Need suggestions for snugging up heat shields on catalytic converter???

[Scott H]

Before I put the exhaust back on the project wagon, I'd like to fix something that caused a random rattle on the old 535. The outer heat shields on the cat are a little loose and shift around a bit. I was thinking of stuffing a boat load of aluminum foil inside the openings I have access to, to take up the space. I was also thinking of taking it to a welder to tack the shields back on in areas where that is possible. Can anyone offer another effective approach?

Thanks!
Scott

[willobmw]

Yeah, I took mine off. No problems so far except for a piece of plastic bag that blew across the road and got stuck. Most aftermarket CATS don't even come with heat shields or the ones that do, serve no purpose.
Just my 02 cents.
Willobmw

[winfred]

tack weld or rip off, i usually rip off

[Bill R.]

place , sometimes you can take a large nut and jam it into the area thats rattling or tack it in place.



Before I put the exhaust back on the project wagon, I'd like to fix something that caused a random rattle on the old 535. The outer heat shields on the cat are a little loose and shift around a bit. I was thinking of stuffing a boat load of aluminum foil inside the openings I have access to, to take up the space. I was also thinking of taking it to a welder to tack the shields back on in areas where that is possible. Can anyone offer another effective approach?

Thanks!
Scott

[Scott H]

sometimes you can take a large nut and jam it into the area thats rattling or tack it in place.

They used the wire feed to plug weld the brackets I needed. Worked out well. With the cat out of the car, it shouldn't be a big deal for them at all.


tack weld or rip off, i usually rip off


Yeah, I took mine off

I'd like to rip it off but with all the road salt and corrosion around here, the shield is my first line of defense.

Thanks guys

[Phatty5BMW]

I mig welded mine, I couldn't stand the rattling anymore. Works so far but doesnt look the greatest underneath.(i got p1ssed) :)

[genphreak]

I mig welded mine, I couldn't stand the rattling anymore. Works so far but doesnt look the greatest underneath.(i got p1ssed) :)I migged my old one twice. First time had a shop do it, they welded all round the pipe (the lower half) but it broke again very quickly, all along the alluminum side of the weld zone. I imagine the shield actually oxidieses or disintegrates there afterwards if too much stress is applied from the motor shaking in normal operation.

I concluded that the allumium expands and contracts at a very different rate to the pipe metal so 2 tacks was the factory method of holding it and would (no doubt) be the ideal.

I welded it the second time myself, tacking in the original locations (sides of the input and output pipes), ie 180 degrees apart. This worked for 2-3 months, but my cat was ratshit- beaten badly from below and rusted, she was actually fouled so was getting too hot anyway. I replaced it with another BMW cat after that, no rattles now... most of the OE cats looked incorrect to me, heat shielded or not!

So be sure to resist the temptation to weld all round... Good luck, I hope your lasts longer than mine did. :) Nick

[winfred]

that's why i usually rip them off, you get tired of re welding them


I migged my old one twice. First time had a shop do it, they welded all round the pipe (the lower half) but it broke again very quickly, all along the alluminum side of the weld zone. I imagine the shield actually oxidieses or disintegrates there afterwards if too much stress is applied from the motor shaking in normal operation.

I concluded that the allumium expands and contracts at a very different rate to the pipe metal so 2 tacks was the factory method of holding it and would (no doubt) be the ideal.

I welded it the second time myself, tacking in the original locations (sides of the input and output pipes), ie 180 degrees apart. This worked for 2-3 months, but my cat was ratshit- beaten badly from below and rusted, she was actually fouled so was getting too hot anyway. I replaced it with another BMW cat after that, no rattles now... most of the OE cats looked incorrect to me, heat shielded or not!

So be sure to resist the temptation to weld all round... Good luck, I hope your lasts longer than mine did. :) Nick