350 TBI - Very High Oil Pressure and Loud Tick

Discussion in 'GM Powertrain' started by ct9a, Sep 12, 2009.

  1. ct9a

    ct9a Epic Member 5+ Years 1000 Posts

    It's a '94 Suburban K1500 with ~215K. The motor has always run strong (not sure if it is the original, or has been rebuilt by previous owners) and showed no signs of any problems. Earlier this week it started ticking loudly on start up, but would smooth out after idling for a few minutes. Yesterday, I noticed that the oil pressure gauge pegged itself out on start up, but returned to normal after a minute or so of idling. Today, it did the same thing when I left the house, but on the return trip, the pressure wouldn't drop back down and blew the gasket on the oil filter. I went and got a new oil filter and replaced the old one (what a f***ing mess to do in a parking lot) and it did the same thing after only idling for 30 seconds.

    Needless to say, my truck is sitting in the parking lot at my brother's work. Hopefully I don't have to tow it home, it'd cost an arm and a leg with how far it is.

    Any ideas guys and gals?
  2. spottweld

    spottweld New Member

    oil pressure

    It sounds as if your filter housing is not bypassing. take your filter off and you will see two bolts up there between the stud that the filter screws on. That is your oil pressure bypass and it is usuallly set around 15 psi, yes not all of your oil gets filterd every time it is circulated. There is a little check ball and spring inside the housing and if that gets stuck open your filter will get the full pressure and blow something out. It sounds to me that your filter is not on that tight if it was it could have blown a hole on the filter. If you look on summit or jegs you can find special filters and non bypass filter adapters. This is an easy fix and you dont need any gaskets, just pull out the two bolts and the filter adapter will come right out and go to the junk yard or aout parts store and get a new one
  3. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Couldnt even guess why the oil pressure is staying high. Possibly some of the oil galleries got blocked.
    The high oil pressure has probably damaged the seals on the hydraulic lifters and thats where the ticking is coming from, I've seen it happen before on an older engine.
    In that case they had just replaced the oil pump.
  4. ct9a

    ct9a Epic Member 5+ Years 1000 Posts

    Is this a job that I could do in the parking lot, or do you think I'm going to have to tow it home? Also, would this cause the pressure gauge to peg out at max. and stay there?
  5. unplugged

    unplugged Epic Member 5+ Years 1000 Posts

    There are two oil bypass points in reference to the oiling system on the SBC engine. The filter mount has a built in bypass in the event that you do not change the filter at the recommended interval and the media is clogged, the oil will bypass the media and return to the engine. This also happens at colder temperatures. (Dirty oil is better than no oil)

    The other bypass located in the engine oil pump and is mentioned in this article from: www.highperformer.com

    The question is which pressure relief valve is not working? The engine or filter bypass? For $20 you can buy a replacement filter mount that has a new bypass valve. If that doesn't work you'll have to consider pulling the pan to replace the oil pump.

    GM filter mount with bypass valve

    Here is a diagram of the oil flow described above:

  6. ct9a

    ct9a Epic Member 5+ Years 1000 Posts

    You rock man. Thanks for the info.! Looks like I'll be towing her home tomorrow and crossing my fingers I don't have to drop the pan. Might be a good time for some upgrades (if I can find the cash....).
  7. ct9a

    ct9a Epic Member 5+ Years 1000 Posts

    Okay. I finally had time to pull the oil filter mount out. I was playing around with it and found that the port in the picture was stuck close. When I pushed on it with a screwdriver it popped open with some effort and now it moves open to close and vice versa very easily. Is this the by-pass port that was causing me problems? Did I just fix the problem maybe?

  8. chadclan

    chadclan New Member

    Did you ever get your oil pressure/flow problem solved?

    Hey there, did you ever get your oil flow/pressure problem fixed? Was it the filter bypass?
  9. Silverado Junkie

    Silverado Junkie Rockstar 4 Years 500 Posts

    Hey guys, while we're on the topic, what is the proper oil pressure of a chevy 350?

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