SGMIS3

Its kind of an intermittent problem, and it usually happens on flat surfaces, although slopes are usually worse. I know it is normal when the car is on a slope to make the noise from P to D, however my car does it regardless. Its a really loud "thunk" sound that has my passengers asking what that was.

I have noticed that the noise it more frequent and louder when there is a full car load (3 passengers at the back). Does anybody know what the cause of this is? hopefully its nothign too serious. Is anybody else noticign this problem?

It sounds like its coming from the driveshaft, near the rear of the car

t0e

iTrader: (1)

Your exhaust might be hitting some metal parts?

Or the gears are just changing under load?

A.C Milan

yup i hear it sometimes too, doesn't happen when the car was warmed up.

mikez

Exactly, only happens to me when the car is cold, and the back end up kick up a bit with a thunk sound

ISF_GG

iTrader: (2)

My car doesn't make any noise like that at all, ever. I'd take it to the dealer and let them have a look at it.

PhilipMSPT

iTrader: (5)

And make sure you're depressing the brake firmly enough...

Eddiebx

try firmly applying the parking brakes in N, then after that letting go of the brake pedal and then shifting to P. and see if that cluck appears anymore.

ryanSC300lover

iTrader: (1)

Have your tranny mounts looked at. Very common problem on older Lexus cars. Its about a 60 dollar part.

triple_c

i have the same issue, and probably has to do with the brakes. when i shift and hold the brake down really hard, that clunk doesn't happen. but as soon as i let off the pedal a bit, it clunks pretty loud. my car clunks going P to R, and R to D in the mornings. sound goes away after i've driven a while.

on a side note, have you ever had your windows down when you shift and it makes that clunk noise? it sounds horrendous.

Little E

iTrader: (2)

My mom had this problem with her 03 Avalon.

SGMIS3

tranny mounts? it must've been that time when i did a coupel burnouts

sincityIS

It is the tranny clunking into gear, mine does it intermittently as well

SGMIS3

yeah i know that, but mine seems to be really freakin loud, sometimes it scares me cause the rear of the car physically almost jumps a bit..
i hope its just the mounts though

ba-b4

It sounds like the parking pin. Our IS's have really loose parking brakes that don't hardly hold the car at all unless you really mash it to the floor. Do what EddieBX recommended. when you park don't shift directly to P yet. Shift it to N first and engage the parking brake firmly. Then let it roll to a stop on the parking brake. This way the brakes are holding the car in place before the transmission and not the other way around. Once the car doesn't move then you can shift it to P. See what happens.. if it doens't clunk then it's the parking pin. I always use this method to all my cars since my WRX day's. That car did the same thing.

triple_c

that's what i do, and i still get that noise...

and if it was the parking pin, it should make that thunk noise every time we shift from P, but the general consensus is that the noise only happens when the car is cold. it doesn't even have to be driven. the noise doesn't happen when my car is parked out in the sun for a few hours.