thumping when easing off gas pedal

[smith1234]

I recently bought a 1993 camry, auto trans, with 88k miles. it shifts smoothly and goes into every gear with no problems. however, many times, whenever i accelerate and then ease up on the gas pedal, the car kicks a bit. For example, i would accelerate from a stoplight and everything is fine. But when i get up to, say, 40mph and i ease off the gas, the car thumps, or kicks momentarily, almost as if it is shifting rough, but i don't think it is downshifting as i am only maintaining a certain speed.

a mechanic suggested the engine mounts need replacing, but my research suggests that is only for massive engine vibrations, and this is not a constant vibration problem.

Any thoughts please?

[yotatechie04]

I'm really not all that sure about this one. It's a very difficult problem to solve. I've been dealing with a similiar problem with my '99, but I've come to find out that it was a misfiring cylinder that caused some severe thumping when letting off the gas. It sounded somewhat similar to bodies being thrown around in the trunk. I've heard that it's possibly caused by a stripped gear in the transmission, and in some cases a motor mount. Also, I've heard that it can be caused by a stripped camshaft, or something slipping in the drivetrain area. I'll keep looking around for you, and see if I can't find anything out in futher detail.

[red-in-la]

Your Camry has 2 engine mounts, a brace and a, sort of, transmission mount.

The brace looks like a dog bone. Easy to find on the passenge side of the engine.

1 engine mount is in front of the engine. Looks like a dome and easy to get to. I have changed this one and the dog bone looking one.

The other one is a stinker and is leaking in my car but my daughter does'nt have the $87 plus labor to change it right now. That one is causing clunks for her. It is leaking oil.

The last one is even more expensive supporting the transmission. If the parts girl gave me the right price it's $137ish. Or it's $87 and the engine mount behind the engine is $137, if she had her numbers transposed.

At any rate, it sounds like u should check the front & rear mounts. Look for oil leaking out and broken rubber in the dog bone looking mount.

Regards

[smith1234]

Would say then, based on the symptoms, that the mounts are the problem?

[smith1234]

thanks. i don't know if i should pay the mechanic to do the engine mounts and then not have the problem fixed. dont want to waste money.

[Brian R.]

Have a mechanic troubleshoot your problem. If he tells you that you have a bad engine mount, then you can believe him. Doesn't sound like a transmission problem. If the mounts are fine, I suppose it could be a bad CV joint, but I have not seen one that bad.

[smith1234]

It appears that the problem is only occuring when I enter 3rd gear. I go into the gear just fine, but a thump occurs when i stop accelerating. By the way, the thumping sound does not seem like its coming from the engine, but from under the car.

I will check with the mechanic again, but would appreciate any advice from this forum

[Brian R.]

There isn't much under your car, except in the front and very back. The sound is probably being displaced and is really coming from the front. If it is really only 3rd gear, then that points to a transmission problem since nothing else is only different at that time. I still think the motor mount is the obvious first place to look.

[smith1234]

Brian, would you say that the motor mount is suspect because of what my mechanic mentioned, or is there another reason that you would suspect the motor mount?

[red-in-la]

Sounds like a torque thing to me...

"whenever i accelerate and then ease up on the gas pedal, the car kicks a bit. For example, i would accelerate from a stoplight and everything is fine. But when i get up to, say, 40mph and i ease off the gas, the car thumps, or kicks momentarily, almost as if it is shifting rough, but i don't think it is downshifting as i am only maintaining a certain speed."

All I know is that those mounts don't last a lifetime and you can't see the rear most one. Front's a snap to change as is the dog bone one.

Also, the symptom you are relating is similar to our '93 with a known bad engine mount. Just get it up on a rack and have it checked. Good Luck and let us know what happens.

Regards

[AndyM1978]

Check your RPMs while this symptom is happening. I get a very minor occurance of what you mentioned at the same speed, but it is only my transmission shifting into a lower gear once it detects that I am not asking for a lot of power. If you see the RPMs drop (fairly quickly) about 500 rpms or so, that would indicate a shift I (BELIEVE the torque converter locking and/or the transmission shifting to overdrive, but I'm not 100% sure) . When letting off the gas completely when in overdrive, however, the RPMS tend to jump up almost 500 rpms or so due to the transmission "unlocking" in order to reduce engine breaking. This doesn't really cause any noises or thuds for me.

I did have a problem where I would feel a "thump" coming from what I thought was under my car (like what you are experiencing) upon hitting the gas after I was coasting, and that ended up being a broken motor mount (the dome one in the front, connected to the manifold). It also caused my car to "bang" into gear when putting the car in "Drive" at high idle.

I am by no means a mechanic and am only telling you my personal experiences with my car. (1992 4-cyl). I think checking your RPMs would be a very good way to narrow down the possible causes however. For me, "thumping" transmission issues were ALL caused by bad motor mounts.

[mrtwo]

my 95 camry has a slight pause when I release the gas. But when i use cruise control, i can not feel it. I don't think it is a big problem, well maybe i am wrong. Please let me know the results.

[Brian R.]

Originally Posted by smith1234

Brian, would you say that the motor mount is suspect because of what my mechanic mentioned, or is there another reason that you would suspect the motor mount?

Motor mounts are the obvious source of thumping when changing accelerator pedal position and the first thing to look at. Nothing else could apparently be the cause. Doesn't make it a sure thing though...

If I could drive it and look at it, I could be more certain, but the way internet advice works, you have to take it with a certain degree of scepticism.

[smith1234]

thanks for all this information. i take it in to the mechanic friday. i'm out at least $225 for the motor mounts. if that doesn't fix it, then i'm just out of luck.

i'll update after the repairs.

[smith1234]

UPDATE-- paid $230 for the motor mounts...no change, thumping is still there. Mechanic said the mounts were bad, needed changing. said the thumping was just natural. oh well. i guess at least i have new motor mounts.