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5.7 liter 350 Engine Trouble

Discussion in 'Chevy Trucks' started by SWC, Apr 23, 2004.

  1. SWC

    SWC Senior Member
    from VA
    Messages: 134

    I've got a knock in my engine, it's sounds like it may have spun a main.

    I'm not sure if I should tear it down or replace the engine all together.

    I can feel the knock in the passenger side valve cover towards the front.

    It's an intermitant knock, and I have steam coming out the exaust pipe.

    Is this just a blown head gasket and a stuck valve, or have I thrown a rod through the block?
     
  2. ratplow408

    ratplow408 Member
    from PA
    Messages: 33

    If you threw a rod through the block there would be oil everywhere and it would not run.
     
  3. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Mains don't usually knock. Rod bearings do. But not intermittently. If it knocks a little cold, and a lot hot (worse) then suspect rod journal problems.

    Intermittant sounds more like valvetrain. Lifters are adjustable.

    Check the oil--is there coolant in it, or a greyish mucky mess? Check the rad--is there oil floating around in there? If no, head gasket is probably ok anyways.

    Rod thru the block would be disasterous... see ratplow408's post.

    Could be a sticky valve or lifter.... try to isolate it with a stethoscope. Valvetrain noises are more like clicks (like exhaust leaks) while bearings are more like thunks...

    Are we talking cold, hot, idling, under load, full throttle or what?
     
  4. SWC

    SWC Senior Member
    from VA
    Messages: 134

    It's not so much intermitant, it's just louder at times.

    The head gasket isn't the problem, since theirs no water in the oil.

    The oil is clean on the dip stick.

    I pulled the intake manifold off, the passenger side head doesn't seem to be getting enough oil, it has some caking on it.

    I'm thinking it's a stuck valve, or a spun rod cap, maybe both.

    I'm going to drain the oil and pull the heads tommorow, if I can't find anthing there I'll pull the block and replace it with one I'm rebuilding, then rebuild the old one completely for the next time something catastrophic happens.

    I think I'll put Slick 50 back in it when I'm done.

    I'm tired of turning bolts and skinning my nuckles.:angry:
     
  5. SWC

    SWC Senior Member
    from VA
    Messages: 134

    We pulled the engine, it was a rod bearing, actually a couple of them, one was bad enough to knock, the other is just starting to loosen up.

    A crank kit, a rod, and a gasket kit should do the trick.

    Nows a good time to replace that throw out bearing, and put in a new set of plugs and wires while I'm at it.

    $300 for parts, and a couple of days work, not bad compared to the $3000 the repair shop wanted to charge me to replace the engine.
     
  6. Dan S.

    Dan S. Member
    Messages: 31

    Did you find out why you had steam coming out the exhaust?
     
  7. SWC

    SWC Senior Member
    from VA
    Messages: 134

    Yes, the truck had been sitting for a few days in cold rainy weather, and I had the breather off.

    It was just sucking in moist air from the atmosphere.

    The head gaskets are good, theirs no water in the oil, and no oil in the water.
     
  8. Big Nate's Plowing

    Big Nate's Plowing PlowSite.com Addict
    Messages: 1,266

    whats the oil pressure reading? 350's should have 10#-25# at idle and 10# per 1k RpM or if it is spinning 3500 on the freeway then 45-60psi of oil pressure
     
  9. SWC

    SWC Senior Member
    from VA
    Messages: 134

    It always ran around 45 to 60 on the road.

    As I recall it ran closer to 35 at warm idle, and higher at cold idle.
     
  10. derekbroerse

    derekbroerse 2000 Club Member
    Messages: 2,377

    Odd that you had that much oil pressure and lost several rod bearings.... How were the crank journals? Or did you just swap out the crank? If its been knocking the rod should be resized too... so if all you did is install new bearings, start thinking about that spare engine again...
     
  11. SWC

    SWC Senior Member
    from VA
    Messages: 134

    I put a rebuilt engine in it.

    The journals on the old one are good to go, it spun the one rod bearing pretty good, and another one just a little.

    I might just put a master rebuild kit in and put it on the cherry picker just in case.
     
  12. 66Construction

    66Construction Senior Member
    Messages: 315

    There's no substitute for quality machine work......
     
  13. SWC

    SWC Senior Member
    from VA
    Messages: 134

    Nope

    I'm having the rods reworked, and the crank turned about .020 before I put her back together.

    Steel, not cast.
     
  14. juggernaut

    juggernaut Member
    Messages: 84

    So if rods are noisier when hot than cold what sounds like a rod knock and goes away when warm? (By the way this is a Ford 300 I6) Yes it is the wrong forum but I thought Id give it a shot anyway
     
  15. SWC

    SWC Senior Member
    from VA
    Messages: 134

    Does the knock seem to be coming from the bottom of the engine, or the top.

    It might be in the valve train or the cam.

    Sounds like you're not getting oil to valve train.

    The heads may be gummed up, or the oil pump might be getting weak or clogged. It could be the lifters.

    I'd pull the valve covers off first to see if the heads are gummed up.

    Then I'd trade it in on a Chevy. :)