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bad sending unit or gage or worse?*updated!*

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by **DONOTDELETE**, Nov 11, 2001.

    i noticed the other day that my oil pressure gage was reading low. at idle it read just above zero and when running it didn't even get above 20 or 30 (guessing- no numbers on stock gage). anyway it used to read higher. i don't hear the rockers clackin and it seems to be running fine so i'm thinking its the sending unit. is this normal for when they go bad or could it be that my pump is going bad?

    <font color=blue> Experience enables you to recognize a mistake when you make it again.

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    <P ID="edit"><FONT class="small">Edited by Blue_Beast on 11/15/01 02:57 PM.</FONT></P>
     
  1. chevyracing

    chevyracing 1/2 ton status

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    Re: bad sending unit or gage or worse?

    could be the gauge, pump, sending unit, an obstruction in a passage, or too much main bearing clearance. In the front of the motor above the timing cover there is a small plug. Take the plug out and put a mechanical gauge (available at any parts store for about 15 bucks complete) in the place where the plug was and see what the pressure is there and that should let you know if there is a problem elsewhere,

    John

    Like to go sloppin' 'round in da mud in a rapid fashion....=)

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  2. Blazer_Boy

    Blazer_Boy 1/2 ton status

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    Re: bad sending unit or gage or worse?

    Take your sender wire and groud it out. If it pegs the gauge and when you take it off the gauge goes back, your gauge is good. Leading you to check your sender..... If it doesn't change than that means you have to go buy a 350 RamJet, should fix the problem then, hahaha, j/k. If it ain't clicking yet then I wouldn't be worried.

    <a target="_blank" href=http://www.geocities.com/bigkern76>http://www.geocities.com/bigkern76</a>
     
  3. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: bad sending unit or gage or worse?

    Well get a mechanical gage and double check that the gage is acurate. Hate to say it but that's exactly the readings I was getting out of the old engine in the Lady's truck. Main bearings went. Still ran fine...never rattled a lifter but it had 3psi at idle when hot. We drove it for a year like that and never had a problem either.

    Women dig dents and flat paint!
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  4. Re: bad sending unit or gage or worse?

    Well crapolla, you guys are starting to worry me. i did disconnect the gage and it pegged out so i'll be getting a mechanical gage next and hope for the best. i bought this motor used and supposedly it was rebuilt less then a year before i bought it. thanks for all the help.

    <font color=blue> Experience enables you to recognize a mistake when you make it again.

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  5. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: bad sending unit or gage or worse?

    Well it's probably main bearings or thrust bearing. Those can be replaced in the truck. It's a PIA but can be done. Not very expensive if your doing it yourself. Should be under $100 for everything. Might want to check the timming chain while you got the pan off. $35 for a stocker and it's best to have the pan off when you pull that cover.

    Women dig dents and flat paint!
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  6. Re: bad sending unit or gage or worse?

    ok, so here is a stuped question- why would bad mains give me low pressure? wouldn't i get some kind of knock or is that only with a bad rod bearing? How will i know for sure if its the mains that are bad? obviousley they might be spun or burned. did you plastigage them to see if they were out of spec?
    shoot, while the pan and timing cover is off i might as well pull the manifold and rad. and stuff in a bigger cam with new lifters and rockers too!

    <font color=blue> Experience enables you to recognize a mistake when you make it again.

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  7. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Re: bad sending unit or gage or worse?

    Nope it may not knock. Like I said We ran one for a full year before I got around to putting in the crate. Never made any noise. I haven't pulled the caps on that motor (still have it in the garage) but my pressure would vary. I could get off the gas and get on the gas real hard and pick up 5psi at the same RPM. Mine had bad thrust bearings from that test.
    If the mains are all over tolerence you will have low oil pressure. Now were talking mains. it's not like a rod bearing. you will not get a knock till it's REAL bad.
    I put a oil pump in the motor hoping. helped a little but not much. While I had it apart I check the cam/lifter journal plugs and they were in place. Only thing left was bearings. I knew the crank had stripped threads for the ballancer so I just yanked it and dropping in a used crate I got for $800 with liess than 10k on it. I may make the old engine a 383. I had other problems with the motor before, it was a cheaply done rebuild. Just couldn't afford any down time.
    Plasitgage the bearings. That's the only way you will know for sure.

    Women dig dents and flat paint!
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  8. Re: bad sending unit or gage or worse?

    ok, things are getting worse. on my way home it started missing and running poorly. misses and sputters at all rpms. oil pressure still low but no rocker or lifter noise. to top it off it's raining and will be dark in less than an hour. and sh!t and 2 is 8!

    <font color=blue> Experience enables you to recognize a mistake when you make it again.

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  9. Brians 60s

    Brians 60s 1/2 ton status

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    Re: bad sending unit or gage or worse?

    Jason, come on by tomorrow when you can. Call first and make sure I am here. I may have an option for you.

    IT'S A 1 TON THING.... IF I HAVE TO EXPLAIN IT, YOU WOULDN'T UNDERSTAND!!!
     
  10. One small victory for the blue beast. installed a mechanical gage and now i'm showing plenty of oil pressure! kick ass! the sputtering and missing that just happened to start up at the same time turned out to be good old fashoned lack of maintainance on my part- bad plug wires. man, this rarely happens that the solution is something simple instead of something horrible wrong. gotta appreciat the little victories![​IMG]

    <font color=blue> Experience enables you to recognize a mistake when you make it again.

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  11. Grim-Reaper

    Grim-Reaper 3/4 ton status Author

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    Glad to hear it was the gage. I was praying it was on mine but no such luck.

    Women dig dents and flat paint!
    coloradok5.com/gallery/Grim
    75 Jimmy, Dollar
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