Sorry another simple question - oil sending unit

[Print Dad 58]

Hello all,

I am sorry to ask what may seem like simple/goofy questions but I need some thoughts.

I was working on the Mach today and decided to ground out the oil sender unit to see what happened.

I ran a jumper wire from the wire from the sender to ground- -turned on the key and oil pressure went all the way up to

high (pegged). If I am not certain this tells me that the gauge is functional and the sender is  at fault. This is about the

3rd sender I have installed in the last 4 years. The one currently in the car is a Motorcraft and is less that a year old.

so I looked and have another sender on the shelf- -

I know these gauges work on resistance but don't understand much of that.

So I guess my several questions are:

1. - what brand sender should I get

2. - How do I test the new sender - - please be kind on this - -I am pretty ignorant on electrical and electronis.

I do have a few meters- don't know why really  LOL

3. - Am I correct that the issue must be the sender?

 

On a side note I tried the horns today after cleaning all the ground contacts and the newly rebuilt steering wheel

the horns sound but not that loud - -could this indicate a ground issue that could affect my sender units???

 

Like I mention I am real bad at this stuff but look forward to any thoughts

 

Thanks - - - Sam

[Midlife 814]

Your test indicates that the wiring and the gauge work correctly, but please do not ground the sending unit line more than just a couple of seconds, as it will burn up the gauge.

[LoneWolf2U 136]

This problem sounds like lack of or poor body grounds. Check the ground straps to the firewall and engine to fender locations.

How do you know the sending unit is bad? It could be wrong type,  like one for light not gauge.

[Print Dad 58]

Hello all.

Thanks - - Mach1Rider - -it is the correct sender - it worked for a bit- -actually stopped right

after I got the car back from the body shop. I will recheck and clean all the grounds.

Are there any grounds under the dash that I should be looking at?

 

Thanks all - -sam

[larryc94 38]

10 hours ago, Midlife said:

Your test indicates that the wiring and the gauge work correctly, but please do not ground the sending unit line more than just a couple of seconds, as it will burn up the gauge.

It's a good idea to use a test light (the old fashion filament bulb type) to ground sending unit wire.  It provides a small amount of resistance as not a direct short to ground to protect the gauge

[Print Dad 58]

Thanks Larry- - I will remember this

Midlife- -I am sorry I forgot to acknowledge you input  and I know you are a WIZZ at this - - sorry

So now does anyone know if there is a ground under the dash I should be looking at.

As for the grounds on the car now - -I have the neg cable going to the block and a ground strap

I installed a few years ago - -going from the back of the pass head to the firewall.

I am not sure but I don't think there is a small ground wire from the battery to the body like on a lot of

GM cars. I will look into this in the morning.

I do have the shop manuals and the electrical section - -but it looks like spaghetti to me

 

Thanks again for all the help ALL - 

Sam

[barnett468 418]

connect the horns directly to the battery . if they are loud, you have a weak ground or other weak connection.

 

your sender is bad . what types have you used?

 

i often use bwd or smp senders from oreilys.

 

[1969_Mach1 333]

I didn't have much luck with a Motorcraft sending unit in my 1969 Mach 1.  Gauge was always reading a lower than I thought is should (below middle of range) when a mechanical gauge would indicate 50 psi.  Easiest thing to do was swap out the oil pressure sending unit.  So I installed a Standard Motors Product (SMP) sending unit.  The gauge reading increased significantly.  I suspect the Motorcraft sending unit is for later model cars and not calibrated quite right for the gauges in these cars.

[Midlife 814]

If your dash or turn signal lights work on your dash cluster, and at least one of the oil, water, or fuel gauges work, then the problem is not the ground.

[Brian Conway 264]

Oil senders on my car.  OE Green top is for the OE dash warning light and the bulbous thing is for the ' added ' console gauge.  Brian

[Print Dad 58]

Hello all,

Thanks for all the help an advice.

Brian, Thanks - -I am familiar with the 2 types of senders

Today I may have solved the issue. It was a bit tuff-  - Gotta explain and hope

a few get a chuckle.  So I loosened the sender with a 9/16 wrench and turned what I think was

about a full turn. It was tight to spin the wrench - -so I figured I would use my super human

strength and back off the sender  .  I grabbed the sender by the "fat bulb" are and spun the sender.

It spun and spun and spun and spun - - - LOL   I was getting nervous, thought perhaps the hole was stripped.

I then noticed even with my super strength - -the bulb are was spinning and not the bolt area that is on the bottom.

I had to use 6 different wrenches but finally got it out. When I looked at the old sender - -there was a bead of

silicone on the bulb area.   So that the bulba area spun but the bolt/shaft was not turning. I am thinking this is

not good. I installed the new sender but couldn't get time to start the car. I will do that tomorrow.

I think the issue MUST have been the old sender - -which was a MotorCraft

 

Thanks again - - -I really do appreciate all the help.

Sam

[barnett468 418]

what do you mean silicone in the bulb area?

 

do not use sealer on the threads.

[Print Dad 58]

Hello Garnett468,

No sealer on threads - -there wa some teflon tape on the unit when I bought it.

I left the tape on - -I think  the threads cut through the tape to make ground.

The silicone I was talking about is a bit hard to explain

If you look at Brian's picture - -see the black "bulb" area - -then there is a silver band,

that is where the silicone was on mine. So where the silver part (above the 9/16 " nut is".  I   think the body shop put it there.

I recall when I took the car to the body shop at first they told me the motor was leaking actually they thought it was

the power steering - -but my car has no power steering. They told me it was the oil sender and I thought I had not tightened

it enough. I learned to tighten - -then check for leaks and then if needed tighten again. I have been known to over tighten things  LOL

Broke a lot of plumbing fittings by going a bit to strongly on things   LOL

 

So thanks for the heads up and I do understand about the grounding of the sender.

I will post tomorrow after I let the motor run - - I think I will be OK - -we will see

 

Thanks - - Sam

[Print Dad 58]

Hello all,

started the car - -guage reading high but reading - -NOLEAKS all is well

Thanks for all the wisdom and support 

 

On to the next project- -Sam

[barnett468 418]

xlnt!