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Gauge says no pressure...and I'm not skeptical anymore


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So, my oil gauge says about 10psi while accelerating and nothing while idling...so I put on a mechanical gauge. Its one of the ones that has the clear hose and is made to go in the dash board. I cranked it up and i have no pressure on the mechanical gauge. If I revv it up I can get it to about 25, but as soon as I let off it goes to 0. I can see oil in the clear line trying to make its way to the gauge...but it never does. While its idling I can see oil in the hose near where it goes into the block just kind of spirting back and forth, no solid stream.

 

The thing is, my oil pressure has looked like this since I bought it in March. I had even put a similar mechanical gauge on it then and it did the same thing as today.

 

I've been driving it pretty hard since I bought it. So my question is, is there any way that I actually don't have oil pressure? It would seem to me something would have let go by now. If I do actually have oil pressure, how come I can't measure it???

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Generally..........if your oil pressure is that low......you park the vehicle until you find the problem.........unless you have a spare engine just waiting to go in........ :roll:

 

Causes of low oil pressure can be........

 

Bad oil pump

 

Using a Fram oil filter......... :roll:

 

Bad main bearings.

 

Or.........the oil passage to the gauge is plugged :dunno:

 

I know the type of oil gauge your using, it's a true mechanical gauge with the ploy line, leading to the rear of the gauge, inside the cap.

 

The true method of "testing" the oil pressure is with a "Good" quality oil gauge directly to the oil gauge port.

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Yeah, I see what you are saying. But it doesn't have any other symptoms of no oil pressure. Its not running too hot, no noise from the top of the engine, and no connecting rod hanging out the oil pan... just the gauges.

 

I only use mobil 1 oil filters :thumbsup:

 

So what do I do about a plugged gauge port?? Is there anything I can spray into the port to clean it out...Maybe WD-40, or would that screw something up?

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I would say to take the oil filter adapter off, and clean it away from the engine, plus change the O-rings at the same time.

 

Then you'll be able to clean out the gauge port ;)

 

http://www.lunghd.com/Tech_Articles/Eng ... -Rings.htm

 

I wouldn't use WD-40 on it, that has Kerosene in it. Just use some pipe cleaners or something similar to clean out the gauge port.

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if you're feeling saucy you could pull the oil pan and check the pickup to see if its packed full of crap. that does happen the screen can get stopped up or partially blocked and cause low oil pressure.

 

edit: or check, next time you drain the oil, you MIGHT even be able to get a light and look up in there at the pickup, i think it's fairly close to the rear of the motor

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Let's face it -- you have THREE oil pressure gauges saying you have next to no oil pressure. It's time to do something (besides buy another gauge). You need bearings and/or an oil pump. Both can be replaced with the engine in the truck, by dropping the oil pan.

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Let's face it -- you have THREE oil pressure gauges saying you have next to no oil pressure. It's time to do something (besides buy another gauge). You need bearings and/or an oil pump. Both can be replaced with the engine in the truck, by dropping the oil pan.

 

 

Thanks for stating that eagle, Ive been wanting to say it to, but didnt want to offend. The very least that needs to be done is drop the pan and put in a melling high volume pump. I bought one for my Gr Wagoneer 4.2 years ago from Autozone. Put a pump in it, and re check pressures then go from there. If you still have little to no pressure, time for a bottom end rebuild.

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Thanks for stating that eagle, Ive been wanting to say it to, but didnt want to offend. The very least that needs to be done is drop the pan and put in a melling high volume pump. I bought one for my Gr Wagoneer 4.2 years ago from Autozone. Put a pump in it, and re check pressures then go from there. If you still have little to no pressure, time for a bottom end rebuild.

The thing is, dropping the pan is a nuisance job, and a set of main bearings isn't THAT expensive. IMHO it just makes more sense to do the job all at once. You have to drop the pan to replace the oil pump ... why not just do the bearings while you're in there? Do the rear main seal while the pan's off, too. Then you'll have a motor that should be good for another 100k

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:smart:

I was wanting to put a new oil pump in the minivan when it was showing extremely low pressure, old guy I know, talked me out of it. He said that if my bearings were worn to the point of causing low pressure, a new pump would increase my pressure, but it greatly increased the chance of having a spun bearing from it, the increased pressure could push one of the bearings out, cause it to ride under the other one = spun bearing. Makes sense to me.

BTW turns out that my oil press. sending unit was bad, replaced that, now I got adequate pressure again.

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Let's face it -- you have THREE oil pressure gauges saying you have next to no oil pressure. It's time to do something (besides buy another gauge). You need bearings and/or an oil pump. Both can be replaced with the engine in the truck, by dropping the oil pan.

 

 

Thanks for stating that eagle, Ive been wanting to say it to, but didnt want to offend. The very least that needs to be done is drop the pan and put in a melling high volume pump. I bought one for my Gr Wagoneer 4.2 years ago from Autozone. Put a pump in it, and re check pressures then go from there. If you still have little to no pressure, time for a bottom end rebuild.

 

I appreciate the replies guys!

 

I agree, the 17 year old electric gauge and sender and 2 $10 oil gauges say I have no pressure. But besides that it does NOT show ANY SYMPTOMS of having no pressure, so I'm thinking I either have to clean out the port or I'm hooking up the mechanical gauges wrong :dunno: ...because its been doing this since I bought it, it should have blown up by now if it had no pressure. I spoke with my cousin who drag races, he said I should bleed the air out of the Mechanical gauge's line so that oil is actually going to the gauge and see if I have pressure. Since this doesn't cost anything i'll try this as soon as it stops raining over here. If I have pressure after that, then it means I just don't know how to hook up oil gauges :dunce: ...If still no pressure, well then I'll be in the market for new bearings and a new oil pump.

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Bleeding the tube in the mechanical gauge is not necessary. It's a pressure gauge. It doesn't know or care if it's reading air pressure, water pressure, or oil pressure. It responds to pressure. Any air in the line will compress by the amount the oil pressure creates, and the pressure will then be the same everywhere in the tube.

 

It appears from your description that you have oil pressure at driving speeds, just not very much. That's possible. I once drove a race car transporter from Connecticut to Maryland and back with a mechanical gauge that showed 7 psi at highway speed. That was (apparently) enough to keep some oil flowing and the oil was "oily" enough to keep things sliding inside the engine. I have no idea how long it had been like that or how long it lasted after that trip, but the owner told me before I left that the oil pressure was low and "don't worry about it" ... so I didn't.

 

I still think your bearings are gone. It may already be too late, but if you catch bad bearings in time all you have to do is put in new ones. Once they wear away the babbit material, you have harder metal from the bearing shell wearing directly on the crank journals, and that can score the crank. At that point, in addition to needing new bearings you also need a new (or reground) crankshaft.

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I know I can be quite blunt and am not good at being PC or sugar coating things. Having stated that I am starting to think that maybe you need a very direct and blunt response to your question since you seem to be ignoring the other answers.

 

You have NO oil pressure! This is called denial. Not only have you used multiple gauges to test this, you have also actually witnessed the lack of oil pressure in the tube to one of your gauges. What more proof do you need? Do you need the engine to throw a rod through the side of the engine and have it land in your lap as your driving down the road? Now is the time to admit it and take steps to correct it.

 

I once wheeled for three days at the Badlands and drove over 500 miles home afterwards with no oil pressure at idle. I then pulled the engine, removed the crankshaft, and confirmed the bearings were bad. This was all with no other symptoms than lack of oil pressure. It still ran great and sounded fine. As we've learned lately several of these engines can even run for way longer than expected with glass solidifying in the crankcase. :eek:

 

My apologies if you don't take this the way it is intended, but you now need to move past IF you have oil pressure and move on to why you don't have oil pressure.

 

Willy

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no offense nut id rather keep the engine in the ruck to fix something kinda simple then go to all the trouble and expense of buying a new motor and as eagles says EVEN IF nothing is bad and its the passage is cloged you got a bottom end ready for another 100K miles......

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Thanks for being blunt guys. I guess I was just being overly optimistic in that I wouldn't have to re do the bearings.

 

I've never changed bearings before. From what yall have said, it can be done with the motor in the truck. Any advice to make my life easier when I change these things?? What about the cam bearings, can I change those while I have mostly everything apart, or does the cam have to come out for that? Don't worry I'll change my oil pump while I'm down there.

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