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Technical Blow by

Discussion in 'Traditional Hot Rods' started by Barret, Oct 18, 2018.

  1. Barret
    Joined: Oct 18, 2018
    Posts: 3

    Barret

    I bought a 1923 project T-Bucket about 2-3 years ago. Chevy 350. When I first got it, took hours to get it running. Finally figured it out. There was a ball valve fuel shutoff under the fuel tank. Why, I asked myself. Soon figured it out. Tried to start it one day and it just wouldn't. Spit, sputtered and smoked. Finally it wouldn't do anything. Checked the oil and it was FULL of gas.

    So, I've hydrolocked it, but when I drained it put new oil in, now it runs. About a year goes by and dang thing is running better than ever. Did some carb work and changed the timing chain. Dreamy, but, the blowby is terrible. It's to the point that something has got to be done. I cannot do an overhaul, $. I have not had the heads off.

    Now I'm going to ask the impossible question. What is causing the blowby? Ring(s)? Rod(but wouldn't that make it run bad)? Stuck valve(run bad)?

    I'm thinking it is a cracked ring. I know that conventional wisdom is not to do just a ring job, but, I can get to everything above the crank without removing the engine and a set of rings can be had for $50-$100. The car may be driven 500 miles a year, so it would take a long time for the lack of a true overhaul to demonstrate itself.

    Is it something other than the rings causing the blowby?

    Thoughts?

    Barret
     
  2. It's somewhat of a Band-Aid but adding a PCV system will help to minimize the blowby.
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 43,430

    squirrel
    Member

    what do you have for crankcase breathers? how about some pictures of the engine?

    Yes, PCV will hide blowby to some extent.

    Yes, you can do a ring job and not replace anything else, besides gaskets, if you so desire. There is a thread going about what it means to freshen up an engine...you'll see that opinions are all over the place. But those who say you need to spend two grand or more freshening up your engine, are not likely to donate the money, so you don't need to listen to them
     
  4. If you don’t already have a compression tester and a leak down tester, then for short money go to the nearest Harbor Freight Tools and get both. (Don’t say “HARBOR FREIGHT TOOLS!” too loudly around here, gets the old farts riled up)

    Spend some time on YouTube learning to do both. This should help you isolate the problem and you will have a better idea what to do about it, if anything.

    If it’s one cracked ring, it’s a pain but you could pull that piston and give it a go.


    Sent from my iPhone using The H.A.M.B. mobile app
     
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  5. squirrel
    Joined: Sep 23, 2004
    Posts: 43,430

    squirrel
    Member

    blowby is usually caused by worn rings in all the cylinders, it's just what happens when you put a lot of miles on an engine.
     
  6. Truckdoctor Andy
    Joined: Jan 13, 2017
    Posts: 847

    Truckdoctor Andy
    Member

    Check the Northern Auto Supply website for parts. They have a re-ring kit with piston rings, rod and main bearings, and complete gasket kit for $85.00. It’s brand name stuff too. Use a “dingle berry” ball hone to de-glaze the cylinders, and your good to go. A valve job on the heads would also be nice if you got the extra dough. As long as your cylinders aren’t scored up, you will be surprised at how long this will last.


    Sent from my iPhone using The H.A.M.B. mobile app
     
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  7. F&J
    Joined: Apr 5, 2007
    Posts: 13,184

    F&J
    ALLIANCE MEMBER

    The amount of slop in that old chain should tell the story ...if it was really worn out, the rings are also the same "high mileage"

    Not being a wise-ass, but if you only drive it 500 miles a year?...is it worth the time, $, and effort to try to make it better if it still runs nice?

    .
     
  8. Lucky667
    Joined: Dec 3, 2008
    Posts: 2,233

    Lucky667
    ALLIANCE MEMBER
    from TX

    Where do you live ? If you aren't too far away, . . . I'll help with tools & labor, . . . no charge.
     
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  9. big duece
    Joined: Jul 28, 2008
    Posts: 5,591

    big duece
    Member
    from kansas

    If there was that much gas in the oil pan, I wonder if some of the oil film was removed from the cylinders and had a few dry start ups, maybe left some scuffing of the cylinder walls.
     
  10. Barret
    Joined: Oct 18, 2018
    Posts: 3

    Barret

    I've replaced the PCV valve and it didn't do much.
    There was lots of play in the timing chain, so I think that is a pretty good indicator like Frank said. The problem with leaving it as is, is that no one wants to ride with me anymore. I basically have 3 exhaust pipes and no windshield(yet). Even a short ride and you end up smelling like an oil field.
    Andy, exactly what I was considering. I'm liking that price for the kit! Thanks.
    Big Duece I think you may be on to something here. It has gotten progressively worse. Could I have done enough damage that I cannot hone out the scuffing?
    For those that have attempted something like this, say I drop the oil pan, remove intake, heads and pistons, what is the best way to prevent debris from the honing from sticking around on the crank and lower end? Any ideas/suggestions?
     
  11. A guy (Lucky667) offers up free help with tools and labor and you're still reluctant to post up your "general" area of residence.:rolleyes:.....
     
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  12. big duece
    Joined: Jul 28, 2008
    Posts: 5,591

    big duece
    Member
    from kansas

    If its in a T chassis, I would think that if your going to tear the engine down to bare block(pistons removed) just remove the engine from the car and do the work on an engine stand. If the timing chain has that much play, there might be some other things needing attention too. After honing a block, it really needs to be scrubbed super clean with soap and water to get all the debris and honing byproduct out of the block. Possibly new set of rings, checking end gaps etc... just sounds easier with the engine out of the chassis. Good winter project.
     
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  13. big duece
    Joined: Jul 28, 2008
    Posts: 5,591

    big duece
    Member
    from kansas

    Gm goodwrench crate motor long block from Jegs is $2k, free shipping 100,000 mile warranty. Could be money well spent if you don't have local access to machine shop or tools to do the work yourself.
     
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  14. R Pope
    Joined: Jan 23, 2006
    Posts: 3,310

    R Pope
    Member

    Hone it with a ball hone and rering it with a set of rod bearings. I have gotten away with that on engines that were way beyond "spec" and they ran great for tens of thousands of miles. The worst was a 390 Ford with .015 taper (!) on the front two holes. A little rattle on a cold start but I drove it for two years with no issues. Went 600 miles to the quart with no smoke!
     
  15. That was my 1st thought and the piston skirts will be a matched set.. junk.
     
  16. In-car rebuilds are tough to do, yet it was the norm 60 or more years ago when engines needed to be freshened up more frequently. I've seen old time mechanics drape shop rags over the crank and before assembly wash everything down with solvent. Granted there is more room around your engine, but it is tedious. You are best off pulling it and putting it on a stand.
     
  17. blowby
    Joined: Dec 27, 2012
    Posts: 5,921

    blowby
    Member
    from Nicasio Ca

    Some will scoff at this but if you're reluctant to rebuild, read the hamb thread on Lucas oil treatment, others say it really helps tired engines. Most you've got to lose is twenty bucks.
     
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  18. squirrel
    Joined: Sep 23, 2004
    Posts: 43,430

    squirrel
    Member

    don't waste your 20 bucks on snake oil....

    I agree that the best way to do it is to remove the engine from the car, so you can get the crank out, look at the main bearings, look at the cam, change the rear main seal, all the freeze plugs, clean things well, etc.

    The extra labor won't cost you anything. You don't need an engine stand, but you will need a hoist or something to remove the engine. If that is something you just can't manage, then I guess you'll have to do it in the car....
     
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  19. Barret
    Joined: Oct 18, 2018
    Posts: 3

    Barret

    Rude, Rude, Rude, on my part. Lothiandonl940 I deserve the call out!

    Lucky667 That would be a loooooong boat ride across the Gulf of Mexico to get here in Tampa. Your offer was extraordinarily generous. Thank you!
     
  20. The reason it might not have done much is that the PCV valve is only one part of the crankcase vent system. The crankcase also needs to be vented to the atmosphere. Do you have breathers in the valve covers or a vented oil fill cap? Are the breather filters clean and able to flow air freely through them or are they plugged with dirt and debris? The PCV valve needs to able to pull clean air from outside of the engine through the crankcase and into the intake manifold to remove blowby and moisture.
     
    Last edited: Oct 19, 2018
  21. Make sure the PCV system is working properly to control the blow-by. Hose not plugged, breather on opposite side. You won't be breathing it anymore, your engine can.
    Rings may be stuck, you could try MMO/Seafoam or similar through the intake to try and get them to free up.
     
  22. ........There may well be other HAMB members there in the Tampa/ Clearwater/ St. Pete areas that would offer up the same level of help. If not, others may be able to suggest places local to you that could do some or all of the work. I like to think that we are a "community" here and we try to help each other out as best we can. Sometimes that's just moral support and advice, sometimes it could be hands on........Don.:)
     
  23. squirrel
    Joined: Sep 23, 2004
    Posts: 43,430

    squirrel
    Member


    which is why I asked for pictures....if we can see what you have, we might be able to help more.
     
    lothiandon1940 likes this.
  24. For goodness sakes! You guys can make everything so complicated. If the pan can come off without pulling the engine, do so. Remove the heads. If the pistons look/check good, install new rings. Bearings may or may not need replacing. Your choice. Back "in the day" [ I do dislike that term ], I did this often. Never had one not get another 30 to 40 thousand. Divided by your 500 per year, that is a LONG time.
    Bigger question, why only 500 per year? I couldn't DO that.

    Ben
     
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  25. classiccarjack
    Joined: Jun 30, 2009
    Posts: 1,427

    classiccarjack
    Member

    When I was growing up, the old timers would remove the pistons and put them in a vice and make them "cam" shaped again. Then hone and re-ring. If they weren't careful, they could crack a piston. I was told that it was done by "feel".

    Then they would emerycloth the crank journals using a piece of twine wrapped around the cloth, and rock back and forth until the journals shined up. Sometimes they would buy .001" over bearings.

    Times have changed, and you don't see it as much because the parts are cheaper than the labor. It was the other way around back in the day I was told....

    So no one you know has a 305 or anything else like it on the cheap to replace your tired engine?

    Sent from my Moto Z (2) using The H.A.M.B. mobile app
     
    Algoma56 and loudbang like this.

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