1999 Mercury Cougar Shudders Like Rumble Strips at 35-40 MPH



Hi Everyone:

My car (about 80K miles) has been rumbling/shuddering intermittently for several months. It’s usually when I’m at around 35-40 MPH, which is the speed limit on the roads I drive on 95% of the time. It usually lasts just a second or two, but this morning it lasted a solid 30 seconds. It does not make a sound, it’s more of a feeling?like driving over rumble strips. It has happened when I accelerate, coast, and decelerate. I’ve been perusing forums all over the internet, and found some possible problems:

?Torque converter

?Trans fluid

?Tires/tire balance

?Fuel filter

?Throttle position sensor/Electrical connection to this sensor

?Exhaust oxygen sensor

?Intake air temp. sensor

?Fuel injection coolant sensor

I’m thinking it’s either the tire- or transmission-related for the following reasons:


?My last oil change (maybe 1.5K ago), the dealership said I needed my tires aligned. Because it was late in the afternoon, they did not have time to do it, and I haven’t been back. They also recommended I get four new tires; I got two new tires that day. I put both new tires on the front and old ones on the back?although the worse wear was on either the driver- or passenger-side. It’s likely still wearing unevenly side-to-side, so I probably have four tires in four different conditions. I live in New Orleans, so my tires/suspension have it rough. About 3-5 years ago, when I lived in Tallahassee (smooth roads, but hills), I had a broken tie rod replaced.


?In December 2008, I got an oil change at Super Lube. The ^%#&*$% idiot working there said I needed my transmission fluid replaced, since it was red. He put green stuff in my car. I drove from Tallahassee to New Orleans with my Low Coolant light on. My dad got that green crap out of my car, and the correct stuff back in there. Often, if I’m parked on an incline, the Low Coolant light will come on and stay on for one engine cycle, then go out. However, lately I’ll start my car in my carport (level) and the light won’t be on. Then, when I’m in the driveway (only slightly inclined) and put the car?still on?into park ever-so-briefly while I close and lock the gate, the Low Coolant light comes on and stays on for the whole cycle. It seems the light should not be coming on when parked for about 30 seconds on the slightest of inclines. Perhaps the fluid really is low?

I appreciate any insight!


Okay, your post is confusing.
"The ^%#&*$% idiot working there said I needed my transmission fluid replaced, since it was red. He put green stuff in my car. "
Are you talking about transmission fluid, coolant, or both? Transmission fluid or level would have nothing to do with a low coolant light. Transmission fluid should be a pink color. Coolant (for your specific car) should be green or orange (depends on which it came from the factory with).

Normally, I would have guessed that the rumble is due to degraded transmission fluid, but that should only be when accelerating, not when decelerating. When was the last time the transmission fluid was changed? (It should have been changed two or three times by now.)

P.S. Never, ever go to any place with “lube” in the title for anything!


There are more than one kinds of transmission fluid, you owners manual, or the bottle the fluid comes in should indicate which one you should have. ditto for antifreeze, though most often it will be a florescent green. I get the feeling you are a person who does not know how a car works, am I right? but that is of course why you are asking and that is good, very good. I am not a pro, but I have owned and worked on a dozen and more cars in my time. This shudder sounds to me like a problem with the tires caused by alignment. Have the front end aligned, it is not expensive. Have the tires checked for uneven wear and scalloping due to missalignment. You ought to have this done anyway, even if it does not solve the problem, it will prevent new ones from developing. If this does not do it, take it to an independent transmission shop, and have the transmission and drive line checked out. Good luck with this.


The post is thoroughly confusing. Please clarify the whole thing about transmission fluid and red stuff and green stuff and what that has to do with the coolant level.

You seem pretty confused about the basics and have been to a Super Lube. Stop going to quickie oil change places. They tend to cause as many problems as they solve, and often sell people things they don’t need.

Find a reputable, local and independent mechanic. Have them give everything a once over and help you maintain your car.

If I had to throw darts at a board to guess at your rumble issue I’d guess at torque converter clutch shudder - based partly on how you described it and on it being in the 35-40mph range.

But based on your post I’ll bet there are plenty of things that need attention on this car.


Okay…I am sorry for the confusion. It was coolant, not transmission fluid, that was replaced. I thought they were the same thing, so yes, I’m not the kind of person who knows a lot about cars.


Thanks so much. I am planning to have the tires aligned anyway, as you suggest. I just made an appointment at the dealership for next week. I last had my tires aligned about 5 years ago…how often should I need to? I’m wondering if the condition of the roads here is contributing to the alignment problems I’m having? For example, I used to go over speed bumps very, very slowly, but know I may go over a random bumps or potholes in the road going 25 MPH (or more). Plus the dips?where one side of my car is 12 inches below the other side. Of course, I try to slow down as much as possible. I basically cringe a lot when I drive.


This is usually caused by aged transmission fluid or the torque converter. Changing the fluid usually takes care of this problem and it’s a common one.

The part that would concern me would be this green stuff in the transmission business. The only thing I could start to think of would be if they put a green additive of some sort in there or, horrors, some fool added coolant to the transmission fluid and diluted it badly.
If this is the case then the transmission may be on the way out.


My dad made sure after the Super Lube incident that I only take my car to the dealership from then on. He was car whiz and took very good care of my car from 1999?2001, until I went to college in 2002. After that, he gave me advice and took care of things when I came home to visit until he died in 2007. Without him, I am totally lost. So yes, some things do need attention, but my car is NOT in as bad of condition as you seem to think.

I’ve only had a little over two years to screw things up. I do keep up on oil changed, check tire pressure (not as often as I should, but…) and pay very close attention to how it’s running, etc. But yes, I do lack the knowledge and vocabulary that would help explain what I’m sensing.


My boyfriend just checked the transmission fluid (he explained to me it’s not the same as collant), and he said it is low and dirty-looking. I honestly don’t know when/if it was changed. He drove it around and of course it wasn’t doing it. He said he felt a little vibration in the gas pedal, but that was about it.


Thanks. It wasn’t transmission fluid after all, it was coolant. Mine is supposed to be orangey-red, but not green. I hope that with this clarification, the whole “transmission may be on the way out” comes off the table. I unfortunately don’t know much about cars, but I know that once the transmission’s gone, you start making cost-benefit analyses?new transmission, or new car altogether?


I wouldn’t take the transmission off the table yet as I would still suspect torque converter clutch shudder. Ask your dad about the transmission service history. This is one thing that official service manuals are not good about.

There are also plenty of choices in between quickie lubes and dealers. Dealers tend to be the most expensive option and often try to sell people things that they don’t need. That’s a blanket statement and some are better than others.

But a good, local, independent mechanic can normally provide service at the same quality level with less cost and more personalized attention.


I unfortunately can’t ask my dad, since he’s deceased. Believe me I wish I could. I will go through my files and try to figure it out.

You are right, there are plenty of options in between. I’ve looked through the Mechanic Files on this website, but it’s like picking blindly out of a hat. That’s exactly my problem?I don’t want somebody trying to sell me stuff I don’t need. But it seems inevitable. At least at the dealership they (seem to) have expertise on my make and model, and are knowledgeable of recalls, etc. Maybe independent mechanics are too?

I just wish I could fix it myself, or at least could walk up to any mechanic?dealership or independent?and say with confidence what the problem is. But, as we all know, I’m very far from that point.

Any little noise (recently a low drone from a cold start), or dimming of lights (happens sometimes when it’s raining) or shudder?to me it’s all related. And all life-or-death. I start telling them what’s wrong, and they don’t know where to start. I basically need to take your earlier advice: “Have them give everything a once over and help you maintain your car.”


Ask around among people that you know to see if anyone has a good mechanic.

Oh, and I keep forgetting to say - check your coolant. It is not going to be related to a 35-40mph shudder. But its really important nonetheless. The owner’s manual will tell you what to do and what to add if you need to.

Sorry to hear of your dad’s passing.


If I were you, and you are an educated person so you can read complexe texts, I would go to a parts store and buy or order a repair manual for your car. Just get the Haynes manual, as it will be the cheepest. and it is also the most general. Read it, not so that you can repair your car, but so that you can understand the variou systems, how they are built, what they do, where on the car they are located, and what the names of the parts are. dont expect to understand it, but just to get a generall knowledge of how your car works, and what to expect when it fails. Take your time on it, but read it all the way through as much of it as you can understand, and talk to your boy friend about what you are learning, as it will help you bond with him, and it will help him too. You will never regret doing this.


Okay, then I would start with a complete transmission fluid exchange, including a pad drop and transmission filter change. This should be less then $200 at a dealer, and it and an alignment may be all that you need.


Thanks so much! That sounds like a great plan.


Thank you. I will check my coolant. Like I said, the light only used to come on after parking on an incline for a pretty substantial amount of time. (Or if someone put the wrong kind of coolant in…) But I can’t, or shouldn’t, keep thinking “Oh, light’s on, must be the ol’ incline again” when I’m only parked on it for 30 seconds! That’s just crazy. It’s probably low. Even if it’s not, if it’s just a quirk or some other problem, I should know, and not keep speculating. Thanks again!


That is an absolutely wonderful suggestion! I’ve wanted for a while to learn about cars, so I can be knowledgeable enough not to describe something like, “that one part, you know, the one that connects to that other part.” Or knowledgeable enough not to confuse transmission fluid with coolant.

And my first thought is: Well, I’ll just have to build one (a car) from scratch. I’m pretty hands-on; I’ve welded and used many-a-power tool. Then I’ll know everything. I thought the same thing with computers a few years ago: To understand these things, I’ll just have to build one from scratch! Why I think this way, I don’t know.

But picking up a Haynes manual will definitely give me an adequate, working knowledge of my car. I especially like the part about talking/bonding with my boyfriend, because he admittedly doesn’t know as much about cars as he’d like to either. Thank you so much!


I’ll also say that you can learn a lot just hanging around reading the threads on this discussion board. No where near as focused as a Haynes manual - obviously - but you can pick up lots of knowledge.