Loose draft caps

[Enplater]

i have a Grandma bear, I think it's about 1978 1979 something like that. The 5 fin draft caps wobble around quite a bit but seem to seal when shut. This thing was very rusty when I got it (for free btw) so I'm thinking the bolts are half gone from rust. Is this a common issue? Am I right by thinking that it's just a bolt and 2 nuts, one on either side of the door? Does it thread through the door too? Do you think adding new hardware would make a difference? And is it worth my time Since it seems to work fine. I was thinking if new hardware was not enough and it was still wobbly I could bring the bolts to work and do a high build of nickel and make them bigger (I'm a metal player)

Thanks for the input

 

[Todd67]

I bought a 76 Grandma Bear that had a loose draft cap. I was all set to order a new pair of draft caps & mounting hardware (bolts and nuts) but I "accidentally" got the loose draft cap to fix itself. It was completely separated from the bolt, so all I did was open the draft cap all the way by pulling out and turning it to catch the threads. Once the cap was firmly opened I slowly and gently turned it some more. I loosened it and tightened it several times, getting the cap a little tighter each time. I think it actually re-seated the metal insert inside the draft cap because now it works great.

If you can't fix your draft cap there is a company that sells new bolts, nuts and draft caps, Barr Casting.
Here is their link... (broken link removed)

 

[Enplater]

Thanks I'll check it out. I bet I can find something at the hardware store though.

 

[Todd67]

Absolutely! It's nice to have more than one option, especially if you ever need a new draft cap or two.

 

[coaly]

The doors are threaded as well. Some fabricators tacked the inner locking nut with weld. If you can loosen them, first remove inside nut, then remove bolt with draft cap from door. See if the draft cap has a steel insert cast in it. Some are threaded aluminum which wears if not greased. If a magnet sticks to the center showing it has a steel insert, the threads wear about 50 /50 male and female, so replacing the bolt or plating it takes up half the thread clearance. When installing, adjust bolt length so you can get on the head of bolt with wrench or socket with draft cap closed. When adjusted too far in, it is difficult to get on the bolt head with anything but a very thin walled socket. Keeping silver anti-seize on the bolt threads prevents wear. Opening draft cap fully allows a brush to reach through the back of door opening to grease threads. Keep it on the hinge pins too. They are the only moving parts to wear out.

 

[Enplater]

Thanks for the knowledge

 

[Enplater]

I replaced the draft cap bolts today with new ones. It helped a little. I bought a couple extra bolts so I think I’ll build up the threads with electroless nickel at work to try to tighten things up a bit, probably not necessary but it’ll make me feel better. A couple things I found: the doors are not threaded, just a jam nut on either side. Also I found the doors are not completely flat where the draft cap meets it. If I shut the cap completely and shine a flashlight from the back side I can see a little light shining through. Is this normal?

 

[Enplater]

Also the caps have steel inserts.

 

[coaly]

The caps normally seal well enough to kill the fire.
The bolts can get bent slightly or have a door drilled and tapped slightly crooked to require tweaking the bold sideways if the cap edge doesn't make contact all the way around.
Can't answer why your door is not threaded. They normally are. Saving time threading and tap cost?? Once the bolt is mounted to the door it doesn't matter if the door is threaded when jam nuts are tight on each side of the door.

 

[Enplater]

Right! I was wondering why the doors were tapped in the first place.

 

[coaly]

Probably for strength of the wall of the intake support. I can imagine fabricators hiring help that doesn't know how to sharpen a half inch drill bit to prevent wobble of an off center bit, increasing the hole size until the support walls are too thin. I'm amazed there is not a demand for repairing or replacement of doors due to broken intake bolt supports.
We're used to seeing things built to minimum standards today. Back then things were built for longevity, not for speed of assembly.