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Unread 12-01-2010, 05:57 PM   #1
Bubba3200
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Bad oil pressure sensor???

The other day I was changing the oil and filter on the 02 4.7 HO. After I drain the oil I started the engine and ran it for a very short while..... to drain some oil out of the filter so it is not so messy. Usually the oil gauge will go to 0 and check gauge light will come on. This time the oil gauge needle stayed put and no gauge light came on. I shut it down right away. I noticed before the oil change the gauge would be pointed at the next to last bar on the high side. Even after warm up the needle moves just slightly lower at idle and goes to the next to last bar on the high side when @ hwy speeds. Now all the oil was let out except the filter and the needle didnt move to 0 and no check gauge light. Oil sensor gone bad???

I do have the correct oil level and I run PL3001 oil filter. 5w/30 high mileage Valvoline

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Unread 12-01-2010, 06:00 PM   #2
Ferenckzy
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Hmm... I usually take the filter off first... no mess.
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Unread 12-01-2010, 07:45 PM   #3
MrBaz
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In what good sense on this earth would you think running the engine with 0 oil is a good idea?
Technically an engine can run on little to no load with no oil in the case but that doesn't mean this should become a commonplace maintenance practice.

If the engine seems to be operating normally, then you probably have a bad pressure sensor. I'd still be worried about something in the engine oil passages that got knocked loose blocking oil from flowing correctly.
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Unread 12-02-2010, 01:57 AM   #4
Bubba3200
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10 to 15 seconds will not hurt anything. Yes the engine runs great with no problems. No knocking, ticking, just smooth power.
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Unread 12-02-2010, 06:56 AM   #5
nlynd1978
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Quote:
Originally Posted by Bubba3200 View Post
10 to 15 seconds will not hurt anything. Yes the engine runs great with no problems. No knocking, ticking, just smooth power.
LOLOLOLOLOLOLOLOLOLOL Sorry had to type that after reading this. You sir are retarded and should not be let near any motor vehicle. The moment you ran the vehicle with out oil you damaged it. May not have been alot but i gaurentee there is damage that in the long run will be very costly. Be it bearings, crank regrinding, cams, lifters or all of it.

Thank you for making sure i will have a job when i get done at school. Idiots like you are the reason i decided to become a mechanic. Job security

Oh as for your problem, the gauge wont move if theres no oil pressure, how ever there may have been just enough in the filter to register on the gauge for the 10 secs you ran the vehicle.

Oh and one other thing, obviously you have done this multiple times to the vehicle. How are you surprised you finaly had an issue with your jeep that you routinely run with out oil every time you change the oil? Oils not in the engine as a suggestion. On the other side, if you start to notice decreased oil pressure, it cause you damaged the motor by running it with out oil.
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Unread 12-02-2010, 08:03 AM   #6
volvite
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Hate to thread jack, but my oil pressure always stays up about the 70 mark, the 2nd to last mark on the gauge. Is that good/bad. Oil level is fine I don't remember it being that high before. It has been real cold here the last couple weeks, with times below 0 F. I use Mobil 1 0W-30 which meets the requirements of 5w/10w-30.
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Unread 12-02-2010, 08:11 AM   #7
nlynd1978
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when is it at the 70 mark? during driving conditions or idling?

4.0 curb idle is 13 psi minimum and 37-75 psi @ 1600 rpm and above

4.7 curb idle is 7 psi minimum and 35-105 psi @ 3000 rpm
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Unread 12-02-2010, 08:29 AM   #8
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When driving. I haven't checked when idle. I'll have to do that after work. I don't think I had ever seen it that high before. I have the 4.7 too.
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Unread 12-02-2010, 08:37 AM   #9
nlynd1978
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your with in range according the specs i got from wj jeeps. Before my sensor broke (put a new one on but it seems to work backwards?? dam autozone crap) i seem to run a constant 60ish psi while driving with some fluctuation.
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Unread 12-02-2010, 09:51 AM   #10
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Under NOOO circumstances should you run the motor without oil especially 10-15 second, ever notice the pressure goes up in about 5?

So you run your motor (thousands of dollars to replace), when you could just wipe oil off with a .005cent paper towel, so its not "messy"....hmmmm.


anyways if the oil pressure gauge stays at zero and it is running fine for a good while I would say the sensor is bad or you would prob have a junk motor by now.
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Unread 12-02-2010, 05:24 PM   #11
Bubba3200
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Quote:
Originally Posted by nlynd1978 View Post
LOLOLOLOLOLOLOLOLOLOL Sorry had to type that after reading this. You sir are retarded and should not be let near any motor vehicle. The moment you ran the vehicle with out oil you damaged it. May not have been alot but i gaurentee there is damage that in the long run will be very costly. Be it bearings, crank regrinding, cams, lifters or all of it.

Thank you for making sure i will have a job when i get done at school. Idiots like you are the reason i decided to become a mechanic. Job security

Oh as for your problem, the gauge wont move if theres no oil pressure, how ever there may have been just enough in the filter to register on the gauge for the 10 secs you ran the vehicle.

Oh and one other thing, obviously you have done this multiple times to the vehicle. How are you surprised you finaly had an issue with your jeep that you routinely run with out oil every time you change the oil? Oils not in the engine as a suggestion. On the other side, if you start to notice decreased oil pressure, it cause you damaged the motor by running it with out oil.
So dumb azz you dont think that you dont damage your engine everytime you start it from a cold start?? I could go on and on about cold start up but since your in school you'll learn that soon enough....when you get to that chapter. A warm running engine has enough oil residue that it wont damage the engine like you suggest. Did you know that every minute you live your dieing? Figure that one out, as it pertains to your comment that I have damaged the engine. Ever seen a prolong commercial on tv? Boy I wish I could see your face when you read that....when I buy a used car I let the oil out and replace it with a gallon of seafoam and let it idle for a few minutes and then drain it to get all the sludge out!!! Need some toilet paper yet sonny??

I have this 97 Isuzu junker that I picked up cheap. Leaked oil like crazy and ticked like a time bomb. 137,000 on the clock and this was a project truck. An old timer told me to run seafoam through it and I thought he was crazy. So I said what the hell. Long story short when I did tear this 3.2 V-6 apart to rebuild the inside was clean as almost new. The overly small oil passages that this engine has (manufacturer flaw) were cleaned up by the seafoam as was everything else on the inside. The seafoam didnt get all the sludge out of the oil pan but it did in the heads etc.
I do not recommend running an engine without oil, and certainly dont rev one up with no oil but get a grip and dont act like the end of the world is here just yet!!!!

I hope you do finish your school because we need good mechanics out there. I just hope you arnt one of those that rip people off.

You may flush now!

Oh one more thing.... If there is no oil shouldnt the needle go to zero and not stay at full pressure and the check gauge light come on? Does the WJ read Oil pressure at the oil filter since the sensor is above it??
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Unread 12-02-2010, 11:05 PM   #12
nlynd1978
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Quote:
Originally Posted by Bubba3200 View Post
So dumb azz you dont think that you dont damage your engine everytime you start it from a cold start?? I could go on and on about cold start up but since your in school you'll learn that soon enough....when you get to that chapter. A warm running engine has enough oil residue that it wont damage the engine like you suggest. Did you know that every minute you live your dieing? Figure that one out, as it pertains to your comment that I have damaged the engine. Ever seen a prolong commercial on tv? Boy I wish I could see your face when you read that....when I buy a used car I let the oil out and replace it with a gallon of seafoam and let it idle for a few minutes and then drain it to get all the sludge out!!! Need some toilet paper yet sonny??

I have this 97 Isuzu junker that I picked up cheap. Leaked oil like crazy and ticked like a time bomb. 137,000 on the clock and this was a project truck. An old timer told me to run seafoam through it and I thought he was crazy. So I said what the hell. Long story short when I did tear this 3.2 V-6 apart to rebuild the inside was clean as almost new. The overly small oil passages that this engine has (manufacturer flaw) were cleaned up by the seafoam as was everything else on the inside. The seafoam didnt get all the sludge out of the oil pan but it did in the heads etc.
I do not recommend running an engine without oil, and certainly dont rev one up with no oil but get a grip and dont act like the end of the world is here just yet!!!!

I hope you do finish your school because we need good mechanics out there. I just hope you arnt one of those that rip people off.

You may flush now!

Oh one more thing.... If there is no oil shouldnt the needle go to zero and not stay at full pressure and the check gauge light come on? Does the WJ read Oil pressure at the oil filter since the sensor is above it??
On a cold start yes, more wear will occur, but i have oil being pumped to the components, my oil pressure and lubrication is there with in secs. Your running a car hot or cold with no oil. Theres a difference.

A warm running engine the oil is thinner then if its cold. Proper pressure pushes oil in to the areas requiring lube. No oil pressure, no oil. Not a hard thing to figure out. The minimal residue your talking about would burn away in secs on a hot motor. Even if it didn't completely burn away you still have no protection since no pressure, no oil, no flow, no cooling.

"Prolongs" a hoax. My friend bought that load of garbage once, he hit a rock wheeling in his truck ripped the pan. Oil drained. Prolongs magical protection properties got him about five minutes before the motor seized. He didnt even make it off the trail. But hey, it was on tv so it must be true.

With a gallon of seafoam in the car, you at least have some sort of lubrication. So again, a little different then no oil. Course i don't run a gallon through at a time, i prefer to drop the oil filter drain a half quart out and add it back in with seafoam. Does the same job, and i don't have to worry about my engine blowing up.

Some once told me to jump off a bridge. Didnt mean it was the right thing to do. Didnt mean i wasnt going to survive. Doesnt make it smart. But hey the 50 year old guy used to working on cars that are way more forgiving, that used way different standards, must mean that todays cars must be just like them. I mean technology hasnt changed in the last 50 years. Nope cars are just like they were 50 years ago.


So, yes ill flush, flush the load of garbage you spewed out becaue you got flamed on a forum. You got flamed for stupidity. It happens. Ive gotten flamed. It happens. Live with it, and wait for your chance to flame some one for being stupid. If you cant handle it. Then the internet is not for you. Go jump on iANT.com and tell them you ran a car with out oil. Even for 15 secs. I was nice compared to what you will get there.

As for why your needle didnt drop, if the car was cold the oil being thicker, may not have leaked fully out of the pump so there was enough oil there to make your gauge read pressure when the car started as it was pushed through the system for that few secs.. The little bit of oil there would not have protected your engine from the extreme wear put on them for that 15+ secs you ran it.

On the flip side, if the motor was hot, not to sure. No oil in the system should have immediately caused the oil pressure to read zero. Unless the pump on the 4.7 is a zero back flow (oil cant leak out of the pump when its not running) its a bit of a mystery. Put a mechanical gauge on it and check the reading you get at idle vrs with the sensor installed. Replace as necessary.

A little bit of info for you. Today's cars hat oil clearance tolerances as low as a couple thousands of an inch. Thats pretty fricken small. with no oil to create the hydrodynamic oil film that the journals ride, the crank, cams, rods ride the bearing directly on the surface of the journals Just a few second of this can be enough to permanently damage your bearings or journals and cause a low oil pressure situation that promotes further damage.

But im sure my 4.0 at school means im just some loud mouth on a forum spewing nonsence. Maybe i am. But im not dumb enough to contently run a car with out oil every time i change the oil cause i dont want to wipe up a little oil.

Oh one other thing, No i dont rip people off. I started working on cars cause i was tired of getting ripped off. then my friends wanted me to work on theirs. Im going into the bussiness cause cars are my passion now. And im already a good mechanic. Ill just be better once im done at school learning what i dont know. I will also say i may have been overly tired and slap happy this morning when i wrote what i did, but i still hold to what i said, If you run a car with no oil, your retarded. It only takes 1 sec for something to fail. you chanced it for 15+. You may have lucked out and nothing happened. You may find down the road your going to be rebuilding that motor sooner. either way. you took a stupid chance on destroying your motor cause you didnt want to bend over and wipe some oil up. In my book thats retarded.
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Last edited by nlynd1978; 12-02-2010 at 11:13 PM.. Reason: spelling and comment.
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Unread 12-03-2010, 06:32 AM   #13
Bubba3200
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Congrats on the 4.0 in school. What you say makes total sense in your post without a doubt and I also have no doubt that you will become one of the finer mechanics out there. All I can say is we will never know if the engine fails @ 250,000 miles if what I did would would have made the engine last to 275,000 I never had a problem with what I have done to an engine and never in 50 years had an oil related problem. OH should I say a lack of oil problem....LOL!!! I applaud you on calling me on my s***.........This is what makes this forum so great. TOUCHE'
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