Oil pressure gauge help needed

Discussion in 'Homesteading Questions' started by cc-rider, Aug 13, 2004.

  1. cc-rider

    cc-rider Baroness of TisaWee Farm Supporter

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    I just bought a used van off of eBay and it was delivered yesterday. It's a 92 Chevy Lumina APV. (If you are interested in seeing it, it's still on eBay under completed. Search for Chevy Lumina APV. Bought by cc-rider)

    Of course, nothing is ever as listed, but I'm concerned because the oil pressure gauge, as soon as the car is turned on, hits the peg and stays there. The gauge is marked 0 (and red) and goes to 60. The needle goes PAST the 60, hits the peg, and stays there until the engine stops. I also noticed that the sticker on the window says the oil was due to be changed at 86K. It is now 91K. (So much for "up to date maintenance", huh?).

    If I could afford a mechanic, I wouldn't be buying eBay cars. :(

    Any clues before I break down and take it to a mechanic? Could that possibly be normal? I had assumed it would stay somewhere mid-range.

    Thanks for all your help!
    Chris (in 51 degree Ohio.... what's up with that!!!!?)
     
  2. kaji1

    kaji1 Member

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    Check the connection on the sending unit.
    I would guess, #1 loose wire and it's grounded or #2 a bad sending unit.
    This thing works off a sending unit that has a varisble resistance in it.
    IE; more pressure, less restance,less pressure more resistance.
    A good connection on the proper sending unit will tell you the truth.
     

  3. Lt. Wombat

    Lt. Wombat Well-Known Member

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    I agree but add the following: If you're going to get down to the sending unit for inspection why not pull it, put on a manual guage, take a reading then fix/replace the sending unit. By doing a manual check you'll either rest your case or open another one based on the readings.
     
  4. cc-rider

    cc-rider Baroness of TisaWee Farm Supporter

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    Oh my.... maybe I better be calling the mechanic. I can probably handle jiggling a connection to see if it is loose (if I can find it!), but now you are talking WAY above me. I own a screwdriver and electric jigsaw... if I can't fix it with that, it doesn't get fixed.

    Do you think there is any harm in driving it a couple days until I can get it done? If there is a problem, would it tell me?? I'll go have the oil changed today, just to make sure it is full and all.
     
  5. uncle Will in In.

    uncle Will in In. Well-Known Member Supporter

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    If you can't afford a mechanic, you shouldn't be buying pig in a poke vehicles on EBay. If the oil pressure is too low you will know it when the motor starts knocking if a rod don't go through the block before you notice it. Keep the oil level on full and drive it. However it wouldn't cost much to have the pressure checked and get a estimate on correcting the problem.
     
  6. Lt. Wombat

    Lt. Wombat Well-Known Member

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    Sending unit is removed with a deep well 13/16 or smaller socket. If you have a library close check to see if they have a Chilton’s or similar manual for your vehicle.

    If it was me here is what I would do.

    #1 complete oil change after using an oil flushing product like 5 minute flush (read directions on bottle). If the oil filter bypass (opens when the filter becomes plugged up) is faulty a new filter and clean oil will solve your issue.

    #2 Check wiring to sending unit. Some vehicles have the sending unit very close to the filter attachment. Others it’s on the engine block while others are hidden very well by geeky engineering types in the design department.

    #3 Do a manual pressure check (Super easy): take out the sending unit (see above), screw in the hose of the tester gauge, start vehicle, get reading from tester gauge, unscrew tester hose, reinstall sending unit.

    If manual gauge reads within normal limits (get this value from the repair manual)
    it is OK to drive until you fix the problem. If the wiring is faulty and you just can seem to isolate the location install a permanent manual gauge. Remember if this was an older vehicle there would only be a light to show low oil pressure, nothing for high pressure, so you would not even know this problem existed. Relax, take your time and you'll get it resolved.
     
  7. cc-rider

    cc-rider Baroness of TisaWee Farm Supporter

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    Well, I really DID do my research before I bought it. I sent many, many emails to him with questions, personally emailed everyone that bought things from him previously and got all good results, and checked out reviews on 1992 luminas. If things were as he said, it should have been OK.

    But hindsight doesn't matter now, all I can do is fix the problem.

    I don't think the pressure is too low.... if anything, it is registering on the high side. And really...the more I think about it, I just think the sending unit is faulty.

    I just took it to a quicky oil-change place and had the oil changed. They said it looked fine and that there hadn't been any leaks or anything. And offered to pay me $200 more than whatever I paid for the car. (I told them my story about buying it off eBay the previous night). They said I should also replace the fuel filter, but that was it.

    I'll try Lt. Wombat's suggestions and then call a mechanic if I can't figure it out. Was just hoping to save that expense. It was a mechanic that told me I had to pay him $200 to fix my clutch cable on my old van, and THEN he'd look and see if my transmission was any good. I just don't trust them. :no:
     
  8. Dont be to alarmed about the matnance sticker not matching the miles...
    I do my own oil changes and often dont change the reminder sticker. This could be the same with the person you bought the van from. As long as the pressure is hight that is usually ok but low is no good. In some engins if there is to much or not enough oil the pressure will show high. I had an old chevy van with a 350 v8 and it always had real high pressure which was good in a v8 but I'm not sure on a v6. I'm assuming yours is a v6? It could also be your oil wieght is too high, If your van takes 10w30 or 5w30 but there is 10w40 or 15w40 in it, it will show real high pressure. some unscrupulous people will do this to hide a knocking sound or smoking. If after you had the right oil put in and the pressure is still high and theres no knocking or smoking, then its either ok or its the gauge/sending unit.

    Some other things to watch for in a newly bought car is milky oil which indicates a blown head gasket or cracked head, oily radiator fluid(same problem), saw dust in the tranny fluid to hide a slipping tranny prob. hope that you dont have any of these thing happen with your van but If you suspect the seller is shady, you might want to check these things out. there simple to do and can prepair you if there is a problem or put your mind at ease if there ok.

    hope all goes well,

    Cody
     
  9. mightybooboo

    mightybooboo Well-Known Member

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    My guess its nothing more serious than a sending unit (or the wire popped off) or gauge,those sending units go dead all the time(been there,done that).To be completely high on gauge legitimately,my guess would be you would know it real fast when engine failed,and it would be making some really obvious noises r/t plugged oil lines somewhere,only way I can imagine a high pressure condition.Just my experiences,Im not a mechanic.Maybe a mechanic will chime in re: how a high condition would occur.Im just guessing.
    You know,thinking about it,they may have unplugged it so you wouldnt see the LOW oil pressure.
    BooBoo
     
  10. CCRider, If the guage isn't reading correct(it isn't!) don't think the oil pressure must be high if anything. There could be no pressure and the guage still pegged. It isn't a correct reading, means don't trust it at all, and don't figure you can get by because of it. It needs to be checked first off if I read your mechanical abilities right. LOL The wire to the sending unit is more than likely grounded out or the sender bad. They're pretty inexpensive. The repair should be real reasonable too if they can find where the wire is grounded quickly. Hope you make out ok. Loren
     
  11. Herb.

    Herb. Well-Known Member

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    If you turn the key on without starting the car and the gauge pegs high you probably have a bad sensor or a shorted wire, take the wire off of the sensor, do not let it touch any metal part of the car or engine, and see if the gauge goes to zero, if it does the sensor is bad, if it stays pegged high the wire has a short in it some where. You will have to follow it back to the gauge to find out where. It is possible for the instrument panel to be bad but not likely. If the gauge reads zero with the key turned to on but pegs when the engine is started the sensor is probably bad, they are easy to change usually. You really should get a Haynes manual and a set of automotive tools, they will literally save you hundreds or thousands of dollars in repair costs. I know if I had to take very much to a mechanic I would have to walk.
     
  12. Westwood

    Westwood Well-Known Member

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    Yup, exactly! The sensor is on the negative side and and grounds to the block. If you take the connector off and it still pegs, there's a short to ground before the wire gets to the sensor. If you take the connector off and it zeroes, the sensor is bad.
     
  13. Shrek

    Shrek Singletree Moderator Staff Member Supporter

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    My 88 S10 blazer did that last month. Turned out that the guage was shot. I ended up adding a mechanical oil pressure guage under dash for $19. Screwed the line right into where the sending unit mounted and plugged the guage backlight into the fuse panel.
     
  14. HermitJohn

    HermitJohn Well-Known Member

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    I know everything is big deal and expensive if you hire it done. However if you or anybody do install a permenant aftermarket mechanical oil pressure gauge, be aware these usually come with a length of plastic tubing. I've had problems several times with these developing leaks either from mechanical injury or from getting brittle with age. I suggest if you want to do this, measure how much tubing you need and go buy copper tubing the same size to use (Napa carries it in bulk, just tell them the length and outside diameter or show them the plastic and say you want the same outside diameter, the inside diameter in copper will be smaller but that doesnt matter). Route the tubing away from any sharp edges or hot exhaust. Its only $3 or $4 and will last forever. Oh, check out JCWhitney. They used to anyway sell very cheap mechanical gauges that worked and held up just as well as any. At least the oil pressure and water temp gauges did. Might avoid adding an ammeter on modern vehicle, usually the cheap ammeters cant handle high current flow of modern vehicles as all accessory current goes through it. Voltmeter is fine and that is what most modern vehicles have do to the high current issue with ammeters (nice to have both if you can). If you want an ammeter get a heavy duty one although it will not be cheap. I consider a set of gauges to be a must with any vehicle especially one with lot miles. If you pay attention to them, they will give warning that can prevent you from getting stranded or paying for a tow or destroying your engine.

    Which reminds me, although I have an oil pressure gauge and an ammeter (came with my little Arrow pickup, yippee!!!), I never did install a water temp gauge. Some ancient Volvo engines (like mine) dont have a standard sized hole to screw the sensor into, its too small for even the sensor end to stick down into so cant just buy an adapter. I have to make a special bit of tubing to splice into radiator hose and screw sensor into that or track down a special Volvo mechanical gauge ($$$$$) for this era engine. The original Mitsubishi engine used an electric water temp sending unit which also didnt fit the Volvo engine. Dont much care for electric units anyways especially the aftermarket versions.
     
  15. boxwoods

    boxwoods Well-Known Member

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    check the oil
    make sure it's clean and full
    start engine
    no clicking or knocking noise

    drive it

    change the oil and filter when you can afford it
     
  16. kitty32_z8

    kitty32_z8 Well-Known Member

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    The cheapest route to fixing:
    Go to your local library in the Reference section and read the appropriate Chilton's Complete Manual for your van. You can then decide if it is something you can handle. You want to read the troubleshooting section at the end of the Engines chapter ( Chiltons likes puting hten at the end of every chapter). This will also assist you in determining cause. If it is there and you want to fix, check out or copy the pages of the manual. Take home and fix yourself.
    If you determine you dont want to fix. Contact one of you local vocational training intsitutes or community college until you find a mechanics program. You can take to one of these and save a mint. The classes are always looking for project cars. Call and talk with the instructor to see if you can get it checked out and fixed. Warning- I have heard that some people have had it take a long time to get cars back.
    Knowledge in car care is power. There are lots of back yard mechanics who will rip you off and sometimes do more damage than good. I am not against them, just too many that think they know what they are doing. Please take time to read up on your car. Even the professionals can tell a complete novice. Being a woman I have diagnosed many problems with my cars. I have had mechanics tell me something else was wrong and told them to fix what I said first. Many times fixing the issue. I wont work with a mechanic (male or female) that wont listen to my dx. and let me dicide if there dx. is correct instead of mine. You may decide after learning about your car that it is not in your skill abilities, but have faith!
    Good luck on you van,
    Kathy