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Technical Oil pump sheared

Discussion in 'Traditional Hot Rods' started by willymakeit, Nov 25, 2018.

  1. willymakeit
    Joined: Apr 13, 2009
    Posts: 1,326

    willymakeit
    Member

    Got lucky when oil pump shaft sheared. No visible damage to rods and mains. Had heard a knock but must have got stopped in time. Will put a apr hardened shaft in.
    Looking at 268h cam for the truck.
    302 , 4 speed t18,3.00 gears with 29” tire. If I remember correctly 2460 rpm at 70 mph.
    Mostly street drive with occasional trailer. Total weight of trailer and load about 3500 lbs. Has headers, performer intake and Edelbrock 600 carb.
    Only power accs. is brakes.
    Thoughts or recommendations
     
  2. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 172

    radarsonwheels
    Member
    from Philly

    Been there. Good job cutting power before thrashing bearings!

    Did you find trash pinched in the oil pump lobes?

    And why put a mild hotrod cam in there? I’d go with an rv cam if anything with small cubes and tall gear with occasional pulling etc.
     
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  3. willymakeit
    Joined: Apr 13, 2009
    Posts: 1,326

    willymakeit
    Member

    Haven’t looked at pump yet.
    On cam just checking. Not sure what I want or need. What’s considered mild RV ?
     
  4. garyf
    Joined: Aug 11, 2006
    Posts: 201

    garyf
    Member

    Hardend, broken up valve stem seals will get in oil pump and repeat broken pump drive.
     
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  5. oldolds
    Joined: Oct 18, 2010
    Posts: 2,774

    oldolds
    Member

    ^^^^^ What he said^^^^^ Time to check those seals.
     
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  6. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 172

    radarsonwheels
    Member
    from Philly

    Just drop the oil pan and pull the oil pump to look for problems. Plastic timing gear bits can get chewed up too and cause problems.

    I build mopars not fords but a lot is the same. A smaller motor will be more radical with the same cam as a bigger motor so you have to watch out not to over cam smaller displacement motors. I have a 318 in my ramcharger (heavy suv) which is a similar displacement/application. I put in a cam that was around 213° @ .050” and less than .5” lift. Along with small headers and a small four barrel aluminum intake it really woke the motor up and kept all the street manners you want.
     
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  7. OKAY, folks. Not understanding here. How in the world can "broken parts" get into the pump gears. Could not happen on a Buick. Suction screen would have to disintegrate. Plugged? Yep, can do.

    Ben
     
  8. Beanscoot
    Joined: May 14, 2008
    Posts: 1,077

    Beanscoot
    Member

    The hard rubbery bits of valve stem seals are soft enough to slowly distort enough to get through the coarse oil pickup screen, but are still big enough to then jam up the oil pump rotors.
    This happened in my first Ford, a 260 that unfortunately was driven by someone else until it seized up. The oil pump drive looked like a piece of ornamental spiral steel, and since I was young and new to these engines it took a while to realize what it was.
     
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  9. Beanscoot
    Joined: May 14, 2008
    Posts: 1,077

    Beanscoot
    Member

    Also, blobs of excess silicone sealer can do this.
     
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  10. egads
    Joined: Aug 23, 2011
    Posts: 499

    egads
    ALLIANCE MEMBER

    Some Ford pick-up screens have a hole( 1/2 inch? ) under the band on the screen, have replaced a ton of pumps, screens and drive shafts because of this. 64-35897[1].jpg
     
  11. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    Yes, many screens have a half inch hole in the center that is normally pressed against the plate across the center of the screen. If the screen plugs, it comes off the plate and crap goes through the hole. in small block Fords, the shaft twists off. In GMs, the debris can get stuck in the bypass valve either lowering the bypass pressure or raising it high enough to blow the filter off. 351 Windsors used a larger oil pump shaft which occasionally lead to the pin shearing in the distributor gear.
     
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  12. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,233

    dirty old man
    ALLIANCE MEMBER

    I learned many years ago that when scrounging around wrecking yards for rebuildable SBF engines that if there was no obvious body damage that caused the car to be junked, the first thing to do was pull the distributor. If the oil pump drive shaft was twisted in two, then don't waste anymore time on that engine. You're lucky that you shut yours down in time.
     
  13. willymakeit
    Joined: Apr 13, 2009
    Posts: 1,326

    willymakeit
    Member

    I was lucky. Didn’t think about silicone. I know nothing about history of motor but cross hatch,lifters everything looked really good.
    I will keep everyone posted when I disassemble oil pump.
    It was supposed to be a “crater motor “.
     
    loudbang likes this.
  14. I've seen a couple oil pump drive shafts break or strip because of someone still having thick summer viscosity oil in the pan on a cold cold day, then racing to leave the workplace parking lot without giving the oil a minute or so to warm up an thin down a little.
    High revving to beat the pack away from work while the oil is still way too thick to pump well has broken a few shafts before.
    Not saying this is the cause of yours, but it reminds me to point out another cause of possible probs to others.


    WHY BE ORDINARY ?
     
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  15. willymakeit
    Joined: Apr 13, 2009
    Posts: 1,326

    willymakeit
    Member

    I had about ten thousand miles on motor . It’s weird just started a flutter like runny out of gas and I looked down and no pressure. Heard it knock as I got pulled over. If crank was bad it would be a 331 but it makes no sense to waste the money at this stage.
    Will know tomorrow nite,
     
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  16. BamaMav
    Joined: Jun 19, 2011
    Posts: 3,437

    BamaMav
    Member
    from Berry, AL

    If you heard it knock, I’d check the bearings to be sure they weren’t hurt. Could have just been a heat knock, but also could be a rod.
     
    loudbang likes this.
  17. The Bridgeport's latest motor, a 59AB, sounded great when cold but would knock as it warmed up. I could shut it off and restart, and the knock would be gone. But one run down the road and the knock would return. Stupid me.

    Using a broomstick to stethoscope, the knock sounded like a valve guide at #7 or #8, tore it down and looked all over. Couldn't find anything. One of my old-timer friends also helped and gave up, said "Oh, it'll blow sometime, might as well drive it."

    About a year later I was compelled to dust some rubberneckers on a 4-lane. Got off the road and onto a less-traveled highway. As I rounded a curve I thought, "Wow, this motor's runnin better than it ever has!" The thought barely had time to pass and !!BOOM!! it happened! Pulled over to see a massive oil/water sheen on the road, and several holes in the pan.

    Turns out it was rod #4 or #5, and when it blew part of it went upward, over the came, and everything came raining down into the crank. Broke the cam in two, knocked a huge hole in the valley, and took out the first four rods.
     

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