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Thread: What seal leaks first on an overfull 350?

  1. #1


    Let's say that a hippy put 6 quarts of oil in his/her 350. Theoretically, what seal would leak said oil out- front main, rear main, pan, valve covers...what?

    Not that I did this....and then replaced my oil pan gasket 3 times...and then replaced my front main 2 times....and then replaced my pan, timing cover, pan gasket, timing cover gasket, timing cover seal, and harmonic balancer...and the whole time refused to stop filling it back up with 6 quarts. I'm just posting this question for a bud.

    Thanks....for helping him figure this out.

  2. #2

    Default What seal leaks first on an overfull 350?

    Your bud is a moron. Why would he do something so stupid.
    Overfilling by one quart should not really cause anything to leak if all your, oops, I mean his gaskets are new and properly installed. What he might run into is some more oil than normal being whipped around the inside of the crankcase. This could make an poor gasket or seal show itself more readily. Tell your bud to pull his head out and take a breath.
    This post is closed-captioned for the hearing impaired.

  3. #3
    Join Date
    Sep 1998
    North Central Wisconsin


    The crank whipping the oil can help break the oil down sooner and make it foam...doesnt lube well as foam...can be hard on he assembly if there is alot of it on the crank as it can change the balance of the mud on a wheel...the faster you go the worse it is...
    On a slightly related topic...
    I once worked in a store where this guy came in and bought 5 quarts of oil....few minutes later he comes back and buys 4 more...then he comes back and asks me how much oil does his motor take? Well this 25-30 year old had poured all the oil into this thing already and since the oil wasnt up to the FILL CAP, he figured it wasnt full.......had no clue what a dipstick was....all he needed was a mirror and he could have seen one!!
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  4. #4

    Default Octane, lead subsitute for the 230?

    Brianna: probably the mains. I still say your damper and seal aren't in sync. Otherwise, it wouldn't be leaking there....
    **I heart Bump_r **

  5. #5


    My frined appreciates your help. What he did was replace all the bearings and as a precaution he filled the filter with a bottle of STP, then added the 5 quarts to the crankcase figuring that the extra 1/2 quart wouldn't matter much, but would help upon startup.
    Then, after running the motor about 10 minutes and seeing that it all went fine he took it out on the highway and ran it for a mile or 2. Upon returning to his shop he noted that the rear main (that he just replaced) ws not leaking, but that there was an oil leak from the front of the motor. So he replaced the pan gasket thinking that it had been installed bad. Filled it back up with 5 quarts. Ran it and there was oil all over the front again. Figured that he installed gasket #2 wrong agian and so he redid it.
    Same thing. 5 quarts back in, no need for a new filter since it hadn't ran much. Leaked from the front. Stumpy got frustrated, replaced the seal around the harmonic balancer, and the pan gasket. Same thing.
    Stumpy then got a whole new pan, a new timing chain cover, and a new harmonic balancer and installed them all last saturday.

    Same thing- no leak at low RPMs, but at 3K or so it starts to leak from around the harmonic balancer. Seal was oiled, harmonic balancer was oiled. Harmonic balancer is new, and the right size.
    Runnig 2 PVC valves. All cylinders show good compression.
    When the motor is running and the oil fill cap is off there is no noticeable positive pressure.
    Chain is new....timing cover is a GM factory one with the bolt-on timing tab. Harmonic balancer is an Autozone deal..but new and all.

    Anyone got any ideas? I'm sick of leaks.

  6. #6
    Join Date
    Sep 1998
    North Central Wisconsin


    "I'm sick of leaks."

    Maybe the motor is sick of him abusing it and its spitting at him out of spite...sorry thats all I got for him...cept maybe ill fitting parts or irregular surfaces that need to be straightened or machined/smoothed/cleaned....
    Lord send your Holy Ghost into our hearts and make the desire of our hearts Your Will.

    Pro-choice, that's a LIE, babies don't choose to die!!

  7. #7


    All kidding aside- The most probably theory I have heard is missalighnment with the crank snout and the hole for the seal. Is that possible? Wouldn't that make the motor eat the bearings quick? When I installed the main caps I double and tripple checked them and there wasn't one that was not seated right or anything like that. And my oil PSI is higher than it was before the bearing install.

    I got a new bearing, a harmonic balancer installer (I had been using all-thread, but it kept stripping) and tongiht I'm gonna regulate and then tomorrow I plan to drive my new non-leaking motor to work.

    I blame Brute for all this as his negative thoughts have tainted the project,

  8. #8


    Brian: before spending any more of The Jeaner's grocery money, take a breath and reflect for a moment. If it's only leaking around the timing cover, what does that tell you? That something isn't sealing there. Since it's not a complicated assembly, the only deductions can be A. The timing cover isself ain't stuck on right, or B. The front main isn't sealed right, or possibly C. There is a mismatch betwixt timing cover seal and harmonic balancer shaft. (not unheard of w/parts store... parts)

    Let me know what you find, SuperSleuth. No more spending until the cause is determined. Throwing money at it hasn't helped yet, has it? hheheh
    **I heart Bump_r **

  9. #9



    Your logic is good. I plan to take the harmonic balancer off again tonight and then 1) look to see if the crank snout is centered in the gasket, 2) make sure the harmonic balancer had no rough edges that possibly ate the seal, and 3) replace the seal.

    I guess that I feel that A) 3 harmonic balancer seals can't be bad, B) I took off the timing chain cover 2 times now and at least one of those should have been reinstalled right, and C) that this is simple and I am a moron.

    I wonder if none of my motor works work because:
    1) I have limited experience assembling a motor,
    2) I rush through said installation
    3) I demand perfection and if there is one drop leaking I rush to replace a seal
    4) I am a moron and should have been drown at birth
    5) I get the parts from cheap sources (Autozone, Ebay, found behind the mall)
    6) The people I get advice from secretly hate me and want me to fail for their amusement.

    Sorry. I realized that this thread is veering into BS. I'll do better.

    Anyone else have any advice. What I'm looking for is "This once happened to me. It was because of XXXXXX and when I realized it I did XXXXXX and felt sooo stupid. Glad I'm not the only one!"

    Thanks all,

  10. #10

    Default Which cartoon is better?

    Brian: I've had a few SBC's leaking due to worn balancer snouts. Parts store.. parts can vary in quality, as can their seals. Your plan is solid, and I wish you luck this time.
    1. limited experience just means you have to go slower for a while.
    2. Don't rush, you get out of it what you put in. As in, I took my time and didn't have to retorque head bolts. Patience, grasshopper.
    3. Perfection is a good aim but unachievable.
    4. No argument here, and even your mom agrees with me. Sad. But yes, veering into BS hahah
    5. Again, you get what you pay for, not always a bad thing to pay less though.
    6. Sure it's amusing to think of you taking off your oil pan 3 times, but I'd like your truck to run. So I can drive it and convince my wife I can't live without a topless.... truck.
    **I heart Bump_r **

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