Radiator petcock issue

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DHort
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Radiator petcock issue

Post by DHort » Mon Jul 15, 2019 6:15 pm

I just got a new Radiator from Bergs. I attempted to install a petcock i got from Snyders long ago and it will not fit.
I do not know if I should tap the radiator or try a different petcock. Snyders number A-8115-RE. It looks like a 3/8-24, but I am wondering if it is tapered toward the top. Thank you for your help.


Allan
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Re: Radiator petcock issue

Post by Allan » Mon Jul 15, 2019 6:28 pm

David, that petcock is the same as those used on the pan for checking the oil levels. It is a tapered thread. The A prefix on the Snyders part usually denotes an A model part. I do not know if the petcocks are the same.

Allan from down under.

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Re: Radiator petcock issue

Post by DanTreace » Mon Jul 15, 2019 6:30 pm

Should be 1/8" NPT, pipe thread. That is what is needed. Check that new one or use another correct petcock.
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Mark Gregush
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Re: Radiator petcock issue

Post by Mark Gregush » Mon Jul 15, 2019 7:21 pm

The only drain on the A is the radiator and it would be the same as T.
I know the voices aren't real but damn they have some good ideas! :shock:

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Re: Radiator petcock issue

Post by TRDxB2 » Mon Jul 15, 2019 8:28 pm

Snyder's descriptions for the A-8115-RE says "This petcock is used for model A and model T. Model A used it in the water return pipe. Model T's used it for the radiator, oil pan, and fuel sediment bowl. 1/8" NPT. U.S.A" I'd take what you got to the local Hardware Store and size it - could be that you got something by mistake.


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Re: Radiator petcock issue

Post by D Stroud » Mon Jul 15, 2019 11:26 pm

Or maybe they didn't tap the hole in the tank deep enough, wouldn't be hard to tell by trying a 1/8" pipe tap in it. Dave
1925 mostly original coupe.


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DHort
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Re: Radiator petcock issue

Post by DHort » Mon Jul 15, 2019 11:44 pm

When you use an NPT tap, I assume there is a way to do it other than just like using a regular tap. Do you just turn to a certain depth and stop? Since it is tapered, how do you know how far to go?

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Re: Radiator petcock issue

Post by Steve Jelf » Tue Jul 16, 2019 12:16 am

It's like tightening bolts (turn them until just before they break). Tap only deep enough to make the threads. :)
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Re: Radiator petcock issue

Post by Hal » Tue Jul 16, 2019 7:33 am

Don't hold me to this, but I've been told that you stop tapping when there are 5 threads left on the tap above the hole.


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Re: Radiator petcock issue

Post by D Stroud » Wed Jul 17, 2019 3:51 am

I always just run the tap in a bit and then try the fitting, repeat as needed. That way, a fitting that may have had the threads chased in the past and is on the small side will still tighten up nicely. Also, fittings, as with most things, have a +or- tolerance which can lead problems if the wrong ones are matched up and you need a fitting to line up in a certain place. Dave
1925 mostly original coupe.


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Re: Radiator petcock issue

Post by John Codman » Wed Jul 17, 2019 1:44 pm

I also have a Berg's radiator, and the original petcock fit perfectly. Unless Berg's didn't tap the hole properly, I would take a close look at the petcock. Once you modify that radiator, Berg's is off the hook for any other problems, so I would be absolutely positive of what the issue is prior to doing anything. Before I grabbed a tap I would call Bergs and explain the issue and see what he recommends.


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Re: Radiator petcock issue

Post by Rich Bingham » Wed Jul 17, 2019 2:53 pm

Whatever you do, when all is resolved, make damn sure the petcock is tightly seated in the outlet !! Usually they're a bugger to get out if you need to remove one. I never thought about mine, presumably it had been in place long before Lizzie adopted me, but one time last summer, I took Lizzie down to the hay field to check the wheel line; I almost took a joy ride around the section, then decided not to. That was fortunate, as the petcock fell out somewhere in that half-mile loop, and Lizzie was mighty hot under the collar when I pulled in the yard - not a drop of water in the system :shock: ! Thank heavens, no harm done.
"Get a horse !"


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DHort
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Re: Radiator petcock issue

Post by DHort » Wed Jul 17, 2019 7:28 pm

IMG_20190717_160513013.jpg
IMG_20190717_160513013.jpg (77.31 KiB) Viewed 1077 times
On the left is the OR (original) petcock and on the right is the RE (reproduction) petcock.

The original petcock would turn about 2 1/2 times and the reproduction would only turn about 1 1/2 times. I applied Megaloc thread sealant and installed the petcock. I then used a crescent wrench to tighten it some more. It definitely will not come out and i doubt that it will leak.

Thanks to all for their input.


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Re: Radiator petcock issue

Post by Allan » Mon Jul 22, 2019 7:00 am

David, that non original petcock looks to have a slotted head screw to hold the turning piece in place. That is the problem with the early original style petcocks. If that screw comes loose, the petcock can/will open and there goes the fluid. When this happened on my 1912 van, I wired it shut; ugly but effective. I have since jetisoned the original, correct petcock for the more reliable later style.The washer, spring and split pin are reliable mechanical components.

Allan from down under.

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