CJ vintage OIL PRESSURE SENDER getting the right one match to gauge depth

Fjguercio · 12-08-2009, 04:54 PM

Needed to replace my failed oil sender and I have a 2" deep orginal gauge on my 1978 CJ7. I found and tested a few that are on the market and some oil senders will work and some will not. So I will post the part number, resistance or OHM reading per press, and the cost and where they can be found.

This info a bit lacking on the web so we will have it in one spot.

They are not interchangable, thin 1" or Thick 2" oil pressure gauges and the price varies by a factor of 3. So I would like 3-4 of each type to report back here with your findings if you have a JEEP oil gauge system that seems to be working properly on a CJ or similar vintage.

This is what I can offer when you go to replace your sender or gauge at some time. I hooked up the pres sender with air and a regulator and measured the results with a multimeter and wrote them down. Here are the results of my findings.

NAPA seems to have a few pres/ohm ranges available. They also have some with theaded ends and some with a flat disk on the end. The flat disk can be mated to a .250" Uninsulated Quick disconnect. My 1978 had a 250 ohm vesion with threaded end. My NAPA also has a old book that has the senders, ohm/pres ranges, and ends, that they say is out of print. Might go back and see if I can photo copy those few pages.

NAPA
#OP6657 $60.00 list price, Threaded end, 250 ohm zero pres..... ORiley had a similar offering for a simlar cost $63.99.
........ PRICEY LITTLE BUGGER and the one I needed for 2" gauge.
PSI..................... Measured Ohms............................. spec chart ohms
0......................... 239.............................................. 227-257
5......................... 239............................................... 146-219
40....................... 108............................................... 83-123
80....................... 40................................................ 22-51

NAPA list price $15 to 20 with disk end, and 70 ohm at zero press
#OP6603................... MUCH Cheaper than above range
PSI..................... Measured Ohms............................. spec chart ohms
0-4................................................. .............................. open
33................................................ ................................ 20-32
63................................................ ................................ 13-25
90................................................ ................................. 9-17

CROWN #3212004 Morris 4x4 carries for $18.99 and 3.99 to ship. They also offer JeepForum a 10% discount so it nets $20 delivered. This is listed for 1975 to 1986 but will NOT work with all gauges. There are two resistance/pres ranges. I called Morris and got, I do not know. They also sell a narrow pres gauge for $23.99 less the discount. The crown gauge and sender should work together so it tells you the gauge resistance measurements with the test info below.

Crown #3212004 $18.99 list price, Threaded end, 70 ohm zero pres
PSI..................... Measured Ohms............................. spec chart ohms
0........................... 70............................................... 68-78
20......................... 33
40......................... 23............................................... 21-25
60......................... 14
80......................... 9................................................. . 7-13

sorrry this web site does not work well with charts. I had to use periods....

Summary.... if this works out like I have found so far.... The Thick 2" gauge is very expensive to buy a new oil sender $60 plus tax for more. More cost effective to guy a new thin gauge and new oil sender for $45 total. So this will help us locate and get the right sender.

BUT I COULD USE SOME HELP.....
This is where I need help, I think one of the Major Info Sources, John's, mixed up two of the blocks. After two months of waiting its time to ask you JeepForum members for a check and verification. Will only take a few minutes and help us out quite a bit.

If you have the 2" gauge please disconnect the wire from bottom of pressure sensor and measure resistance, ohms, of the sender output connection disconnected and measure resistance to any ground with everthing turned off, ie zero press. I believe you will have approx 250 ohms. Please report back here.

If you have a 1" gauge please disconnect the wire from bottom of pressure sensor and measure resistance, ohms, sender output disconnected to ground with everthing turned off, ie zero press. I believe you will have approx 70 ohms. Please report back here.

Fjguercio · 12-10-2009, 09:42 AM

Quote:

Originally Posted by Fjguercio

BUT I COULD USE SOME HELP.....
This is where I need help, I think one of the Major Info Sources, John's, mixed up two of the blocks. After two months of waiting its time to ask you JeepForum members for a check and verification. Will only take a few minutes and help us out quite a bit.

If you have the 2" gauge please disconnect the wire from bottom of pressure sensor and measure resistance, ohms, of the sender output connection disconnected and measure resistance to any ground with everthing turned off, ie zero press. I believe you will have approx 250 ohms. Please report back here.

If you have a 1" gauge please disconnect the wire from bottom of pressure sensor and measure resistance, ohms, sender output disconnected to ground with everthing turned off, ie zero press. I believe you will have approx 70 ohms. Please report back here.

Whats up guys??? No interest in know what the correct oil pressure sender to get. I could use some help and it will only take a few minutes to read the resting resistance.

So how about a little help.

Fred

**John Strenk** · 12-10-2009, 09:59 AM

Yeah, Yeah, yeah 3 kids in sports oldest in High school who has any time anymore...

When I'm putting my gas tank back in this weekend, I'll pop a couple of resistors on my oil pressure gauges and check the range.

However I have searched the internet looking for FSM online and have found 4 of them. The years cover 1974, 1976, 1982 and 1984.
Each one has a wonderful Gauge diagnostic testing section that puts mine to shame. The each have a table of specification for the sending units. For convience I will include all sending units here.

Fuel Gauge Sending unit Resistance (Ohms)

Year----E----1/2----F
74------72---23----9
76------73---23----10
82------61---23----10.3
84------73---23----10

Coolant Temperature Gauge Sending Unit Resistance

Year--------C-----Begin------End------H
Temp-----130*F---171*F----242*F---270*F
74----------73-----36--------13-------9
76----------73-----36--------13-------9
82----------73-----36--------13-------9
84----------73-----36--------13-------9

Oil pressure Gauge Sending unit Resistance in OHMS.

PSI-------0----------10---------40----------60----------80
Year
74|-----68-78-----------------21-25--------------------7-13
76|-----57-63------35-38-----19-21--------13-15------9.5-10.5
82|---234-246---149-157*--100.5-105.5----65-69----32.5-34.5
84|----234-246---149-157*--100.5-105.5----65-69----32.5-34.5
----------------* @20 PSI

So sometime between 1982 and 1984 they switched gauges and went to a new style oil gauge and a different sending unit.

Looking at the picture From the 1984 Factory Service Manual it clearly shows the 4 post Oil Gauge which is the 2" deep gauge so I think I will have to be making some changes in my webpage ASAP.

Thanks for finding the inconsistency.

So this should work correctly now.

CJ Gauge Specification Chart

I still need to verify the info for 1983. Eithe a FSM or pictore of your original Oil gauge would be nice.

**John Strenk** · 12-10-2009, 12:42 PM

Quote:

Originally Posted by Fjguercio

Needed to replace my failed oil sender and I have a 2" deep orginal gauge on my 1978 CJ7. I found and tested a few that are on the market and some oil senders will work and some will not. So I will post the part number, resistance or OHM reading per press, and the cost and where they can be found.

This info a bit lacking on the web so we will have it in one spot.

Looks like if you have a 2" gauge in there it was replaced at one point down the road. I can see this happening if someone whent to a dealer and he installes the latest and greatest gauge. Or simple some PO replaced the gauge with a 2" one. Reviewing the FSM for 74 thru 82 looks like the 1" gauge was used these years.

Quote:

They are not interchangable, thin 1" or Thick 2" oil pressure gauges and the price varies by a factor of 3. So I would like 3-4 of each type to report back here with your findings if you have a JEEP oil gauge system that seems to be working properly on a CJ or similar vintage.

This is what I can offer when you go to replace your sender or gauge at some time. I hooked up the pres sender with air and a regulator and measured the results with a multimeter and wrote them down. Here are the results of my findings.

NAPA seems to have a few pres/ohm ranges available. They also have some with theaded ends and some with a flat disk on the end. The flat disk can be mated to a .250" Uninsulated Quick disconnect. My 1978 had a 250 ohm vesion with threaded end. My NAPA also has a old book that has the senders, ohm/pres ranges, and ends, that they say is out of print. Might go back and see if I can photo copy those few pages.

NAPA
#OP6657 $60.00 list price, Threaded end, 250 ohm zero pres..... ORiley had a similar offering for a simlar cost $63.99.
........ PRICEY LITTLE BUGGER and the one I needed for 2" gauge.
PSI..................... Measured Ohms............................. spec chart ohms
0......................... 239.............................................. 227-257
5......................... 239............................................... 146-219
40....................... 108............................................... 83-123
80....................... 40................................................ 22-51

Use the one above for 84 and later CJ's Check the front of the gauge to be sure.

Quote:

NAPA list price $15 to 20 with disk end, and 70 ohm at zero press
#OP6603................... MUCH Cheaper than above range
PSI..................... Measured Ohms............................. spec chart ohms
0-4................................................. .............................. open
33................................................ ................................ 20-32
63................................................ ................................ 13-25
90................................................ ................................. 9-17

Use the one above for 74 thru 82 CJ's Check the front of the gauge to be sure.

Quote:

CROWN #3212004 Morris 4x4 carries for $18.99 and 3.99 to ship. They also offer JeepForum a 10% discount so it nets $20 delivered. This is listed for 1975 to 1986 but will NOT work with all gauges. There are two resistance/pres ranges. I called Morris and got, I do not know. They also sell a narrow pres gauge for $23.99 less the discount. The crown gauge and sender should work together so it tells you the gauge resistance measurements with the test info below.

Crown #3212004 $18.99 list price, Threaded end, 70 ohm zero pres
PSI..................... Measured Ohms............................. spec chart ohms
0........................... 70............................................... 68-78
20......................... 33
40......................... 23............................................... 21-25
60......................... 14
80......................... 9................................................. . 7-13

Also use the one above for 74 thru 82 CJ's Check the front of the gauge to be sure.

Quote:

sorrry this web site does not work well with charts. I had to use periods....

Summary.... if this works out like I have found so far.... The Thick 2" gauge is very expensive to buy a new oil sender $60 plus tax for more. More cost effective to guy a new thin gauge and new oil sender for $45 total. So this will help us locate and get the right sender.

BUT I COULD USE SOME HELP.....
This is where I need help, I think one of the Major Info Sources, John's, mixed up two of the blocks. After two months of waiting its time to ask you JeepForum members for a check and verification. Will only take a few minutes and help us out quite a bit.

If you have the 2" gauge please disconnect the wire from bottom of pressure sensor and measure resistance, ohms, of the sender output connection disconnected and measure resistance to any ground with everthing turned off, ie zero press. I believe you will have approx 250 ohms. Please report back here.

If you have a 1" gauge please disconnect the wire from bottom of pressure sensor and measure resistance, ohms, sender output disconnected to ground with everthing turned off, ie zero press. I believe you will have approx 70 ohms. Please report back here.

Fjguercio · 12-10-2009, 03:47 PM

Thanks John,

I had a hunch your chart had the 250 ohm and 70 ohm sender data blocks switched.

That also makes sense about the thin gauges being most of the years..... the old time jeeper here in MPLS said they are all the same. I knew that was not quite right but close if the 2" gauge was only used the last two years 1984-1986.

I also have the digital FSM of those years you posted/ref above and I also have a hard copy of the 1979 FSM. So I will look thru those also to see what I can gleen. I did not think to look in the FSM for the answer of 1" gauge & 2" gauge what ohm range oil sender do they use. I will let you know if I can confirm the limited use of the 2" gauges with review of the FSM(s).

I also have go back to my local Napa and call Morris and let them know the true skinny when complete the last few steps of confirmation. So looks like Crown Desc of fitting most years is correct then.... they went a little too far in years becasue they claim to 1986.

I now have both oil senders, (250 ohm and 70 ohm) and both thick 2" and thin 1" gauges. That is $80 of senders so not a cheap mistake folks. One sender is $60 to $65 plus tax and the other is $20 plus shipping.

The only other odd thing is both my oil and volts are the thick 2" gauges and I have a 1978 CJ. So looks like they both might have been changed at one time. Seems everyday I find out more about these little CJ's.

I got my oil gauge working well over a month ago, by replacing my 250 ohm sender with a 250 ohm new one.... But as we discussed it did not match your chart. So now we have a better picture.

I will let you know what else I find out.

Fred

**John Strenk** · 12-10-2009, 06:09 PM

Let me know about the 79 gauges so I can confirm the resistants charts for each year. The info was under specifications in the electrical section.

On a side note. Did you notice the actual temperature for the temperature scale? up to 270*F at the "H" mark !!!

Still would like to find a picture or a FSM for an 83 CJ. At least you can tell which gauge is which from the front.

SO anyone got a picture of an 83 CJ dash??

Fjguercio · 01-13-2010, 11:14 PM

John,

You will not like what I found on the 1979 FSM..

It shows the 2" deep gauge and the 250 ohm reading at zero pres.
So the combo of gauge&sensor is what I expected but the 2" deep gauge is not used in those years per your chart.

So looks to be some funny stuff on the charts again. I will also note they had the 3 post back pictured in the beginning of section but at the end it was clearly the 4 post gauge and deep on. The dual use of pics/ drawings in the FSM is where we might be getting this confusioning.

I will look at the digital FSM next

Fjguercio · 01-13-2010, 11:28 PM

1974-76 FSM

show the oil pres range to be 60 ohms/ 0 psi.... so that would be the thin gauge 1"

Interesting the only pic I see shows a Voltage Gauge that looks more like the 2" than 1" but not exact match to either one??? They do seem to keep us on our toes.

Fjguercio · 01-13-2010, 11:38 PM

1982 FSM

used the 250 ohm/0 psi sensor and the 2" gauge.
also shows a 4 post back

Fjguercio · 01-13-2010, 11:52 PM

1984-86 FSM

Shows the 4 post back, but did not list the ohm range for sensor in the areas I found
Face of oil gauge looks to be the 2" face from pics
So looks like the 2" gauge

**John Strenk** · 01-14-2010, 04:42 AM

I've stripped a '76, '77, '78, '79 and an 84 CJ and kept the parts. I made my list at first from what I found in each dash. Obviously, anyone could of put any gauge in the dash. The 84 was the only one with the 2" gauge.

However there was a MAJOR change to the electrical system in 79, fuse panel, light switches, heating system, They probably changed the gauges then also.

But what is really important to me is getting the right sending unit with the right gauge. The years and what was replaced in there could be different. At least a user can look at the front of the gauge and pick the right sending unit to go with it. I will modify the page to what we can verify but have to make a note remining them that anything could be in the dash.

Got links to the Digital manuals?

The 1981-86 Part list still shows the 1" gauge being used. Go figure.

I think they do a lot of copy paste until there is a big revision to the Vehicle that it warrants a new FSM

Would be interesting to cross reference these part numbers:

This shows 4 different gauges depending upon if it's Gas, diesel or export.

Fjguercio · 01-14-2010, 09:43 AM

John,

Well the 1979 FSM did show the 250 ohms, so that might be the year of change. My 1979 FSM is a book.

I do not have the 1978 FSM figures..... its the year I own, and be nice to know if 60 ohm or 250 ohm.

LITTLE HELP>>>
Anyone reading this that has a 1978 FSM could you please look at the Instrument or Electrical sections and see the Oil Gauge information. The info is at the end of the section and shows the back of the gauge and will show the oil sender resistance range... 0 psi is the one we reference

**mtbtweety** · 01-14-2010, 10:01 AM

ok, dumb question, but the SENDING unit resistance should be measured from output post to ground, correct? I'm getting an open ckt when I do that (at zero pressure), but the oil pressure gauge actually works, so I'm not sure how that's possible. Thoughts?

**mcmud** · 01-14-2010, 10:15 AM

While this may actually be very little help with your request since I see that this link does not offer a '78 or a '79 manual it does however list an availability to the '77 through the '86 build years, except of course for those years.

It may have been published as a supplement to the '77

Maybe this will provide some help.
Jeep Service Manuals

**John Strenk** · 01-14-2010, 11:24 AM

Quote:

Originally Posted by mtbtweety

ok, dumb question, but the SENDING unit resistance should be measured from output post to ground, correct? I'm getting an open ckt when I do that (at zero pressure), but the oil pressure gauge actually works, so I'm not sure how that's possible. Thoughts?

Quite possibly the wiper arm in the sending unit if moving past the end or it's contaminated. They have been known to develop leaks letting oil inside the housing.

Just like this one: