'04 New Noise

[i_am_jim]

Starting about a month ago I began to notice this. I'll describe it best I can.

When I take my foot off the accelerator at a fairly low speed, say 10-30mph, then reapply the accelerator there's a thump. It seems like maybe there's play in the transmission such that when coasting it's at one end of the slop, then when giving it gas it catches up suddenly reaching the end of the play creating this thump. It doesn't seem to be slipping. After the thump it's solidly in gear.

This does not happen if I come to a complete stop before accelerating. Also, it seems like it doesn't happen if I very gently ease on the accelerator.

[JohnGD]

I'd check condition and level of the ATF. Maybe even replace it along with the felt filter in the pan.

Originally Posted by i_am_jim

Starting about a month ago I began to notice this. I'll describe it best I can.

When I take my foot off the accelerator at a fairly low speed, say 10-30mph, then reapply the accelerator there's a thump. It seems like maybe there's play in the transmission such that when coasting it's at one end of the slop, then when giving it gas it catches up suddenly reaching the end of the play creating this thump. It doesn't seem to be slipping. After the thump it's solidly in gear.

This does not happen if I come to a complete stop before accelerating. Also, it seems like it doesn't happen if I very gently ease on the accelerator.

[i_am_jim]

Thanks for the reply.

I checked the tranny fluid. The level is correct and the fluid looks pink, not burnt.

[BlackCamSe]

That's the trans downshifting. How many miles sence ur last trans service?

[somick]

Originally Posted by JohnGD

I'd check condition and level of the ATF. Maybe even replace it along with the felt filter in the pan.

You may also want to check your motor mount.

Good luck,

Sam

[i_am_jim]

Originally Posted by BlackCamSe

That's the trans downshifting.

Perhaps, but it only happens at the moment of accelerating.

How many miles sence ur last trans service?

It's never been serviced (not sure what that means) and it has 70K miles on it.

[gdanaher]

Originally Posted by i_am_jim

It's never been serviced (not sure what that means) and it has 70K miles on it.

Humm. Perhaps you should take a look at the owners manual and see what it says about maintaining the transmission.

That said, I vote for checking the motor mounts.

[i_am_jim]

Originally Posted by gdanaher

Humm. Perhaps you should take a look at the owners manual and see what it says about maintaining the transmission.

The Maintenance manual for my car doesn't say anything about "servicing" the transmission. It says to "inspect" the fluid. I interpreted this to mean look at it and smell it. It looks pink and smells like transmission fluid. If it means something else they need to be more specific.

[johnfrisco]

Originally Posted by i_am_jim

The Maintenance manual for my car doesn't say anything about "servicing" the transmission. It says to "inspect" the fluid. I interpreted this to mean look at it and smell it. It looks pink and smells like transmission fluid. If it means something else they need to be more specific.

Yeah Toyota maintains the Transmission fluid is lifetime--whatever that means? If your fluid is a nice pinkish color then the fluid is fine.

How many miles on your car?

My first thought was also a bad motor mount as someone as already suggested.

[Donald E. George]

I have noticed something like this when trying to keep the speed at 25mph in our small town. It seems to be that the computer has a hard time determining what gear the transmission should be in. Never see this problem at normal acceleration or deceleration.

[i_am_jim]

Continuing the story, I took the car to a well regarded local shop. They charged me $100 for not figuring out what was causing this. I can’t face taking it to another shop and paying another $100 to learn nothing, so I’m back asking a couple more questions.

Having observed more closely I can narrow down the speed range. The problem is more likely to happen between 10 and 20 MPH rather 10-30, and slower is more likely to exhibit it. Also, I failed to explain earlier, the car has an automatic transmission.

1) If I put the transmission in low and leave it there the thump still happens. I’m under the impression that when it’s in low the clutches are always engaged. If so, there should be no play in the tranny to be causing the problem, because like I said earlier, once engaged there’s no slipping. So, is it true the transmission’s engaged from the moment you put it in Low until you shift out of Low? If so, it seems like that rules out a transmission shifting problem.

2) Two people said they thought it was motor mounts. On older cars with rear wheel drive, if the motor mounts were broken the engine would lean dramatically to one side when you gunned it. But, I don’t know if that’s true of transverse engines. I watched as my wife gunned the engine, and though the engine moved a little, it wasn’t remarkable, and I think it almost has to move a little. So, how can I test for broken motor mounts?

[olympicgold]

Does this happen to you all the time? Do you feel little jerk forward or simply hear thump sound?

I also get similar problem when I let my foot off the gas and then press it and it actually jerk a little bit forward. You know the feeling when you are not used to the car or have new shoes and press gas pedal too hard and it jerks the car? Same thing to me only I actually don't press it hard so it shouldn't be happening.

[i_am_jim]

Originally Posted by olympicgold

Does this happen to you all the time? Do you feel little jerk forward or simply hear thump sound?

I also get similar problem when I let my foot off the gas and then press it and it actually jerk a little bit forward.

Hmm . . . No, I feel and hear the thump, but don't feel a jerk froward. It seems like if it were a transmission slipping and then engaging one should feel the jerk. That suggests we have different problems and yours is a tranny issue.

[i_am_jim]

Well, to whomever may be interested, the people who suspected motor mounts were right.

I took it to a highly recommended shop nearby who charged me $100 to tell me they couldn’t figure out what the problem was.

I then took it to a mechanic in a nearby town who'd also been recommended to me. He figured it out in less than two minutes and didn’t charge me anything for diagnosing it. After putting it on the lift, he said two mounts were broken and charged me $475 to replace them. I don’t know if that’s a reasonable price or not, but since he figured out what it was I felt he deserved the job.