When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Stock Problems/IssuesDiscussions related to warranty related issues and repairs, or other problems with the OEM parts and software for MINI Cooper (R50), Cabrio (R52), and Cooper S (R53) MINIs.
I was thinking about doing the fix done by R53fort, referenced in the last post on the thread, #14. Pain in the butt, having to pull the whole thing off. Why doesn't MINI put another joint in there? Has anyone else re-welded the precat, and did it hold up? When it cracks like that on the outside, does it compromise the inner guts?
I didn't know about precats until this and I've just been researching them. I get the purpose - quicker heat up than the main cat for cold start emissions. Engine-hot emissions aren't really affected by the precat, I think?? Other than cold start and of course legal (I'm not in CA, so there's that), is there a down side to removing or gutting the precat?
Has anyone else used a Race X header? Look at the pic, it appears not to have a precat at all, and the main cat is tiny, which makes me wonder how it can do it's job and have any flow capacity at all.
What do y'all think? If there are other old threads you know of that I should be reading, please reference them here. Thanks!
So if you want to go that route go with the Megan as you will have them to warranty if you need rather than fighting ebay. Either way without a cat you will get a light, we do include a spacer with a Megan headers which can prevent you from getting a light as it works most the time.
If the break is where I think it is, take a look at this thread. All fixed, no dis-assembly, a bit tricky to get to but all fixed for $125 by the local exhaust specialty shop.
WAY - thank you. So the part on the Megan-copy that I thought was a tiny cat must be a resonator or some such. Not the direction I want to go.
Jaz, did you cut the heat shield back out of the way? Or did you weld it up as part of the structural assembly?
Blah - when you say you removed the precat, what do you mean? Removed the header from the car and welded the assembly back closed with the precat intact? Knocked the guts out of the precat and then welded the can closed? Or did you cut the precat out and weld a piece of pipe in there?
Peters - thanks, I've checked out your threads, very helpful. Did your exhaust guy weld the heat shield up as part of the structural assembly?
I guess I need to get some gaskets on hand and set aside time to pull the header out to weld it. People have welded this a couple ways - cut back the shield to access the old weld and re-do it, or weld up the gap at the end of the heat shield, incorporating the shield as part of the structure. How important is this heat shield? With either of the above methods, it's effectiveness is greatly reduced because it will get much hotter on its outer surface than it does stock, or part of it is no longer there.
I removed the precar and welded it back up, popular mod overseas and quite a few of us stateside have it. Helps above 5000 rpm, the car will be louder fyi
Gearhead
Yes, my welder ran a bead all around the 'heat shield', which I think is already part of the structure, not a separate 'shield', although it does seem to be double-skinned. Others may know differently.
It was done about 2,000 miles ago.
It was a fraction of the cost of any of the alternatives, all of which need dis-assembly, replacement parts etc..
I left the shield in place without cutting it, cleaned the broken joint thoroughly then tig'd the original weld back together with more heat penetration for a thicker weld.
I took mine out (pretty simple operation) and took it to a local welder. My guy cut the outer shield back about a half-inch, welded the broken seam, and I was back on the road for $100 and maybe an hour of my own labor. One note if you go this route - be SURE to make clear, precise marks on both halves of the assembly BEFORE you take it out of the car, so your welder can be sure to line things up correctly. Mine came back just a couple of degrees off; there was barely enough play in the system to let it go back in. Another couple of degrees and things would have started to get expensive.
I punched it on an onramp to the Throgs Neck Bridge yesterday to pass a slow poke.......and of course at the exact moment I went over one of those metal expansion plates.....and all of a sudden my car turned into a Nascar truck. I thought my entire exhaust fell off but didn't hear any metal scraping. Lo and behold the weld at the precat failed just like everyone else.
I thought I'd post a few pictures so everyone can see exactly where it is.
Also, I took it to a local shop in Yonkers and while they probably took me for a little ride, they serviced me right away and I was out of there within an hour.
I saw what he did - he trimmed back the shield a little bit with an acetylene torch and then wire welded it at the existing joint.
This update came up and I realized I never closed this out. I did the weld repair myself - removed the header and did it on the bench. I cut away part of the heat shield, welded the pre-cat case back up, then welded the heat shield back together so it's fully, well, shielding. I attached some pics. Some are pre-removal; you can see that mine did not come completely apart, but the crack is visible. The other pics show various stages of welding it back together. I did this last winter and it's fine thus far.
