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Why bypass the oil filter?

Discussion in 'The Hokey Ass Message Board' started by devotion, Jul 27, 2013.

  1. devotion
    Joined: Apr 15, 2009
    Posts: 193

    from idaho

    Going to try and get my Chevy 235 fired up this week and was having a look over the motor before I do so. I noticed something strange. Stock oil filter is in there, but bypassed for some reason? There is a line that comes out of the block, then just goes right back into it...bypassing the filter completely for some reason. Also in this line is a "T" with a line going up to a hole in the top of the head, dead center for some reason...any ideas before I fire it up?
  2. rld14
    Joined: Mar 30, 2011
    Posts: 1,609


    Why? I dunno... stupidity?

    My guess is something is wrong in there and this was how the PO decided to "fix" it.
  3. devotion
    Joined: Apr 15, 2009
    Posts: 193

    from idaho

    I just read an article on another site that said this was a fix to get more oil to the rockers...apparently something that was done quite a bit in the past (wrong or not). Im fine with that, but would like to add the filter back into the equation somehow. So do you think I should add that T after the oil goes through the filter or before...or just do it stock, and plug up the mystery hole? This is of course after I make sure the oil pump is getting oil up to the top of the motor...
  4. saltflats
    Joined: Aug 14, 2007
    Posts: 10,236

    from Missouri

    Plum it as factory and use the proper weight oil.
    It worked back then.

  5. The line going to your head is your rocker shaft oil feed-make sure you still have oil flow there.
  6. There is a valid reason for a oil filter,,I would plumb it back to original.

    Without a filter you run the risk of damaging the engine,,and like the old Flatheads running without a filter means changing the oil very often. HRP
  7. Atwater Mike
    Joined: May 31, 2002
    Posts: 10,237

    Atwater Mike

    Those old Chevy sixes had an oil galley running up to that center head bolt bore, passenger side. The galley would get MAJOR clogged down below, 145 PSI of compressed air wouldn't 'blow it out'.

    The fix: Remove the head bolt, find a piece of cold rolled rod that fits tightly in the head bolt bore. (head is 3-3/4" thick before you get to block threads) (1/2" dia., if memory serves...we used a Plumb drift, with a 4" shank)

    Fill the bolt hole with 140 wt. gear oil. Set the punch and hit it HARD, 2-3 lb. hammer...Just hit it once or twice, stop before hitting the block threads. Do this 3 or 4 times, then crank the engine and watch for a 'gusher'.
    If the rocker shaft is clogged, you'll have to clean that out, obviously...
    But this fix saves a teardown...and it's a GOOD one. (been doing it since 1956)
  8. Ole don
    Joined: Dec 16, 2005
    Posts: 2,915

    Ole don

    We should remember the oil change interval in those days was 1000 miles. Very few could afford the new on the market "detergent" oil. After all, it was 20 cents more!
  9. devotion
    Joined: Apr 15, 2009
    Posts: 193

    from idaho

    OK, finally had a minute to get into the motor. Took off the valve cover and turned the oil pump with a drill...Im getting oil to the top of the motor no problem...still have that extra line. Should I leave it just to be safe? Seems like it was added for no reason
  10. I added the line that you talk about to my 261. When the PO rebuilt the motor he put a regular head bolt in there and I wasn't getting any oil to the rockers. That specific head bolt has a groove in it to let oil up to the top of the motor. I added the line as extra insurance. T'd off the line that returns from the oil filter.
  11. mr.chevrolet
    Joined: Jul 19, 2006
    Posts: 6,843


    those old filters didn't filter more than 10% of the oil anyway. you could get by without one and just do reg. oil changes.
  12. Rusty O'Toole
    Joined: Sep 17, 2006
    Posts: 9,270

    Rusty O'Toole

    They only filter part of the oil but they filter it very clean. All the oil goes thru but it takes 1/2 hour or so.

    Any filter is better than no filter. Take one out after 5000 miles and see how much grit and sludge it kept out of your bearings.

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