Nylon vs Copper for Mechanical Oil Pressure Gauge

Discussion in 'General IH Tech' started by Randall Barringer, Oct 14, 2011.

  1. Randall Barringer

    Randall Barringer High Wheeler

    I am going to install a mechanical oil pressure gauge and would like to know what everyone thinks about nylon vs copper tubing.
    I think I'm going to go with copper tubing, but would like some opinions on what is best.
    Nylon tubing sure is easier, but is prone to heat.

  2. Mark Aycock

    Mark Aycock Farmall Cub

    I had an interesting engine fire from using nylon. USE COPPER !
  3. Super Scout

    Super Scout Farmall Cub

    I know a lot of drag strips will not let you run if you have nylon line. I know your not racing but non the less copper is better.
  4. Tim Potter

    Tim Potter High Wheeler

    Yep nylon doesn't like heat. It must be kept away from exhaust. If you go with copper make sure to put a coil in it so that it has the ability to stretch as the engine moves. I just wrapped mine around a 3/4 wooden dowel a few times starting about 6" from the galley fitting
  5. ihscoutlover

    ihscoutlover High Wheeler

    Copper. I bought a gauge to read the pressure correctly after we toasted the upper half of the engine in Melissa's Traveler bringing it home from WA. After being a little inept with IH's at that point(or at least that one), I bought the gauge. It comes with the nylon tubing, but I went ahead and got a spool of the copper and I am glad I did. Not only is the nylon subjective to heat damage, over time hot & cold will also play a part in how it "degrades". Even though it doesn't hold a whole lot of pressure, its similar to your brake lines, those aren't nylon are they?? We have had that setup for the last 7 years and I constantly check it for leaks/problems and so far its holding up well.

  6. fredsterra

    fredsterra Y-Block King

    Copper is best. But I have nearly always used 1/8" Nylon air line. And used 1/4" over the 1/8" to inulate from rubbing on anything.

    I keep telling myself one of these days I am going to change the line on my Scout to copper or teflon braided hose. But I also have an oil pressure switch for my fuel pump. So if I were to loose oil pressure it would cut off the pump. I hope before any major damage.

    I don't use the clear cheap hose they send in the kits. It is nylon air brake tubing. It can handle the warm oil pressure and the heat. (As long as you tie it away from the manifold!)
  7. Dennis Bernth

    Dennis Bernth Moderator Staff Member Moderator

    If you go to someplace like Summit or Jeg's you can get braided stainless hose for mechanical oil pressure gauges. They're not cheap, but they should be pretty much a 'install and forget it' fix. Copper is OK, but as mentioned, you need to put coils in it ( I put coils on both sides of the firewall) to keep it from 'working' from vibration and cracking. This post has me wondering about the copper/nickel tubing I now use for brake line- it's a lot more 'bendable' than steel tube, but is DOT approved for brake pressures, never rusts, and it's way stronger than straight copper. Still would need the 'coil' in it, but it forms by hand so that's easy. I may have to investigate that for the 'new' Scout's mechanical gauge.
  8. TBAKPhi22

    TBAKPhi22 Binder Driver

    Copper at a minimum, the braided is even better. I used the stupid nylon one once when I didn't have the copper yet. Got too close to the header and melted it. Luckily I caught it in time...
  9. ikavo

    ikavo Farmall Cub


    What kind of 'sender' and guage are you guys buying? Anyone have part numbers by any chance? I'd like to do this too.


    73 T-all 1010
  10. Carl Wiese

    Carl Wiese Moderator Staff Member Moderator

    The gauge doesn't have a sender, you use a fitting to connect it to the oiling system and oil pumps at pressure up the gauge via the line they are discussing and the gauge registers the pressure.
  11. Thomas

    Thomas Dreams of Cub Cadets

    ---The biggest plus with flexible line compared to soft copper is vibration. If it were an Accura or something, I'm sure you'd hear the rattling/humming down the copper line, but that won't be the case with a beast of a truck, so while the engine vibration transferred might not be so much a comfort thing, noticeable by ear, it is still extra vibration to the dash.

    ---I snapped pics of my oil pressure line, but never uploaded the pics to a server. I'll attempt to upload through the cell/wifi later, but...

    ... I used -3AN Braided SS Teflon Hose (brake or N²O line) to do mine. A 45° -3AN x 1/8" Male NPT/MPT Fitting at the block/galley, a Swivel, crimped -3AN x -3AN x 30" line from the block to firewall, a 90° -3AN x -3AN Bulkhead Fitting (+ two -3AN x 3/8-24 Bulkhead Nuts) at the firewall , a Swivel, crimped -3AN x -3AN x 34"line from the firewall to the gauge and a straight -3AN x 1/8" Female MPT/FPT on the Mechanical Oil Presssure Gauge.
    ---While fairly expensive, it will last a good long time without issues thanks to the flexibility, but primarily because it is PTFE. Ease of disconnecting is a major plus! The -3AN/-4AN fittings are only torqued to about 14lb-in (don't have the chart handy but it can be found online). The -3AN lines (Goodrich) and fittings (Fragola) were all purchased on eBay, total for all was $53.26 shipped between the two sellers. Fittings purchased from one and lines from another, both at the lowest price at the time; Which fluctuates, so price can easily be much lower if not needed in a pinch... as was my situation. Also, shop around cause distressed packaging often can cut the price 50% or better and the 34" line only runs around $23 retail. New Old Stock can also lower the price.

    ---As for cheaper yet, -4AN drops considerably in price because -3AN is mainly for N²O (and some Motorcycle Brake Line). -4AN would be used mainly for Brake Line. There would also be a little better response from the -4AN as well, with -3AN being about equal in ID as the copper or nylon.
  12. bobn

    bobn Binder Driver

    just running my yap here, not that it applies to our scouts>nhra has made nylon oil pressure tube illegal. i switch to copper on my hot rod merc, i did make a double loop on both ends to give some flex....fwiw, bobn
  13. Barney

    Barney Farmall Cub

    30 years ago I installed a Stewart Warner oil pressure gauge using copper line on my 1210 4x4. This truck has been driven over the roughest roads in the woods during those years and I have never had any problems with the gauge or the copper line.
  14. Will Marsh

    Will Marsh Moderator Staff Member Moderator

    I'll start here with a quick lesson to make Thomas' post easier for those who aren't hydraulic gurus to understand.

    Dash sizing in hydraulics refers to hose ID in 1/16ths of an inch. IE -3 hose is 3/16" ID and -4 hose is 1/4" ID.

    Fittings are sized by standards based on the hose ID they're designed to be used with. the common ones you need here are NPT (National Pipe Thread) and AN (Army/Navy) 37deg flare. JIC 37deg flare is 100% compatible with AN and more commonly used in hydraulic applications.

    You can thread any male -4AN fitting into a female -4 JIC or vice versa, as long as the dash sizes are the same. Adapters between sizes and standards are readily available.

    Now back to Thomas' post:

    If you're willing to go to -4AN ( AKA 1/4" JIC ) any hydraulic shop and most parts stores stock the stuff to build them, at about 1/4 of the cost Thomas quotes here. The biggest problem with that is that 1/4" 2-wire hose is about 1/2" OD, and needs about a 5/8" hole to get the fittings through the firewall. 1/4" 1 wire hose is a little smaller OD, but the fittings are the same and 2 wire is more common. Total overkill since the1/4" 2 wire hose is rated 5000psi, and 1 wire is 2000psi +. It will typically have a black rubber cover instead of the stainless braid, like a power steering hose.

    At my current prices a 5ft 1/4" 2 wire hose with a 1/4" JIC swivel on each end would run about $20, add a couple bucks each for the 1/4" JIC / 1/8" NPT adapters to the gauge and engine block.


    Will Marsh
  15. J Brad

    J Brad Farmall Cub

    I did the -4 or 1/4" hydraulic line. It's been on it since 2001 (I think) & it was used line & fittings I took off a forklift we had at my work that lost in a collision with a train bridge in Las Vegas.

    Attached Files:

  16. Thomas

    Thomas Dreams of Cub Cadets

    ---Wish I was a hydraulic Guru. They make good money traveling to job sites to fix heavy equipment!

    ---The 8AN stainless steel teflon lined hose is roughly 1/2" OD. I have 3/8" wire loom over my -6AN & -8AN fuel lines where my 5/8" nylon line clamps hold it to the body/frame and it holds it snug. 3/8" fits over the -6AN loosely. These are Aeroquip fuel lines and when you get into true AN (Army Navy) for aircraft, like Aircraft Spruce manufactures, it will be a lot larger in OD as well as Aeroquip's double braided. The 12" piece of Aircraft Spruce -8AN line between my fuel filter and pump is probably 3/4" OD if not 11/16"! Don't even want to know what the bend radius is. The -3AN here has about a 2.5"-3" bend radius, so it's easy to route.

    ---When I opened the box with my oil lines (brake lines really), I almost* giggled... almost, cause they were so "dainty" :nono: it was funny. Seriously, -3AN was about as thick as a pencil. So now, the Bulkhead Fitting... makes passing it through the firewall/bulkhead that much easier. All you have to do for the -3AN fitting is drill a 1/2" hole and maybe add a chrome or stainless washer on the outside for looks. Connect the hose to the outside and inside, a 30" piece outside and a 34" piece inside. Pics will be coming soon. Adding close-to-scale image of the fittings and part number for fittings to that image. PIP. Not the greatest* quality for a roughly a $600 camera, but you'll see 1/4" wire loom covering the stainless steel braid completely, routed... even the crimp covered with zip-tie holding it closed and in place. I drilled the 1/2" hole about 16" to the right, center of the hood latch and about 4" below center of hood latch. StoneThrower isn't on site, so I can't give true measurements.

    ---Fragola, Made in China, but good quality. It can be had for $1-$3 a fitting retail rather than the competitors' $5-$20 (speaking relevant non-swivel). The 37.5 flares were clean and fit the Goodrich hose well as well as the -6AN Aeroquip hose I used for supply from my carb to Zenith-style (tractor) sediment bowl filter and from filter to pressure regulator.

    ---Here's the pics. Nothin to it. Hardest part is shopping.

    ---I put the correct terminals in the gauge connector/block rather than the temporary too long, POS, RadioCrack terminals (for non-automotive electrical) I had, so the back of the Oil Pressure Gauge looks a lot better now than in the pic.

    Attached Files:

    Last edited: Oct 15, 2011

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