M54 3.0i Exhaust Gasket Replacement at Catalytic Converter
 

Hey everyone, looking for some tips here. Our 2005 3.0i began leaking from a blown out exhaust gasket where the catalytic converters bolt to the center muffler (diagram attached). This seems like an odd spot for an exhaust leak, and is the first exhaust leak I've experienced on a modern BMW in over 10 years.

The removal of the four nuts looks treacherous, so I'm bringing this one to a local shop so they can use a torch if (when) needed. I'll be providing the shop:

Two new gaskets, BMW part number: 18107502346 (number 3 in the diagram)
Four copper nuts, BMW part number: 18301737774 (number 2 in the diagram)

Gasket being replaced is #3 in the attached diagram image.

My question is, how often do the studs strip out during this job? Is it possible this turns into a difficult job where the studs need to be drilled out from the cat pipes and replaced with bolts?

Thanks!

They will likely strip or have to be cur out so new ones are not unusual replacement.
But if you're taking it to the muffler shop, this is standard stuff that they're ready for and do it daily so why worry?

You should be fine. I have done a head gasket on an '05 X5 3.0 and removed the exhaust nuts you are referring to...my X5 w/ 125k miles has spent its entire life on the salty roads of NH & MA..

Unlike other BMW series (E39 & E46) the E53 X5 uses nuts AND BOLTS at the downpipe connection. The E39 and E46 uses pressed-in studs that rot away, and if they snap (likely) they have to be pounded or drilled out, which is very difficult when underneath the car.

Its a little awkward getting a wrench on both the nut and bolt at the downpipe connection on the E53 but not that difficult. If they do snap, they simply pop out with a tap.

It's unlikely that all four will snap, but if you want to be thorough, add 4 new M10 x40mm exhaust bolts, part #11621427586. They are a little pricey

I had no problems with those parts on my 2001 3.0i with 186k miles at the time when I did the engine work. I actually reused nuts and bolts (and I'm not even sure if I replaced the gaskets) with no problems. California car, so that does make this a little less surprising and maybe relevant.

The fact that you had a failure in the first place suggests you might not find things easy to work on in there.

Had to replace the same gasket on clients e92. He broke a bolt when he hit a big pothole.

I had to get new gasket but I replaced both bolts with some m8 10.9 bolts. Nuts were "fun" to hold on the back side I think I cut some flange out of my way.

Thanks for all of the replies. This is exactly what I was looking for. I didn't realize it had bolts, I assumed studs like the rest of the M54's came with! Cool.

The bolts are on the catalytic converter diagram under engine, but don't show on the exhaust diagram for some reason. You're right, a set of four bolts is $67... yikes. Hopefully the originals don't snap or strip lol.

As to the comment for "why worry"... well you can't always trust a shop to take things to the finish line. My contingency plan is to have nuts, bolts, gaskets ready so they don't have to be ordered and have the car tied up for 2-3 days at some shop. Sometimes hand holding is required haha.

Good thinking.
What do you do for a living by the way are you a project manager?

Means and Methods are usually left up to the contractor. I was a PM for 15 years and I would never tell a contractor how to perform a task. I will just call them out if they fail to follow the contract documents.

I am not a PM. I have a few select places I bring my cars, 90% of work is DIY but some things I have to bring to the following places:

1. The Dealer $$$
2. The Skilled BMW Indie $$$
3. The Local General Repair Shop $

My exhaust gasket is going to number 3, where they will charge one hour labor for this repair. The Indie place will happily charge 3 hours for this simple job.

Now that I know there are bolts present, not studs, I may even attempt it myself this weekend after all. Sprayed it up with PB blast to help get it started!

Easy to do with a good 1/2 inch drive battery impact gun and sockets. On the tougher-to-access bolt heads, use a range of longer handles open end wrenches to hold. The long-handled offset metric box wrenches at harbor freight are a big help in this job.

3/8 impact gun probably wouldn't get it done.

M54 3.0i Exhaust Gasket Replacement at Catalytic Converter
 

I believe I use my 3/8 stubby impact to get the seam bolts off of the E 92 I worked on. come to think of it though I think two of the four bolts twisted off I did replace all the bolts. if you use hardware store bolts make sure you get hardend ones.

The advantage of the hardware store bolts was I got slightly longer ones and that was much easier to get them online because the exhaust pipes love to be bent where you don’t want them. I had to redo that connection because it was in the way of changing the transfer case

Thanks for the additional tips. My two year old Husky air compressor appears to have died after using it maybe 3-4 times ever! Junk. That being said, I can't use my Ingersol Rand 1/2'' impact gun until I buy a new air compressor.

This battery impact driver looks decent, 300 ft-lb of torque.

https://www.homedepot.com/p/RYOBI-ON...261K/313581565

May also grab this inflator/digital tire gauge as well, seems very useful for only $20.

https://www.homedepot.com/p/RYOBI-18...737D/307627867

More expensive but look at the M18 series of impact. Actually I have my original high torque model I would be open to selling. 1100/760 ft·lb of torture (I typed torque but the autocorrect also fits). Ive stretched a few bolts with the sucker. I bought the 1400/900 ft·lb model to upgrade.

Wow, that is powerful. Three times the power (900 ft-lb) is also three times the price ($300) but not sold in stores around here in Connecticut.

Might try the $100 version out, if it is weak, return it and buy another air compressor.

I love my Kobalt (Lowes) 24v impact guns.. Maybe 2 years ago, I got two guns(1/2 & 3/8), two batteries, and a charger for like $250..Online coupon, etc.

the 1/2 Kobalt impact gun I have has 650 ft lbs of torque.

I know they are pricier now, but I would recommend them.

Funny you mention Kobalt, I was just looking at Lowes. They appear to have two versions both at $199 right now.

650 ft-lbs:

https://www.lowes.com/pd/Kobalt-24-V...ded/1000604927

1,200 ft-lbs:

https://www.lowes.com/pd/Kobalt-XTR-...ded/1002274076

Milwaukee sold at home Depot. Also same or next day with Amazon.

I bought mine specifically to remove axle nuts. I changed two bearings on wife's car and was able to remove with long pipe on breaker bar but I learned a trick to not break the breaker bar (which I have done a few times) and that is: use 1.5–2" PVC pipe not metal for extending a breaker bar. You can tell by the deflection when you are about to break the tool.

Anyhow the high torque tool couldn't even take out my caliper bolts the other day (because extension required to fit in acts as a torque stick) I had to use breaker bar and a hammer. Kicking it old school.

I finally bought the tool to do subframe bushings and after years of thumps and bumps from back I can finally replace them. Why I bring up is if memory serves the exhaust is right in the way so I either have to re work the same joint you are describing to remove most of the exhaust or get creative bending the welded hangar out of the way to drop the rear and risk damage to the same joint by leaving it attached.

I will of course report which route I take.

Saw one Milwaukee available at Home Depot. I ended up trying the $99 Ryobi with 300 ft-lb of torque on my E32. The wheel bolts are stuck on! Jumping on breaker bar didn't work either.

The $99 Ryobi didn't do the trick for the wheel bolts, so I returned it. Drove further out to Lowes and purchased the big daddy XTR Kobalt gun for $199. Overkill for exhaust studs, but should be good for wheel/tire changes.

All of this run around due to my air compressor failing.

I wouldn't ask this of many people, but I expect you can give a good answer ...

What is the difference between those two torque ratings for the same tool? How can nut busting / breakaway torque be 50% or more higher than "max torque"? The tool is symmetric. Is there a difference in rating methods such as how long they'll hammer on it? Do they rely on heating of the part due to installation? So they install a nut to 1400 ft-lb, and while it is still hot from that, break it loose and declare victory?

I don't doubt that it's true, since everyone uses two different numbers. I just want to understand.

BTW, I've got a bunch of DeWALT tools (for example, spent most of yesterday using my DeWALT XR 20V Chainsaw = amazing), and picked up some really nice impact wrenches a couple of weeks ago. Their 899 1/2" with about 700/1200, I think, with bag, charger, and 4 Ah battery for $200. I think both HD and Lowes have this same deal.

https://www.homedepot.com/p/DEWALT-2...99M1/206387892

But I might not use that one since the smaller 894 1/2" is so powerful at about half the weight. Rated 330/600, really cool precision mode where for example it will pause for a half second before impacting - so you can release the trigger if you don't want it to impact. And the trigger is so smooth and controllable. I'll probably use this for 99% of things I do, and have the air impact for when that won't cut it. May end up gifting the 899 now that I see how good the 894 is. Half the torque, half the weight, same price, LOL.

https://www.lowes.com/pd/DEWALT-XR-2...nch/1000404679

That DeWALT looks nice too, a bit more compact than the XTR Kobalt I just purchased. The Kobalt did the job, barely. It has the same specs approximately, however the Kobalt as a 5-year warranty vs. DeWALT's 3-year, which is nice.

Nice for $100: my battery cost more.

I have cancelled this mission, going to let the repair shop handle it. A torch will be needed, perhaps drilling out the STUDS, not bolts.

Wow..sorry to hear.. and sorry for incorrectly confirming that you have bolts - I was pretty sure of it. Maybe some X5’s have bolts and others have studs..

Very strange.

M54 3.0i Exhaust Gasket Replacement at Catalytic Converter
 

If you haven't already pulled the trigger on the shop there is another option I've used in the past:

https://shop.advanceautoparts.com/p/...275/10237537-P

https://uploads.tapatalk-cdn.com/202...6862b8fc18.jpg

It pinches around the part. This particular one is pricy. I didn't pay anywhere near this much.

I took a quick look under my 2001 3.0i just now, and I do have studs, not bolts, as well. :thumbup:

The studs are in the cat/manifold end. They are tapered, conical, coming almost to a point. As I mentioned earlier, mine are in fine shape and are original as far as I know at 196k miles.

AWR's suggestion there does look interesting. Depending on what exactly is wrong under there, one or more of those may solve your problem without needing to go anywhere.

I may be opening up that same connection soon as I am going to change my subframe bushings (only 60,000 miles overdue) and if I don't want to bend or cut the exhaust hangers I think I have to remove the whole thing.

If I do I will surely share the how

M54 3.0i Exhaust Gasket Replacement at Catalytic Converter
 

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No problem bud! I think this will definitely be a torch required job, I made an appointment last week for this upcoming Wednesday. Gotta know when to fold em lol

I had my customer pay a shop to change electric water pump on N52 vs charge customer $300 to do it because not worth it to me. $300 may sound like a lot of $.

It ain't. What a pain in ass job that was.

What do you California guys know about this? Nothing! (Photos attached)

I think our next SUV will be purchased from California, pay the $1,500 to ship it out to CT.

They are splined bolts, not studs. They are not pressed in. Mine were rusted away like in the picture above. I removed the nuts, popped out the studs with a punch, and replaced them with stainless steel bolts and nuts (and new gaskets).

That's what I would do too. For just about any car. They are priced more out here, but as far as I can tell from whenever I see people posting cars they're looking to buy, the condition of rust-free cars is not fully reflected in the pricing difference.

I grew up on the East Coast (PA and MA) and thought rust was inevitable until I moved out here. I thought it was completely normal to get a full new exhaust system every two years. :D (the steel they used back in those days made it even worse)

And yes, those pictures basically match mine.

Update. The shop did a nice job, and yes it required an acetylene torch and BFH. Not exactly the DIY job you'll do on your back in the driveway. Charged us one hour labor, $125. Totally worth it. I believe they installed new nuts/bolts but will confirm once I get under there again and look.

Definitely. It is worth the additional $1500 shipping cost in my opinion. The downsides to this strategy are:

Buying a car across the country site unseen
Getting a seller to sell it to you in this format, and trust you're not a scammer
Finding a California car with heated options, seats, winter package items
Finding a Cali car whose leather isn't dried up from the sun damage

But, cars out there exist that have been garaged and ordered with options. Just takes some effort and patience.

Glad you got the job taken care of.

After looking at that rusty hardware I think my strategy would have been twist fail the bolt/stud and plan to replace.

My 4.4i is a little different exhaust set up but I had the same rusty hardware on my manifold/exhaust flange connections. All 4 studs broke off during exhaust removal. I used a torch to heat up the manifold and then drive out the studs with a hammer and a long punch (1/2" extension). I was really dreading this task but it sounds worse than it was. The MAP+ torch was a difference maker, propane never got it hot enough.

Plane ticket, food, and gas is usually cheaper than shipping. Of course take a lot more of your time than shipping, but you can at least walk away from the deal if the car is misrepresented.

I flew out to San Jose to get Red. Was an annoying experience at times, but rewarding. Think the total for the trip (2 tickets as I flew a buddy out to help me drive), 1 night in a hotel, food, and gas was somewhere around $700? Would have to go back and check the records.

I know this thread took a bit of a left turn into buying a car from a dry state...But I whole heartedly agree. I look at 12 cars a year in MA, NH, RI & CT( I should really stop), and 11 are rusted out.

15-20 yr old BMW's in New England/rust belt are at least as expensive - sometimes more - than a BMW from a dry state. I think this represents a mis-pricing

I did just find an '06 325ci 'vert w/110k mi in RI in white/tan with a mint, rust -free exterior & top. It was purchased in Florida and spent most of its life down there...in a garage apparently. It has trans and engine problems, so I picked it up for $1k.

I bought my 6-speed ZHP 'vert in Florida on Ebay a couple of years ago for $6k Don't think the seller knew what a ZHP was..or cared...I won auction, flew down to FL w/in 3 days, inspected/drove it, and then decided to pay for it. I shipped it home..