Oil cooler adapter bypass valve

Discussion in 'Gas Engines' started by 7228sedan, Mar 4, 2013.

  1. 7228sedan
    Joined: Nov 2009
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    7228sedan Senior Member

    Can anyone tell me what this valve does? (see attachment)

    I have my oil cooler, adapter, and remote oil filter adapter removed as I am replacing the oil lines and seals in the adapter. I understand this valve to be a bypass valve. I was wondering if anyone could tell me specifically when it opens.
     

    Attached Files:

  2. Submarine Tom

    Submarine Tom Previous Member

    If it is what I think it is it allows bypassing the filter.

    If the filter is clogged or flow is not up to demand it allows bypassing the filter.

    So, to answer your question, when pressure necessitates it too.
     
  3. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    It opens when the filter is clogged. It keeps the oil flowing and the filter from exploding if the pressure is too high.
     
  4. Petros
    Joined: Oct 2007
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    Petros Senior Member

    why do you ask? Not a good idea to run without it, even new oil filters can be defective and block flow. Also the by-pass valve usually opens when it is really cold to prevent the oil filter from rupturing because the oil is cold, thick and difficult to press through the filter. If the filter ruptures it really makes a mess in the engine compartment, and can result in engine damage if you not notice your oil pressure dropping to zero in a few seconds.
     
  5. gonzo
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    gonzo Senior Member

    The picture looks like a GM bracket. It should pop open at about 65-70 PSI or so. Usually, the oil pump has a relief valve too.
     
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  6. powerabout
    Joined: Nov 2007
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    powerabout Senior Member

    It measures the differential so it opens at way less pressure than that which is obvious if you have one in your hand
    All GM pumps have a relief valve in them which is for setting the oil pressure
     
  7. FAST FRED
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    FAST FRED Senior Member

    On a cold start the oil can be cold enough & dense enough to make high pressure in the oil cooler , so it will be bypassed.

    This is good as the oil does not require cooling at that point , so the engine oil will warm up faster in the bypass mode.

    Many buypasses will have a thermostat , not just a pressure sensor.
     
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  8. powerabout
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    powerabout Senior Member

    sure but it also means its unfiltered
     
  9. 7228sedan
    Joined: Nov 2009
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    7228sedan Senior Member

    I ask because the spring appears to be fairly weak. I certainly would not remove it, however I was thinking of replacing it. I can easily open the valve with light pressure. I was curious if it was designed to open at high pressure situations. The motor is a Mercruiser 7.4L. Last season I was experiencing a slight loss of oil pressure when I brought the motor up to 3700 RPM or higher when hot. I would notice that the pressure would drop about 10 PSI from 40-30 at 3700 then at 3500. If the motor is still "cool" it maintains pressure around 50 PSI all the way up to 4000/4200. By cool I mean just brought up to about 160 from cold, not well warmed after running all day. I have heard that this relief valve could be the issue. I am not sure exactly how though as whether it is open, or closed it sounds like the pressure in the motor should be constant...
     
  10. powerabout
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    powerabout Senior Member

    light spring opens with your finger is Normal.
    If our engine had 10psi or 200psi oil pressure it would be the same part and do the same job
    It sees the pump pressure on one side and the gallery pressure on the other so its protecting the differential over the filter/cooler.
    Filter clogs, diff increases, valve opens
     
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  11. 7228sedan
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    7228sedan Senior Member

    Ok, it sounds like that is not my problem then...

    Thank you all as usual for the responses!
     
  12. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Fred has it right, the bypass is designed to reroute oil, when it's in a cold start situation and the viscosity of the oil is too heavy to get through the filler AND up to the main gallery, in time for the spinning bearings to get lube. It also works, in case the filler gets clogged, but this is fairly rare. Powerabout is correct, it's a light spring.
     
  13. tom kane
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    tom kane Senior Member

    There is something terrible wrong if an oil filter ever blocks up. That just should not happen. Look at your maintenance and engine set up.Running too cold, wrong oil, water in oil, something wrong some where.
     
  14. powerabout
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    powerabout Senior Member

    It happens just after you spin a bearing but you will still get home as you still have oil pressure as opposed to none
     

  15. 7228sedan
    Joined: Nov 2009
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    7228sedan Senior Member

    The more research I do, the more it looks like it might be my oil filter. I was using a FRAM which unbeknownst to me are known to have problems with pressure... Needless to say I will be giving the motor an oil change prior to splashing for the season which will include a better filter. I have had good luck with WIX filters previously, does anyone have any other recommendations?
     
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