2008 Scion xB - AT - Metallic knock into reverse

[xBa380]

For the past few months, I have been increasingly aware of this loud, metallic knock noise my car makes when I start it up for the day and put it in reverse to back out of the driveway.

It only happens when the car has sat overnight usually, when cold. No movement, just going from Park to Reverse. If I let the car settle a bit with the idle before going to reverse, it usually lessens or eliminates the noise. So I generally try to do that, but it still happens time to time. Once in gear, its fine. Sometimes I may get a little knock when I give it gas, but that is quite rare. It's only a singl e knock, it does not repeat.

Normal operation of the transmission is great though. No other noises, shifting issues, etc... I change the fluid every 15K or so (drain/fill) with the Toyota WS fluid and all that. Feels as good as it did new for the most part. No vibrations in the cabin at idle, in fact sometimes it is hard to tell the engine is even on it can be quiet/damped.

Looking to understand what may be causing this noise. Car has 80,000 miles on it right now. Doing some searching around, it may just be a normal trait of this car/tranny/etc... But I am thinking maybe motor mounts or something. Not sure.

Thanks!

 

[GSCJR]

Check the tranny mounts.

 

[jrustles]

Originally Posted By: GSCJR
Check the tranny mounts.


indeed. check all mounts, including the exhaust hangers

 

[Rand]

any mounts? transmission, engine, etc.

 

[xBa380]

Not sure exactly how to check/diagnose mount issues personally. Any suggestions?

2AZFE Engine and the 4-spd auto tranny.

 

[artificialist]

Originally Posted By: xBa380
Not sure exactly how to check/diagnose mount issues personally. Any suggestions?

2AZFE Engine and the 4-spd auto tranny.

Have someone put the car in drive, and hold the brake pedal while revving to 1500 RPM.
Then do the same thing in reverse.

If the engine moves more than about 1/2 inch each time, a mount is weak and needs replacement.

Many Toyota cars have a hydraulic and conventional engine mounts. Be sure to get the right one. Go to your dealer, there exist no quality aftermarket mounts I know of.

 

[xBa380]

Sounds good, thanks!

My brother works at a Toyota Dealership, so maybe I can get some type of discount on service there... I know he gets parts discounted, but not sure how easy/hard the job is to do myself.

 

[artificialist]

Originally Posted By: xBa380
Sounds good, thanks!

My brother works at a Toyota Dealership, so maybe I can get some type of discount on service there... I know he gets parts discounted, but not sure how easy/hard the job is to do myself.


It depends on the mount type, the location, and the cars design.

Some mounts on certain cars take 15 minutes. Others take 3 hours.

I am sure it isn't too expensive for your car, because your car is not very complex.

 

[xBa380]

I just did the check and watched the engine movement carefully.

It looks to move about the same amount in reverse and drive gears when rev'd... No odd sounds or anything. It does seem to move 1-1.5" it looks like, you can see it quite a bit.

I took a video of it, so I will get a link here shortly so you can view it. It also has the knocking sound as well.

 

[xBa380]

Here is the video!

http://www.youtube.com/watch?v=u3WXvkJczSo

Appreciate any input!

 

[jrustles]

Originally Posted By: xBa380
Here is the video!

http://www.youtube.com/watch?v=u3WXvkJczSo

Appreciate any input!


Hey, did that noise happen in the video?
Was it that loud click when you moved the gear lever??

 

[xBa380]

One of the knocks happen at the 33 second mark... It may be hard to pickup, but there is a faint knock sound when the engine is rev'd.

No abnormal noises that I hear when just moving the gear lever, except when cold, it will make that knock sound when just put into R. Sometimes it happens when rev'd, like above (@33sec). But otherwise, nothing out of the ordinary.

There is no other unique noises at all, or rough shifting, etc... When being driven. This only tends to happen when cold, when the car is put into reverse. Sometimes it will also make that knock when in reverse and you gas it a bit.

 

[jrustles]

Yup, heard it @33sec. It occured at the first loading of the engine in Drive, though you mention it happens when just going into reverse.
It almost sounds like a cam phaser filling one of the chambers with oil after having drained out, or a tumble control valve.

Do you feel it in the body of the car, or is it just audible?

 

[xBa380]

I think at that point in the video, the car was in reverse. The first few rev's are in Drive, switched to reverse at 30 sec... It should be in reverse for that knock at 33sec. I then switch it back to drive at 52 sec, then to park at the very end. (But maybe I got it backwards though, very possible!

)

I don't feel it through the car or anything, just audible for the most part. At least that I have noticed!

At idle, the car is very smooth. No vibrations or anything unless AC is on and may get some shuddering... Feels perfectly fine for the post part, except for this knock I am concerned with!

 

[jrustles]

Originally Posted By: xBa380
I think at that point in the video, the car was in reverse. The first few rev's are in Drive, switched to reverse at 30 sec... It should be in reverse for that knock at 33sec. I then switch it back to drive at 52 sec, then to park at the very end. (But maybe I got it backwards though, very possible!

)

I don't feel it through the car or anything, just audible for the most part. At least that I have noticed!

At idle, the car is very smooth. No vibrations or anything unless AC is on and may get some shuddering... Feels perfectly fine for the post part, except for this knock I am concerned with!




haha yea, if the top of the engine leans forward, then you're in reverse and vice versa

Given that you don't feel it in the body, I'd be tempted to rule out a mount or exhaust hanger, it doesn't sound like that either.

 

[xBa380]

Anybody else have any ideas looking at the video? Is the motor mount fine?

 

[afoulk]

That amount of movement looks completely normal. Could it be your cold air intake making contact with something, or loose?

 

[xBa380]

I will check that out! There is only one mount point for the CAI, so be easy enough to check.

 

[xBa380]

Inspected that and it was OK. Good idea though!