c didy

Okay guys, wintertime, time to do the cat bypass and chip change on the C2. Two of the the cat heat shield bolts are spinning. I want to remove it for access to remove the cat. What's your go-to method to remove them? Drill baby drill?

Then there's the o2 sensor which needs to be switched over to the new bypass pipe. Who can say what is best for removing these notoriously pesky little buggers?

Searches here have been only partially helpful so far.

FeralComprehension

In my garage those get the red-hot treatment. Judicious use of an oxy-acetylene torch to get the bung red hot and then put a wrench on the sensor hex.

Use high-temp anti-sieze during reassembly.

mr pg

I managed to get my cat off with the heatshields in place. Just makes it more difficult, but doable. Also worth while just getting a new O2 sensor, rather than trying to get the rusted one out. Only about 60 UK pounds money wise.

-nick

I think that I ended up using a cutoff/wiz-wheel on the heads of the bolts. Be careful and you won't even scratch the heat shields.

Replace the stock speed nut$ with M6 extruded U-nuts and you'll never get a bolt that just spins again.

Marc Shaw

Angle grinder for the bolts. Replace with stainless.

Marc

Silvertarga

I borrowed the O2 sensor removal wrench from AutoZone and used my jack handle for additional leverage, it came off without any additional chemical assistance, try Amazon for the replacement...direct plug in OEM Bosch was only about sixty bucks

c didy

hhmm. yes, something like these?


http://www.nutsandbolts.com/m6-10-sc...-25-p-939.html

PNine64

If you are going with a cat bypass why reinstall the heat shield? I understood the lack of restriction results in cool enough temps not to worry.

BTW...good call on borrowing autozones o2 socket.

c didy

no chemical assistance? no heating/thermal assistance? had you used high temp antiseize previously?


Seems like, refresh my memory, 22mm?

c didy

It looks like it might be easier to access the primary and exchanger mounting bolts with the heat shield off. Is that not necessary?

Also, when I put the cat back on I'll want the bolts replaced so they don't rattle and bug me. Yeah, it bugs me, hope the beancounters got themselves a raise for saving 1 penny per car when they spec'd those fasteners.

Otherwise I agree and will not run the heat shield with the cat bypass. I don't think it's the air restriction that makes it hot, it's the exothermic (heat generating) ongoing catalysis of exhaust gases that makes it extra hot and cleans up the exhaust as it does. There is no catalysis in a bypass cat, (go figure), so it doesn't get any hotter than the exiting gases already are after they leave the exchangers or headers.

c didy

"Angle grinder for the bolts. Replace with stainless."

Marc


It looks like the bolts are fairly recessed so my angle grinder can't really get to them with damaging the shield but I like the idea of going stainless.

"I think that I ended up using a cutoff/wiz-wheel on the heads of the bolts. Be careful and you won't even scratch the heat shields.

Replace the stock speed nut$ with M6 extruded U-nuts and you'll never get a bolt that just spins again. "

This looks like the way to go probably.

c didy

ok, here's the deal on removing the cat.

"You remove the cat with the shields in place (except the curved one leading behind the rear wheel). Make sure of course that you reinstall the far shield before putting the new cat back in place! Soak all bolts in WD40 overnight although you may have to cut through some that are rusted in place so have some suitable bolts and nuts just in case. Biggest problem I found was removing the O2 sensor and bolting the cat to the secondary muffler which was not in line on fitting the cat back (may have to loosen off more of the exhaust system to make this job easier. "

Is it better to remove the O2/lambda sensor before pulling the cat off?

Laker

Yes,
good luck getting the 02 Sensor out with the cat removed. The cat being installed will work better than any vise at holding the cat still why you try to remove the 02 sensor.

c didy

it may be obvious but, do you unplug the wires/connector first so they don't spin as the sensor spins off happily, or do you leave them connected?

also, how do you read the bolt sizes/lengths from the diagrams to order new bolts/nuts before starting since they are going to break anyway?

Laker

I was doing an 02 sensor replacement so started by unplugging the wires in the engine compartment.