First off, don't let the cut-away view of the TH200-4R transmission above intimidate you. Everything associated with this repair can be done in your driveway and does not involve removing the transmission from the car. It took me about 4 hours to perform, at a leisurely pace, with intermissions for lunch and parts runs. I won't fool you though, this task is more involved than your typical oil change (and certainly involves a lot more mess).
After reading this, you may opted to have a transmission shop perform the work. At very least, you will know what is involved in the work.. and will be better able to direct the transmission shop on what to do, and be aware of the approximate labor involved. An informed customer is always a better customer. Look for more tips at the end of this write-up if you plan on letting a transmission shop perform the work.
A side benefit of doing this repair (at least for me) was the knocking down of the self imposed intimidation of working on a transmission. I've never dropped a transmission oil pan in my life, but now I feel I can do it with ease.. and will perform all future transmission filter / ATF maintenance myself. I took some steps to ensure that next time, the job will be a lot easier, and a heck of a lot less messy. The tools involved in the repair are typical shadetree mechanic type; the most exotic of which was a torque wrench.
"The Problem" Defined:
After 30 minutes of Overdrive (OD) driving at highway speeds, the transmission appears to downshift late, causing near engine stall with very low RPM when coming to a stop; then with acceleration from a stop, the transmission appears to upshift early, again causing very low RPM at the shifts and loss of torque. What is really happening here is the torque converter's lock up feature locks up earlier than it is supposed to on acceleration and unlocks too late on deceleration. I have heard from people who have experienced an extreme version of this problem where the engine actually stalls out.
I have found that you can delay the appearance of "The Problem" by using the Drive (D) gear position to drive around town. This assumes that the majority of your around the town travel time is spent at 45 or less MPH. This doesn't help for highway driving at speeds above 45 MPH where engine RPM in the Drive gear would be excessive.
To test the lockup feature of the torque converter on your car, put the transmission in Overdrive (OD), accelerate to 45-50 MPH and maintain a constant speed. While maintaining the constant 45-50 MPH, tap the brake pedal briefly with your left foot, not enough to apply the brakes, only enough to light the stop lights momentarily. You should feel a slight "downshift" and engine RPM should increase slightly, then an upshift along with a lower engine RPM. This is the Torque Converter going out of and back into lock-up mode. Note, this test can only be performed once the engine/transmission have reached operating temperature as this feature is controlled by the car's computer, which only allows lock-up at temperature. "The Problem" only appears after an extended period of OD driving.. so you should be able to feel the correct operation of the torque converter lock-up feature within a few minutes of starting the car. Once the problem present, there is no "downshift" or "upshift" felt, the torque converter remains in lockup mode while performing this test at 45-50 MPH. Compare the good and bad lock-up conditions.. you'll see what I mean.
"The Problem" History:
"The Problem" showed up on my 1986 Monte Carlo SS back in 1991 while driving one day. Since then, I've had numerous transmission shops look at it and had the transmission rebuilt twice. Each time, the problem persisted. Each time the problem was described and demonstrated to the people doing the work.. and each time, the repairs failed to solve the problem.
I started to do some research on my own.. and soon zeroed in on the Torque Converter Clutch (TCC) system. The first transmission shop indicated that they had replaced the TCC Solenoid. So, when it came time to rebuild the transmission again (grinding noises and leaking ATF) I looked at other options to solve the problem. I had the second shop replace the torque converter with a B&M Holeshot 2000 converter that I supplied to them. I also instructed them to replace the TCC Solenoid and have them install a B&M Shift Kit (Stage II) to replace the shift kit that had been installed at the first shop years before. To my dismay, the problem continued. A tip from a Monte Carlo Email List member pointed me in the direction of the "pressure switch" in side the transmission. This ended up being the 4th Gear Pressure Switch that the CZ model (for the Monte Carlo SS) of the TH200-4R uses to tell the ECM when the transmission reaches 4th gear. That lead ended up (logically) to be the wrong path.
The ECM controls the TCC lock-up feature by grounding negative side of the TCC solenoid, enabling lock-up. Power to the TCC Solenoid is provided through a switch on the brake pedal that interrupts power when the brakes are applied. This is what causes the lock-up to disengage in the test above. When the brakes are applied, the TCC should not be locked up, because power to the solenoid is removed. For this reason, I concluded that the problem was not electrical in nature, and therefore was not caused by the 4th Gear Pressure Switch (signal to the ECM).
The more I thought about it, the more I convinced myself that, despite what the two transmission shops had told me, the TCC Solenoid had not yet been replaced, and was in fact the cause of "The Problem". I ordered the parts, and performed the repair outlined below on Sunday, March 14th. The problem disappeared and has not returned! Yippie! After 8+ years, it's really nice to drive around town with a normal transmission again.
"The Solution": Parts, Tools and Supplies Required
The Solenoid, Filter Kit and Pressure Switch part numbers listed below are specifically for the 1986 Monte Carlo SS, with TH200-4R model "CZ" transmission. If you don't have an SS, or a Monte Carlo, or an 86 model; check with your GM dealer parts counter for exact part numbers.
- TCC Solenoid; GM Part Number 8634960, $41.53 (THIS IS 1986 SS SPECIFIC, YOUR PART NUMBER MAY BE DIFFERENT!)
- Fram Transmission Filter Kit; Fram Part Number FT1057B, $13.99
- 5 Quarts of Dextron III automatic transmission fluid (ATF), $1.59/qt
- Optional: 4th Gear Pressure Switch; GM Part Number 8683502, $18.00
- Optional: B&M Transmission Drain Plug; B&M Part Number 80250, $7.99
- Highly Recommended: 1 box of "Shop Towels in a Box", 200 count
- Tool: Metric and Standard Socket Sets
- Tool: Torque Wrench
- Tool: Standard Screwdriver (to pry transmission pan off if necessary)
- Tool: 15" Jack Stands
- Tool: Catch pan for draining ATF
- Highly Recommended: Small trash can to contain the ATF soaked shop towels
- Highly Recommended: Hand Cleaner (suitable to remove oil, available at auto parts stores)
- Highly Recommended: Driveway Oil Spot cleaner
- Optional Tool: Drill with 1/2" bit (for drain plug installation)
"The Solution": Repair Instructions
(Hint: Check out the tip in the Avoid the Mess section below.)
First off, resign yourself to the fact that you WILL get dirty. You WILL get ATF in your hair. You WILL be smelling ATF for a day or so after the job. All of these are temporary, and part of the joy of doing work on your car yourself. The satisfaction and pride of doing it yourself (not to mention the labor cost savings) will vastly out weigh any amount of dirt and grime. Above all, have fun while you are taking on this task. The instructions below may seem excessive at first glance. They are straight forward, with a lot of detail for those not accustomed to doing a lot of work on their cars. Once you get in there, everything is almost self explainitory just by looking at the transmission with the oil pan removed.
A short word of warning. Automatic Transmission Fluid is somewhat flammable. Be smart, don't smoke while you are anywhere near a large amount of ATF, or throw semi-lit cigarette into a trash can full of ATF soaked shop towels. No, I'm not saying this out of experience. Just fore-warning.
The instructions below are specific to the Monte Carlo SS with a TH200-4R "CZ" model transmission. If you don't have an SS, the internal wire harness instructions may differ slightly. Consult a shop manual first.
- Block the rear wheels of the SS; parking brake on; transmission in park.
- Put the front of the car up on jack stands. I used 15" jack stands.
- Place plenty of those handy shop towels on the ground under the car with the catch pan on top. Have the Box-o-towels with you under there, trust me, you'll need them.
- I recommend cleaning the external surfaces of the transmission oil pan, the transmission itself and the associated connecting links as much as possible prior to proceeding. The object is to reduce the possibility of contaminating the internal parts of the transmission with external dirt and grime when the pan is removed.
- Image #1 - With the catch pan placed underneath the transmission oil pan, remove the oil pan attaching bolts from the front and sides of the pan. ATF may start to leak out at this point. Let it subside, trying to catch as much as you can in the catch pan. Trust me, you won't catch it all.
- Image #2 - Continue loosening the attaching bolts proceeding from the front to the rear of the transmission. The pan is strong enough to be held in place with the rear three bolts in place. As you proceed, more and more ATF will leak out from around the edges of the transmission oil pan. Take your time, sop up with the shop towels as you go.
- If the transmission oil pan has been in place for along time, you may need to pry the pan loose from the transmission with a standard screwdriver. Remember not to bend the lip of the oil pan, otherwise, you will be haunted by transmission leaks in the future.
- At some point, you'll be ready to go the last mile, and remove the pan. Start by loosening the three rear bolts by a few turns. Next, hold the pan up in place, while you use your other (ATF soaked) hand to manually remove the three remaining bolts. Gingerly lower the pan, tilting the pan to drain the remaining ATF contained there-in into the catch pan. Remove the oil pan from underneath the car, place on a thick stack of newspaper (your driveway will thank you later).
- Image #3 - With the oil pan removed, the transmission will continue to drip ATF from the various passages. This won't stop... it will slow eventually, but not stop and is normal. At some point you should be able to remove the catch pan from underneath the car, and manage the remaining ATF dripage with shop towels under the car.
- Now is probably a good time to clean up a-bit. Sop up and remove as much of the ATF that the catch pan did not catch. Trash all ATF soaked shop towels. Then clean up yourself. Trust me, you'll need to be cleaned up. Take a break, have a (insert beverage of choice here). The worst (stage 1) is over.
- Inspect the transmission oil pan for signs of metal flakes and other foreign particles. A small amount of metallic dust is normal. Larger flakes and shavings are not. Excessive shavings may be a sign of other problems with the transmission that need attention by an experienced person.
- Ok, get back under the car, and take a good look at the insides of the transmission. You won't get to see it often. From the side wiring connector, follow the wires (three of them) to the 4th Gear Pressure Switch (1 wire) and the TCC Solenoid (2 wires). Take note of the routing scheme. The wires pass through small clips to hold them in place. Also take note of the metal clip. It's job is to push the filter down into the tranny pan. It should be under the filter, pushing it down, not over the filter. (The pictures here were taken with the filter already removed.)
- Remove the Transmission Oil Filter: Gently rock the filter back and forth while pulling the filter tube out of the pump bore. The filter should pop out without too much difficulty. A small amount of ATF will leak out when the filter is removed. Take note to make sure that the O-Ring(s) come out with the filter tube. If not, you will need to remove them from the pump bore with a screw driver. (I had to do this.) Take care not to scratch the sides of the pump bore. Use your finger and eyes to detect if any other O-rings are in the bore. Remove as necessary.
- Image #5 - Remove the TCC Solenoid: Using a 10mm socket, remove the two bolts that attach the TCC Solenoid to the valve body. Slowly rock the solenoid back and forth while exerting a downward pull on the solenoid bracket. The Solenoid should pop out from the valve body. Ensure the O-Ring at the mouth of the solenoid comes with the solenoid. Fish it out if necessary. Again, a small amount of ATF will leak out when the solenoid is popped out.
- Image #4 - Remove Wire Harness: Remove the electrical connector lug from the top of the 4th Gear Pressure Switch. Remove each of the three wires from the wire clips proceeding back to the side electrical connector.
- Unplug Internal Wire Harness Connector: The internal transmission wire harness plugs into the electrical connector on the inside of the transmission. It is held in place by a small plastic retainer. Gently bend the retainer clip up while pulling outward on the wire harness connector. The wire harness connector should pop out. Take note of the orientation. There is no need to remove the external transmission electrical connector.
- Install Wire Harness Connector: Compare the new Solenoid and wire harness with the one just removed. Install the wire harness connector on the side electrical connector in the same orientation as the one just removed. Ensure the wire retainer clip engages the harness connector properly. Route the wire harness through the same wire clips as the old harness. Refer to this image out of the shop manual for reference if you need. The proper diagram is the lower one for the "CZ" Model TH200-4R transmission.
- Image #6 - Install new TCC Solenoid: Ensure the new solenoid has a new O-Ring at its mouth. Coat the new solenoid's o-ring with some ATF (there should be plenty at hand hehehe). With the solenoid wires pointing toward the rear, gently rock the solenoid up into the valve body. Ensure the solenoid bracket is flush with the valve body. Attach the two 10mm bolts that were removed earlier. Torque each bolt to 8 ft/lbs using a torque wrench. (Notice in these photos, the vast color difference between the new TCC solenoid wires in Image #6, and the old TCC solenoid wires in Image #5.)
- Image #7 - Optional Install of 4th Gear Pressure Switch: Since I already had the 4th Gear Pressure switch in hand, I replaced that too. It's easy to replace, and a relatively cheap part... It's up to you. Remove the pressure switch using a socket or wrench. Replace in a like manner. Torque to 10 ft/lbs using a torque wrench. Whether you replace the 4th Gear pressure switch or not, connect the electrical connector lug to the top of the switch at this time.
- Take a moment to re-inspect the wire harness. Ensure that all wires are clear from binding with other parts, and are properly routed to the side electrical connector. (Refer to Figure)
- Image #8 - Install the new transmission oil filter: Install the filter kit supplied O-Ring on the new filter intake pipe. Lubricate the O-Ring with ATF.
(Note: the shop manual indicates that two O-Rings are used on the CZ model of the TH200-4R. The O-Ring design has been changed. The O-Ring provided in the filter kit has multiple ridges that perform the same function as multiple old style O-Rings. There is no need to install a second O-Ring.)
Install the filter into the pump bore and position as shown in Image #8. The metal clip toward the back of the filter should be behind the filter, not over the filter. It's job is to push the filter down into the tranny pan to ensure that it picks up ATF. This picture shows it incorrectly placed. I found this out after the job was done. Make sure the clip is on the back side of the filter.
- Take another break, enjoy another (insert beverage of choice here). Stage 2 is complete!
- Prep the Transmission Oil Pan for Re-installation: Wipe down the inside and outside of the oil pan, removing all ATF from the surfaces. Ensure that all of the old gasket material has been removed from the pan. This may involve some scraping to remove all of the gasket material. Make sure you remove any and all metal dust / filings/ shavings from inside the oil pan. The cleaner the better.
(Note: There should be a small magnet affixed around the dimple in the rear center of the transmission pan. This magnet helps collect the metal dust and fragments, keeping them out of the transmission's circulatory system. Carefully clean the metal flakes and dust from around the magnet. Some transmission shops lose this magnet, or fail to re-install it. That occurred in my case. I did not realize there was supposed to be a magnet there, and used the dimple by mistake as the location to install the drain plug.)
- Image #9 - Optional: Drain Plug Installation. By now, you will definitely see the benefits of adding a transmission oil pan drain plug to your transmission. Future transmission filter maintenance would be slightly more involved and no less messy than a normal oil change with a drain plug installed. There are some disadvantages to a drain plug however. They can leak, or be knocked off if you bottom out on something. If you can live with the mess of a traditional transmission pan removal, don't install the drain plug.
The B&M drain plug kit that I picked up requires a 1/2" hole be drilled in the oil pan at a safe location. I incorrectly chose the small dimple that is in the center of the oil pan, just rear of the end of the transmission filter. As stated earlier, it turns out this dimple is used to center the magnet that collects metallic dust and flakes on the transmission pan. My transmission did not have this magnet installed when I dropped the pan. It was most likely left out by one of the "professional" transmission shops that rebuilt the transmission earlier. So, do NOT use the dimple as the location for the drain plug. Look carefully at the transmission, and map out a clear location to install the drain plug. I suggest a location on the side of the pan. Just be sure there are no internal interferences. Before you drill anything... use the wise adage: "Measure twice, cut once." Make sure you deburr any hole that is drilled, and remove all metal shavings from the oil pan. Install the drain plug kit as depicted in the kit instructions. You're ready to continue.
- Place the new transmission oil pan gasket on top of the pan. Insert from the bottom, a few of the attaching bolts through the oil pan holes, through the gasket in the front, sides and rear of the pan. The gasket should hold them in place. Note: DO NOT USE RTV SEALANT ON THE GASKET! The RTV will damage the transmission if it gets into the fluid inside.
- Take one last look inside the transmission. Inspect everything. The setup should look identical to that when you first pulled the oil pan. When convinced everything is ok, continue.
- Ensure the mating surface on the transmission for the oil pan is free from dirt, grime, ATF, and old gasket material. Scrape off and clean if necessary.
- Image #10 - Oil Pan Re-installation: Place the transmission oil pan up against the transmission with one hand, while manually starting the few bolts already on the pan by your other hand. Snug up hand tight. Insert the remaining attaching bolts to their respective holes.. and hand tighten. Make sure you don't cross thread or strip any of these bolts. Once all the bolts are snug, tighten and torque to 12 ft/lbs using a torque wrench. Again, do not over tighten these bolts.
- Image #11 - Clean up the exterior surfaces of the transmission and oil pan. If you installed a drain plug, ensure it is secure and tight.
- Lower car off of jack stands. Relax, enjoy another (insert beverage of choice here). Stage 3 is complete.
- Remove the transmission dip stick, insert a funnel and fill the transmission with 4 quarts (8 pints) of Dextron III automatic transmission fluid (ATF). The shop manual says a normal filter change will require 7 pints of ATF to fill. In my case, after performing this repair, it took 5 quarts (10 pints) to get to the full mark. (See Below)
- Remember, to test the level of your transmission fluid, the transmission must be at operating temperature, with the engine running, and the transmission in park. GM defines the operating temperature as that obtained after 15 minutes of highway speed operation. GM also recommends that you move the transmission gear selector through each position, with the engine running and the parking brake on. End in the park position to measure the ATF level.
- After filling with 4 quarts of ATF, I started the car, and took it for a test drive that lasted roughly 15 minutes. I then checked for ATF leaks underneath the car, and checked the ATF level. I found that I was greater than 1 pint low, so I added another pint, and took another 15 minute drive. Again checked for leaks and the ATF level and found I was now 1 pint low... so again added another pint (10 pints, 5 quarts total) to bring the transmission to the full mark. Still no leaks and best of all, "The Problem" was gone!
- Time to clean up the driveway and your tools, and most of all, enjoy that last (insert beverage of choice here)! You're done!
Avoiding the Mess, an alternative method.
The following tip for avoiding the ATF mess when dropping the tranny pan was received from Scott Wheaton:
JC Whitney carries a 12 volt oil pump that allows you to remove 95% of the ATF from the tranny pan through the tranny dip-stick tube. The part number is 15JE5180Y and costs $18.99. The pump is normally used for removing oil from boat engines but works equally well for this application. Just put the supplied plastic hose down the tranny dip-stick tube, connect the pump's alligator clipped power cable to the battery and suck up the ATF into a suitable container through the outlet hose (approximately 5 minutes). Once drained, remove the tranny pan as described earlier, although this time without the ATF shower.
This avoids the big drain mess, and eliminates the need for a drain plug (another possible place for leaks to occur). This also works great for the once yearly ATF changes (you do this right?) without mess.
Thanks for the tip Scott.
"The Alternate Solution": Let someone else do it!
I think I am qualified (from experience) to say that even if you tell a transmission shop to replace the TCC Solenoid in your SS, you're still at their mercy in trusting that they do the job right (or at all). As stated earlier, I twice was told by two different transmission shops that they had replaced the TCC solenoid during a transmission maintenance (the first time) and complete rebuild (the second time). If either of these "qualified personnel" had done what they had said, I wouldn't have had to put up with this problem for more than a few days back in 1991.
Here are a few tips that I've learned in regard to any out-sourced automotive work.
- Where possible, provide the shop with the parts you expect to have installed. This means getting the parts from an aftermarket / mail-order / GM parts house, and hand delivering the parts to the shop. Some shops may have a problem with installing customer supplied parts. Find one that doesn't mind. They do exist. It's your right to know the source of the parts going into your car... especially a performance car like the SS. In the case of this repair, order the TCC Solenoid, 4th Gear Pressure Switch, B&M Drain Plug, and yes, even the Fram Transmission Filter Kit . With the knowledge gained from this write-up, they'll know you're an informed customer, which will keep them on their toes. They're less likely to pull something over on you.
- Demand the return of the used parts pulled from the car. This is your check to ensure that they indeed replaced the parts you provided. It also gives you a first hand look at the condition of the parts coming out of the car. If they tell you that some doohicky needs replacement, you will be able to confirm this yourself. Also, knowing that you will get all the parts, again, they are less likely to pull something over on you. No respectable shop will balk at doing this. If they do.. go find another one. It's your right as a customer.
- Ask the shop if you can see the transmission (in this case) with the oil pan removed. Some shops will balk at this, saying their insurance doesn't allow it. Other shops (all with the same insurance concerns) don't mind. Let them know you want to see the completed work before it's closed up. This is a good time to ensure that the magnet is still in place around the dimple in the transmission pan. If it's missing, have them replace it with a new one. If you don't get to see the transmission before it is buttoned back up, you should be able to detect the presence of the magnet around the dimple from the outside by placing a metallic object up to the dimple. If you don't feel the pull of the magnet, it's probably not installed on the inside.
- Know the procedure you want performed. Reading through the instructions above should give you a good idea what is involved in doing the work. Keep in mind these guys do it for a living, and should be able to perform the work faster than the average shadetree mechanic. If their labor bid is higher than you expect, ask for a breakdown on the hours required. If they don't come up with a satisfactory answer to your liking, go find another shop. By this time though, they should key into the fact that you are an informed customer.. and should be on the level with you.
- Every automotive shop of decent size that has been in business for along time usually has a wise old sage mechanic. This isn't the guy at the counter. This isn't the shop manager. It may not even be the guy that works on your car. Look for the short fat guy with the unlit cigar sticking out of his mouth. The only reason they keep him around is because he's been around.. and knows it all. Search this guy out.. ask him questions. Respect his answers.
- Where possible, get recommendations from other car enthusiasts / car clubs on where the good automotive shops are located in town. Or, if none are known, ask the shop for some references. Ask the references what type of work was done, time it took, cost over estimate, etc etc. Ask the shop if they've worked on your type of car / transmission before. Get as much information about the shop before signing on the dotted line, and committing to letting them do the work.
- If you have a favorite tip for out-sourced automotive work that you think I've missed, please email me.. I'd be happy to add it here.
Torque Converter Resources
Here are some links to great web pages that will tell you everything you ever wanted to know about how a Torque Converter Clutch (TCC) works. I used these pages when I started research on the problem I was experiencing.
- Introduction into the Torque Converter Clutch (TCC)
- Torque Converter Clutch Application
- TCC Solenoid problem as described for a GM Transaxle 125C type front wheel drive transmission. Obviously our TH200-4Rs aren't the only GM transmission with this problem!
- B&M's Application notes on Torque Converters
- How to change your transmission fluid write-up on the Turbo-Regal Web Page.
- Torque Converter Basics write-up on the Turbo-Regal Web Page.
- TCC Solenoid Replacement write-up on the Turbo-Regal Web Page. Much more basic than this write-up.
- TH200-4R TCC information on Chief's Monte SS Page
- Great Drivetrain Information by Steve Parker. Note: Steve's website has been temporarilly recreated here on MonteCarloSS.com since his original site disappeared. It will remain this way until we can get a hold of Steve.
- ECM TCC Methodologies by Robert Rauscher. A fantastic and detailed write-up on how the ECM controls the TCC function.
I hope you found these repair instructions and tips useful and easy to follow. If you have any questions, please drop me an e-mail. If you have performed the repair and are happy.. drop me an e-mail.. if you're not happy.. drop GM an e-mail and complain about their TCC Solenoids. :))
Send Mail to: Paul Carreiro
Return to PaulC's '86 Monte Carlo SS Web Site.
Return to www.MonteCarloSS.com Web Site.
©Copyright 1999-2003, MonteCarloSS.com, All Rights Reserved