jarrett wininger

Hi so I'm stumped on relocating my oil pressure sender.. here's the story..

I have a 64 Nova with an LS1, and I have a classic industries guage cluster that uses the bell style sending unit with 1/8npt male fitting. When I emailed them about location they said just use the rear passenger port with an adapter. So that's what I did but because of it's size and my fast intake I had to use an adapter that out it out at a 45*. After about 500 miles I noticed it was leaking from the adapter on the block to the 45* angle fitting and nowhere else. Tried another fitting, tried 3 different sealant types. Still had a leak. So I decided to remote mount it from the oil filter adapter plate (using a moroso f-body pan). Got the proper earl fittings to run it 90* and up via steel braided line. When I tested the remote setup, the needle moved opposite direction, like it isn't grounding. So I took off the hose thinking it was that. Mounted it straight off the port with an adapter and made a new wire to the guage wire. Still the needle goes down when starting up...

The fittings I used for the original location were brass, with Teflon tape and they read 50+psi. The fittings for the lower pan mount were aluminum earls with tape and without tape. I'm thinking I just have to go back to mounting from top location and double up on Teflon even though it says not to... Running out of ideas. Anyone got any suggestions? Thanks you.

Che70velle

iTrader: (6)

Show a couple pics of what you’ve done here. I’ve seen guys drill and tap the plate there to feed a turbo. In doing so, the fitting screwed in too far and blocked the oil flow there, starving the engine of oil. Maybe the Moroso pan has a different block-off plate? Pictures please…

jarrett wininger

This is where I originally had the sender mounted using extensions because there's no room to go straight down with my manifold.

This is the current location off the oil filter adapter plate from the moroso pan

This was the extension

Running straight out as just a test, I would run a 90* elbow so it would face upwards, as well as solder that connector, the butt connector is just a place holder.

LS1 TJ

More a less a guess on my part but the gauge doesn't ground from the sender. The gauge grounds off the back of the gauge to the chassis (At least on the Auto Meter gauges I've used) or where ever you have your grounds. I've always used the adapter above the oil filter to tap into for oil pressure. Bad sender?

jarrett wininger

I will double check the cluster ground but it was working just fine (minus the oil seepage issue) as far as the guage goes, before I tried relocating the sender. Would it matter that I'm using earls anodized aluminum fittings vs the brass fitting for conductivity? I'm going to move it back to original position just to see if anything I added caused a break in the circuit. And I'm also gonna try a brass fitting coming off the lower mounting position to see if somehow the fitting type matters..

QwkTrip

iTrader: (23)

I don't know about a '64 Nova, but on my '80s GM vehicle the oil gauge will peg HIGH if open circuit, and peg LOW if short circuit. In other words, the lower the electrical resistance to ground the lower the oil pressure reading on gauge. If yours is the same concept, then that suggests you've got a short to ground somewhere. Maybe check for short circuit between your terminal and the case of the sensor. Perhaps the insulator broke from being over torqued or something like that.

Or.... maybe you really do have low oil pressure at the gauge.
Maybe wise to double check with a mechanical gauge at the top of the block.

jarrett wininger

Yeah gonna double check my connections. I highly doubt it went from perfectly good pressure at idle (50+) to 0 after simply sitting in the same spot for a week. Like I said the needle actually forces itself downward on startup. My fuel gauge did the same until I grounded the fuel cell properly. So I think it's conductivity related. I read that anodized fittings don't conduct electricity and that's what I've been testing off of...so I ordered a brass elbow adapter and will try again with that. Brass is what I was using for the adapter fittings up top.

QwkTrip

iTrader: (23)

Fuel gauge also pegs LOW (empty) when there is a short to ground, and goes HIGH (full) when electrical resistance is high. What exactly did you do with grounding to make the fuel gauge work right? What you're saying is confusing to me because my intuition would predict the opposite. Seems maybe this same weird behavior is happening with your oil gauge too. Or maybe I'm just lost in conversation (which could be).

jarrett wininger

So with my fuel cell I actually forgot to hook up a ground to the cell (in my trunk) to the body. That's why I got a negative reading. So I made a wire and attached it to a spot on the trunk pan. Problem solved.
In the case of my oil pressure sender, it was working just fine with the ground going from my block ground straps, I presume, to the negative firewall terminal. The wire going from the sending unit provided the cluster with the other end of the circuit, at least from what I understand. When I moved the sender to the pan port, I used anodized fittings instead of brass, so that's where I believe my issue is now coming from. I read that anodized fittings don't conduct electricity. So that's sort of where I'm at. I'm also not an experienced electrician or even builder. This is my first build so forgive my ignorance.

QwkTrip

iTrader: (23)

I guess I'm still confused how your fuel gauge went LOW when the ground was omitted, I would have thought it goes HIGH. But that's history, not worthwhile spending more time on that.

Oil pressure gauge gets +12V from the battery and has 2 grounds. One ground is at the gauge cluster (I hope you hooked that up). Other ground is the oil pressure sender. The pressure sender is basically a variable resistor dependent on oil pressure, which causes the gauge needle to move with changes in oil pressure. The higher the current draw through the pressure sender, the lower the needle will read in the gauge. So there are two ways that needle might be pulled low:

(1) Short circuit in the circuit to the sender.
(2) Poor or no ground at gauge cluster (the other ground i talked about for the gauge).

jarrett wininger

The cluster is daisy chained into a single ground to the chassis. I will double check that it's good but considering all my other gauges work fine, I would assume for conversation it's solid. The wire to the sender I just made an extension to in order to reach the new location. I used butt connectors just for testing purposes but I would solder or use no insulated for aesthetics if it worked. But from the sender to the block it's now an anodized fitting, which I before mentioned could be my issue. I don't have any brass fittings to replace that spot with but I think I'll just try and move it back to original top mounted spot (with brass adapter) to see if it is the wire extension and not the ano fitting. The adapter at the top is natural aluminum with a 1/8npt female so I can run brass. But the lower is a 1/4npt and the only adapter I have for that to 1/8npt is anodized... Does that make sense or have I lost my mind lol?

QwkTrip

iTrader: (23)

No, you haven't lost your mind. You've got some good ideas to look into. Sorry I couldn't be of more help. I'm still wrestling with this in my mind too. Things are acting the opposite of how my mind thinks they should act, which makes me wonder if the adapter really is choking oil flow (resulting in low pressure). If changing materials doesn't work then I'd maybe consider next step to use a mechanical gauge at top of the valley to verify whether the numbers are real.

jarrett wininger

I Appreciate you offering your knowledge, it helps me outline the things I need to back track. When I work on carburators I often go back to the last thing that worked, hence me thinking I need to return to what was working before. But I also want to figure this out the way it's supposed to work. Thanks for the help, I'll report back once I've gotten the new brass adapter.

jarrett wininger

Turns out anodized fittings don't conduct electricity, at least not what's required for this circuit. Got a brass 90* and guage is back to normal. Thanks for the help.

Rick Dorion

iTrader: (1)

Kudos to you. Thanks for following up and posting back!

grinder11

iTrader: (1)

Glad you figured it out, and posted. It was acting similar to a reverse polarity situation..

Old Buzzard

Been doing this for a looonng time. Have never found an anodized fitting not grounding.
"The fittings I used for the original location were brass, with Teflon tape and they read 50+psi. The fittings for the lower pan mount were aluminum earls with tape and without tape".
We use liquid teflon on the fittings. Never an issue.
We've also used plumbers liquid seal on water system fittings with a high success rate.
Good that it's solved.

Che70velle

iTrader: (6)

Anodizing has zero bearing on conductivity of electrons. It’s too thin to affect current. I’d say you had a loose connection and found it by accident. Either way, it’s fixed.

grinder11

iTrader: (1)

I agree with both posts above. Never any issue with anodized anything being a non conductor. As the NPT threads tighten to each other, they're an interference fit, meaning the anodizing quickly get wiped off the thread pitch diameter..