those days are long gone.

Admittedly the clutch is the main point of failure and that has gotten worse with the introduction of the Pulse Width Modulated (PWM) lock up engagement. It basically translates to gradually engaging the torque converter clutch to reduce shift feel. Or in layman's terms the clutch slips until it is fully applied. But since the lock up is not used at low speeds I know that the converter clutch probably has nothing to do with the OP's problem.

Since the vehicle does seem OK in second I would suggest that the forward clutches are holding since they are applied in both 1st and 2nd. The difference between the two is that 1st uses the low sprag and second uses the 2/4 band. The low sprag is not a common failure point with the 4L60E transmission but I wouldn't completely rule it out. You can assist the sprag to check it by placing the shifter in 1st gear. the low/reverse clutches will then be applied assisting the low sprag in holding the rear planetary. If that doesn't change anything then the low sprag is probably sound.

If that checks out you can check solenoids and valve body for possible failures. I would be more suspicious of the solenoids and they are a cheap and simple to replace. All the solenoids on this transmission are held in by easy to remove spring clips. The shift solenoids are located at the rear of the valve body. The 3-2 downshift and TCC PWM solenoids are at the front. The PWM solenoid is directly under the lock up solenoid which extends upward into the pump. The shift solenoids and the 3-2 are the ones that would be suspect if any.

While I don't believe the valve body would cause any problems of this nature I wouldn't rule out the valve body separator plate. Since 2002 there have been some that caused problems because of a small orifice hole becoming clogged with debris. This can be repaired with a new updated plate that utilizes bonded gaskets and the small hole has been replaced with a larger screened one.

 

[Christobevii3]

Your transmission is failing.

 

[amdhunter]

The torque converter in my old Galant split in half...lol

 

[joutlaw]

I got this from a S-10 forum. It applies to the 4L60E.

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, 3rd gear starts, manual 2nd available but no 1st, no 4th, and no TCC lockup: No power to transmission, or trans is in limp-home mode. Check trans fuse underhood, and make sure transmission electrical connector is plugged in. Easy fix.

11. No 1st or 4th available; trans shifts 2nd to 3rd by itself in D or OD : ShiftA solenoid failed. Easy fix in the pan. Or a wiring problem from PCM to trans.. or PCM.

12. No 2nd or 3rd available: 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. 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.

25. 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.).

26. 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.

27. 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.

28. All fluid pumped out through the vent tube: Plugged cooler line. Flush the transmission cooler and cooler lines. Also could be overfiled transmission.

29. 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:Internal crossleak feeding the forward clutches all the time. Most likely a cracked input housing. R&R required. Car can safely be driven gently in forward gears until the repair.

30. 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.

31. 1-2 or 2-3 shift is slow/soft above part throttle: Trans is on its way out. R&R.

 

[deadken]

TCs go bad fairly often, at least back in the day. I suspect its caused by quality control issues.

happened on 3 different cars of mine. ...

Then you should know from personal experience that his problem has nothing to do with his torque converter. I think that your comments, while perhaps personally validating, do nothing to help the OP with his concern. IMHO, your comments add to the confusion and imply that his car could in fact have a Torque Converter problem. Seriously, based on what he described, HIS Torque Converter is NOT the problem.

Actually torques converter failure has become quite common these days. ...
Admittedly the clutch is the main point of failure. ... But since the lock up is not used at low speeds I know that the converter clutch probably has nothing to do with the OP's problem.

Since the vehicle does seem OK in second I would suggest that the forward clutches are holding since they are applied in both 1st and 2nd. The difference between the two is that 1st uses the low sprag and second uses the 2/4 band. The low sprag is not a common failure point with the 4L60E transmission but I wouldn't completely rule it out. You can assist the sprag to check it by placing the shifter in 1st gear. the low/reverse clutches will then be applied assisting the low sprag in holding the rear planetary. If that doesn't change anything then the low sprag is probably sound.

If that checks out you can check solenoids and valve body for possible failures. I would be more suspicious of the solenoids and they are a cheap and simple to replace. All the solenoids on this transmission are held in by easy to remove spring clips. The shift solenoids are located at the rear of the valve body. The 3-2 downshift and TCC PWM solenoids are at the front. The PWM solenoid is directly under the lock up solenoid which extends upward into the pump. The shift solenoids and the 3-2 are the ones that would be suspect if any.

While I don't believe the valve body would cause any problems of this nature I wouldn't rule out the valve body separator plate. Since 2002 there have been some that caused problems because of a small orifice hole becoming clogged with debris. This can be repaired with a new updated plate that utilizes bonded gaskets and the small hole has been replaced with a larger screened one.

Thank you for your input TonyH. I admit that I am NOT specifically familiar with this GM transmission. And I am glad to see someone who knows specifics help this guy out. I am glad to learn something new today. In the Dodge / Chrysler transmissions that I worked on selecting 'Low' on the shift selector also engaged the band around the planetary, but that only ruled out an overrunning clutch failure. IOW, on a Chrysler product (of that era) the test you suggested wouldn't isolate the 1st clutch pack as a possible failure point. So, I have to ask, what is engaged on this GM transmission to activate 'Reverse'? Wouldn't 'Reverse' use the clutch pack in question in order to help isolate it as a source of the defect?

 

[TonyH]

Thank you for your input TonyH. I admit that I am NOT specifically familiar with this GM transmission. And I am glad to see someone who knows specifics help this guy out. I am glad to learn something new today. In the Dodge / Chrysler transmissions that I worked on selecting 'Low' on the shift selector also engaged the band around the planetary, but that only ruled out an overrunning clutch failure. IOW, on a Chrysler product (of that era) the test you suggested wouldn't isolate the 1st clutch pack as a possible failure point. So, I have to ask, what is engaged on this GM transmission to activate 'Reverse'? Wouldn't 'Reverse' use the clutch pack in question in order to help isolate it as a source of the defect?

Reverse is achieved with the application of the Low/Reverse and Reverse Input clutches. Neither of these two components are used for low gear except for one in only one gear lever position.

There is no "1st clutch pack" in this transmission. Only Honda transmissions and the TAAT used in Saturns use an individual clutch pack for each gear. Those transmissions are designed more like standards utilizing mainshafts and countershaft assemblies with free floating gears that are "engaged" by applying the corresponding clutch packs. Much like the shift forks and synchronizer assemblies engage gears in a standard transmission.

Gears are accomplished in all other tranny types by the application of two or more components in the transmission. The application of components will control the flow of power through the planetary system which will determine the gear ratio.

First gear is accomplished in one of three different ways depending on gear lever position with the 4L60E.
D4 or D3
Forward clutches
Input Sprag (Holding)
Low Sprag

D2
Forward clutches
Input Sprag (Holding but ineffective due to the the application of the Overruns)
Overrun Clutches
Low Sprag

D1
Forward clutches
Input Sprag (Holding but ineffective due to the the application of the Overruns)
Overrun Clutches
Low Sprag (Holding but ineffective due to the the application of the Low/Reverse clutches)
Low/Reverse clutches.

 

[TonyH]

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.

First installer in my shop that tells me that he has to remove the cross member to access the VSS on a 4L60E will be packing his tools.

 

[joutlaw]

First installer in my shop that tells me that he has to remove the cross member to access the VSS on a 4L60E will be packing his tools.

Keep in mind this came from a S-10 forum. It was stolen from another forum, possibly a F-body one I'm not sure.