Exhaust Rattle

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JRB99
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Exhaust Rattle

Postby JRB99 » Mon Jul 29, 2002 4:50 pm

I just put a HKS hyper exhaust on my 91 240. When I get off the highway, or after doing highway speeds, it rattles between 2 - 3k rpms. Has anyone had this problem or knows how to fix it?

Thanks!


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MaineExport
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Postby MaineExport » Mon Jul 29, 2002 4:50 pm

I have the same rattle you mentioned (between 2k and 3k) As far as I know it's the cat. I think they start to turn to crap at some point and just rattle. Someone said it's the heat shield, others have said it's the internals. I don't really know, all I know is I'm looking for a test pipe to replace mine.

GoofyATX240
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Postby GoofyATX240 » Mon Jul 29, 2002 4:50 pm

Just get a new test pipe or make one PDM has some for sale.

tkrolo
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Postby tkrolo » Mon Jul 29, 2002 4:50 pm

From most of the posts that I have seen, including my experience, the exhaust rattle is probably caused by the heat shield that covers the cat. My shield actually rusted away from a couple of the bolts so I had to remove it completely.

JRB99
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Postby JRB99 » Mon Jul 29, 2002 4:50 pm

I have been thinking about getting rid of my cat, either with a dump pipe or a high flow one. I hope it does get rid of the problem, it is very annoying. Thanks everyone for the help!

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Tx-Sx-FS
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Postby Tx-Sx-FS » Mon Jul 29, 2002 4:50 pm

i just took all heat shields off except the one on cat...im thinking that the inside of cat is messed up cuz its still makes a bubble or bloob bloob bloob bloob noise when i release gas pedal...is that the cat?? what precaution would i take about taking off the heat shields??

lok
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Postby lok » Mon Jul 29, 2002 4:50 pm

My exhaust was diong to the same thing a while ago. I just tightened on the 12mm bolts that holds the exhaust hangers to the car. The 2 in the back.

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Tx-Sx-FS
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Postby Tx-Sx-FS » Mon Jul 29, 2002 4:50 pm

where at on the exhaust would i see those?? by cat or by tip?

lok
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Postby lok » Mon Jul 29, 2002 4:50 pm

They are located on the end of the exhaust. It is where your hangers mount to the car. My rattle came out of no where. Basically the washer was rattleing at 2600 rpm.

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Camel
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Postby Camel » Mon Jul 29, 2002 4:50 pm

Tx-Sx-FS wrote:i just took all heat shields off except the one on cat...im thinking that the inside of cat is messed up cuz its still makes a bubble or bloob bloob bloob bloob noise when i release gas pedal...is that the cat?? what precaution would i take about taking off the heat shields??


that doesn't sound like the cat, that sounds like a lack of backpressure. Unless it sounds like a baby rattle, it is probably the low backpressure causing rumbles not rattles. It subsided some for me when i put on a high flow cat. Not sure exactly why. My old cat was in perfect shape with less than 70k on it.

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Postby slo40 » Mon Jul 29, 2002 4:50 pm

On my 240 the exhaust shield above the cat rattled at 2500-2800rpm. Just took it off and yeah that was the problem. Also, haven't noticed the floorboard being any hotter either.

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Tx-Sx-FS
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Postby Tx-Sx-FS » Mon Jul 29, 2002 4:50 pm

slo40- when u took off the shileds..did u wrap ur plugs wires with anything to protect from heat? what about other stuff that could melt or overheat??

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Postby slo40 » Mon Jul 29, 2002 4:50 pm

How would plug wires have anything to do with removing the heat shield around the cat? Hmmm anyways no I didn't wrap anything, and everything has been all good for the last 2,000.

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Postby SHIFTrl240 » Mon Jul 29, 2002 4:50 pm

i believe he has the impression you removed the heat shield that goes over the header in the engine bay

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Postby slo40 » Mon Jul 29, 2002 4:50 pm

I didn't remove that heat shield myself, but the previous owner had removed it. So who knows how long it has gone without that shield. The spark plugs are fine without the heat shield and nothing else is close enough to melt. Especially if you remove the AIV to open up that side of the engine bay.

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Postby SilviaS14KA24DE » Mon Jul 29, 2002 4:50 pm

i didn't even know that there was a heat shield above the cat. I took of the one above the rear muffler, and the rattling stopped in that area. :) i will take out the cat heat shield...sounds like it's coming from there anyway

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Tx-Sx-FS
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Postby Tx-Sx-FS » Mon Jul 29, 2002 4:50 pm

i think its either the cat itself ..or like Camel said that theres not enough backpressure...ill find out nex week when i get paid and have some money

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Postby TurboKA37 » Mon Jul 29, 2002 4:50 pm

i had the same problem at 3000 rpm and a more recent one at about 2200 rpm. i had the first one at 3000 rpm looked at when i got inspection and the guy put some more clamps on the cat heat shield and it didnt solve the problem so he concluded that it was the internals of the cat.

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Tx-Sx-FS
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Postby Tx-Sx-FS » Mon Jul 29, 2002 4:50 pm

thats what im thinking it is..the cat...but not sure with my emissions if i should just get a high flow...another factory..or test pipe...what would be best? and cheap

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niznos
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Postby niznos » Mon Jul 29, 2002 4:50 pm

The cheapest thing you can put in there is a test pipe. Cats are expensive, either stock or high flow. If you are in an emission controlled area, you'd better get a real cat on there though.

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Postby SilviaS14KA24DE » Mon Jul 29, 2002 4:50 pm

well, it may sound like it's coming from the Cat, but what I will do tomorrow is remove ALL the heat shields from the cat to the back. There are small, heatshields screwed onto the piping, so Imma see what happens when I remove it :) I'll post results after.

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Ender_Zero
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Postby Ender_Zero » Mon Jul 29, 2002 4:50 pm

make sure you look for any wires in that area and insulate them good before driving around too much without the heat sheild. id hate to see you burn up some of your wires...

SilviaS14KA24DE
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Postby SilviaS14KA24DE » Mon Jul 29, 2002 4:50 pm

so far, no wires :), and I don't believe there will be wires that run along the exhaust piping.

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Tx-Sx-FS
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Postby Tx-Sx-FS » Mon Jul 29, 2002 4:50 pm

i asked about that earlier...what wiring do i need to protect from the heat? spark plugs? anything else?

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extheflow
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Postby extheflow » Mon Jul 29, 2002 4:50 pm

could be something like a nut or washer between the heatsheild and the exhaust.get it up on some stands(or a lift if you're lucky) and beat and bang on them.you might find a foreign object in there.if not you'll probably find the loose sheild in the process.

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Postby SilviaS14KA24DE » Mon Jul 29, 2002 4:50 pm

well, I got it done. I removed ALL the heat sheilds from the cat to the back, and that one heat shield that is from the down pipe to the cat. There is still a small rattle. I don't mind this cause it's not loud at all. The last rattle i believe is the heat shield that goes around the down pipe. I'll have a look at it tomorrow but so far, everything is good with the non-rattling.

Oh, If you think you're gonna "burn" a wire" for the s14, there aren't any that is in danger. Before my friend bought his s13, the previous owner changed the whole exhaust system (he changed it and made it stock, so nothing special). Obviously since he replaced it, there are no stupid heatshields from teh down pipe to the back to make it rattle. So to further prove you won't mess any wires up, that is it.


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