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Technical SBC oil pan

Discussion in 'The Hokey Ass Message Board' started by Ron Brown, Jun 24, 2021.

  1. Ron Brown
    Joined: Jul 6, 2015
    Posts: 1,625

    Ron Brown
    ALLIANCE MEMBER

    Can someone tell me what causes the SBC to require a regular or a thick pan gasket....is it the pan or is it the timing cover or both...the pan I have now takes the the thick gasket but Ive been chasing a leak and finally found the pan gasket is leaking where it goes over the rear main. I replaced the pan gasket, for the 3rd time, and it still leaks at the back, so all this being said, if I get another pan will it still take the thick gasket or the thin gasket...
     
    Stogy likes this.
  2. AGELE55
    Joined: Jan 4, 2018
    Posts: 343

    AGELE55
    Member

    You sure it’s the pan and not the rear main seal? Just asking..
     
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  3. Belle53
    Joined: Aug 13, 2019
    Posts: 46

    Belle53

    it's all in the pan....most oil pan gasket sets include both front seals and how to measure for it

    not sure why the rear is your problem
     
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  4. bchctybob
    Joined: Sep 18, 2011
    Posts: 3,094

    bchctybob
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  5. Dennis D
    Joined: May 2, 2009
    Posts: 743

    Dennis D
    Member

    Only applies to the front gasket. Rears are the same as long as it is the two piece main seal. IIRC
     
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  6. squirrel
    Joined: Sep 23, 2004
    Posts: 49,311

    squirrel
    Member

    The rear is the same on all of the two piece seal pans.

    If it's an aftermarket pan, it's probably just badly made. If it's an original pan, then it might be damaged?

    As they said, the difference in pans is that in 1974, chevy decided to make it easier on the mechanics doing the warranty work to replace all the failed plastic tooth timing sprockets, by opening up the front so it would be easier to work on the timing cover without having to drop the pan. So they started using a different pan and thicker front gasket.
     
  7. olscrounger
    Joined: Feb 23, 2008
    Posts: 4,329

    olscrounger
    ALLIANCE MEMBER

    aftermarket pans are always a problem.
     
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  8. bchctybob
    Joined: Sep 18, 2011
    Posts: 3,094

    bchctybob
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    Couldn't hurt to perform that same check on the rear of the pan just to see if it's capable of adequately clamping the gasket or if it was made wrong or damaged.
     
  9. Ron Brown
    Joined: Jul 6, 2015
    Posts: 1,625

    Ron Brown
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    OK....so the pan I have now takes the thick gasket so a replacement pan needs to be the same....correct? It is not the 2 piece rear main seal leaking (new), it is definitely the gasket as I reached up and tapped the flange (bent it slightly) with a drift punch and nearly stopped the leak, so I know its the pan gasket (using Felpro 34510 part no).
    My only concern in ordering a new pan was if all the pans are the same and the timing cover makes the difference in gaskets or if its the pan that makes the difference? Looks like its the pan....Can I use a pan made for the thin gasket and just use the thin gasket or would I need to change the timing cover as well.
     
  10. After 3 times,,,I believe I would do some careful measurements .
    That is a real headache !

    why change the timing cover,,,it’s the pan .
    I would measure the pan,,,,and do some sweet persuasion on the lip that fits the rear gasket .
    You said you almost had it stopped,,,,they are pretty ply able,,,,,some gentle,,tough love should fix it .
    And a healthy dose of good sealer .

    Tommy
     
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  11. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 630

    MAD MIKE
    Member
    from 94577

    Another vote for check measurements and to check the straightness of the tin.
    Even the OEM original steel pans may not be truly square to their original block.
    Before you start pounding on the front or rear seal surfaces, verify the pan with no gasket will sit flat on the block. If you spend time fixing the front/rear seal surfaces, but don't fix the pan itself, once you bolt it down the pan will twist the front/rear seal surfaces out of square and it will leak again. It can be a PITA, especially on car, but well worth the effort when the oil pan stays dry.
     
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  12. Lloyd's paint & glass
    Joined: Nov 16, 2019
    Posts: 4,900

    Lloyd's paint & glass
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    Are you using the one piece gasket, or the rubber front and rear with the cork sides? If you're using the latter, put a pretty good dab of rtv at the cork/rubber junction, or they'll always leak. At least that's my experience.
     
  13. Ron Brown
    Joined: Jul 6, 2015
    Posts: 1,625

    Ron Brown
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    using the 1 piece Felpro #34510....used one without gasket maker...leak....then tried with gasket maker on engine side only...leak...then tried gasket maker both sides....leak

    I can see the leak hanging off the pan lip at bottom of main cap...it is not the rear main seal, its the pan gasket...

    I just read on another site that some guys had issues with the supplied bolts being a little too long and bottoming out before getting tight enough...I will pull the 2 corner bolts and the next 2 1/4" bolts on both sides and use shorter ones, just to see.
     
    Last edited: Jun 24, 2021
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  14. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,397

    2OLD2FAST
    Member
    from illinois

    I'll echo the " are you sure its the pan " sentiment , oil leaks can be very frustrating & difficult to diagnose , you certainly wouldn't be the first to get focused on one idea , overlooking the real problem !BTDT !
    Keep in mind there is virtually zero pressure on the oil pan gasket , just like V/C gaskets , intake " China wall" gaskets , etc.
    The front & rear main seals have very low oil pressure also .
     
    Last edited: Jun 25, 2021
  15. Budget36
    Joined: Nov 29, 2014
    Posts: 6,773

    Budget36
    Member

    Will the 1pc RMS pan “spreaders” work on older stuff? The ‘89 block I took apart had a steel piece that went along each side of the oil pan. I’ll take a pic of them later, but assume it should work on earlier blocks as well.
    Spreads the bolt load out evenly.
     
  16. Not quite "always".........my son's SBC has an aftermarket pan, installed properly, and has not leaked a drop in over 25 years......
     
  17. Dennis D
    Joined: May 2, 2009
    Posts: 743

    Dennis D
    Member

    One other thing you may want to check is the crank endplay. Sometimes when the balancer gets installed with a BFH, it will damage the thrust surface of the brg. The crank working back and forth will cause a leak in some cases. Also, excessive clearance in the rear main brg to crank journal will cause problems also. I have in the past chased a pan leak only to find the rear on the intake or the oil line or sending unit was the culprit. Just some thoughts..... D
     
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  18. X-cpe
    Joined: Mar 9, 2018
    Posts: 1,191

    X-cpe

    If you are getting a radial spray pattern on the back of the flywheel it's most likely the rear main oil seal.
     
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  19. Ron Brown
    Joined: Jul 6, 2015
    Posts: 1,625

    Ron Brown
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    dry as a bone on the flex plate...its dripping straight down off the pan lip...I actually ordered a new pan from JEGs this morning.
     
  20. So did you order thick or thin gasket ?
     
  21. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,701

    Blues4U
    Member
    from So Cal

    Same here, the 283 in my A pickup has a chromed and finned aftermarket pan on it that was there when I got it. Has never leaked a drop. The transmission now, that's another story.... ;)
     
  22. SS327
    Joined: Sep 11, 2017
    Posts: 293

    SS327

    It might be the rear main seal retainer gasket that is leaking.
     
  23. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,397

    2OLD2FAST
    Member
    from illinois

    Huh ?
     
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  24. 2OLD2FAST
    Joined: Feb 3, 2010
    Posts: 3,397

    2OLD2FAST
    Member
    from illinois

    Doesn't leak a drop , 15 years... Screenshot_2021-06-25-21-26-50.png
     
  25. SS327
    Joined: Sep 11, 2017
    Posts: 293

    SS327

    The one piece rear main blocks used a paper type gasket under the rear main seal retainer. Sometimes they would leak if a little etc was not used on the seam. It would look like a pan gasket when infact it is not.
     
  26. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,586

    6sally6
    Member

    I don't use a pan gasket!!!
    Clean with lacquer thinner REAL well........put a THICK layer of RTV all around the area where the gasket would go...while it's still tacky set the pan in place and bolt it down.
    Don't be wiggling it around.....set it in place and bolt it down. Wait about 12 hours before putting in oil and running engine.
    Shouldn't leak IF you put the RTV on thick enough!
    It should be YEARS before you need to pull the pan so...........a near permanent fix.
    6sally6
     
  27. Ron Brown
    Joined: Jul 6, 2015
    Posts: 1,625

    Ron Brown
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    comes with a gasket...thin
     
  28. SS327,
    It’s a two piece rear seal engine.
    Way back near the start of the thread .

    Tommy
     
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  29. SS327
    Joined: Sep 11, 2017
    Posts: 293

    SS327

    Sorry damned ol eyes. I always offset the ends of the seal with the block surface about 3/16. I also use a slight smear of anaerobic sealer on the ends of the cap. Never had a pan or rear main leak. I have had 2 oil pans rust out though. 1 stock and 1 Moroso.
     
  30. This is exactly what International did on the Ford 7.3 diesel. It works, but can be difficult to get sealed if the engine is still in the truck and internal oil is seeping down from above while installing the pan.
    The only aftermarket pan I’ve ever used is Moroso and it never leaked a drop.
     
    olscrounger likes this.

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