Exhaust: Stupid Studs instead of Bolts?

My flex pipe flange was rusted to such a degree that the neck of the flex separated from the Y-pipe, which resulted in a sonic boom of thunderous proportions. Miraculously the flex pipe was not damaged so I purchased a split flange to be mounted behind the remnants of the rusted flange and bolted to the Y-pipe, and a new gasket.

Problem is that the two holes of the Y-pipe flange are plugged with what I had assumed to be rusted bolt stumps, but a closer inspection revealed that those stumps are actually the protruding remnants of studs seated into the Y-pipe flange. The end of the studs is mounted flush on the back side of the flange. The stumps have no thread left so they can't be used to join both flanges.

What would be the best way to remove those studs taking into consideration that I am working flat on my back under the van, outdoors in the ice, with about 16" clearance? Please don't say "go to a muffler shop", the idea is to spend as little as possible because next Spring I am replacing both exhaust manifolds and the flex pipe.

I've been there. Older exhausts, especially in salty climates, rust to pieces, surely as the sun rises in the morning.

A professional mechanic would clean up the rusty stud remains, and weld a nut on the end. They they would heat up the flange bright red with an acetylene torch, turn the nut and the stud would unscrew easily. This would take maybe 20 minutes, tops.

However, you have no torch or welder. There might be enough stud left to grip it with Vice-grips. You might try heating up the flange with a cheapo plumbing propane torch and ease it out.

The alternative would be to cut off the flange flush. Then drill-out the stud and tap new threads and install 2 new bolts. But this assumes you have a decent drill, bits and taps.

Good luck. :)

I've been there. Older exhausts, especially in salty climates, rust to pieces, surely as the sun rises in the morning.

A professional mechanic would clean up the rusty stud remains, and weld a nut on the end. They they would heat up the flange bright red with an acetylene torch, turn the nut and the stud would unscrew easily. This would take maybe 20 minutes, tops.

However, you have no torch or welder. There might be enough stud left to grip it with Vice-grips. You might try heating up the flange with a cheapo plumbing propane torch and ease it out.

The alternative would be to cut off the flange flush. Then drill-out the stud and tap new threads and install 2 new bolts. But this assumes you have a decent drill, bits and taps.

Good luck. :)

Thank you for your reply :)

I am the proud owner of drills, some bits, a propane torch and an ace torch... which is not working atm :crying:

With regards to rusty exhaust parts I was somewhat puzzled by the sight of the extremely well preserved cats (they looked almost new) compared with the rusty exhaust manifolds and frayed flex pipe. Downstream components are ok I guess, not punctured anyway. Everything including the cats are at least 7 years old because that's how long I have owned this vehicle. It receives rust treatment every year.

The thick heavy Y-pipe cat flange itself has no rust at all, it looks like corrosion started with the flex pipe flange then spread to the studs and just stopped there. There is very little left of the visible part of the studs, about 3/4" on one side and no more than 1/4" on the other. The former still had half a rotted nut clinging to it by the grace of God. The latter has been eaten to the core, it is about the thickness of a toothpick but the part that is still inside the Y-pipe flange appears to be intact. That's the reason I didn't put a vise-grip to them, they would likely snap flush. I do not know of what metal the studs are made of but their end that is visible on the back of the Y-pipe flange is brass colored.

It is not brass though, much harder. I could not center punch them and I broke two metal bits, but that is likely due to the lack of clearance up front and using a cordless drill. Tomorrow I will try again but from the rear (that would be the front of the Y-pipe flange) where there is room enough to use the more powerful electric drill. I have decided it isn't important to me to preserve the threads inside the flange holes when I can just as well use a bolt and nut to join the flanges like I have done my whole life, never had a car that had exhaust flange studs downstream from the cats before, always bolts and nuts. Seen them on light trucks though and I suppose that technically, second-generation Winnies are trucks.

So what I intend to do is cut off the protruding stumps and then drill through the bottom of the studs clear to the other side of the flange using a bit the same diameter as the hole. What do you guys think? Is this feasible and if so, what is the most appropriate type of bit to use for this purpose?

I have decided it isn't important to me to preserve the threads inside the flange holes when I can just as well use a bolt and nut to join the flanges like I have done my whole life, never had a car that had exhaust flange studs downstream from the cats before, always bolts and nuts.

So what I intend to do is cut off the protruding stumps and then drill through the bottom of the studs clear to the other side of the flange using a bit the same diameter as the hole. What do you guys think? Is this feasible and if so, what is the most appropriate type of bit to use for this purpose?

i've done what you proposed on 2 different vehicles, not really on a windstar

also i'm noticing on some service manuals that the manufacturers are adding an additional ground strap down there to connect the exhaust pipes to the body of the vehicle :eek7:

all exposed to the elements and broken within a few years

you're lucky to have those tools; i had a small dremel with a case of cutoff wheels & went through a few of them to cut off the rusted studs/ welded nuts:runaround: then i slid the cat-back off the remaining studs to cut them off

I actually grab the Dremel at first ... by slow grinding with the 1 1/2" dia cut-off wheels: the temp of the metal can get quite high ... ususally aiding disassembly. But I think I have also already converted those studs to bolts.

i've done what you proposed on 2 different vehicles, not really on a windstar

also i'm noticing on some service manuals that the manufacturers are adding an additional ground strap down there to connect the exhaust pipes to the body of the vehicle :eek7:

all exposed to the elements and broken within a few years

you're lucky to have those tools; i had a small dremel with a case of cutoff wheels & went through a few of them to cut off the rusted studs/ welded nuts:runaround: then i slid the cat-back off the remaining studs to cut them off

Dremel still beats a hacksaw :D

I couldn't get the studs out today and there's a snowstorm on its way here for the next two days. I had to return my summer car to its shelter because it has summer tires. So for the meantime the flanges are pressed together with hillbilly clamps: two pairs of old Vise-Grips with their tightening bolts J-B Welded so they won't come loose. Temporary solution obviously, but the van is now quieter than it has been for years. It is in fact so quiet it's hard to tell if the engine is running when you're not moving. Hard to believe just yesterday it sounded like a Harley-Davidson.

Small incident occurred after I finished the "repair". Forgot to remove one of the jack stands I had placed under the front axle and when I backed up the stand rolled and pressed into the lower radiator coolant outlet, disconnecting it. Lost most of my antifreeze but nothing was broken so can't complain much. Prestone was on sale at a nearby hardware store so I got two jugs for $15 and poured them in, all is back to normal now.

I actually grab the Dremel at first ... by slow grinding with the 1 1/2" dia cut-off wheels: the temp of the metal can get quite high ... ususally aiding disassembly. But I think I have also already converted those studs to bolts.

Something interesting about those studs. I have the 2000 Windstar Workshop Manual from Ford, was given to me by an acquaintance who works at a dealership. In the manual the Y-pipe flange fasteners are bolts and nuts, not studs. Dropped by NAPA this afternoon and casually mentioned this to an employee. He said the cats are probably Magnaflow units. To his knowledge Magnaflow is the only replacement parts supplier that ever had studs on cats for Essex engines, and they don't use them on 2 1/4" pipes anymore.

I guess I'm not the only driveway mechanic who got PO'd over this. I do understand why studs may make a superior fastener on a factory-new exhaust system but for the cheap chap like me who does their own maintenance they are just too much of a beotch to deal with. Prior to this my take on exhaust repair below the cats was that it was straightforward and easy, if not always comfortable.

I had the problem of getting a rusted flex pipe front flange off a couple weeks ago. Needed to separate it to drop the engine and transmission. Was able to use a lift so was much easier than you have with just 16." I used a powerful disc grinder to cut the corroded heads and separate the flex pipe. Then ground the corroded studs flat on each side of the flange of the Y pipe. A dremmel will do the job too. Now I think this is where you are. So I centered punched the outline of the studs on the flange and drilled them out. Good quality drills diped in a little container of oil as you go to cool them. The best cutting speed for hard metal is SLOW, prob 600 - 800 rpm, it takes a good drill motor. Slowly vary the speed with good pressure untill you find the speed that cuts best. Spiral metal out the bit is best but hard to manage with a hand drill. Oily chips coming up the fluts are good, you've found the right speed and pressure. Too high a speed will heat up and dull the bit and probably only make a little dent. I started with a small bit, 1/8 or 3/16 and drilled all the way through. Then reamed with progressivly larger bits. You don't want to brake a bit off in the hole though cause you know you can't drill a drill bit out.
Good luck there Windstartled, we're rooten for ya.

I had the problem of getting a rusted flex pipe front flange off a couple weeks ago. Needed to separate it to drop the engine and transmission. Was able to use a lift so was much easier than you have with just 16." I used a powerful disc grinder to cut the corroded heads and separate the flex pipe. Then ground the corroded studs flat on each side of the flange of the Y pipe. A dremmel will do the job too. Now I think this is where you are. So I centered punched the outline of the studs on the flange and drilled them out. Good quality drills diped in a little container of oil as you go to cool them. The best cutting speed for hard metal is SLOW, prob 600 - 800 rpm, it takes a good drill motor. Slowly vary the speed with good pressure untill you find the speed that cuts best. Spiral metal out the bit is best but hard to manage with a hand drill. Oily chips coming up the fluts are good, you've found the right speed and pressure. Too high a speed will heat up and dull the bit and probably only make a little dent. I started with a small bit, 1/8 or 3/16 and drilled all the way through. Then reamed with progressivly larger bits. You don't want to brake a bit off in the hole though cause you know you can't drill a drill bit out.
Good luck there Windstartled, we're rooten for ya.

Thanks for the tips Waxhaw! Should I use cobalt bits or just good-quality HSS? My experience with cobalt is that they don't dull easily but have a tendency to break without warning and like you said, I don't want to have to deal with a broken bit lodged in the stud. Plus they are quite more expensive than HSS. With all that snow in the forecast I will probably go to the DIY mech shop near here to do this, it only costs $10 an hour to use a lift there. I only go there once I'm fairly sure I know exactly what the problem is and what I need to do to fix it.

You're welcome Windstartled. Yes, I have found the same as you with colbalt bits, expensive and, esp in smaller sizes, brittle. They don't flex much, a little side load and they snap. I used good quality High Speed Steel (HSS) drill bits. Was able to borrow a 1/2" Milwauke 0-850 rpm, 5 amp drill motor and using about half the speed or so cut best. At first I had a Black & Decker 3/8" 0-1200 rpm, 4.5 amp motor but couldn't control lower speed very well and wasn't cutting very good. Would have been doable though.

I also had the complete Y pipe with catilitic converters on a bench to do the drilling. I needed to remove it anyway to drop the engine and had a manifold to Y stud break too. I was able to get that one out of the manifold by soaking with Kroil and using vicegrips once the engine was out. Our van spent time on salty roads and I hope I never need to take the heads off as those bolt heads are very corroded.

Glad you have use of a lift. With a rusty sustem I wouldn't suggest taking the whole Y pipe out from the manifolds unless you really have to. If one of those studs break (like mine did) it would be real hard to repair in the van, not much room.

I know you're doing this yourself to save money like the rest of us but as you have it driveable now you might price out the job. At least you'll know how much you're saving doing it yourself! I've had exhaust welding done very reasonably at exh shops. But of course that's not nearly as much fun or satisfying doing it yourself! And not having a money tree to pick from I find myself doing stuff way over my pay scale thanks to this forum.

You're welcome Windstartled. Yes, I have found the same as you with colbalt bits, expensive and, esp in smaller sizes, brittle. They don't flex much, a little side load and they snap. I used good quality High Speed Steel (HSS) drill bits. Was able to borrow a 1/2" Milwauke 0-850 rpm, 5 amp drill motor and using about half the speed or so cut best. At first I had a Black & Decker 3/8" 0-1200 rpm, 4.5 amp motor but couldn't control lower speed very well and wasn't cutting very good. Would have been doable though.

I also had the complete Y pipe with catilitic converters on a bench to do the drilling. I needed to remove it anyway to drop the engine and had a manifold to Y stud break too. I was able to get that one out of the manifold by soaking with Kroil and using vicegrips once the engine was out. Our van spent time on salty roads and I hope I never need to take the heads off as those bolt heads are very corroded.

Glad you have use of a lift. With a rusty sustem I wouldn't suggest taking the whole Y pipe out from the manifolds unless you really have to. If one of those studs break (like mine did) it would be real hard to repair in the van, not much room.

I know you're doing this yourself to save money like the rest of us but as you have it driveable now you might price out the job. At least you'll know how much you're saving doing it yourself! I've had exhaust welding done very reasonably at exh shops. But of course that's not nearly as much fun or satisfying doing it yourself! And not having a money tree to pick from I find myself doing stuff way over my pay scale thanks to this forum.

I considered either pricing it out or use an ace torch at the shop but since I'm replacing the exhaust manifolds and flex in a couple months that means I'll have the whole front exhaust out then anyway so maybe I'll just leave the vise-grips there until then and hope for the best. It looks completely ridiculous but none than me can see them and I have no inspection scheduled so...:cool: