sktn77a

iTrader: (2)

Hi all:

I have a 1999 RX300 AWD with 120,000 miles on it. It has a noise coming from the exhaust as you rev the engine to take off - sounds like either a heat shield vibrating or one of those "sporty" (straight-through) exhaust noises (only not as loud). It had the flex-pipe replaced 18 months ago and the manifold replaced (supposedly had a crack in it) just before Christmas.

Are there any muffler/pipe/catalyst heat shields that develop this rattle/vibration? Seems to be coming from the front of the car, not the rear. Anyhting else it could be?

Thanks

salimshah

You are already on the right track, exhaust leak (most probably) or rattle.

Check the flex pipe for the leak or crawl under (when every thing is cooled down) and physically shake things. [note the exhaust and catalytic converter can be very hot]

Salim

TunedRX300

Bolts holding the heat shield of the catalytic convertor may be rusted out. If it is feels like little rocks rattling inside the cat then you need to change it sooner or later.
The cat is right down the driver's seat so just bend down like Salim suggested and take a closer look.

habeeb89

iTrader: (3)

I would probably check the bolts or the heat-shield, I use to have this problem in my Accord a while back ago, it turned out to be the cat shield.

sktn77a

iTrader: (2)

No it doesn't sounds like that - sounds more like an exhaust leak or vibration more than a rattle.

Lexmex

I might have someone else drive the car on a dead end street and then you might be able to narrow down the location further that way.

UNOHOO

iTrader: (3)

ok guys, stop me if this is a bad idea.

What if while the car was cool you pulled to AF sensor in the front and dropped a single drop of something like saaaaaayyy super glue in the exhaust manifold, put the AF sensor back, start it up, then got outside and waited to see the smoke come out of your mystery hole?

Lexmex

If you wanted to go exhaust leak hunting you could go underneath the vehicle and hold your hand a bit from the the pipe at joint areas and see where the leak was, too. I don't think the above is going to work quite right.

UNOHOO

iTrader: (3)

well what made me think of that was because i have an exhaust leak too, it seems kinda strange though. Sometimes you hear it and sometimes you dont. It seemed like everytime i went to look for it the car was in a position that pressure was being applied to the coupling or whatever you want to call it and you wouldnt be able to see it or feel it until one day a few weeks ago when it was hellaciously cold outside and i fired the car up to warm it up. smoke/steam/whatever it is (running on 2.5 hours of sleep so youll have to excuse me) started billowing out from the undercarriage below the driver door. I bent down and finally found that thing. So I was just trying to think of a way to "recreate" that effect.

sktn77a

iTrader: (2)

That's a good point - I've been focussing on the noise but maybe I can look more carefully for water vapor coming from under the car instead of from the exhaust at the back. It's been pretty cold here for the last week!

UNOHOO

iTrader: (3)

HOORAY!! I am useful

mikey00

A common exhaust leak point on the RX, located about below the drivers door, is the gasket at the junction just in front of the cat. It is 2 flanges held together by 2 14mm bolts on springs. Lexmex has some good pics of it here:
https://www.clublexus.com/forums/rx3...uspension.html

And here is a parts diagram of it. It is #16 Gasket Rear Converter.

http://www.trademotion.com/partlocat...layCatalogid=0

Mine has been leaking for awhile. I just started soaking the bolts the last couple of days in hope of being able to remove them. They are rusted pretty bad so I may end up breaking them and having to drill them out and replace with nuts and bolts. Anybody know the part number of this gasket or any other tips?

salimshah

Shops use a chisel (air driven) to knock out the head or the bolt. With heat cycles and exposed to air the thing would be hard to budge .. so only use a 6 point socket. One end may be welded. For replacement you can try stainless steel.

Salim

mikey00

Both Lexus and Toyota part # for this gasket is 17451-0A010. I picked it up for less than $18. at the Lexus dealer. I ended up having Midas put it in for $20. I figured it wasn't worth messing around to save $20.

sktn77a

iTrader: (2)

My kinda guy! "Why have a dog and bark yourself"???