|
|
Veteran
Posts: 143
 
Location: Denver, Colorado, USA | Does anyone know the 1955 - 1958 (and maybe later) Mopar oil pressure hose fitting sizes at the engine and the gauge?
My '56 Dodge came to me with the oil pressure gauge hose missing and the engine port plugged. I know I can get a reproduction hose and that the engine port is NPT, but I need to sort the hose fitting sizes/types to decide if I go with a reproduction hose if I can source the fittings either at the parts house or through a salvage yard or abandon the factory gauge if I can't find the fittings or figure a way to use copper tubing like many other manufacturers used; I'm running a separate Stewart Warner numeric oil pressure gauge under the dash but would like the factory gauge to work for aesthetics. The factory service and parts manuals say nothing about type/size and only give part numbers (see image below). According to the part manual, I'm looking for the type and size of
Engine Elbow 694660
Gauge Nut and Sleeve 1319043
The aftermarket hose shows a fixed female fitting at the engine and a male line at the gauge, and I found an image of the gauge end with a male compression nut and a ferrule. I read somewhere (that I now can't locate) that the gauge line is 3/16" OD. Does the engine end attach to a standard male SAE flare or a compression fitting with ferrule? Does the gauge end take a 3/16" male compression nut and standard 3/16" ferrule?
I can't be the first person who didn't have the engine or gauge fitting, and I appreciate any help.
 (OP Gauge.jpg)
Attachments
----------------
 OP Gauge.jpg (206KB - 63 downloads)
|
|
| |
|
Expert 5K+
Posts: 9681
  
Location: So. Cal | Yes, at the engine side, it's a standard inverted flare fitting into a pipe threaded adapter. At the gauge side, unfortunately, it isn't a standard fitting. The reproduction fittings are close, but they don't quite work. You have to really crank down on them to get them to seal, and you risk stripping the threads when you do that. I haven't looked into what the proper fitting is, exactly, but I know it isn't something easy to get. It is probably best to adapt the old fitting to a new hose. But if you do use the new reproduction hose, tighten it down tight to a junk gauge first before trying to use it on a good one. |
|
| |
|
Expert
Posts: 3967
Location: DFW, TX | To expand on Nathan's point, you will never get the aftermarket oil pressure line's compression fitting to seal at the gauge. Fortunately the fix is pretty easy: remove the aftermarket ferrule and replace it with an OEM one, then install it.
The only downside to this is you will need to find an original hose to scavenge it from. The upside is you will have an OEM hose to measure as much as you want. 
I can't recall exactly which is which (I think the OEM hose is on the right), but you can see the ferrule difference pretty plainly and understand why the aftermarket ferrule will never mate and seal.
Edited by 57burb 2023-05-15 7:14 PM
 (ophose.jpg)
Attachments
----------------
ophose.jpg (92KB - 68 downloads)
|
|
| |
|
Extreme Veteran
Posts: 353
| the photo is what I have done on my car 3 years ago and not a drip. Hope it helps! No one can spot it under the dash.
Del S
 (Oil Pressure Line.jpg)
Attachments
----------------
Oil Pressure Line.jpg (84KB - 56 downloads)
|
|
| |
|
Veteran
Posts: 143
Location: Denver, Colorado, USA | Thanks Nathan, 57burb, and dels56.
It took me digging through the Weatherhead and Edelmann fittings catalogs to find the engine fitting. Edelmann 261320 is a 1/8" male NPT (correct for the A-block engine) to 3/8"-24 male inverted flare (image below). On the gauge side, I see what Nathan and 57blurb describe in the photos. It looks to me that I could take a 3/8"-24 male inverted flare nut and machine off the end square to remove the inverted taper, creating the flat end that the OEM nut has for compressing the ferrule. Alternatively, I'll have to use a non-OEM ferrule as 57burb suggests or find and cannibalize a junk used hose that still has the nut since I can't find a source for a new nut. I know I've come across an online source for a 3/16" line 3/8"-24 male nut that has a flat end (possibly for an aftermarket oil pressure gauge), but I can't find it in my many bookmarks.
dels56, the part about your system I'm leery of is that, if I'm reading the schematic correctly, the 3/16" hard line runs straight from the engine port, turns through the firewall, and then converts to the hose. Unless the line had at least one loop in it before passing through the firewall, with the engine roll from acceleration/deceleration and road vibration the 3/16" line will be prone to work hardening and likely crack at the engine fitting over time. The purpose of the OEM hose design, unlike many GM and Ford vehicles of the era that used a copper hard line, was to solve the work hardening issue by running a hose through the firewall. If I couldn't figure out how to make an OEM aftermarket hose work, which it looks like I will be able to, I would use a 3/16" copper line with a compression fitting at the engine, put two loops in the line above the engine connection, run the line through the firewall, and use a factory male nut or machined 3/8"-24 male flare nut at the gauge with a ferrule. Depending on how much you drive and how rough the roads are, your design should be fine for a long time, but I'd carry a 1/4" NPT plug in the toolbox and visually inspect the line at the engine connection at every oil change. I'd suggest the same thing for anyone running a copper line as well.
 (edd-261320.jpg)
Attachments
----------------
edd-261320.jpg (10KB - 61 downloads)
|
|
| |
|
Extreme Veteran
Posts: 353
| I did miss mentioning the 3/16" line does have a couple of curls and loops in it to take up the movement between the engine and body and make it's way through the fire wall. I just pictured the line as being straight for reference. I don't have my notes with me today to know what length of 3/16 line I used or the length of the whip hose. The hose is not just straight either. I left those details up to whom ever might want to follow my lead. As I said, 3 years and I have not seen any issue with it.
Del |
|
| |
|
Veteran
Posts: 143
Location: Denver, Colorado, USA | dels56 - 2023-05-15 7:57 PM I did miss mentioning the 3/16" line does have a couple of curls and loops in it to take up the movement between the engine and body and make it's way through the fire wall. I just pictured the line as being straight for reference. I don't have my notes with me today to know what length of 3/16 line I used or the length of the whip hose. The hose is not just straight either. I left those details up to whom ever might want to follow my lead. As I said, 3 years and I have not seen any issue with it. Del
Thanks for clarifying. It sounds like a good system to replace the OEM. |
|
| |
|
Extreme Veteran
Posts: 446
Location: Beaumont TX | I used 5/16 copper tubing to replace my hose because I didn't want the chance of a hose breaking and flooding my car with oil. I know a remote chance but I didn't feel good about the hose. I used a swedgelock fitting to connect the tubing to the pressure gauge and a double flare to connect the other end to the engine. I put shrink wrap on the tubing in anyplace the tubing got close to metal to keep any noise down and to prevent rubbing a hole in the tubing. It is not original but another option.
I like Del's option above too and it takes some of the worry out of the tubing flexing but I put expansion loops in my tubing to take care of movement. |
|
| |
|
Veteran
Posts: 143
Location: Denver, Colorado, USA | samstrader - 2023-05-16 10:02 AM I used a swedgelock fitting to connect the tubing to the pressure gauge and a double flare to connect the other end to the engine. @samstrader, While I don't have an OEM nut for the gauge, I fit a thread gauge and then a caliper into the gauge's female fitting, and it looks to be 1/8"-27 thread per my measuring, but I think they are on add SAE straight thread. It's definitely not 3/8-24 SAE like a flare nut for 3/16 line. What swedgelok did you use to connect the 5/16" tubing to the gauge? Were you able to get a good seal into the gauge (I assume with Teflon tape or paste) before the fitting bottomed out and without cracking the gauge fitting?
If the gauge fitting is 1/8"-27 NPT, I'm all set. I'll use a 1/8" male NPT to male -3 AN fitting at the engine and gauge and a 28" long -3 AN black sheathed braided stainless brake hose. That will look clean and will be the strongest hose setup. Plus, it costs $25.
Edited by PolyJ 2023-05-16 9:04 PM
|
|
| |
|
Extreme Veteran
Posts: 353
| The Female thread in the back of the oil pressure gauge is not NPT (pipe thread). At least not in my 56 Dodge CRL.
Del |
|
| |
|
Expert
Posts: 3967
Location: DFW, TX | dels56 - 2023-05-16 5:14 PM
The Female thread in the back of the oil pressure gauge is not NPT (pipe thread). At least not in my 56 Dodge CRL.
Del
Yeah, it's not NPT. It's what we've been describing so far, a compression fitting utilizing an odd ferrule. I'm sure the ferrule is a standard somewhere but it's no longer common.
Interesting that local2Ed didn't have any issues getting an aftermarket gauge kit to seal using his stock gauge. Maybe it's just that easy!
Edited by 57burb 2023-05-16 9:36 PM
|
|
| |
|
Veteran
Posts: 143
Location: Denver, Colorado, USA | Mystery solved on the gauge female threads. They are 1/8"-27 SAE. The only thing I could find that uses that thread is the male threads of a standard 3/16" tubing compression fitting that accepts a female nut. I had one in my fittings drawer, removed the nut, and threaded the male end into my gauge. It threaded in smoothly until it bottomed out. I haven't been able to find a source for new 1/8"-27 SAE male nuts that take 3/16" tubing like the factory nut, so I'll leave that sourcing mystery for the next person. I couldn’t find a plug that uses that thread that I could drill through with a 3/16” bit either.
As for my plans, I'll use a compression fitting for 3/16" tubing that goes from the tubing to 1/8" male NPT followed by a 1/8" female NPT to male -3 AN adapter, a length of black coated 3/16" braided stainless brake hose, ending with a male -3 AN to 1/8" male NPT adapter at the engine port. To seal the male 1/8"-27 SAE threads of the compression fitting into the gauge, I'm thinking of experimenting with taking the standard copper ferrule from the fitting and soldering around the sealing rim of both sides. Once installed between the compression fitting and gauge, the solder should marry to the gauge's surface and seal on the compression side with little torque. I think using the standard copper ferrule with its sharp edges as-is will dig into the gauge sealing surface and require too much torque to seal on the compression side, similar to what 57burb noted before about using the ferrule off a used OEM hose.
This oil pressure hose design was used on so many pre-Forward Look and Forward Look cars/trucks that I think I'll write up an article about alternatives to a factory hose in the event one cannot locate a factory nut for the gauge connection or wishes to go with a different setup.
|
|
| |
|
Expert
Posts: 3967
Location: DFW, TX | And I believe it. Nathan and I may have had issues with ours due to some other factor, but we both had major issues with getting a replacement hose to seal to our gauge. When I took a closer look at the ferrules, it was obvious they did not match, so I swapped them out and that fixed the issue for me. YMMV  |
|
| |
|
Veteran
Posts: 143
Location: Denver, Colorado, USA | local2Ed - 2023-05-17 9:32 PM Del Yeah, it's not NPT. It's what we've been describing so far, a compression fitting utilizing an odd ferrule. I'm sure the ferrule is a standard somewhere but it's no longer common. I think the odd ferrule is causing more confusion than it should. Like I stated above, it's been several years since I've done this but I remember looking at the odd ferrule and feeling if the common ferrule within the aftermarket gauge install kit would not seal I would just install an aftermarket oil pressure gauge so I would have a working oil pressure gauge. To my surprise the fitting and common ferrule in the kit worked fine without any over-tightening or any unusual problems.
At least for my part, the ferrule is not a concern. I agree that the ferrule included in poly tubing aftermarket gauge kits would likely work without requiring excessive torque on the nut since it is a similar shape as the factory ferrule and designed to collapse easily onto nylon tubing. The issue is the 1/8"-27 straight SAE male nut that screws into the OEM gauge since a new replacement for 1/8" or 3/16" tubing doesn't appear to exist. All SAE aftermarket gauge kits I've ever used or can find use an 1/8" male NPT to 1/8" or 3/16" tubing compression fitting. If you used that adapter, you would have had to cross-thread it into the gauge. Do you still have the '57 Dodge?
|
|
| |
|
Expert 5K+
Posts: 9681
Location: So. Cal | It's entirely possible that the correct ferrule & nut for the Chrysler gauge isn't the same as the one on the Dodge/Plymouth/DeSoto. Common sense assumptions like that aren't always true back then. |
|
| |
|
Extreme Veteran
Posts: 580
| I had to go look at my gauge connection under the dash of my 1957 Dodge Sierra.
The information I posted above is not correct.
What I had done to replace a rodent chewed hose was to remove the gauge end fitting with the complete steel tube from the factory hose, install flare fitting and flare the end that the hose used to attach to.
I then used a flare to NPT fitting and on the end of that I used the female NPT fitting that accepts the tubing and ferrule from the aftermarket gauge kit.
So in fact I did use the factory fitting and ferrule.
I know this does not help PolyJ with his question.
I apologize for the misinformation and have tried to delete or edit out my above posts but have unable to do so. |
|
| |
|
Veteran
Posts: 143
Location: Denver, Colorado, USA | local2Ed - 2023-05-18 4:45 PM I had to go look at my gauge connection under the dash of my 1957 Dodge Sierra. The information I posted above is not correct. What I had done to replace a rodent chewed hose was to remove the gauge end fitting with the complete steel tube from the factory hose, install flare fitting and flare the end that the hose used to attach to. I then used a flare to NPT fitting and on the end of that I used the female NPT fitting that accepts the tubing and ferrule from the aftermarket gauge kit. So in fact I did use the factory fitting and ferrule. I know this does not help PolyJ with his question. I apologize for the misinformation and have tried to delete or edit out my above posts but have unable to do so.
No worries on my end; thanks for getting down on the floorboard to confirm how you set up your modification. I cooked up what I hope is a slick plan and ordered the fittings and hose, but I don't want to post just yet for fear I'll jinx it. I ordered fitting to allow me to hook up my compressed air hose to the pressure hose at the engine fitting so I can put 50 psi to my contraption and see if it will hold pressure for half a day or so, and I'll report back once I get everything, build it, pull the gauges, and test it. Then I'll patent the system and make millions selling 1949 - 1958 Mopar oil pressure hoses and fittings, lol. |
|
| |
|
Expert 5K+
Posts: 9911
Location: Lower Mainland BC | .
Late to the party but I bring photos to confirm what 57burb was saying about the gauge-end ferrule. It is not a bevel/taper/ It is a "ball" (half round). (Same issue shows out on some modern mag wheels - like the ones on my 94 Audi - the wheel bolts are "ball" type, not tapered).
Edited by 56D500boy 2023-05-21 6:30 PM
 (56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Attached.jpg)
 (56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Removed.jpg)
 (56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Detail.jpg)
 (56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Detail_Ferrule.jpg)
Attachments
----------------
56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Attached.jpg (145KB - 63 downloads)
56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Removed.jpg (146KB - 62 downloads)
56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Detail.jpg (149KB - 65 downloads)
56DodgeOilPressureGaugeWithRemenantOfPressureHoseFitting_Detail_Ferrule.jpg (147KB - 71 downloads)
|
|
| |
|
Extreme Veteran
Posts: 446
Location: Beaumont TX | Here's how I connected my oil pressure gauge to the engine with 5/16 copper tubing.
The first picture is the completed connection to the pressure gauge. Just for an overview.
The second picture is Dave's picture of the hose connection to the pressure gauge. I'm sure glad he posted this because I couldn't remember exactly what I did until I took pictures of my car and saw Dave's picture. On the hose end that originally connected to the pressure gauge, I cut off the hose crimp and left as much of the 3/16 inch tubing that went into my pressure gauge as I could. I reused the factory connection to the pressure gauge ferrule or ball or whatever that is. I've never seen one before.
The third picture is the Swagelok B 300-R-4, (the 3/16 Tube OD X 1/4 in Swagelok tube adapter). I connected the Swagelok ferrule to the reused stub of the factory fitting that went into the pressure gauge.
The fourth picture is the Swagelok B 500-6-4, (the tube fitting reducing union, 5/16 X 1/4 inch tube OD). I connected the 1/4 inch Swagelok ferrule to the fitting in the 3rd picture and connected the 5/16 inch Swagelok ferrule to the 5/16 inch copper tubing.
The fifth picture is my Swagelok order.
I'll post the other end on the next thread.
Edited by samstrader 2023-05-22 6:46 PM
 (Plymouth 35.jpg)
 (Dave's Picture of Pressure Gauge Fitting.jpg)
 (Swagelok B-300-R-4.jpg)
 (Swagelok B-500-6-4.jpg)
 (Swagelok.jpg)
Attachments
----------------
Plymouth 35.jpg (231KB - 65 downloads)
Dave's Picture of Pressure Gauge Fitting.jpg (159KB - 65 downloads)
Swagelok B-300-R-4.jpg (103KB - 57 downloads)
Swagelok B-500-6-4.jpg (99KB - 63 downloads)
Swagelok.jpg (163KB - 63 downloads)
|
|
| |
|
Extreme Veteran
Posts: 446
Location: Beaumont TX | I connected the engine end with double flare or inverted flare fittings. The picture shows a 5/16 double flare fitting connected to a 45 degree 5/16 double flare X 1/4 inch pipe thread adapter and then the pipe thread is connected to a 1/4 pipe thread X 3/16 double flare reducer and the 3/16 inch double flare reducer is connected to the original engine tube that the hose was connected to. There is a loop in the 5/16 copper tubing that goes up and it's a little too big. I put it in there to protect the tubing against the movement of the engine compared to the firewall and also to give a bigger air space so the pressure gauge would only see air instead of oil. That is according to the original design.
I think 1/4 inch tubing would work fine and if I did this again, I would use 1/4 tubing. The fittings would be easier and it would be easier to run the tubing. I think I used 5/16 because the ID of the hose was 5/16 but don't remember exactly.
Edited by samstrader 2023-05-22 6:15 PM
 (Plymouth 36.jpg)
 (Plymouth 32.jpg)
Attachments
----------------
Plymouth 36.jpg (166KB - 65 downloads)
Plymouth 32.jpg (203KB - 61 downloads)
|
|
| |
|
Extreme Veteran
Posts: 580
| Why did you use 5/16" tubing when the factory hard line off the hose to the gauge is 3/16"? |
|
| |
|
Extreme Veteran
Posts: 446
Location: Beaumont TX | Good question Local2Ed... I don't have a good answer for that. I was thinking I wanted plenty of volume inside the tubing so that air compressed and moved the pressure gauge instead of oil getting to the gauge. And I felt like 1/4 or smaller tubing would be sort of flimsy under the dash but now I don't think that. I would be very comfortable running 1/4 copper tubing and also 3/16 copper tubing if I could find it.
If you ran 3/16 tubing and then all you would need at the pressure gauge is a straight coupling 3/16 x 3/16.... And Swagelok makes these. They don't make a 3/16 tubing to 5/16 tubing reducer so that it why I had to use two fittings to get the connection to work. I would still use Swagelok instead of a standard copper tubing ferrule. Swagelok fittings will hold extreme pressure without leaking. Copper tubing ferrules are only good for 150 psi to 200 psi. I saw a demonstration for Swagelok once where 3/8 tubing was pressured up until it burst at something like 6000 psi and the Swagelok fitting never leaked any. I've seen standard copper tubing ferrules leak at less than 150 psi.
Edited by samstrader 2023-05-22 11:57 PM
|
|
| |
|
Veteran
Posts: 143
Location: Denver, Colorado, USA | I finished the new oil pressure gauge hose and wrote up a detailed article for those interested (not yet indexed on Google but live): https://poly318.com/oil-pressure-hose-dodge-plymouth-chrysler-desoto/
It should apply to 1949 - 1958 DPCD gauges according to the parts and interchange manuals.
While I go into more detail in the article, the issue with a standard compression ferrule isn't the shape but the length. I got a good seal by sanding the ferrule as described in the article. Here's a photo of the setup after testing it for 24 hours at 80 psi without issue.
 (oil_presure_resized.jpg)
Attachments
----------------
oil_presure_resized.jpg (148KB - 53 downloads)
|
|
| |
1955 - 1958 Oil Pressure Hose Fitting Sizes
