Jeep Oil Sender Gauge Options & Ranges
Many sellers of Jeep Gauges are listing their product for working for all JEEPs and it is just not true….. not true if you want the oil gauge to match the oil pressure on the PRESSURE GAUGES mounted on the engine often done for new engine rebuild start ups…….
The old Jeep Sender and Gauge parts and information is messed up at this time. I went thru this about a year ago, there is a general mixed up of the SENDER resistance ranges and the OEM electric gauges that will work correctly with them. So I dug in to fix my issue and this is what I found on the resistance ranges of stock CJ gauges and senders……….. this what is being sold new and what will work for our CJ..
The older CJ's of the 70's use a 2" thick gauge and their own Specific sender and resistance range.
The newer 80’s Cj's have a 1" gauge and a different sender and resistance range.
Full Size Jeeps for the 70s & 80s… also called the FSJ, for these same years have yet another gauge and sender combo with another resistance range. The Field Service Manuals have the resistance levels / ranges listed for the jeeps years of interest if you need to ck the numbers further…
The Gauges and senders cannot be mixed up or the mix combo will not read the correct oil pressure level. I ordered several and many combos do not work… So it is very easy to get the wrong stuff and pair up the wrong stuff. …….. Many sellers of Jeep Gauges are listing their product for working for all JEEPs and it is just not true….. not true if you want the oil gauge to match the oil pressure on the PRESSURE GAUGES mounted on the engine often done for new engine rebuild start ups……. I like having the oil gauge on the engine so decided to keep it there. I currently use the engine mounted/ installed gauge and OEM Jeep oil gauge/ oil sender….. and yes they do match and can match in psi readings.
The 1970's CJs use a 2" gauge
The sender to use is from NAPA #OP6657
Expensive little bugger and is $60, maybe you can get a discount, and if needed can also consider getting the Crown Gauge & Sender because the cost will be similar. I will give Crown info after the Napa Info.
I hooked this up to a presure regulator and gauge and ploted the pressure and resistance ranges using a multimeter.
Pressure............Measured............spec range CJ 1979 FSM
0-3 psi..... ..........239 ohms...........234-246 ohms
3-7......................239..................146-219
40........................108..................100.5 – 105.5
60………………………………………………………..65.69
80........................40....................32.5 – 34.5
Some time in the 1980's Jeep CJ went to a 1" thick gauge and the oil sender resistance ranges are different. Crown does have a sender that will work, Crown #3212004 and sells for about $20. Morris 4x4.com was selling at 10% discount for a forum discount at the time so it cost me $19 and $4 to ship. Morris and Crown at that time list this for 1975 to 1986 for all CJ, Wagoneers and THIS IS NOT TRUE. THE CROWN SENDER WILL ONLY WORK WITH THE CJ NARROW 1" GAUGE.
This is what I measured with the Crown sender and a pressure regulator, gauge, and multi meter.
Pressure............Measured............spec range
0-3 psi..... ..........70 ohms...........68-70 ohms
20........................33......................
40........................23..................21-25
60........................14....................
80.........................9....................7-13
FURTHER caution is the CJ and Full size use a different gauge and sender. I went thru about 15 years of Jeep Field Service Manuals, FSMs, and they do list the resistance ranges and have pictures / drawings of the oil gauge face. The 1" and 2" gauges do have different faces. I would measure the oil sender pres/resistance range before installing any.
The Crown gauge is in the $20-30 range is I remember right. So it might be less expensive to get the Crown Gauge & Sender compaired to the $60 Napa sender needed for the 2" gauge. I have also been looking for a spare 2" CJ oil gauge and they are not easy to come by. Just thought I would mention this option as well.
TEMP SENDERS are also a issue. I purched 3-4 inexpensive units and the temp/reistance range was not correct. I ordered Napa's premium unit,Elchin? Brand, double the price, and boiled it in water prior to install to test, can also be returned as new if does not pass test, and the boil waster is 212 Deg F or very close and will have a resistance value about 35 ohms. Take it out of boiling water FAST put on paper towel, something that is not a heat sink, and measure the resistance with a multimeter. This needs to be done FAST you will see the resistance change in seconds. Thought I would throw this into the conversation about CJ gauge solutions.
My Temp gauge was bairly reading with PO set up. That temp sender and 3-4 more all failed till I tried the Napa Elchin premium version for the CJ Temp Sender. That one measured correctly.
I have seen the pressure and temp issues dozens of times.
Hope that helps.
