Technical Electronic oil pressure sender/guage, problem

Have another problem I sure could use the HAMB help on.

Have a electronic Stewart-Warner vintage looking oil pressure (0-80) guage, bought new in the '90's. 5-6 years ago, mounted the guage, and a (suposidly) SW electronic oil pressure sender bought new at Advanced.

Last week I was "priming" the bone stock engine, 30w ZR-1 Valvoline oil, with a common (well used) 3/8" electic dill motor, and a "priming tool" I made out of a old distrubitor. Dedcided to turn the ignition witch on and see now much oil pressure the drill was churning through the motor. The guage rose ''normally" when the drill was started, however the guage pointer went clear past 80, and "hit the peg"!

Now, I am more familiar with a mechanical oil and temp guage systems. But this time used electronic, because a single wire was easier to hide.

So, where do I start troublshooting? Those electronic sending units now are in the $70 range! Just can't run down and buy another one "just to see"!

Thanks for your help!

 

Sounds like a mismatched gauge and oil pressure sensor. Photos or part numbers would help.

 

Do you know the part number of the sender you bought? And the gauge?

do you have a digital voltmeter? and know how to use it?

 

Is that 'bone stock engine' a fresh rebuild? Cold 30W oil on a tight clearance motor can have some pretty high pressure numbers.
Or there could be a mismatch between the new sender and the gauge.

I think I would start out with some 10W 30 oil and see what the gauge reads.

 

Try pulling the sender and hooking it up to a regulated air supply fitted with an acceptable/good pressure gauge and compare apples. The sender won't care if it's an air or oil pressure signal.

 

Ah,,,,, I was wondering "if" the sender had to be matched to the guage, like the gas tank float sender and guage. I'm more of a "mechanical" guage units, I understand them.

Squirrel. Part #'s!? it was in the '90's when I bought the oil pressure guage. It was tucked away in the drawer until 5-6 years ago. That is when I took it out, mounted it, and bought the sending unit at that time from Advanced and wired it up. There is no way I could find any part #'s!

Wonder, if I bought a new(er) SW guage,,,,, might get "lucky" in matching?

Son In Law, is looking to see if he has an old mechanical oil pressure guage laying in his junk drawer. I'll start there, with a known pressure.

31, good idea. Glad you thought of that. BTW, which end of "Down Under" are you loacted? I sold a Ply Vert to a guy who lives clear on the bottom in the middle.

Gene, the motor has been run before a short while after it's been re-built. It's been 10 years since I have last run it.

Thanks for the ideas.

 

Tight clearances and dead cold oil , it will peg the gauge . I just did it priming my fresh 289 for the Tiger . My 32 will still maintain 80 psi rolling down the highway and the engine is 30 years old .

 

Use the mechanical gauge first to determine actual oil pressure. Then switch in the sender unit and measure resistance between sender and ground while spinning the disty shaft. Take the resistance measured and use the same resistor value in place of sender. If the gauge still reads different than the mechanical gauge then sender is not correct for the gauge.

 

Well,,,, after talking with the Stewart-Warner Rep and following his troubleshooting procedure suggestions this afternoon. The sending unit is the correct one, but it's bad, as in totally Ka-Plooie!

Was it a bad unit from the beginning? Could have been, no way of telling now. No way Advanced will replace it as in defective.

I'll order another one, same part #. I didn't know the part # was stamped on one of the hex faces. On one hex face it's stamped, 10 something 4. Directly under that it's stamped 80. On another hex flat it's stamped, 411 J. Directly under that 12-V. To find those #'s, I had to stick my tongue out, squint one eye shut, and use a magnifying gl***.

I'll let you know what happens when I get another sending unit.

 

SW gauge uses a sender that had an ohm range of 240 - 33 ohms.

It looks like the Stewart Warner sender part # 279-A.
Price $60

Speedway
Summit
Jegs

 

SN54 from Cl***ic Instruments registers

240 ohms at 0 psi
33 ohms at 80 psi

Sells typically for $43.

The sender and gauge MUST match ohm rating requirements!

 

yes...electric gauges
resistance of the sending unit changing the voltage that is scaled to the engineering units of the dial face
it's a good thing that the reading changes from some unknown value to another when you run the drill...that is a pretty good indication that oil pump is building pressure....

 

A sending unti is one it's way, straight from Stewart-Warner. Same price as Summit.
I'd like to know why the SW 411-J sending unit I bought 5-6 years ago failed up on first try?
Thanks

 

Ok, UPDATE! More comfusion. Recievived the new oil pressure sending unit. Had son-in-law, check the ohms. They were correct for 0, 40, 80 psi. Installed the new sender unit, hit the drill trigger and it pegged the guage again!

I couldn't bum, borrow, or setal a manual oil pressure guage from anyone. So out of desperation I hooked up a spare air compressor guage I had in the drawer.

Squeezed the drill trigger, WOW, EIGHTY SEVEN pounds of pressure! That can't be right! No wonder the electronic guage was *******!

This is a bone stock 283, when running a decade ago was little over 40psi

Ok everbody chine in. WTF is goin on? Thanks

 

Sounds like the pressure regulator is stuck.

 

How fast is the drill spinning?

 

Why not just get a good quality mechanical gauge with a plastic line kit as d2willys suggested, for a temporary setup ? If back to 40/50 psi with drill , then go from there.

 

Curious how fast your spinning it with the drill.

Remember oil pump runs off of distributor, distributor off of cam and cam turns half speed of crankshaft. So if the drill is running 2500 rpm that's 5000 rpm crank speed.

Also too, check pressure relief valve/ball ***embly in oil pump to see if it's stuck...


...

 

With this in mind, check what the typical oil pressure is at 2000rpm for the 283. Motors manual probably has 35-40 psi @ 2000rpm. Now run the drill @ 1000rpm and see what the gauge reads. If good, run drill at 2300, which puts the crankshaft @ 4600rpm. My guess is if a reading of greater than 60psi is observed, then pressure regulator is stuck with possible clogged oil p***ages or tight bearing clearances. Another check to do is to observe what oil flow is like at rocker arms while drill is running.
Too much oil flow might mean pressure regulator issues.

 

I already did that,,,, sort of. Used a spare 0-150 psi air compressor guage directly into where the electronic gauge was plumed into the rear of the block. That is how I came up with 87 psi.

 

It's an old vari-speed 3/8 Dewalt almost work out drill. I do not know the rpm range.

I did not know ab out the 1/2 speed difference. (Old dogs new tricks)

I'm going to go ahead and stick the distributor in, finish making the spark plug wires, then run the motor, see what the oil pressure is.

 

It probably won't make a bit of difference. But when turning the pump with a drill motor I'd try manually turning the crankshaft maybe 45° or 90° at a time thru at least one complete revolution. (Mostly just to satisfy my own curiosity.) A breaker bar and socket on the end of the crank should do the trick. A second pair of hands might be helpful too.

 

When the 283 was running at 40 psi a decade ago, was the oil fresh out of the can, or about due for an oil change? Did it have straight 30 w oil in it then, or did it have 10 w 30 oil in it? Was that oil pressure seen after a cruise on a hot summer night?

A cold motor with straight 30 W oil in good condition could show 90 psi for a short time. 30w oil is for mid summer heat, not a cool spring morning.

 

When I bought this project, it had 10-40 "hi-Zinc" Amsoil. Switched it over to 30w ZR-1. (Advanced had it on their shelf)

I had emailed most of the brand name (off the shelf, API "S" ) oil companies, asking their ppm's of Zinc-Phosphate. Mose brands of 30w conventional oils had suffecitnt required ammounts. Way more than the same brand of multi-grade "energy -saving" oils. I remember, the Valvoline ZR-1 Racing Oils had the highest number of zinc-phosphate. This was all done 8-9 years ago, and I don't have those emails, or (CRS disease) remember the exact numbers. I DO rmember, every oil was at or above 1200 ppm's.

And yes, I have changed the initial VR-1 fill/filter after installing a differnt oil pan/one piece gasket 5+ years ago.

Now "this" is overkill, but I was very sastisfied in preforming it. But every year, after the new pan, and after running the oil through the motor with the drill severl times each year. I took the filter off, cut it open and dumped it out on a old clean white T-shirt seeing if there was any "FOD" (foreign object damage) the filter captured. Meaning, each year a 1/2 quart of new oil got mixed in.

 

The point I am getting at is, a 10w 40 oil is much thinner then a straight weight 30 w oil is. Thicker oil makes higher oil pressure in the same motor, with nothing else changed.

A 10W 30 (or 10w 40) means the oil has the thickness of 10W oil, but has additives to bring the high temperature operation protection up to the same protection level as a 30W (or 40 weight). Your 283 motor will be perfectly happy with a 10W 30 oil, even going through the desert in the summer. And if the outdoor temps drop, the lighter oil will flow through the motor better then the straight weight 30W would, and the oil pressure in that cold motor won't blow up the oil filter.

If you can get your current oil brand in a 10w 30 rating instead of the 30W rating you now have, your oil pressure will probably return to what it used to be.

 

Similar to 10W40 I have been using this 20W50 high zinc oil for several years.
https://www.amazon.com/dp/B09QXWLY2Y/?tag=atomicindus08-20

For my 60k+ mile sbc it raised the oil pressure, especially at idle on hot days.

 

This can be handy.

https://www.harborfreight.com/engine-oil-pressure-test-kit-62621.html

 

Yes, I remember now writing to Castrol back then, but don't rememeber what their ppm's were. I'm gonna guess, it was between 1300-1400.

Before the "cadillac" converter oil feisaco, 1400 ppm's were the required zinc-phosphate for the tappet/cam lubrication.

Mr. pprather, do you happen to know what the amount of ppm's zinc-phosphate that Castrol GTX you use has?

 

Some info here
https://msdspds.castrol.com/bpglis/...24C71DF8025867E0048CB89/$File/wepp-bybe5y.pdf

 

THANKS! I'll pick one of those up next time I'm over our Harbor Freight location. Cheaper than buying a mechanical guage.