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Technical SBC steams

Discussion in 'The Hokey Ass Message Board' started by AGELE55, Jan 16, 2022.

  1. AGELE55
    Joined: Jan 4, 2018
    Posts: 620

    AGELE55
    Member

    Opinions anyone?
    I have an sbc 350 that I pulled from another vehicle for use (hopefully) in my 39 Poncho. I had dreams of a minor refresh (hone, rings, bearings,etc)
    The engine ran fine when pulled but would steam excessively for about 20-30 minutes at idle, so I was hoping to find a bad head gasket. I finally got around to doing a compression test and pulling the heads and I’m a bit baffled.
    Compression as follows- first reading/ reading after squirting oil into the cylinder.
    #1. 165 / didn’t oil it.
    #2. 165 / didn’t oil it
    #3. 140 / 150
    #4. 90 / 100 Evidence of water intrusion?
    #5. 140 / 150
    #6. 110 / 130
    #7. 90 / 130
    #8. 120 /160
    So much for the el cheapo refresh…
    The #4 cylinder wall looks “mottled” like it’s been full of water? It’s not pitted, just discolored. I thought I saw evidence of a crack in the wall, so had a buddy perform a dye penetrant inspection and it looks good. There was no evidence of a blown head gasket. The plug looks the same as the others. Cylinder head valve area and piston surface are not “steam cleaned” and look like the others.
    I’ll call the local machine shop this week I guess and have the heads and block checked out..
    I’m just wondering if any of you HAMB’ers out there have seen anything similar?
    42ADAB70-E0BC-4255-A565-DA2588B9FAD6.jpeg
    5E492A8C-1634-49E6-A441-D3A0E9AD2346.jpeg
     
  2. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 6,250

    Ebbsspeed
    ALLIANCE MEMBER

    When you say "steams excessively" do you mean there is vapor coming out of the tailpipe?

    Sure looks like #4 has had some moisture in it at one time or another. Do you know the history of the motor?
     
    SS327 and hrm2k like this.
  3. lumpy 63
    Joined: Aug 2, 2010
    Posts: 2,603

    lumpy 63
    Member

    #4 had water in it for sure, most likely was stored uncovered in the past and the intake valve was open on that cylinder.
     
    hrm2k and squirrel like this.
  4. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    yeah, condensation from an open valve, during storage, leaves pitting over a large area of a bore. But usually you can feel the pits.
     

  5. AGELE55
    Joined: Jan 4, 2018
    Posts: 620

    AGELE55
    Member

    The engine came out of my school bus. It came with the bus and has an unknown past. I drove it all over the southeast US with no issues, except the steaming. When started a LOT of white steam would come out the tailpipe. Kind of like a steam locomotive…big cloud. At idle, it would take 20 minutes or more to clear up, regardless of weather, and then no steam at all. Didn’t seem to use water at an excessive rate either. The bus has a cavernous exhaust, so I figured maybe it’s just condensation boiling out? BUT, after planting a new engine in the bus, no steam, so it has to be something with the engine.
    hmmmm …
     
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    block or head cracked or a rust or casting defect hole through one, or a head gasket leaking, are the likely suspects.
     
  7. AGELE55
    Joined: Jan 4, 2018
    Posts: 620

    AGELE55
    Member

    Well…you’re exactly where I’m at, except I find zero evidence of any of them. Hopefully the machine shop can shed some light.
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    the few engines I've seen with a lot of steam, had a very clean spark plug to point me in the right direction.
     
  9. indyjps
    Joined: Feb 21, 2007
    Posts: 5,377

    indyjps
    Member

    Can you post a pic showing the deck. Looks like head gasket is still on there.

    From the discoloration around that cylinder looks like head gasket issue, could be deck or head related. Better pics of the gasket and deck itself will give more info.
     
    Last edited: Jan 16, 2022
  10. Glenn Thoreson
    Joined: Aug 13, 2010
    Posts: 925

    Glenn Thoreson
    Member
    from SW Wyoming

    I see possible evidence of water leakage on #4 just above the water passage to the lower left in the picture. I would have it checked for cracks, decked and bored to the next oversize. Overhaul kits are not too expensive to make a good engine.
     
    Kevin Ardinger likes this.
  11. lippy
    Joined: Sep 27, 2006
    Posts: 6,825

    lippy
    Member
    from Ks

    Look how clean the outer edge of that piston is. Lippy
     
  12. lippy
    Joined: Sep 27, 2006
    Posts: 6,825

    lippy
    Member
    from Ks

    I'm with Glenn, looks like a deck issue maybe.
     
    AGELE55, SEAAIRE354 and mad mikey like this.
  13. Asside from the compression numbers, and what the cylinders look like...White smoke out the tailpipe could also be a blown transmission modulator valve...sucking trans fluid into intake
     
    squirrel likes this.
  14. I agree, possible deck issue- head gasket.
     
    AGELE55 likes this.
  15. X-cpe
    Joined: Mar 9, 2018
    Posts: 1,958

    X-cpe

    Trans fluid usually gives the smoke a bluish tint.
     
    gimpyshotrods likes this.
  16. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,263

    gimpyshotrods
    ALLIANCE MEMBER

    Also smoke propagates and dissipates differently in the air from steam.

    Depending on the weather conditions, smoke will hang in the air, while steam will cool and disappear.
     
  17. My experience in this regard was an off topic 70's era Ford product. The smoke was white. No blue tint that I could see...the other telltale that the smoke had something to do with the transmission was how erratically it shifted.
     
  18. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    Around here, steam usually disappears very soon after it leaves the tailpipe.

    And I've seen white from ATF burning, also.
     
    Desoto291Hemi likes this.
  19. badshifter
    Joined: Apr 28, 2006
    Posts: 3,535

    badshifter
    Member

    That right there looks like a blown/leaking/seeping head gasket. Also seems to correspond with the clean area of the piston top.
    C2605601-A7C8-4B57-B0D7-2A723B612049.jpeg
     
  20. SEAAIRE354
    Joined: Sep 7, 2015
    Posts: 537

    SEAAIRE354
    Member

    I’m with every one else on the deck issue. Pic of the heads would help. And I would pressure test the heads if it were mine before I spent any money on machine work.
     
    AGELE55 likes this.
  21. Bad shifter ,
    Good eye !

    Tommy
     
  22. that cylinder looks like it is cracked around the 7 o,clock position just below the blue mark that "badshifter' put two post up,
     
  23. AGELE55
    Joined: Jan 4, 2018
    Posts: 620

    AGELE55
    Member

    The clean area is from a wipe down for the dye penetrant.. I will reinspect the area though.
     
  24. AGELE55
    Joined: Jan 4, 2018
    Posts: 620

    AGELE55
    Member

    Clean area on piston is from a wipe down for dye penetrant.
     
  25. AGELE55
    Joined: Jan 4, 2018
    Posts: 620

    AGELE55
    Member

    Yep, I remember a past blown head gasket where the plug, piston were really clean. Steam cleaned!
     
  26. tomcat11
    Joined: Mar 31, 2010
    Posts: 821

    tomcat11
    Member

    Sure looks that way. Need to remove the gasket and inspect that deck.
     

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