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Technical 302 rod knock or piston slap, is it salvageable?

Discussion in 'The Hokey Ass Message Board' started by tlmartin84, Jun 30, 2021.

  1. squirrel
    Joined: Sep 23, 2004
    Posts: 49,859


    I use a few foot long piece of heater hose as a stethoscope to isolate exhaust leaks...

    that sounds like slop in the timing chain. The cam is harder to turn than the crank, so you'll feel some easy movement as it takes up the slack.
  2. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,955

    from So Cal

    I think I have pretty good ears, but maybe too many years of playing music has had a larger effect than I realized, but I'm not hearing anything in those videos that would cause me to be too worried.

    NOT hearing a rod knock...
  3. oldiron 440
    Joined: Dec 12, 2018
    Posts: 2,427

    oldiron 440

    I think what you described with the rotation is the timing chain slack, what I was talking about was front to back movement in the crankshaft.
    All the 302/5.0 I've taken apart in the last few years have had problems with the thrust bearing and bearing delamination.
  4. tlmartin84
    Joined: Jul 28, 2011
    Posts: 891

    from WV

    The videos are hard to hear, but in one it is noticeable at 12 seconds. The other at 4 and 24
  5. tlmartin84
    Joined: Jul 28, 2011
    Posts: 891

    from WV

    What about the metal in the oil...
  6. Blues4U
    Joined: Oct 1, 2015
    Posts: 5,955

    from So Cal

    Any visible metal in the oil is not good. But it's hard to say where it came from just from those pictures. Oil analysis labs can analyze the oil and tell you what type of metal it is (ferrous or non ferrous) and they can even magnify images and capture photos of the particles and tell you what type of wear caused them, sliding wear, grinding wear, are the particles chips or cuttings, etc. It's a little expensive, hard to say whether it's worth it to you or not, but it can be done. But just looking at your pictures, I can't tell you much about them. You could try pouring the oil through a paint filter and washing with some brake clean or some naptha or mineral spirits and then photograph what you got. Let them dry and put them on a clean sheet of paper and run a magnet under them and see if they are ferrous or not. But, in any case metal in the oil is not good. I think I would be tempted to change the oil & filter and run it, and check it again after 50 miles and see what's in it. If this was a daily driver, or road trip car, or a race car it'd be different, but this is a weekend night cruiser, you can probably make a lot of trips to the Dairy Queen in it.
  7. Truck64
    Joined: Oct 18, 2015
    Posts: 5,106

    from Ioway

    Let's define our terms.

    Chunks with legible serial #'s = Really Bad!
    B Bay Barn, Aaron65 and Algoma56 like this.
  8. RichFox
    Joined: Dec 3, 2006
    Posts: 10,020

    Member Emeritus

    I was going to write about using a hose to locate the source of the noise. But Squirrel beat me to it. Which brings me to point #2. Listen to what Squirrel says. This is written in cast iron. Dip a magnet in your drain oil and see if the metal sticks to it. If it does it's probably a lifter failing. Go back and check your valve train again. If not, try to figure out what it is. All this after you check for an exhaust leak. More than one time an exhaust leak sounded like a rod knock to somebody.
    lippy and Desoto291Hemi like this.
  9. nosford
    Joined: Feb 7, 2011
    Posts: 558


    I worked for a Ford dealer back in the 70's and like a lot of people have already said, cracked piston skirts were fairly common and would show up as all sort of weird noises, but mostly would cause oil consumption issues. Wrist pin slop would happen as well. Did you try to put a magnet on the metal particles that came out of the filter? If the magnet sticks to the particles it isn't from a piston. We used to replace ONE piston in those engines as that's all Ford would pay for at the time and they seemed to be fine after that.
    saltracer219, Algoma56 and Blues4U like this.
  10. TA DAD
    Joined: Mar 2, 2014
    Posts: 501

    TA DAD
    from NC

    100 lbs in the cylinders it is at the end . Drive it and enjoy.
    norms30a and Deuces like this.
  11. Joe Travers
    Joined: Mar 21, 2021
    Posts: 430

    Joe Travers
    from Louisiana

    Hear some noise on the drive audio, not the other (and I've been a musician for 50 years) :rolleyes: The '68 302 (first year) was notorious for piston failure but I've never seen it in later engines. Have you hooked up a timing light to determine speed of the noise? Sounds like crank speed but I would double-check and make sure it isn't valvetrain noise first.

  12. finn
    Joined: Jan 25, 2006
    Posts: 885


    Might be worth doing a used oil analysis.

    Blackstone will ship you a sample bottle for free, but their service costs about $40 if I remember, and another $10 if you want a TBN analysis in addition to wear metals.

    Wix is a little cheaper, and is available on Amazon, or was when I used it.

    FWIW, the skirt on one of the pistons of my late father’s 289 broke while the car was still under warranty in 1966, and my Boss 302 broke the skirts, as did they all.

    I have also heard of broken cranks in 302 powered pickups, vans, and 5.0 Mustangs. They run fine....until they don’t.
    Desoto291Hemi likes this.
  13. tlmartin84
    Joined: Jul 28, 2011
    Posts: 891

    from WV

    Well I thought screw it...

    Torqued the headers down to about 45 lbs...I swear it is way quieter...but still there.

    Im afraid to go any tighter. Think I should Take them off and smear some permatex copper on them, or will it be too hot?
    Desoto291Hemi likes this.
  14. harpo1313
    Joined: Jan 4, 2008
    Posts: 2,307

    from wareham,ma

    Unbolt them and check both surfaces with a strait edge , If good new gaskets.
    Deuces likes this.
  15. deathrowdave
    Joined: May 27, 2014
    Posts: 2,700

    from NKy

    Ford changed firing order , to help with this nose issue years ago . I just can’t remember when , why or what’s all involved . Do some research on this
    Deuces likes this.
  16. F-ONE
    Joined: Mar 27, 2008
    Posts: 2,902

    from Alabama

    If you care about the engine, pull it take it apart and find out what's wrong. If you want to run it to death and find another, continue on and run it to death.

    I have learned that if a SBF is making a noise, something is wrong with it.

    They are not a cllickety clack engine like a SBC, a FE or even a Yblock. If they make a noise, there's a big problem.
    My 1968 302 (Aug of '67) "ticked". I decided to take it down. It was the #1 Piston skirt. #4 and # 5 were cracked. The #1 skirt was bouncing in #1 cylinder. It sounded minor, like a lifter tick. I caught it in time. Aluminum was in the oil pump screen chunks were in the pan. Some bits were in the bearings but nothing had scored the journals.

    New pistons, new bearings and she was good to go. If I had waited longer...who knows.

    My advice...Get Tom Monroe's How to Rebuild the Small Block Ford book, pull it and fix it.
    Deuces likes this.
  17. Sometimes you can see metal flecks.. or worse.. caught up in the residual oil that pools up on the head under the valve cover. A little effort may tell you a lot.
    Deuces likes this.
  18. X-cpe
    Joined: Mar 9, 2018
    Posts: 1,250


    To check for timing chain slop, pull the distributer cap off and see how far you have to turn the crank before the rotor moves.
  19. tlmartin84
    Joined: Jul 28, 2011
    Posts: 891

    from WV

    While Im pulling the headers Ill pull the valve cover and see...when replacing the covers the top was CLEAN.

    Whats your opinions on these header gaskets...should I try tightening them more? Or pull them and use Copper RTV?

    Ditch the gaskets and straight copper rtv?

    Gaskets with copper rtv?

    They are cheap headers...were flat when installed...but they are also chinese and about the inly long tube that fits an early bronco.
  20. DDDenny
    Joined: Feb 6, 2015
    Posts: 15,378

    from oregon

    302 what?
    Chevrolet or Ford?
  21. Deuces
    Joined: Nov 3, 2009
    Posts: 21,311

    from Michigan

    Chevy!!!!!......:D:D:D 3gears.gif
    Last edited: Jul 1, 2021
    Budget36 likes this.
  22. tlmartin84
    Joined: Jul 28, 2011
    Posts: 891

    from WV

    Deuces likes this.
  23. SilverJimmy
    Joined: Dec 2, 2008
    Posts: 311


    Coulda been a Jimmy….
    Just saying!
    Budget36 likes this.
  24. JeffB2
    Joined: Dec 18, 2006
    Posts: 8,980

    from Phoenix,AZ

  25. Guy Patterson
    Joined: Nov 27, 2020
    Posts: 266

    Guy Patterson

    Had a 74 block with bad main bolts that stretched and caused all sorts of problems. yes had metal in the oil and slop in the timing set, it was an mess. had the sound like rod or piston slap and was a complete surprise to find stretched bolts. Drop the pan an check for stretched bolts on the mains and replace them and the main bearings
  26. 55blacktie
    Joined: Aug 21, 2020
    Posts: 458


    Timartin84, as you can see, opinions are all over the place. Your problem could be any/all of the above or none. I think the best advice is drive it until it breaks, but don't venture too far from home, unless your insurance covers towing. In the meantime, either look for a rebuildable engine/rebuilt crate engine.
  27. big bird
    Joined: Feb 16, 2014
    Posts: 101

    big bird

    I've taken apart several good running 302/5.0 engines and found piston skirts in the oil pan. No real problem symptoms, usually middle cylinders on driver's side.

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