Oil Pressure Gauge

Stock FSJ Tech Area
Post Reply

Topic author
Kayparkah73
Posts: 11
Joined: Sat Aug 01, 2020 6:42 pm

Oil Pressure Gauge

Post by Kayparkah73 »

Hey guys,

So I have a question about my oil pressure gauge in my 89 Grand Wagoneer. It has the 360 in it. So, as soon as I start the Jeep the oil pressure gauge skyrockets as far as it can go. It stays here the whole time your driving it, and the temp gauge stays at normal temp, even a little low.

On my 73 the oil gauge is mechanical, so I’m assuming the same for this 89. Is this true, and any ideas what could cause this?

Not sure if it helps, but I have a picture of the dash after driving it for about 10 minutes
You do not have the required permissions to view the files attached to this post.
User avatar

tgreese
Posts: 7117
Joined: Fri Jun 08, 2012 6:31 am
Location: Medford MA USA

Re: Oil Pressure Gauge

Post by tgreese »

Unless you've replaced the original gauge with a mechanical gauge, these OEM oil pressure gauges are electric. No mechanical gauges from the factory since the M38A1 (ca Korean war), AFAIK. Maybe the M7xx mil trucks got a mechanical gauges. None in civilian vehicles.

Bad connection would be the first thing to check. I'm sure that the TSM has a section on checking the sender and the gauge. Typically you use a fixed resistor in place of the sender to check the gauge, and measure the sender resistance to ground with your multimeter.

No excuse not to read the TSM for 1989 - free to read and download here https://oljeep.com/89FSM/89Jeep_FullServiceManual.pdf

This is for a CJ, but the idea is the same: http://www.earlycj5.com/xf_cj5/index.ph ... er.143458/ I built this on a lark... you don't need a fancy tester. Just buy a few fixed resistors from Digikey or Mouser and some clip leads on Amazon and go to it. Easy.
Tim Reese
Maine beekeeper's truck: '77 J10 LWB, 258/T15/D20/3.54 bone stock, low options (delete radio), PS/PDB, hubcaps.
Browless and proud: '82 J20 360/T18/NP208/3.73, Destination A/Ts, 7600 GVWR
Copper Polly: '75 CJ-6, 304/T15, PS, BFG KM2s, soft top
GTI without the badges: '95 VW Golf Sport 2000cc 2D
Dual Everything: '15 Chryco Jeep Cherokee KL Trailhawk, ECO Green
Blockchain the vote.

sirrus
Vendor
Posts: 717
Joined: Fri Sep 13, 2019 11:13 pm
Location: Hillsboro, OR

Re: Oil Pressure Gauge

Post by sirrus »

If it stays pegged high all the time it’s probably a broken wire or bad sender. There are 3 reference points for sender resistance given in TSM - 0 ohms at 0 psi, 46 ohms at 40 psi and 90 ohms at 80 psi. Broken wire equals infinite resistance and would result in behavior you’re seeing. I’d check wire from gauge to the sender(it’s near oil filter and oil pressure switch) for continuity first. Might also be a bad contact in bulkhead connector or connector at the back of instrument cluster
Sometimes we reinvent the wheel not to have more wheels but to have more inventors

1988 Grand Wagoneer - AMC 360 with ProFlo4 MPFI, TF727, NP229 FOR SALE
2021 JLU Willys EcoDiesel - new shiny toy

Dorien
Posts: 23
Joined: Sat Apr 11, 2020 1:05 pm
Location: ON Canada

Re: Oil Pressure Gauge

Post by Dorien »

Easy enough to replace the sender, down near the oil filter.
Dorien
Post Reply