Installing Mechical Oil Pressue Gauge

[dubhead74]

In the process of installing a mechical oil pressure gauge I noticed that my universal block doesnt have the oil pressure temp sending unit in it.I know I will need to tap a hole in the block to install the fitting for the nylon tubing.any suggestion or advice where to drill the hole?Is there any quess as to how much difference in psi is there between mounting the gauge upfront near the dash vs mounting it closer to the motor like maybe on the rear firewall?and yes I know if i do I wont be able to see the gauge while driving but I want a accurate reading of the pressure.I will decide mounting when I have an idea of the difference in mounting location.
I have searched some of the fourms to help but no luck on the search phrase needed to find out what I need.

Thank you

[Marc]

The only cases that aren't threaded for an oil pressure sender are Type III (theirs is on the oil cooler).
I'd use the normal Type I location; I don't recommend installing (permanently) a mechanical gauge anywhere - IMO potential leakage problems outweigh any good one will do you. But if you must, by all means use a Tee so you can retain the stock warning light.

[dubhead74]

You are correct that the block numbers list it as a type three block.Unfortately at some point no one put any type of oil sensor on the block and someone swaped out the type three oil cooler for a type one cooler.
where in the block would you recomend i tap the hole?
Thank you again

[Marc]

The Type III case casting has the same boss as the Type I, it's just not drilled/tapped at the factory.

[allenparker]

I may catch heat for this, but it works well for me. I usually use a copper line from the fitting to the oil gauge. I use a 3/16" line with the proper fitting on the block and a step-down adapter at the gauge. The larger line helps the gauge respond faster.
With a little bit of work and some choice words, you can route the line through the tunnel. just make sure the line is away from all moving parts and is secured.

Once I fit the line to the block and make the run to the gauge, I bleed the line at the gauge end. when I have a full stream of oil, I connect the line and clean up any spills etc. I restart the engine, look for any minute leaks, before test driving the car.

Always drive the car and then re-check for leaks. It is amazing what a little vibration can do.

[Ol'fogasaurus]

Allan, not jumping at you but some information; not many racing organizations’ allow copper for liquid/pressure lines because copper has a tendency to work harden and fracture due to vibration. When in doubt I follow the advice of the racing rules as their rules usually come from experiences, usually bad ones.

I usually use nylon type tubes made for the gauges but I don't like to run it long distances either. I was not a big electronic pressure sender person either, as they didn’t seem to be accurate, were slow to read pressure and a long wire is needed, until during a discussion like this I was told to mount the sender with the dome facing down. Apparently this stops the potential for air bubbles to form in/around the sensor and they become more accurate. It was also stated that the dual purpose sender was not an ideal thing to get and to use a Tee to add both but I don’t have practical experience with this myself.

Like Marc said, use a brass Tee, this way you can install both a sender/pressure line and a sensor for an idiot light/horn/buzzer or any of several other attention getting devices.

Personally, I found that the idiot lights came on well after the pressure gauge read "0" oil pressure. The idiot lights are designed to come on at about 7#’s of pressure but they are either slow to read pressure or the +/- manufacturing tolerance is great enough that they are late in coming on. Off-road I also use a larger light (a truckers cab light for example) and one that shines bright even in direct sunlight to see; one of the reasons for the horn/buzzer options. I’m not sure I would use an electrical cutoff switch option though because the one time I started to lose an engine out on the dunes I was able to get back to camp before because the gauge gave me plenty of beforehand notice of a problem before the pressure dropped to where the engine would have been shut down by the thermal switch. The “idiot” light came on just as I was entering camp; the case/block was saved because of the heads up and I noticed it.

I did have one bad experience though as the nylon (Im not sure if it is nylon or not but it use to be) line came into contact with the “over the top” style of exhaust I run when the Panduit tie slipped and allowed the tube to drop and come into contact with the exhaust. I had enough slack and carried a just-in-case kit (parts and tools) with me to fix the tube on the sand.

You need one or more device to tell you what is going on. Idiot lights do serve a purpose as ell as a gauge does; especially on an air cooled engine where the oil is so much a cooling agent that you know quickly if you have broken or thrown a belt. Electrical charging gauges for also are a bit slow to read also but… the most important reason of all, you have to develop the habit of reading a gauge. Several times I have told someone to check the rear of your buggy or get back to camp as: didn’t you notice that your idiot light is on or flickering?” The reply was usually .

Lee

[Piledriver]

You need a bit of flex in the hose/mount so the mech gauge dosen't vibrate to death over time.

IME hard mounted doesn't last long, even with good quality gauges.

BTW, you can get "idiot light" swiches for MANY pressures.

Seems logical if you have a big pump and you motor normally makes 20PSI at hot idle you might want an alert if it falls <10.

[Marc]

...The commonly-used 021 919 081B switch is rated at .3±.15 bar (2.18-5.63 psi).
There are some other switches available...made for Rabbits, they have longer straight threads and shouldn't be screwed directly into the tapered threads of an aircooled case, but they can be adapted. The 068 919 081A, for example, is rated at .9 bar (13 psi). There're also .25, .3, 1.4 and 1.8 bar models available.