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Thread: 2 New Seals Leaking - Please Help

  1. #1
    Join Date
    Jul 2014
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    Jacksonville, FL
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    Default 2 New Seals Leaking - Please Help

    Finished resealing my valve covers with Right Stuff. Those are doing great.

    I also replaced my harmonic balancer and front crank seal, as well as, the oil pan gasket (which has the Fel-Pro gasket and the rear rubber pan seal).

    It’s the front crank seal and the rear rubber pan seal that are leaking, and they leak pretty bad too.

    The rear pan seal I get. I should have used Right Stuff silicone along with it.

    But it’s the front crank seal that i don’t understand why it’s leaking.

    Any thoughts? I need to try to get this fixed this week.

    Thanks in advance! I really appreciate it.
    1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.

  2. #2
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    Feb 2000
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    The front seal leak is likely due to a seal installation problem - or a nick on the seal surface of the damper - which damaged the seal. Also, there is a front/back to these seals. And, a front crank seal need to be installed with sealant around its outer diameter so it properly seals inside the aluminum front cover.

    The rubber half-circle seal that seals the rear of the pan against the rear main cap is not supposed to installed with sealant against the main cap. It's designed in a way that a "squish" during pan installation will prevent leaks.

    Do not use the perimeter pan gasket supplied with the Fel-Pro gasket kit. Use only a 5mm bead of silicone (i.e. Right Stuff). Using Fel-Pro's perimeter gasket will increase the odds of a pan rail leak. Also, the thickness of the pan rail gasket reduces the amount of "squish" on the oil pan's rear half-circle rubber seal.

    Question: How do you know that the rear pan seal is leaking and not the rear main seal?

  3. #3
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    Quote Originally Posted by More Power View Post
    The front seal leak is likely due to a seal installation problem - or a nick on the seal surface of the damper - which damaged the seal. Also, there is a front/back to these seals. And, a front crank seal need to be installed with sealant around its outer diameter so it properly seals inside the aluminum front cover.

    The rubber half-circle seal that seals the rear of the pan against the rear main cap is not supposed to installed with sealant against the main cap. It's designed in a way that a "squish" during pan installation will prevent leaks.

    Do not use the perimeter pan gasket supplied with the Fel-Pro gasket kit. Use only a 5mm bead of silicone (i.e. Right Stuff). Using Fel-Pro's perimeter gasket will increase the odds of a pan rail leak. Also, the thickness of the pan rail gasket reduces the amount of "squish" on the oil pan's rear half-circle rubber seal.

    Question: How do you know that the rear pan seal is leaking and not the rear main seal?
    Thanks for the feedback. As it turns out, I may actually be mistaking a front pan seal leak for the front crank seal leak. Will be able to inspect further once I get the pan back off.

    I made the mistake of using the Fel-Pro gasket and no silicone at all.

    I used only Right Stuff on the valve covers, and of course, they do not leak and the oil pan does.

    I'll be dropping the oil pan here shortly to reseal with Right Stuff only and the rear rubber gasket.

    As for how I know its the rear pan leaking and not the rear main seal ... simply put, I can see it. With the inspection cover off, I can watch it and can see oil seeping out between the pan and the rubber seal, right at the very bottom of the half circle. Perhaps it's because the pan is mis-shaped, I am not sure. I imagine I'll probably put a small amount of Right Stuff between the pan and the half circle gasket, but not between the half circle gasket and the main cap.
    1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.

  4. #4
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    At this point, I’m about 98% confident it’s the pan. I pulled it off, and felt my way around the crank seal, and detected no trace of fresh oil from the crank seal. The front pan seal, however, was definitely leaking.

    Working on scraping the gasket off the pan now. Will reseal with Right Stuff, reinstall, and let cure over night before adding oil and test driving.

    Will post up results tomorrow.
    1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.

  5. #5
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    I'm sure it'll be fine after this.

    Start all of the pan bolts before tightening any of them - leave them just loose enough that the pan can move around. The pan will need to move a little - shift a little to get all of the bolts started, especially the front-most bolts that angle upward into the aluminum front cover. Jim

  6. #6
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    Quote Originally Posted by More Power View Post
    I'm sure it'll be fine after this.

    Start all of the pan bolts before tightening any of them - leave them just loose enough that the pan can move around. The pan will need to move a little - shift a little to get all of the bolts started, especially the front-most bolts that angle upward into the aluminum front cover. Jim
    Done. Thanks for the guidance. I’ve got it in and bolts just barely snug. Will tighten it all down in 24 hours. Hope it DOES work out because this is dirty work .
    Last edited by AugustDiesel; 02-25-2019 at 16:12. Reason: Correction
    1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.

  7. #7
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    Jacksonville, FL
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    Oil pan leaks are fixed! And NO crank seal leaks. Let it idle for about an hour and then drove it around the neighborhood for about 20 miles. Glad to put this behind me.
    1988 K10 Suburban. 6.5L NA Goodwrench Engine: 506 block cast on August 12, 1996. Heavy Duty built 700R4. Full-floating 14 bolt rear axle. 3/4ton 10 bolt front. Brand new 305/75R16 Procomp AT Sport tires on brand new 16x8 steel wheels.

  8. #8
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    Quote Originally Posted by AugustDiesel View Post
    Oil pan leaks are fixed! And NO crank seal leaks. Let it idle for about an hour and then drove it around the neighborhood for about 20 miles. Glad to put this behind me.
    Good job! You're now an expert on sealing the oil pan.

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