Hellp!! Coolant always low but no leak.

Discussion in 'GM Powertrain' started by kamiksuburb, Dec 28, 2012.

  1. kamiksuburb

    kamiksuburb New Member

    Hi guys i need your help. my coolant keeps going low but i have no apparent leak.:grrrrrr: I read somewhere about the cylinder heads being defective in the 5.3 heads from '01-'06.:gasp: So I'm hoping thats that's not the case. I have 144k miles on it. also my second problem is oil gets really low to with no leak visible, I changed the oil about less than a month ago and already its almost 2.5 quarts low. please let me know what you think. also my check engine light, and ((brake)) light is on. If you have any questions please feel free to ask Thank you.
  2. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    What year is your truck? There is a known problem with the cast tech heads. Most had a "706" stamped on the ear of the head. Here is the TSB: http://ww2.justanswer.com/uploads/Bluegorilla/2008-12-05_142924_Coolant_loss_5.3.pdf . As far as your brake light and check engine light goes, I would take it to an autoparts store and have them scan it. They do it for free and it will give you a starting point on what to repair. The check engine could be due to low coolant.
  3. kamiksuburb

    kamiksuburb New Member

    The info is below. and i had went to a parts store before and they checked it and it gave me the trouble code i dont remember exactly what code it was but if i remember correctly it had something to do with the evap canister. do these go bad? or defective? maybe a broken hose? is it common?? the one that has me asking questions is the brake light. all my brakes are brand new and my fluid isn't low.

    2001 Chevrolet Suburban LS

    5.3l V8, 2WD 148k Mi
    [TABLE="class: cms_table, align: center"]
    Magnaflow Exhaust
    Volant CAI
    Airraid TBS

    Head Unit: Alpine
    Speakers: 6.5 pioneer 5 ways All Around
    Subs: 1 12" Kicker Solo X 2500W RMS
    Amps: Soundstream TX1.2000D FOR SUB, KICKER 400.4 For DOORS
    3 Farad Capacitor

    06 Silverado Z71 Rims

    Remote Start Alarm
    55W HID Headlights
    07 Suburban Badging
  4. Conlan Rose

    Conlan Rose Epic Member 5+ Years 1000 Posts

    Is it the abs light or just brake light. The brake light goes one when the parking brake is on or there is a major fault in the system. You may need to go to a shop that has a better code reader they will use it for free usually but ask u to consider having them fix the problem. My local shop usually tells me what they should fix and what I can do easy my self.
  5. kamiksuburb

    kamiksuburb New Member

    It is just the brake light and not the abs. and yeah ill have to go to a shop to have them scan it, how do i find out if i have the defective heads or not?? are they stamped on the heads under the valve covers???
  6. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    You will have to read the TSB to identify the heads, the info is right there. "706" is stamped on the outside of the head, not under the valve cover. But, having 706 does not mean that you have or do not have the bad heads. You would need to pull the valve cover and look for the castech symbol as described in the tsb. (looks like a battery) Advance auto parts will scan the engine and brake codes for free. I don't know if autozone has the scanner that will read brake codes. There are multiple evap codes that can point to anything from a bad gas cap, bad valve, to a major leak in the system, so an actual code will be helpful.
    Last edited: Dec 28, 2012
  7. kamiksuburb

    kamiksuburb New Member

    I read somewehere that there is a casting mark as well. thats is visible on the head to the rear of the engine. http://www.agcoauto.com/content/news/p2_articleid/148

    this is a link i found on the defective heads. actually now that im thinking about it i hope this is not the case since my coolant does keep going low every week and a half or so. let me know what you think.
    Last edited: Dec 28, 2012
  8. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    I guess that if you are very concerned about it I would pull a valve cover. It should give you your answer rather quickly
  9. kamiksuburb

    kamiksuburb New Member

    Ok so the codes i got are p0446 and p0453 this was at autozone and no there scanners dont pull brake codes lol and i hope when I pull the valve covers it isnt a nightmare
  10. Pikey

    Pikey Moderator Staff Member 5+ Years ROTM Winner 5000 Posts

    for the PO446 check this out, http://www.justanswer.com/chevy/1bo37-code-po446-evap-emission-control-system.html it has pictures and park numbers. You can actually search this forum and find a thread about cleaning the valve that you have.

    I found this on the Po453:
    The po453 ispretty straight forward code pointing to a fault in the Fuel Tank Pressure sensor, and if it was already changed, then there was something either done wrong, or a deeper problem. What you are going to need to replace in this case, is going to be, like i say, the Fuel Tank Pressure Sensor. This sensor is mounted to the top of the fule pump assembly, located on top of the fuel tank. The tank will need to be dropped to access this sensor.

    Have you tried replacing the gas cap?

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