I was putting some things back on the car and had some problems with my exhaust nut. As I tighten the nut it just keeps turning. The threads are not pulling out but the nut seem to big for the manifold, like the threads are worn down.
I know this might be a case for a new nut and manifold but it seems like if you could get some type of thread tape on the manifold, it would seal. I really don't want to buy a new manifold and nut and have to re-flare the exhaust pipe.
Any ideas here? Someone must have come across this at some point along the way.
Is this a true packing nut where I need some type of packing like rope in the bottom of the nut or was it originally just the friction of the flare on the pipe.
Is it typical for the threads of the exhaust nut to wear down.
Of course the real fix is to get parts that fit properly. For a temporary fix you could try wrapping the male manifold threads with aluminum foil then thread the nut over the foil. You don't say how far off the fit is, but if it's not too much this could buy you some time.
The pipe SHOULD be a slip-fit into the muffler, if an original or correct reproduction, so one just removes the pipe to install a new nut - no need to re-flare the pipe end.
I have sawed thru one side of the nut then squeeze the cut together and braze it back together.
Kind of a back yard fix but has worked for me.
It's possible you need a new manifold and nut, but more likely you just need a new nut. No, there was originally no packing or gasket.
Adam, Here's a fix that worked perfect for me after I bought a new nut and had the same trouble.
Take a hack saw and cut one side of the nut then using a quality worm drive radiator hose clamp form it around the nut and tighten it slightly so you can start the nut. After you get the nut started then you can adjust the tightness so the threads won't slip. Retighten the clamp and nut after the engine has been hot.
Worked for me
Bob Bergstadt is making a really nice reproduction pack nut. I think he gets $10 for them. I sent my manifold to him to run his die on the threads. Everything was fine when he returned them.
Steve, unless you have a 1909 or 10, most exhaust pipes were flared to fit against the manifold that is shaped to accept the exhaust pipe.
The early manifold had a slot on each side on the end and the exhaust pipe had a pin in each side that slid into the slots. (pipe slid into manifold) It also used a packing to seal the pipe. I think the packing nut had to be put on the pipe before assembly as it will not fit over the pins from the manifold end.
This should be shown in some of the early books like the one by "McCalley"
To many Steves, I should have included Tomaso.
Here is a manifold nut locking clamp from Texas T Parts. Clamps on exhaust pipe tight against nut and the tab folds over the nut to keep it from loosening. Jim Patrick
I drilled and taped the side of the nut and put a set screw in it to lock the nut tight.
The manifold was pretty bad to begin with.
I have one which does the same thing. This is the fix I did: I sawed two sides of the nut from the edge of the thread almost to the flange. Then I squeezed it in the vice and put a large hose clamp around it. Then screwed it back on. So far, so good.
Hey Norm, That's another great way to fix the worn threads. I would add the hose clamp around it to lock it down after tightening.
I like it!
If you have a bad pack nut, replace it. You certainly don't need the accessory clamp listed above. The problem with most T owners is they don't know how to tighten the nut properly. First, and most importantly, you need a pack nut wrench. Make sure your exhaust pipe is cool when you do this: Tighten the nut snugly, and with your left hand wobble the exhaust pipe back and forth while tightening the pack nut. Pretty soon you will feel the looseness go away, and the exhaust pipe will be securely seated. I've been driving T's for over 50 years, and have never had one loosen up yet. Bob Bergstadts pack nuts are very nice, but sometimes you have to file some of the flats to get an original pack nut on, which we shouldn't have to do!
Many repro exhaust pipes have a incorrect angle at the first bend which does not allow the flange on the end of the pipe to butt up to the exhaust manifold equally all the way around. Be sure the mating surfaces where the end of the exhaust pipe fits the manifold is proper before you try to apply the nut. I have had to rebend 5 repro exhaust pipes over the years to get a proper/aligned fit.
Did you figure out the pak nut issue, Adam ?
Adam did you try using a new nut? I have had this issue before and for what ever reason the nut was swollen greater that it was supposed to be. Maybe was overheated at some time. A new nut fixed the issue as well as a new nut stop. Remember not too over tighten, run it for a while and re-tighten again.
Hello I just got back to the computer. I will try a new Exhaust nut. I will report back with my findings here soon when I get time to get back out to the garage. Can I just disconnect the pipe at some point and slide the old nut off and the new one on. I have not have time to really look this project over yet. Should there be an easy connection point for the pipe or do I have to cut and re-flare?
The easy way out Adam is to take the two bolts loose where the muffler hangs from the frame now take the muffler off, loosen the packing nut take the section of pipe out slide off the old nut and slide the new one on. (Re-install in reverse steps)
If you try to pull the pipe out the front your not going to like the results...
Hope this helps.
The perpetual problem may be that brass is being tightened to secure against iron in a very hot spot. Different properties of the different metals, expansion rates, tensile strength, etc.
Aluminum heads shoved up against iron engine blocks can have problems too, as I understand. The problem has to do with the differing properties of the metals.
So, wouldn't iron nuts on iron exhaust manifolds be preferable to brass, or even bronze nuts, on iron manifolds?
Are iron nuts, having the same properties as the iron exhaust manifold, available?
I think iron nuts on an iron manifold would tend to rust tight in the threads after a time. Brass being impervious to corrosion and softer can still be loosened. Just a thought.
Shoving an inner pipe up into the exhaust manifold and then down into the exhaust pipe seems to work well, such as the short piece of pipe displayed in this link:
http://shop.advanceautoparts.com/p/walker-exhaust-pipe-41951/18370593-p?cm_mmc=A CQ-_-Google-_-GPLA-_-18370593&ci_src=17588969&ci_sku=18370593&ci_gpa=pla&ci_kw=& gclid=CNzwquH8g70CFZTm7AodZ2cAww#utm_source=acq&utm_medium=google&utm_campaign=g pla&utm_content=18370593
Such an inner pipe results in less stress on the nut, whether it be brass or iron, because the inner pipe lessens the stress on the nut to hold up the exhaust manifold tightly against the exhaust pipe.
Note that the upper portion of the short pipe is larger than the lower portion. The inner pipe needs to be a tight fit in both the exhaust manifold and the exhaust pipe.
Yes, it is a modification to the original system, but it is an unseen modification.
The trick is to align the exhaust manifold, the inner pipe, and the exhaust pipe in a straight line, all tightened up together with the nut. It works well when aligned and tightened.
I should have said the inner pipe would cause less stress on the nut holding the exhaust pipe tightly against the exhaust manifold. I mistakenly stated it backwards. In the end, it's a matter of gravity acting on all the parts. As you know, gravity is one of our enemies in this regard. Heat, friction and movement of separate parts are our other enemies.
The older aircraft engines used brass nuts in the exhaust system for the reason Max mentioned. You might want to loosen them some day. I think that today they use stainless which doesn't corrode?
Royce who is a A&P IA may probably jump on me now.
Does anyone know where I can get one of Bob Bergstadt's Exhaust nuts?
At Bob's ?
Thanks Roger, Wow . . . I can't believe I didn't put that together. Sorry about that. I have ordered from him before just didn't know he was the same BOB.