I had to replace my exhaust pipe (rusted out) with a new one. Had to heat nut to get it to break loose. When I put nut back on it starts to tighten and then just slips like it stripped. New nut that came with pipe won't start on manifold it seems thousandths smaller diameter. This is a vaporizer. Need some ideas.
Here's a recent thread about exhaust nut problems:
Gene Carrothers solution may work for you with either of your nuts:
"The threads on my manifold didn't hold the new brass nut. I took a hack saw and cut one side of the nut and formed a quality s/s hose clamp around it. When I was sure the threads were started I tightened the clamp then tightened up the nut and a final on the clamp when the pipe was snug. This clamped the nut tight on the manifold threads and hasn't loosened now in years."
The problem with heating brass to a very high temperature in that situation is once it expands it stays that way.
Same thing with stubborn brass plugs.......heating them to near red will cause the brass to relax in the hole but they will stay that way too.
Conversely, brass plugs are used in boilers because brass has a higher coefficient of expansion than steel so as the boiler gets hotter the plugs actually get tighter but TOO much heat will result in what I said above.
Hmm. If you have a hose clamp on the nut how do you tighten it??
Gene reads here and should answer, but the nut is a fairly wide one, wider than most hose clamps I've seen. Or you could grab over the clamp. There are other ways, as you can see in the linked thread + other threads you can find by google.
This will work really nice on the nut that slips on the threads.
Take your new nut and cut it across the threads on one side with a hack saw. Use a quality hose clamp and form it around the nut. You may want to slightly tighten it when you start it on the manifold so you don't cross thread it. Once you get it started tighten the hose clamp just enough so it doesn't slip on the old worn manifold threads.
Tighten the hose clamp to squeeze the threads and lock it on the manifold. You may want to tighten it again after your first drive. Then forget it.
Worked for me.
It's interesting that on the barn find '14 Roadster that my friend has, that's exactly what the previous owner did. And it hadn't been touched in 65 years! The nut was extremely tight, but all I had to do was loosen it and then I was able to take the nut off by hand. Sounds like a great solution!
I should have mentioned that it was the hose clamp (a very old fashioned one, I should add) that I had to loosen.
Talked to Ted Dumas today about heating the nut to take it off. Sounds like I may have over heated it and permanently oversized it. Suggested I heat the new nut slightly and immediately install it. Cutting the nut comes next.
this is how I solved my bad threads problem. I'll put two set screws in it to keep it in place . Ken
Are you sure that you can't get at least one thread started?
I find the replacement nuts are in fact a tad too tight, but can usually pick up at least one thread.
When faced with one of these new ones, I put the manifold in a vice, get the one thread started then 1/4 turn on, 1/8turn off, 1/4 turn on...etc...until it makes up tight. Then take it off (it's a tad warm all by itself) and it always then makes up good, easy, and tight after.
I also have found after many years of denial that a real manifold wrench does a much better job of sealing up tight and staying tight then using a pipe wrench.
What I really need is a donut between pipe and manifold. Nut has to go too far on manifold to get pipe tight.
Ivan: Try a muffler shop for a donut.
If your threads are somewhat good, send me the manifold, I have the die for chasing threads, not the whole vaporizer, just the manifold, Bob
I don't think you're going to be too pleased with using anything between the pipe and the manifold.
Do what George advised, using a little valve grinding compound on the threads...you'll be satisfied with the results as the nut will thread on correctly.
Note: I had to replace the exhaust pipe on my dad's car while on tour and found the pipe to be incorrectly formed and nothing was going to get that nut to go on, as it was approaching the exhaust manifold at the wrong angle. A couple of tweaks to the pipe aligned things and everything fit as it was supposed to. Once the nut fits the exhaust manifold, make sure the pipe flare fits the manifold correctly and you'll be in business.
George - "Suspicions confirmed!" For years, I always had to struggle with a pipe wrench when tightening or removing the brass exhaust manifold nut. I finally bought an actual Model "T" exhaust manifold nut wrench a couple years ago, which, quite frankly, is a rather crude looking hunk of iron. However, ever since starting to use that big, ugly crude looking wrench, I am always amazed at hot I am able to turn the nut with much, MUCH less of a struggle with the nut feeling tight, but is merely binding like always happened with a pipe wrench! Not sure why the actual exhaust nut wrench works so much better, but it sure does!.....harold
P.S. In thinking about it, brass being somewhat soft, it might be that the "gripping" action of the jaws of the pipe wrench actually distorts the brass nut just enough to cause binding,......???
Oops,..... meant how,....not hot! Even proof-reading misses "typos" when the same guy that wrote the post does the proof-reading!
I had the same problem with the nut having to go too far on the manifold for it to seal the pipe correctly. I backed the nut off and then welded a bead on the backside of the flare, then used a grinder to smooth it out. That let me basically add a 'donut' thickness to the backside of the flare - so I needed less threads for the nut, but it still used only the pipe and manifold to create the seal. Better than having a donut between the manifold and pipe.
I bought a 27 touring that has a custom made pipe. It was expanded to slip over the threaded portion, has two short slits cut in it and clamps with a standard exhaust clamp. I just wished the guy that made it had written down all the machine settings as it is perfect and looks like the factory did it.
Took off my manifold today with help from Royce and took it to his shop. Cleaned up threads with file and finally got new nut started. Was able to get nut on about 3/4 way. Will order new manifold gaskets tomorrow . Nut is extremely hard to turn. Will use heat to try to tighten up with manifold back on.
If your exhaust pipe does not reach the flange, take off the exhaust pipe clamp at the muffler (if it has one)and slide the pipe up to the manifold. Toss the clamp in the scrap bin, it is not needed. The exhaust pipe to muffler is a slip fit, and yes it may leak some but it has to expand and contract someplace and this is where it does it. Unless you have a tail pipe, in's not like that length of the muffler is going to make a lot of difference on the smell!
Bob Bergstadt is making a really nice reproduction pack nut. I think he gets $10 for them. I had to file the flats down in a couple of places to get my pack nut wrench to fit, but other than that, it is just like Ford made it. What we really need is someone to make 100% correct exhaust pipes!