Sounds like ticking but I'm not sure where from

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by i_build, Apr 7, 2009.

  1. i_build

    i_build Rockstar

    99 Suburban C1500 LT 5.7 130K Miles

    While in park I can rev the engine up to 4-5K no tick whatsoever and runs smooth, but under load in drive it sounds like a tick. I did an engine flush and put in fresh oil but it's still there. Dont understand why it does it in gear but not in park unless its something else.

    If I am in gear and I ease on the gas you wont hear it, but the harder I get on the gas the more you can hear it. It's not a CV joint type noise. I would swear it was a valve ticking.

    Any help appreciated.

    Also... my oil pressure sits at 10-12 PSI at idle and will go up a bit over 40 on a moderate accel. Is that ok?
  2. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    Your oil pressure sounds VERY low for this motor. When you first start the engine from cold, the pressure should be between 50 and 60 PSI. Once the motor warms up and is at an idle state, it should be around 30-45PSI. When you accelerate once it's warmed up, the pressure should rise to somewhere around 50ish PSI. If the pressure drops below 30PSI, you have some issues and you very well could be inadvertedly promoting engine wear and eventual failure by continuing to run the motor like this. The ticking you're hearing is most probably lifter tick from them being starved of oil....not good. I'd guess you're either low on oil, have a plugged up oil filter, or have some other oil obstruction in the motor.
  3. i_build

    i_build Rockstar

    When first started the oil pressure is at about 50 but after it warms up at idle it will be a bit past the 10psi mark.

    The Jiffy Lube flushed, replaced the filter, and put in 10w 40. Could that weight have anything to do with it since I saw the oil cap has a different weight indicated? I had them change the oil right after I bought it and thought the pressure was higher before.

    I checked the oil level and it is fine, could this be a bad oil pump? Should I try flushing again and using a different weight oil?
    Last edited: Apr 7, 2009
  4. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    Using a heavier weight oil (I'm assuming the cap said to use 5W-30) especially in cooler weather will result in a slightly lower oil pressure and a longer time for the oil to get up to the lifters. That said, 10PSI at idle is still sounding quite low to me. I'm not sure if it's the oil pump or not, but I'd be wary or driving it until you can get a better understanding of what the problem is and how to fix it. I'm hoping some of the more knowledgable members here will pipe up and come up with some ideas.
  5. i_build

    i_build Rockstar

    I have been reading every post with the word pressure in it and googled 5.7 low oil pressure and bought the repair manual which mirrors what you said in your first post.

    I feel bad that I might have gotten a bad deal. It runs so well and you cant tell it's running at idle. It doesnt go over 165 degrees even last weekend 85 degrees outside with the a/c on in traffic for 45 minutes.

    It was sitting at 50 psi for a good part of my commute home @ 2,000 rpms. It only drops to 13 psi after it's completely warm and at about 600rpm idle.

    I'm going to flush with seafoam and do another change with new oil and new filter myself. I'm not going back to Jiffy lube... just did that because I had to take the Suburban for a 300+ mile trip to my daughters school FSU and had no time.

    It sounds a bit like it might be an exhaust leak under heavy load so I am going to get it up on ramps and check that. If that's not it I read that I should try a manual oil pressure guage to confirm the electric guage isnt off. If still low... I'll look at putting in a heavy duty oil pump and pray that resolves it.

    But... one step at a time... If anyone can add like you mentioned I would appreciate it.

    This was good reading
    Last edited: Apr 7, 2009
  6. meash20

    meash20 Rockstar

    not sure how much this will help, this is from the Service Guide:

    Oil Pressure Diagnosis and Testing

    1. With the vehicle on a level surface, allow adequate drain down time, 2-3 minutes, and measure for a low engine oil level. Add the recommended grade engine oil, and fill the crankcase until the oil level measures FULL on the oil level indicator.
    2. Operate the engine and verify low or no oil pressure on the vehicle oil pressure gage or the oil indicator light. Listen for a noisy valve train or a knocking noise.
    3. Inspect for the following:
      • Engine oil diluted by moisture or unburned fuel mixtures
      • Improper engine oil viscosity for the expected temperature
      • Incorrect or faulty oil pressure gage sensor
      • Incorrect or faulty oil pressure gage
      • Plugged oil filter
      • Malfunctioning oil filter bypass valve
    4. Remove the oil pressure gage sensor or another engine block oil gallery plug.
    5. Install an oil pressure gage.
    6. Start the engine and then allow the engine to reach normal operation temperature.
    7. Measure the engine oil pressure at the following RPM:Specification
      1. 42 kPa (6 psig) minimum, at 1,000 RPM
      2. 125 kPa (18 psig) minimum, at 2,000 RPM
      3. 166 kPa (24 psig) minimum, at 4,000 RPM
    8. If the engine oil pressure is below minimum specifications, inspect the engine for one or more of the following:
      • Oil pump worn or dirty
      • Malfunctioning oil pump pressure relief valve
      • Oil pump screen loose, plugged, or damaged
      • Excessive bearing clearance
      • Cracked, porous or restricted oil galleries
      • Engine block oil gallery plugs missing or incorrectly installed
      • Broken valve lifters
  7. i_build

    i_build Rockstar

    Funny... I was just about ready to post this link in this thread

    And found that you responded with the same information. Thank you!

    Sounds like 6psi @ 1000RPM is the minimum and I am more than double that at 600RPM :money: while it may not be as high as others it seems within spec.

    I'm still lost as to why I can bring the RPM's up in park and you dont hear any noise however once in drive under load accelerating hard I hear noise. A friend that rode with me said he thought it was exhaust also... but why wouldnt it make the same noise hitting those rpm's in park unless the exhaust is twisting under load???? Going to try to record it and put it up on youtube.

    I'm a newb when it comes to chevy 350's... but i have worked on all my cars even rebuilding the engine in the mazda and custom fabbing a blow through turbo...

    I did change the plugs and air filter and the old ones looked very good (a little normal brown but not bad).
  8. PontiAddict

    PontiAddict Rockstar

    Have you scanned it for KR? Could very well be you're hearing some knock. Then again, as you said, it could simply be an exhaust leak..which proposes the next question of...are all your engine mounts alright? It could have excessive movement causing some major exhaust flex.

    For the low oil pressure...there is always the possibility that your bottom end is toast.

    And also, someone mentioned that higher viscosity oil has the effect of lowering your oil pressure, the opposite is actually true, with a higher viscosity oil, you RAISE your oil pressure, but you LOWER your oil flow, obviously especially true in an engine specified for very low viscosities. Keep using 5W-30 as specified, and don't waste your money on Jiffy Lube's bull**** flush services and the like....use that money for a better oil if you're going to spend it.
  9. L0sts0ul

    L0sts0ul Rockstar 100 Posts

    As far as your ticking noise sounds, this is completely outta wack here, but listen first.

    I was having the same problem in my 93 burb, and I just turned up the radio for about 2 years.

    then I Came outta my house to go to work one day, and found a pool of gas underneath my truck. I smelt it and sure enough it was gas.

    I had it towed to my mechanic, and turns out that the ticking noise I heard the whole time.... THE FUEL LINE (return thank god) from the TBI to the frame rail had broken loose of the bracket and had been hitting a sharp corner on the body by the framerail.

    so, check that out... sounds like a long shot... but blieve me... its better that risking blowing up :)

  10. Cableguy

    Cableguy Epic Member 5+ Years ROTM Winner 1000 Posts

    My theory is a bit different. I'm thinking it might be just exhaust related. Manifold crack, flange gasket and so on....just a thought

    By the way a motor with the bottom end ready to fall out will make the same noise and never indicate in oil pressure...from experience of course :whistle:
    Last edited: Apr 9, 2009

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