Low rpm rattle w/ fix...
 

Throughout my first month of ownership, I've noticed a low rpm rattle that sounded like it was coming from the exhaust area right below my seat. The noise would start when I first depressed the gas pedal and go away above 2000+ rpms... :confused:

As I had some free time this weekend, I decided to prop my car up and see what was amiss... I was horrified to find that one of the bolts that attached my exhaust to a hanger, in front of the secondary cat, was completely missing! :eek:

Not sure how it came to be missing in the first place, but I knew that the dealership I bought my car from had to replace both primary cats and O2 sensors. The mechanic must have ended up with an extra nut & bolt at the end of the install and probably just tossed them in ignorance! :mad:

Anyway, I found a strong nut & bolt in my toolbox and they worked just great. Afterwards, I took the car out for a spin and the rattle was gone! :)

-Chike

P.S. That's the second bolt I've found missing from my SVX - the other one was in the engine bay area and attached one of the fuel lines to a bracket - I noticed that one the day after I bought the car and replaced it right away!!! :D

i have a rattle coming from underneath my car when going uphill. I dont think it happens when i am traveling on a normal road but if i have my windows down and am traveling uphill i can hear a rattle. I have no clue what it is.

Rattle
 

Hi everyone, I believe the sound you are hearing is the heat shield that goes around the exhaust system. It can be fixed. There should be a how to fix if you look for it. Take care, BOBB

What is the heat shield that you speak of? Each cat convertor has a 'shield' covering it. I checked the one covering my secondary cat, and the bolts were on tightly. I didn't check the primary cats, but the noise went away so I didn't bother...

-Chike

Shields
 

Hi Chike, If you have an OEM exhaust like from the factory, then you have shields over most of the exhaust system. If not then some previous owner removed them. I also had a rattle in the rear muffler but it was only heard from the rear of the car, on the outside. Just ift the SVX and bang on the shields/exhaust and see if you hear the rattle. Take care, BOBB

Re: Shields
 

Thanks Bobb. I'll have my car jacked up this weekend and take a look. The OEM exhaust is still on there but I didn't look at the shields near the rear of the car...

Your input is always welcome. :)

-Chike

There are heatshields around the exhaust headers, from behind the headers up to the piping to the primary cats, the primary cats, and from behind the primary cats up to the secondary cat. I'm not 100% sure if there is a shield around the secondary cat, but I don't think so.

The only other heatshield is on the underside of the gas tank, for obvious reasons.

Would there be any -ve effect if I removed the heat shields? The only one 'relatively' close to the trans is the secondary cat, but the primary cats and headers are far away. Also, other members who have added complete aftermarket exhaust systems had to do away with the shields w/ no ill effects.

I'm thinking of weight reduction here, those heat shields must add a few pounds... ;)

-Chike

P.S. I wouldn't touch the gas tank one for obvious reasons! :D

Precisely. :)

Keep cool
 

The heat shields are there for a reason.

No doubt many have taken them off because of the buzzing or rattling, or changed to a system that did not use shields. The -ive effects will be long term, mostly.

More radiated heat will get to the floor of the car, which will then heat up the interior. In summer, this will give your aircon much more to do.

A possible worse effect is long-term, this extra heat may harden and perish any wiring harnesses around the transmission tunnel, and possibly any other rubber parts in there.

Long term, as I say, problems from this would not show up for a while.

You pays your money and takes your choice.

Joe:D

Re: Keep cool
 

Hmmm.... (contemplates shaving ~10lbs off of his already 'bloated' ride) ;)

-Chike

Don't the heat shields keep the exhaust at some sort of "optimal" temperature or something like that??





Dave

I had a similar rattle and it was caused by a loose baffel (sp?) within the primary muffler. I had it cut out and replaced with a straight pipe.

http://www.subaru-svx.net/photos/fil...95SVX/5786.jpg

Re: Keep cool
 

I've spoken about the shields with an excellent local exhaust shop around here. Apparently, the shields can also have long-term negative effects by being there as well.

The shields essentially insulate the piping, which holds the heat between the shields and the pipe. This causes the piping to heat up more than it would if it didn't have the shields. Apparently, this can corrode and break down the piping.

I haven't had the car long enough to know if it's true, but everything else about them has always been very reputable.

Looks like that loose baffel was somewhere in your resonator? :confused: That straight pipe appears to be in the place where the resonator would normally be...

-Chike