350 Oil pressure problems! Trouble shooting tips requested.

Discussion in 'Small Block Tech' started by Twixter75, Mar 3, 2024.

  1. Twixter75

    Twixter75 Member

    Hello All!

    Brand new build on my 69 350 stock skylark.

    Bored out the oil passages to 1/2 inch. Same thing with the pickup passage. Got a new pickup tube from TA performance as the old one had a tear in the screen from a child twisting my philips head through it (I love my kids and their hijinks) but I thought "better safe than sorry."

    Build Details
    10.5 Compression Pistons
    CAM: TA_304S-350
    Iron heads.

    Kept as many stock parts as I could including the dented oil pan.

    I clearanced the pump at .002-.003.
    I filled up the filter with oil, packed the oil pump with Vaseline.

    Started. Runs rough as expected, and the lifters rattled for a bit but then the lifters stopped making noise. All the pushrods coming up from the lifters turned (I had marked them before start) and seem to have limited play. Used a head gun and all the exhaust manifolds were at 300 degrees except for cylinder #7 which I suspect is miss firing. Checked the plug and it was coffee brown and didn't smell like gas at all.

    Dummy light goes off when I start her up, (from what I've read 10 lbs of pressure turns it off) but after running for a while at 1000-2000 RPM the light comes back on.
    Oil is getting up to the valve covers as its pooled there in the low spots when I pull the covers off.
    I also put a oil pressure sensor sender at the rear of the block but since the dummie light goes off, I know the pressure is WAY low at the front, so it hasn't even made sense to me to check it at that back.
    Also I installed the high volume gears and the new faceplate from TA performance.
    I've also tried getting oil pressure by using a old distributor I cut apart to prime the pump with a 1,000 rpm drill. Dummy light goes off but the oil pressure gauge on the same t is brand new and doesn't read pressure.
    I've checked the oil bypass valve and spring. It wasn't stuck.

    I didn't clearance the oil pickup tube, and kinda had an issue installing it as the oil pan was dented. It was a cute story involving my parents who were the original owners, so I didn't worry about knocking the dent out.

    lifting the engine to drop the pan, get a new gasket and seal and clearencing the pickup tube DOESN'T sound like a party.

    What I'm trying to think about is order of operations for testing, lifting the block to clearance the oil pickup tube as a last resort. Here's what I'm thinking:

    1. Blocking the oil filter outlet with a plug. That way I could use a manual pump to see if I can build pressure to the drivetrain and valve train. Maybe the problem is there? Checking at the rear of the block to see if the pressure I'm building at the front is within 10 psi.

    2. Trying to manually add pressure with a pump via the pressure sender I added to the back of the block to see if I can get it to hold pressure running backwards.

    3. Help! :)

    As you can see I'm having a bit of trouble organizing my thoughts so I thought I'd reach out for help!
  2. Matt Knutson

    Matt Knutson Well-Known Member

    Screw a guage into the block and determine pressure coming off the pump. Straighten out the cute dent in the pan or buy a new pan and hang the memory on the wall. It must be making some kind of pressure if oil made it to the top - both sides I hope.
    Max Damage and TrunkMonkey like this.
  3. Twixter75

    Twixter75 Member

    I'll check the other side to make sure the oil made it up there. Too. Lifters got pumped so SOMETHING made it over to the passengers side.
    I have a brass barb screwed in to where the oil pressure sending unit goes, then a length of hose up to a T that gives pressure to the sending unit itself and an after market oil gage. The oil gage wiggles, the sender goes off, but that's as much pressure as I can build.
  4. 436'd Skylark

    436'd Skylark Sweet Fancy Moses!!!!!

    You gotta put a gauge on first and see what you actually have.

    If the dummy light is accurate and its on at 2000 rpm, then I hate to say it, but you are cooked..
    Matt Knutson likes this.
  5. Jim Nichols

    Jim Nichols Well-Known Member

    Did you forget the little gasket between pickup and block? I like about .001 at pump. Did you have too much clearance on rod and main bearings so that is why the High Volume gears?
  6. Max Damage

    Max Damage I'm working on it!

    What kind of oil are you running? 10-30? The fact that it has pressure cold and then it goes away isn't good. As others have said, get an accurate reading first.

    The fact that it has pressure cold pretty much eliminates the pickup being blocked by the pan in my mind.
  7. Twixter75

    Twixter75 Member

    Really? I have read that minimum Clarence was .002!
    I got the high volume gears just because.
    Clearance on rod and main bearings was in spec. Did it like Santa Clause and checked it twice.
    Nope. Got the little gasket on there and the bolts torqued to spec.
  8. Twixter75

    Twixter75 Member

    I did use the back grooved cam bearings.
    The builder didn't have them installed per the instructions, but I took pictures and sent them to TA performance and got the thumbs up from Mike. What was your thought?
  9. Twixter75

    Twixter75 Member

    Using 10-30.
    Thinking that maybe the pump is pushing the oil out of the full oil filter at first, and getting pressure, then dropping when no more oil comes into the pump from the pickup.
    Max Damage likes this.
  10. Twixter75

    Twixter75 Member

    No, I got pressure when it was first running. Upped to 2000 rpm....checked. Was okay. Adjusted timing a bit to bring the vacume up at idle. Went back to turn it off at the key and saw the light on again. Probably 5 minutes max all together.
  11. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    I would not run the engine until you verify oil pressure. Screw a pressure gauge directly into the oil pressure tap at the front of the engine. Remove the distributor, and run the pump directly with a good drill. With cold oil, you should have no problem getting 40-60 psi of pressure, depending on which relief spring is in there. If pressure is good cold, and falls off when hot, that is an indication of too much end clearance inside the pump, or at the bearings.

    Ditch the high pressure gears, you do not need them with proper clearance on a stock pump.

    I would also remove the filter and cut it open to check for bearing material.

    If the filter is clean, that could mean good news.

    Make sure you didn't pop a front galley plug. That would destroy your oil pressure.
    Last edited: Mar 3, 2024
    Max Damage likes this.
  12. alec296

    alec296 i need another buick

    What rockers did you use? Lifters and pushrods? 69 heads oil thru head not pushrod. Did you pack pump with Vaseline? Or fill with oil?
  13. Jim Nichols

    Jim Nichols Well-Known Member

    oil press relief.jpeg Some people use the wrong relief spring too. I think the newer metric cover uses a shorter spring than the older cover. If you have too short of spring you would have very low oil pressure.

    Oil pressure concern # 412 | V8buick.com
    Last edited: Mar 3, 2024
    Max Damage and knucklebusted like this.
  14. knucklebusted

    knucklebusted Well-Known Member

    If you have too short a spring, you probably didn't contact the spring while installing the end bolt.
  15. Twixter75

    Twixter75 Member

    Okay ya'll, bad news.

    No mess in the oil filter. But, I suspect, that's because no oil came into the filter from the pan.

    Drained the oil from the pan. Found two or three 1/32 inch gravel like chunks when I drained the pan that were shiny. Likely barring material. Bad news.

    I suspect that the oil pressure I had was from the oil pump pushing oil out of the filter with air. But alas, not enough to create real oil pressure nor save my berrings.

    Likely, I no longer have to just drop the pan, but probably have to order new bearings all around and work through it all again since I don't know what pieces of what I found in the pan.

    I think that my mistake was using a drill to try and create oil pressure....and when I got 5-10 lbs of pressure, I assumed all was primed and good. Never felt the drill twist in my hands like it should have if I picked up prime.

    Good news is that I learned so much that I can probably tear down the engine, replace the bearings, fix the pickup problem and get it running again in no time.

    I embraced the journey, knowing that I may not know enough to try and succeed on my first pass.

    TA performance is going to get a bit more of my money, and they are a great company to give it to. I won't be starting the engine till I get a solid oil pressure reading from the get go!

    If it was easy, everyone would do it...and where's the fun in that?!?@!

    Thanks for the ideas and suggestions! I'll try to keep ya'll updated.


  16. Twixter75

    Twixter75 Member

    Filling this in after I did my previous post:
    Stock Rockers. Solid lifters. Stock pushrods. You are correct: heads oil through enlarged bolt holes, and not the pushrods. I did pack the pump with Vaseline...AND filled the filter with oil. Don't think that saved me though when the pickup didn't pickup oil!
    knucklebusted likes this.
  17. knucklebusted

    knucklebusted Well-Known Member

    Ouch! That's a tough one. Do you think the pickup was mashed against the bottom of the pan and starved it?

    I always use a little silly putty cone on the top of the pickup while it is inverted on the stand. Then I put the pan in place without a gasket to see how squished the silly putty is. If it is mashed into the pickup without the gasket, it is too close. Gaskets are only about 1/16" think once cinched down.

    With any luck, you can polish the crank and only be out rod, crank bearings, gaskets and a little machine shop verification time.
    Max Damage likes this.
  18. Mark Demko

    Mark Demko Well-Known Member

    Bad move, is the dent on the bottom?

    Faceplate....... you mean the oil pump cover?
    If so, remove your oil filter and see if the cup plug for the filter bypass popped out, I had that happen to me on a TA pump cover, pressure dropped to 20 psi MAX.

    LOL, yah better hope oil got on that (right) side, that side feeds the main bearings!
  19. Mark Demko

    Mark Demko Well-Known Member

    SLOOOOOOOOOOOOOOOOOW DOWN, take your time, ask questions, theres no rush.
    TrunkMonkey likes this.
  20. alec296

    alec296 i need another buick

    Any chance a front oil galley core plug got blown out?

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