Hey guys,

 

I own a 99 Legacy GT with about 100k km. For the last 30k km or so I've experienced a grinding/shrieking/creaking sound coming from the front end of the car.

 

The sound only occurs when the car is in drive, at around 1600rpm. If I accelerate quickly past that point, the sound does not occur. If I keep it at 1600 rpm the sound is constant.

 

I believe it might be the transmission but I just got it replaced about a year ago. The sound was present even before the replacement so I don't really know what to believe anymore.

 

Any ideas before I head back to the shop?

 

Thanks in advance.

heatshields on you're exhaust

heatshields on you're exhaust

Wow really? I would have never thought.

 

A brief google searched pulled up the same symptoms with heatshields being mentioned but there was no follow-up.

 

If that is the case, am I looking at an expensive repair?

what we do to fix loose heatshilds were i work is just take a few self tapping screws and screw them right into the heat shield.....just enough threads until it hits the exhaust pipe and you will see the heat shield kind of backing away...give it a few more turns for some tension and wola.....

good call Gloyale, i'll bet that's right!

 

were i work is just take a few self tapping screws

BEWARE - THIS GUY WORKS AT A TIRE SHOP!!!!!! just kidding - but man does that sound like flats waiting to happen!!??

 

heat shields are benign anyway. i rip them off, much easier than dealing with them. i understand the concept, but they certainly aren't needed. and if you had an exhaust shop completely replace your exhaust, they wouldn't bother installing a heat shield unless it came already bolted to the exhaust (which it wouldn't!).

same thought as others, it's a loose exhaust heat shield shroud on your exhaust system. It is a low tech problem, therefore, I give it a low tech solution. I drive my car up on ramps, crawl under the car, tap on the shroud with a screw driver to learn where it is loose and makes noise. I then hammar in place (wedge) a good size bolt between the shroud and the exhaust pipe. This prevents the shroud from vibrating. Sure, a low tech fix, but it works. No shroud noise from my car for two years now.

good call Gloyale, i'll bet that's right!

 

BEWARE - THIS GUY WORKS AT A TIRE SHOP!!!!!! just kidding - but man does that sound like flats waiting to happen!!??

 

heat shields are benign anyway. i rip them off, much easier than dealing with them. i understand the concept, but they certainly aren't needed. and if you had an exhaust shop completely replace your exhaust, they wouldn't bother installing a heat shield unless it came already bolted to the exhaust (which it wouldn't!).

 

I have worked for the fire department in a metropolitan area since 1974 and I can assure you that heat shields are NOT benign! If you remove the heat shields and park in grass, you may very well come back to find your car in flames (have seen it numerous times, even with heat shields in place). You may say that you'll never park off the road, why are you driving an AWD car then?

 

Removing your heat shield exposes the carpet and sound insulation to temperatures high enough to cause a fire (once again I have personally seen it).

 

DO NOT remove the shield, Use one or two stainless steel dryer vent clamps or screws to stop the shield from rattling. Removing the shield is irresponsible and asking for trouble.

Scews??? Wedging bolts??? C'mon, what about good ole fashion welding??? A few tacks in the right place and she's all done. I would worry about self tapping screws diggin into my pipe, seems like a rust attraction for sure.

 

 

The other reason not to remove them is that they aren't just heatshields, they are armor. At least on the older Legacies and I believe on most outbacks. The pieces above the pipe (between car and pipe) are heat shields, The lower panels are substantialy thicker and have a stamped shoulder for rigidity. Those pieces are armor.

i'm glad i know this now before i've had a fire!

why are you driving an AWD car then?

i didn't know heat shields were that important.

 

i am surprised they make any difference though - have you ever seen a car that's been off road in the nasties? i drive through fields all the time, grass stuck everywhere, been buried in mud, mud and water pouring into the car when i open the door, had it stuffed all up underneath with grass, mud, and debris in every corner and crevis available. i don't think heat shields keep that stuff away from the exhaust when you're in that much stuff. grass and mud find it's way into every opening available. it's hard to imagine doing any real off road driving without having grass in contact with the exhaust...even with a heat shield.

 

i've never had a fire in all my years of off road driving. i'm glad i know now that, i'll be sure to keep an eye when i'm off road - which is every fall at a minimum.

Not everyone has a welder, nor knows hoq to use one, nor should be allowed too use one.

hhhmmm, i have one...and i know i don't know how to use it very well so i guess i fit in one of the lasts two categories!!! probably depends on the job i'm attempting!

i'm glad i know this now before i've had a fire!

i didn't know heat shields were that important.

 

i am surprised they make any difference though - have you ever seen a car that's been off road in the nasties? i drive through fields all the time, grass stuck everywhere, been buried in mud, mud and water pouring into the car when i open the door, had it stuffed all up underneath with grass, mud, and debris in every corner and crevis available. i don't think heat shields keep that stuff away from the exhaust when you're in that much stuff. grass and mud find it's way into every opening available. it's hard to imagine doing any real off road driving without having grass in contact with the exhaust...even with a heat shield.

 

i've never had a fire in all my years of off road driving. i'm glad i know now that, i'll be sure to keep an eye when i'm off road - which is every fall at a minimum.

 

The main danger is from the catalytic converter(s), fires typically don't result from brief contact with grass, rather from longer contact such as when parked in a field. I have seen a clogged or malfunctioning converter ignite carpeting and insulation on the floor of the passenger compartment even with shields in place.

I really appreciate all the suggestions and feedback.

 

And I'm relieved that the problem is nothing serious. Although I still don't quite understand why the heat shield only rattles at that particular RPM.

 

I'm bringing my car in for brake maintenance next week so I will have the mechanic secure the heat shield. I park my car on grass all the time when I go to my cottage so I don't want to assume risk by removing the heat shield.

 

Thanks again, you guys are great!

I really appreciate all the suggestions and feedback.

 

Although I still don't quite understand why the heat shield only rattles at that particular RPM.

 

Yes, it is typical to have the heat shield rattle only at certain engine rpm, like around 1800 to 2000 rpm. My guess, is that only a certain rpm causes the shroud shield to vibrate to cause the noise. Lower or higher then that specific rpm must not set up a harmonic vibration.

oh yeah...sign up for a class in vibration and flutter, or system dynamics or just look it up on line!

 

now i'm curious - can a properly function car/exhaust still start a fire? back in my younger years i used to think it was cool to leave all the mud fling and grass stuck in my car while i was driving around after a day in the field.

 

since you're in the fire business - why is it that cars with massive oil leaks don't catch on fire more often even when it's dripping and "burning" or smoking on the exhaust? there's any number of threads about smoke machines and smoke filling cabins...but rarely a fire.

during my many forays of off roading the grass probably burned up and just never ignited the field? another good reason not to live in california i guess!! hard to believe i never saw smoke/fire with those numbers - burn at 180 - exhaust at 500+ degrees. i won't forget that from here on out!

I had the headers on my honda set some grass smoking.....Now that i think about it that was after removing the heat shield too.

 

I regularly used to drive that thing hard enough to have the pipe glowing bright red as far back as the cat. It looked freakin awesome parking up at night with a faint red glow coming from under the car and through the grille.