Compression Fitting

[Lloyd]

Hey everyone, The oil pressure line on my 39 P8 was cut below the dash and had a short rubber hose on it with flare fittings then it went outside the dash where another rubber hose was connected to make a turn down to the oil pressure outlet. Its always had a small drip below the dash from one of the fittings to the hose. Tried tightening it up a while back and it didn't really help. I have been wanting to swap it out for a single line to outside the firewall then place a rubber hose on it to absorb vibration before connecting to the engine. The problem has been the connection that screws into the back of the gauge itself. I don't know what type of compression fitting that is before the nut and if I need a special tool to put one on. But if I want to run just a single connection from the gauge then hard-pipe from the gauge to the firewall I'll need to swap out the entire line. 

Does anyone know what type of fitting this is and how to install it on the end of some tubing? (BTW that's 3/16 inch tubing)

 

[desoto1939]

This is a very special fitting and a bubble flare fitting might work, but the nut that screws into the back of the oil guage is also very special it is not your standard 24 pitch thread if I remember correctly it is 27 thread, yes 27.  Lots of the older dodge truck up into the mid 50's used the same fitting and nut.

 

DO NOT discard the brass nut or you will not beable to find this fitting.

 

 

Rich Hartung

Desoto1939@aol.com

[Lloyd]

16 minutes ago, desoto1939 said:

This is a very special fitting and a bubble flare fitting might work, but the nut that screws into the back of the oil guage is also very special it is not your standard 24 pitch thread if I remember correctly it is 27 thread, yes 27.  Lots of the older dodge truck up into the mid 50's used the same fitting and nut.

 

DO NOT discard the brass nut or you will not beable to find this fitting.

 

 

Rich Hartung

Desoto1939@aol.com

Hey Rich. Thanks for the tip on the brass nut. What about the collar? The bell shaped fitting on the end? I thought it might be a compression style seal but I just did a web search for bubble fittings and all it shows is the nuts. First time I’ve ever heard of it. Does a bubble fitting use a collar? A simple flare won’t work the way it fits into the gauge. It has to be bell shaped and crimped or compressed onto the tubing. I just don’t see how putting the nut on some tubing and screwing it into the back of the gauge will keep the tubing from pulling out of the gauge. 

[LazyK]

It's a form of compression sleeve. You might try McMaster Carr. Definitely don't loose the nut

[Lloyd]

Ok. I just watched a utube. How to make a bubble flare using a double flaring tool.

This guy said just flip the crimping part of the tool over so your flaring against the backside of it. The flat side. It did make it concave starting from the top and getting bigger towards the nut just opposite of a regular flare. It might work but the flare he did didn’t have the size of the original one. Still might work though. I scan try it and if it leaks I’ll have to cut the tubing under the dash and put the old one back in. Then add another connection to the rest of it. 
still like to know how and what that original collar is about and if I can still get one. 
 

[Lloyd]

9 minutes ago, LazyK said:

It's a form of compression sleeve. You might try McMaster Carr. Definitely don't loose the nut

Thanks LazyK, I did look thru McMasters and Grainger to. Plus Amazon and some other sites. Didn’t see it. 

[Ivan_B]

Are you able to reuse the old nut and sleeve? If the sleeve would not compress onto a new copper line, you can probably solder it on. A layer of soft fresh solder would probably also help to seal the resulting connection when you put it back into the gauge.

 

41 minutes ago, Lloyd said:

Ok. I just watched a utube. How to make a bubble flare using a double flaring tool.

 

I do not believe that a half-done double flare, inverted the wrong way, really qualifies as a bubble flare. Would not use that on my brakes ?

 

Edited September 12, 2023 by Ivan_B

[Lloyd]

Hello Ivan. Yes I would agree. I wouldn’t try to use it on my brakes neither. But I would be willing to try it on my oil pressure gauge. Just have to put a drip can under it just in case.
Solder  isn’t a bad idea but I doubt if I can get it off without buggering it up. 
Somewhere, somehow or some time - like maybe 1939 someone put that collar on that tubing. 
If it does leak then I’ll just put the original back on and do a hard splice rather than a rubber hose on the connection under the dash. 
thanks for your input. 

Edited September 12, 2023 by Lloyd

[Jerry Roberts]

Lloyd ,  You called that tube 3/16 " , It is a 1/8 ' tube . That fitting has been discussed here many times and you might be able to find those discussions by doing a search on the topic . If the fitting and stub of a tube that you have doesn't leak , why don't you use it and a  1/8 ' compression union to get to a common 1/8 " break line . Then you can put in the common rubber hose for flex , with flare fittings that mopar uses . 

[vintage6t]

The collar probably is compressed on the nut side. You may be sorry of you do this but it may allow you to re-use the collar on a new tube: To get the collar off the old tube, carefully crush the old tube in until the collar will slide off. Once off the collar may not slide onto the new tube. If not put the new tube in the freezer for a few hours. Heat the collar with a torch and then quickly try to slide it onto the new tube. 

 

I say you may be sorry because if it doesn't work you won't  have your old tube/collar stub to use.

[Ivan_B]

33 minutes ago, Lloyd said:

If it does leak then I’ll just put the original back on and do a hard splice rather than a rubber hose on the connection under the dash. 

Lloyd, that would've been my next alternative proposition, as well

I am still curious if you can reuse the old sleeve, though. Try to heat it with a household propane torch and then grab it with a glove or something soft. I suspect it will slide right off.

 

2 minutes ago, vintage6t said:

Heat the collar with a torch and then quickly try to slide it onto the new tube.

 

That reminds me of a wheel bearing sleeve, on a RWD axle, I once changed. You were supposed to heat it up to glowing red, then quickly drop it over the axle and hammer it down with a 5-feet pipe... Very exciting garage performance, I tell you what ?

 

Edited September 12, 2023 by Ivan_B

[Jerry Roberts]

Before you try to take your fitting off from the tube and chance ruining it , try to reuse it . Here is one that I have reused many times when testing oil gauges . 

[Sniper]

I would suggest going to an industrial fitting supplier or maybe even a ag supplier with your old fittings and seeing if they can help, those guys usually know what stuff is

[desoto1939]

I have gone to McMaster and they have nothing. I even went to a Plumbing and Heating company. I was asking for a Pilot fitting for a hotwater heater. They had nothing and also the 27 Threaded nut is not available.

 

So my best suggestion is to look on Ebay and search for Oil Gages for Dodge Trucks.  They all used the same bubble end with the same brass 27 pitch thread nut.  You just might luck out.  I did find one long oil gage metal line with the bubble end and the correct fitting.

 

If you find these metal lines then you had better by them when you see them.

 

These are the small hard to find parts so know what you are looking for.

 

Rich Hartung

[LazyK]

5 hours ago, Lloyd said:

Thanks LazyK, I did look thru McMasters and Grainger to. Plus Amazon and some other sites. Didn’t see it. 

Seems the correct name is

"Brass compression self align sleeve" https://fastfittings.com/products/brass-compression-self-align-sleeve

[Lloyd]

1 hour ago, LazyK said:

Seems the correct name is

"Brass compression self align sleeve" https://fastfittings.com/products/brass-compression-self-align-sleeve

That certainly looks like it. Thanks LazyK for finding that. Looks like the best bet. 

Thanks for your input Jerry. I’m fairly certain it is 3/16”. I’ve picked up a couple 40” straight links of brake line and some fittings from AZone and and they are the same size as the original. The whole reason I’m trying to find the collar is so I can run straight tubing from the gauge to outside the firewall. The original was cut somewhere along the line and they put a rubber hose and more tubing to reach the firewall. I did do a search on the forum yesterday and found plenty on brake line flare and fittings but nothing on this fitting. I always do a search before I post. Usually works out, also come across posts that have nothing to do with what I’m looking for but lots of info all the same. 
 

Ill keep an eye on eBay Richard. You were right about the thread count. I tried some new flare fittings in my thread checker. They were 3/8 fine thread. The original nut would not screw in. It fit but the threads would not catch hold. It did thread into a metric #4 fine thread but it was a loose fitting. 
 

thanks to everyone for your help. 

[kencombs]

The  27 pitch thread is the same as 1/8pipe,  except that normal pipe is a tapered thread.   I'd expect that one could make the nut by using a hex head pipe plug, drilling a hole to fit the tube and tapering the opening to mate with the ferule/sleeve.  

 

A pipe die, installed on the plug in reverse (starting/tapered side first) would work to remove the taper from the plug.

[9 foot box]

   The last time this subject was mentioned, the consensus was that you buy the fitting available and chase the threads. I did that and tested the fitting attached to the gauge @ 40psi with soapy water, with no leakage. I wouldn’t use the gauge to chase the threads from 24tpi to 27tpi on the fitting. All other connections are inverted flare with double flare line ends. 

Edited September 13, 2023 by 9 foot box

[Lloyd]

Yep you could chase the threads for the fitting and it should give you a new one. That would work for the nut. But where did you get the compression collars?

[Lloyd]

6 hours ago, 9 foot box said:

   The last time this was subject was mentioned, the consensus was that you buy the fitting available and chase the threads. I did that and tested the fitting attached to the gauge @ 40psi with soapy water, with no leakage. I wouldn’t use the gauge to chase the threads from 24tpi to 27tpi on the fitting. All other connections are inverted flare with double flare line ends. 

 

Never mind, I found them on the https://www.robertshaw.com/products/listing/?q=4590-067 website. The ferrule comes with the nut. I guess the ferrule will "breakaway" when you tighten it. Never seen that before but it certainly looks like the critter I'm looking for. Having a little trouble finding a place in Houston to get them. The Robertshaw website shows 2 locations in Houston one is Grainger, but it seems Grainger has discontinued the item. The other is United Refrigeration but not sure if they sell to walk-ins. Might be contractors only - don't know. Google search shows a few other locations. I'll make some phone calls when they open up.

 

In the photo above the installed fitting on the left is one of those fittings. Did you just screw it into the back of the gauge to compress it?

I appreciate your input, thank you.

Edited September 13, 2023 by Lloyd