69 430 oil pressure in cooling system

Discussion in 'Street/strip 400/430/455' started by Andyshooter, Nov 10, 2019.

  1. Andyshooter

    Andyshooter Member

    I'm new to buick big blocks. I have a fresh 69 430 that has oil pressure in the cooling system upon initial start up. I suspect it may be getting in from the head gaskets. I have removed the heads and see nothing out of the ordinary. I have lots of experience building small block Chevy engines but have never seen anything like this. Please help with this conundrum.
     
  2. flynbuick

    flynbuick Guest

    We moved your thread to a better section for your issue.
     
  3. LARRY70GS

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

    I'm not sure what "oil pressure" in the cooling system means. Oil in the coolant can simply be a leaking trans cooler into the radiator. Is there coolant mixing in with the crank case oil making an emulsion? You should have done a compression check first before you removed the heads. There is also a test for combustion gases in the coolant as well as a radiator and system pressure test.
     
  4. LARRY70GS

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

    I always thought that very unlikely. Coolant and oil passages are pretty far apart. External oil or coolant leaks are much more likely.
     
  5. Andyshooter

    Andyshooter Member

    Oil is being forced into the cooling system with significant pressure. When started the radiator immediately overflowed with fresh oil and coolant. I am a 25 year master technician and from my experience I'd say it full oil pressure being forced into the cooling system.
     
  6. Andyshooter

    Andyshooter Member

    I did do a compression test and all was good. The engine pumped 3 quarts of oil from crankcase to cooling system in 15 seconds therefore I believe the oil leak must be under pressure
     
  7. Andyshooter

    Andyshooter Member

    I agree with you Larry. I will install the heads again Monday with new head gaskets and prime it to see if maybe it was just the head gasket. The timing cover is brand new by the way.
     
  8. LARRY70GS

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

    A 430 would oil the rockers through the block and heads, so you have that hole in the deck. I suppose if the head gasket failed from there to a coolant passage, that would do it. Is the engine converted to push rod oiling? If so, is that passageway blocked off?

    Blockmods101-1493913082.jpg
    Doesn't look like there is a coolant passage anywhere near it though.
     
    Last edited: Nov 10, 2019
  9. Mark Demko

    Mark Demko Well-Known Member

    So its transmission oil, NOT engine oil?
    If so, then the transmission cooler in the radiator is leaking.
     
  10. Andyshooter

    Andyshooter Member

    There is a coolant passage on the head side just 3/8ths of an inch from that oil passage.
     
  11. Andyshooter

    Andyshooter Member

    It is 100 percent engine oil.
     
  12. LARRY70GS

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

    OK, next question, do you have hollow pushrods and and 70 and up lifters? If so, you should block that hole in the block.
     
  13. Andyshooter

    Andyshooter Member

    I have solid pushrods but the lifters are comp cam #910-16. They would definitely be able to take hollow pushrods. Like I said before this is the 1st 430 I have ever worked on so I didn't know if I could just plug those passages and go hollow.
     
  14. Andyshooter

    Andyshooter Member

    Is there any way I have the heads on the wrong side? I did see a casting on the heads one has a 3 on it and the other has a 4 . The numbers are on the block side of the heads below the intake runners. I'm used to chevy 350s where it doesn't matter. Maybe I'm the cause of this issue.
     
    Last edited: Nov 14, 2019
  15. 1969RIVI

    1969RIVI Well-Known Member

    The heads are interchangeable and not side specific.
     
  16. Andyshooter

    Andyshooter Member

    Good. I'm glad that's the case.
     
  17. Mark Demko

    Mark Demko Well-Known Member

    I would explore what Bill said.
    That's the only area I can think off too that has coolant and oil in close proximity to one another.
     
  18. Brian Albrecht

    Brian Albrecht Gold Level Monkey

    What are the casting numbers on the heads? If they've been sourced from a '72 or later 455, that maybe your issue as Buick changed water jackets. There are probably numerous threads on here. I've personally been a victim (hated those water pressure jokes).
     
  19. 1969RIVI

    1969RIVI Well-Known Member

    This is true, you can use earlier heads on later blocks but not the other way around. The engine in my car now is 72 455 block and heads but the engine I'm building is a 70 455 block with 68 430 heads. I didn't ask that question when I made my earlier post sorry about that.
     
  20. Andyshooter

    Andyshooter Member

    This is the original engine for my riv. I only rebuilt it because it had been sitting since 1973. The riv only has 16k on it. Someone had taken the carb off years ago and left the intake wide open. It's a true barn find. It was in a field 6 inches in the mud. The tags on the plate expired in July 73
     

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