Park Thud Revisited (1 Viewer)

[alaskacruiser]

I wrote earlier about a "thud" I hear after putting the cruiser in park and several people confirmed my suspicion that it was the parking pawl. Now I am following cdan's advice and doing the (neutral->ebrake->let off brakes->let it rest into place->brake->park) method when I want to put it in park. Now, even though the vehicle is not rolling at all after placing it in park, about 5 seconds after shifting into park, I hear and feel a "thud" just below the tranny/transfer case area as if someone took a small hammer and whacked the floorboards lightly. My ebrake DOES hold the vehicle in place when the surface is anywhere from level to a slight incline, so it's not that the ebrake is allowing it to roll into the parking pawl. This has been happening on very level surfaces, no inclines as far as I can tell. Any ideas?

 

[cruiserdan]

My, that's a good one.


A scientific wildass guess would be one or more valves sticking in the valve body. How many miles? What is the condition of the transmission fluid?

Thinking more about it.....D-

 

[alaskacruiser]

Hi cdan,
Thanks for hazarding a guess. More info:

- 50k miles on the truck ('97 LX450)
- tranny fluid changed at 30k, then changed again when I switched to Mobil 1 Synthetic ATF at 50k (did a tranny flush)
- thud has been there ever since I've owned the vehicle (it had approx. 30k on it when I got it) so it has not been affected by the tranny flush / fluid change

 

[Beowulf]

>> about 5 seconds after shifting into park, <<

Does the noise coincide with shutting off the engine, removing foot from brake pedal, or anything else you can associate it with?

-B-

 

[alaskacruiser]

Hey Beo,
There's really nothing I can associate it with, because it has happened after I turn the engine off, and sometimes while it is still on, although I do think it happens more after I've turned it off. My foot is off the brake pedal when I hear the noise. I know the truck is not rolling anywhere and it is not the same sound I was hearing earlier (I could tell that that was the parking pawl because it was obvious the truck was rolling into the pawl and the tranny lever would move slightly and "click"). It is a "thud" you can feel and it seems to originate right below the tranny and transfer case shift levers. This is a real stumper, isn't it?

 

[cruiserdan]

So,

We are talking "thud" thud, whereby you feel some type of impact or bump? Also it can happen with the engine running or shut down? Does this only happen in Park?
Does it happen if you shut the engine down in Neutral?

I'm gonna ask a guy I know about this one......


D-

 

[alaskacruiser]

Thanks cdan,

In response to your questions:

- Yes, it is like an impact or bump you can feel through the floorboards

- It only happens in park, not in neutral with engine running

- Will try shutting the engine down in neutral and let you know

- I notice it happens more when the engine is turned off, but I believe it has happened with the engine still running (will try to verify this one)

 

[cruiserdan]

He he he he, [glow=red,2,300]FOUND IT[/glow]

"Some 1997 LX450s with A343F automatic transmissions may produce a chatter noise when shifted from Reverse into either Neutral or Park. To prevent this noise, a check ball has been added to the valve body as indicated in the illustration below".

The above quote comes from Lexus TSB number TC001-98, February 13, 1998. It goes on to detail the removal of the valve body and where to add the check ball.



Dan (I am a bad dude )


Oh, forgot. I knew the 343 didn't have enough balls, this proves it.

 

[wob]

[quote author=cruiserdan link=board=2;threadid=5423;start=msg43042#msg43042 date=1064003757]
Oh, forgot. I knew the 343 didn't have enough balls, this proves it.
[/quote]


Booooooooo

 

[alaskacruiser]

Thanks, cdan! I'd seen this TSB before but I didn't relate the thud to the chatter it mentions. Will get it checked out and let you guys know how it turns out...

PS: I seem to remember someone mentioning bad solenoids and an ancient tranny...hmmm...

To be honest, though, I'm curious to find out how many miles people are getting out of the A442F vs. A343F. Obviously, a controlled study can't be done because of different levels of offroad use, maintanence, etc. and the 343Fs haven't been around as long, but still...

 

[Riley]

So my question is why does the TSB only mention the LX450?

Since the tranny is the same, why doesn't the TSB mention the LC?

 

[ELLTEE]

Yep, this thread is interesting to a lot of us -- my 99 UZJ100 also has the A343F tranny. :-\
LT
8)

 

[cruiserdan]

Riley,

I cited the Lexus bulletin because of the patient in question. There is a Toyota bulletin that covers the exact same issue. I failed to mention that fact in my earlier post. I got so excited when I actually found hard evidence that the 343 doesn't have enuf balls, I forgot.

 

[Riley]

Thanks Dan -

I figured so but I was just hoping that maybe the 343 in my truck didn't have the issue.

Good digging, now all us 343 owners can have one more thing to worry about.

It will be interesting to see how this turns out. It seems wierd to me that a guy can just "add a ball" to his tranny and then carry on with life (but then I never did understand autos).

 

[k91]

I also have this bark problem while shifting from reverse into any other gear. How do do obtain that TSB, I'm assuming that means Toyota Service Bulletin? Thanks, Matt

 

[Scamper]

So to eliminate this thud/chatter, you have to remove the valve body and drop a ball bearing into your tranny.

I'll ask the obvious question (to me anyway): what's gonna happen if you don't do this service? Sounds like it's an annoyance, not a real problem? I personally would not want to go thru all that work just to prevent a thud...

 

[landtank]

I'm actually trying to find the time to do 2 TSBs to my tranny. The ball in the valve body and the spring as well. The spring is only half of that TSB but I'm not gutting the tranny to do the whole thing. It's on my list, just don't know when I'll get to it.