Oil Pressure Gauge

[bobcat481]

Ok.....my oil pressure gauge used to read one line above 40 running down the road, and one line short of 40 at idle. Over the past few weeks, the "range" of the gauge has been dropping, never getting up to 40 even running down the road. My question is, can an oil pump go out slowly, or do I more than likely have a gauge problem? Also, is it possible the the screen is clogged? It gets regular oil changes, so shouldn't be that slugged up. As far a running, it runs and sounds fine. Any thoughts? Thanks

 

[Team Twisted Off Road]

Ok.....my oil pressure gauge used to read one line above 40 running down the road, and one line short of 40 at idle. Over the past few weeks, the "range" of the gauge has been dropping, never getting up to 40 even running down the road. My question is, can an oil pump go out slowly, or do I more than likely have a gauge problem? Also, is it possible the the screen is clogged? It gets regular oil changes, so shouldn't be that slugged up. As far a running, it runs and sounds fine. Any thoughts? Thanks

As long as you have 10psi or more your ok but it could be the oil pump or a rod/main bearing or sending unit going out.. (i had that happen) it could be the gauge just ohm it to see if that is good.

 

[Team Twisted Off Road]

CAUSES OF LOW OIL PRESSURE
In a [COLOR=blue !important][COLOR=blue !important]high [COLOR=blue !important]mileage[/COLOR][/COLOR][/COLOR] engine, low oil pressure is often due to a combination of worn main and rod bearings and crankshaft journals. The oil pump itself does not create pressure. It produces flow and the resistance to that flow produces pressure. Resistance is created by the orifices in the [COLOR=blue !important][COLOR=blue !important]engine [COLOR=blue !important]block[/COLOR][/COLOR][/COLOR] through which the oil flows, and the amount of clearance between the bearings and crankshaft journals. As the bearings wear, clearances increase allowing increased flow which reduces pressure



DIAGNOSING LOW OIL PRESSURE
Bad oil pressure sending units are quite common, so many technicians will replace the unit without checking anything else to see if that cures the problem. This approach might save you some time, but it is risky because unless you measure oil pressure directly with a gauge attached to the engine you have no way of knowing if pressure is within specifications or not. Most warning lamps won't come on until oil pressure is dangerously low (less than 4 or 5 lbs.). So don't assume the absence of a warning lamp means oil pressure is okay, especially if the engine is making any valve or bearing noise.


anyway here is a little info hope it will help..

 

[bobcat481]

Thanks man. the gauge isn't reading under 10 (yet). The motor only has 85,000 on it, so it's not quite "high mileage" (again, yet). What resistance should I be seeing out of the gauge, and how do I go about reading it? Do I just read across the terminals/wires on the back? Is it variable? Meaning I should be seeing different values at different times? Can/will a gauge go out slowly i.e. read less values over time? Does the gauge ground to the firewall or something (could I have a bad ground and be getting a false reading)? One last thing, where you a check oil pressure from within the motor itself? Sorry to throw so many qeustions back at you. Take a break from typing if you need to and go out to get some fresh air! Thanks for your help, Brad

 

[Team Twisted Off Road]

Thanks man. the gauge isn't reading under 10 (yet). The motor only has 85,000 on it, so it's not quite "high mileage" (again, yet). What resistance should I be seeing out of the gauge, and how do I go about reading it? Do I just read across the terminals/wires on the back? Is it variable? Meaning I should be seeing different values at different times? Can/will a gauge go out slowly i.e. read less values over time? Does the gauge ground to the firewall or something (could I have a bad ground and be getting a false reading)? One last thing, where you a check oil pressure from within the motor itself? Sorry to throw so many qeustions back at you. Take a break from typing if you need to and go out to get some fresh air! Thanks for your help, Brad

Pressure (PSI)Resistance (ohms)0234-24620149-15740100.5-105.56065-698032.5-34.5

but i would look at the sending unit first it should be arounf the oil fillter.. there around $20.

 

[bobcat481]

I'll probably just change out the sending unit. For $20 it can't hurt anything. It's a pretty easy swap I assume. I didn't erealize it was that cheap, or I would have just changed it out and been done with it. Anything funky I need to know about, or just bolt-off, clean gasket (I assume) bolt -on? Heading to the Chilton's book now. Thanks for the help, I appreciate it. LAter!

 

[bobcat481]

ok....checked into it. The sending unit is what gives signal to the gauge. I'm guessing that's it. Either way it's a easy swap with a wrench and I assuming some pipe tape. Thanks man.

 

[PS89YJ]

None of my gauges were working very well so I removed them from the dash then removed each gauge from the circuit board cleaning all contacts with a pencil eraser. I also removed the wire loom and cleaned all those contact points. The net result is all gauges are working like new. I also cleaned every ground I could find and the battery terminals. When things get old and dirty they don't work as well, myself included.

 

[Sine Deviance]

When my oil pressure sender was dying it did the exact same thing. It started getting lower and lower over the course of a month or so. I also thought it was the oil pump on it's way out or a clogged oil passage. Then one day I was driving down the interstate and my gauge suddenly went to zero. I started freaking the eff out because I had just changed the oil in the Jeep about 20 minutes earlier, so I was thinking I didn't tighten the drain plug or the filter enough and the oil had all spewed out.

Pulled over, checked my oil, all was fine. Engine also seemed to be running fine. I decided to take a chance and drive it to the auto parts store. Sure enough, it was the oil sender.

Here's a tip: When you buy the new sender, go to Advance Auto. Auto Zone and some of the other stores I tried carry the wrong one but it's listed for this application (so it's the wrong part number.) The plug and the housing are the same but the threads are a bit off and the sender won't work with our Jeeps. Advance has exactly the right one. I had to buy and return three senders from three different stores before I found the right one at Advance.

Here's another tip: When you go to replace the sender, be EXTREMELY CAREFUL when tightening it into the seat. DO NOT over-tighten it. AT ALL. The sender seat is just this little brass elbow and it cracks very easily. Also, the sender has a tapered end, which makes it even easier to crack the brass. If you DO crack it open you can replace the elbow with any generic $1.50 brass elbow that has 1/8 and 1/4 NPT threads I think. It just screws out of the block. Alternatively, you can buy the correct elbow from the dealer for about $5. Also, the threads going into the block are different than the threads for the sender seat, so make sure you match the sender with the elbow before trying to screw it into the block.

 

[bobcat481]

Ok...bought one one the way home. I didn't see your reply Sine, and stopped at "The Zone" (only place on my way home). But, the Jeep Gods were with me and all is well. Part fit on perfectly, and I now have proper readings at the gauge. I didn't happen to see the threads were brass, but I was lucky that my Spidey senses kicked in and I withheld my urge to go one more turn. Thanks guys for all the input, I can sleep better tonight knowing I'm not going have something really bad happen, and probably at a bad time (it's snowing here now, and they are acting like it's "White Death 2010"). It's only like 6"-8". I wish it were more. Something like, look out the window in the morning >>Call work>>Go back to bed >> Get up go play in da Jeep! Anyways thanks again!! Later, Brad