How to Diagnose & Fix Transmission Shudder Yourself – A Reader’s Story

The following is a detailed account of how Jack (a reader of the Transmission Repair Cost Guide) isolated and solved his transmission’s shuddering problem. Jack was kind enough to write this valuable resource that outlines exactly what steps he took at every stage – from educating himself through research online to inspecting the transmission pan for debris. His story also includes the lessons he learned along the way and what he would do differently next time.

That’s enough from me. Over to Jack…

Alex, It is a delight to hear from you and thanks for asking how things are going. I thank you for the recommended repair shop for a transmission flush here in Florida but they were just too far away. I likely would have had to spend the night in a motel there.

We know a good transmission shop in your area.

Some Background

My 2000 Crown Vic is sort of a garaged cherry inherited in 2002 with 14K on it. It’s been used mainly as a “road” car for annual round trips from Fl to VA. Total miles in 16 years is 110K or about 7K a year, most of which is Interstate. Only use Mobil-1 and change the coolant every 2-3 years and fuel filter. No collisions. Never changed ATF, just checked it annually for “redness”, smell, and level. My bad. But lately, have experienced occasional transmission “shudder” between 45-50. At 75 years old, and ignorant of automatic transmissions, I was concerned and a bit intimidated as to what to do.

Since I was 15 I have always done vehicle maintenance — with the exception automatic transmissions. I’ve rebuilt engines, changed out springs (dangerous), manual transmissions and clutches, CV joints, complete brake jobs, front wheel alignments (yes wheel alignments), AC charging, replacing shocks, body work, headlight alignments, etc. One learns by education, doing, and by making mistakes.

But in the last five years I learned that the Internet can answer most questions in life, if you know how to ask the right questions, including how to fix almost anything. I also learned that it is very dangerous to just watch one video of some guy who happens to be able to put on a good show.

Researching Online

One has to wade through perhaps 20 videos and websites on the same exact issue to learn that almost every video gives you another pearl of wisdom, but also a potentially costly bad piece of info or an important missed step. Any guy with a camera can make a video and they rarely follow a script. (Notice that you won’t see a video with certificates of professional training on the garage wall. If you do, he was probably fired from someplace.) So you have to be skeptical and use your intelligence, diligence and instinct to decide which parts of each one to adopt and follow. Taking notes as you watch can be very important.

Same is true for websites. There are a lot of guys popping off about stuff that turns out to be wrong. If they seem to be a bit full of themselves be cautious and then research more for confirmation from others. Of course, that goes for me too. 😉

The above was said in expectation of doing the work myself. But I also recommend doing some research to better prepare one for selecting a mechanic or shop to do it for you. An excellent example would be changing your own ATF.

Tips for Changing Your Own Automatic Transmission Fluid

As you know so well there are several ways to do this. Almost all ATs have ATF in three places; the transmission, the torque converter (TC), and the transmission cooler. In my Crown Vic there are about six qts in the transmission pan, about four in the TC and a couple in the cooler for a total of 12. Yes, they are all interconnected by hoses and galleys. But draining one does not drain the other two.

All three should be drained as well as the transmission filter changed. To know you have done it right, you must know how many total qts are in your vehicle and be sure that all of it gets removed and that all of it gets replaced.

A less than honest shop could simply siphon 4-5 qts. out of your transmission and bill you $175-$200 for 20 minutes work. Until the transmission pan is removed completely the health of the transmission cannot be properly assessed and the transmission oil filter cannot be changed. Otherwise you could just be throwing money away and worse, do additional damage to your transmission. If you are having the work done for you ask up front for a report on what is found in the transmission pan. Try to be there to eyeball it if you possibly can.

What to Check – Ruling Out Causes of the Shudder

Assuming you are confident enough to do a complete ATF change or “flush”, first you must do the research which tells you that you have ruled out several other possible causes of the shudder.

  • Is the ATF still red and not brown?
  • Does it smell “burnt”?
  • Do you have spark plugs or igniter coils that are misfiring?
  • Are your igniter coils properly grounded?
  • Do you have transmission fluid leaking into your engine coolant?
  • Have mice or rats chewed on any wires, especially those going to your transmission?
  • If your brakes are not properly installed or brake pedal travel is incorrect this could contribute to the problem.
  • Is there a possible leaking heater or radiator hose that is getting coolant into your spark plug socket?
  • Is your fuel filter clogged or partially clogged which can result in fuel starvation and a transmission that acts up?
  • Do you have a “check engine” light?

If so get the codes read and find out what they mean.

Some codes can point to specific transmission problem or problems. And there probably are other potential issues I have missed. Regardless, if you have any of these problems they must be fixed first because your vehicle’s computer can sense some of them and send incorrect signals to your transmission which could be causing the shudder. Simply changing the ATF fluid before making sure all other systems are working properly could lead you to replacing a transmission for thousands of bucks only to learn later that you had a much less expensive problem in the first place.

Need Your Transmission Repaired? A good repair shop can be hard to find – especially on short notice. We’ll have the Cost Guide Certified shop in your area give you a call with a free estimate.

Changing the ATF – The Process

So first, I resolved that I had none of the above problems in my Crown Vic, and I had already just replaced the plugs but the shudder was still there occasionally. So I concluded it was time to try a change of ATF on the chance that was my problem. After all, my ATF was 17 years old.

So I purchased a transmission filter and gasket and 12 qts of Mercon V ATF indicated in the manual. Be very careful to replace the fluid with exactly what the manufacturer recommends and don’t mix and match. (Some videos suggest putting in an additive as well but from what I have read that is not a good idea unless your transmission is close to not worth fixing.)

If you are still reading this, you likely have a decent set of 3/8″ drive sockets with extensions. Also, you are resourceful enough to have access to:

  • a safe set of ramps and wheel chocks
  • a large pan to catch the ATF fluid (I used a large and cheap plastic shoe storage box which worked well)
  • a fairly large funnel
  • some empty one gallon milk jugs to measure how much total fluid you actually get out of the vehicle transmission and to transport it for recycling,
  • a roll of paper towels and lots of old rags.

At this point, there are a lot of common sense things to do like don’t drive your 6,000 lb vehicle up onto a rickety ramp and get yourself killed. And wear some tight fitting goggles. ATF fluid is not good for the eyes. Bad economy. Doctors and funerals are expensive.

The next question is, are you really up to this? Are you really? Ok. Go watch 20 videos to learn how to drop the pan without sloshing ATF all over your garage floor or driveway. Pay attention to the sequence of removal of the pan bolts, the amount of torque needed to remove the pan bolts and do your best to replace them with the same degree of torque.

Do you know how to crank your engine around manually to line up the drain plug on the torque converter? A breaker bar/socket on the front main crank pulley is the easiest. Do you know which hose to remove to pump out the ATF in your ATF cooler? If you don’t have the answers to these questions you are not ready. And if you can’t easily distinguish the difference between the engine pan and the transmission pan stop here and have a reputable shop do the work for you. Finally, do you know how to appraise what you will find in the transmission pan when you remove it? I’ll try to answer the last one.

Inspect the Pan for Metal Debris

After you measure out all the ATF from the AT pan into something for recycling (don’t wipe or clean the pan yet) look at the interior very closely. In the pan there is a circular magnet. On this magnet you should find a very fine gray powder. Feel it gently between two fingers. It should be so fine you don’t feel anything but slick. This powder is extremely fine pieces of ferrous metal from years of normal wear. There should be nothing else stuck to the magnet that you can see with the naked eye or feel between your fingertips than a fine powder.

If you see any pieces of metal or any little piece of anything shiny in the empty pan it means your transmission may well have some critical parts breaking down like clutches, bands, solenoids or gears that likely will lead to having the transmission replaced with a factory rebuild — or a complete overhaul if your mechanic is well trained and experienced. Compare the total cost of a rebuild by your mechanic or dropping in a factory remanufactured transmission. If the cost and time difference is close consider a factory remanufactured. And know what the differences are in the warranties.

Emptying the Cooler of Old ATF

If all is well at this point be sure you have a good understanding from the videos of how to empty the cooler of old ATF. (Some newer and smaller vehicles might not have an ATF cooler. Find out.) The process likely differs from one vehicle to another. You likely will need two people to do the final step. After you have configured the right cooler hose properly to pump out a couple of quarts of ATF, refill the transmission with about 2/3 of it’s recommended capacity with the required ATF. (Make sure the transmission is in neutral with the emergency brakes on and the rear wheels chocked.) Have someone else start the engine (no racing it) as you monitor and measure out about two quarts of the old ATF that were still in the cooler and quickly signal to your helper to turn off the engine. Replace cooler hose securely.

Remember, the vehicle still is only about 1/2 full of ATF. With the car on ramps, you will not get a reliable reading of the fill level. So use the brakes and slowly and carefully let it roll off the ramps to a level position. Don’t try to refill it completely on a ramp which could result in ATF backing up in the fill tube. Crank it up and immediately begin replacing the remainder of its full capacity except the last quart. Look for any leaks around the pan gasket and any hose connections. Run it through the gears R, D, 1, 2 without racing the engine. Then continue to slowly fill the transmission, checking the level every 2-3 oz to avoid overfilling. When the engine is completely warm and at the proper fill level check again for leaks.

Success – No More Chattering/Shuddering

Well, I am delighted to report that I managed to avoid any major screwups and got all the parts back where they are supposed to go with no bolts left over and only about a quart of transmission fluid spilled on the garage floor. (Actually, from the videos I watched that is about average.) Took it for a test drive and do not hear the intermittent “chatter” in the transmission that was there before. Today took it out on the Interstate for about 80 miles at 60-70 in hot weather and another 20 miles stop and go which allowed enough speed for normal up shifting to the final overdrive. Shifts beautifully and smoothly with no shudder.

At this point am feeling somewhat satisfied having spent less than $100 for parts and fluid. But a 17 year old tranny is not going to hold up forever. Eventually I will have to have a factory remanufactured tranny put in which should carry a 3 yr. warranty. We intend to keep driving this thing until it drops or we drop.

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2 thoughts on “How to Diagnose & Fix Transmission Shudder Yourself – A Reader’s Story

  1. Hello I have a 2000 mitsubishi lancer cedia auto cvt that has a winding sound in all gear and slippage when I stop at the stop light after a long drive what could be the prob car drive once moving along

  2. I have a 2002 Chrysler Concorde that I took to the transmission shop because I thought it needed a transmission. I was told it did. It also had some electrical problems with the interior lights coming on and off randomly. I asked them to fix them both. They rebuilt the transmission and said they fixed everything, polishing the headlights and other little things. It cost over $5000 when I got the bill and I had to scrape to get the money so they would not keep the car. When I picked it up on a Friday, they were closing so I took the car. After driving home, I saw the mileage gauge was not working. The engine light was on. Monday they fixed it, checking the code and said they had to use a different code, suggesting the computer could be the blame. Now it is not running again and all the panel lights came on, then it stopped running. I feel like I got ripped off. I don’t have money for this. What should I do with this car? I can’t afford another one. I feel sick thinking about it.

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