How to fix Rod knock

Posted by mha5055, Mar 15, 2010
Newbie Forum - Beginner DSM modification questions and discussions. Common, repetitive, and general discussions will get dumped here from other tech forums. Unless you're a Probationary member you shouldn't post threads here.

  1. mha5055

    mha5055 Probationary Member

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    erie, Pennsylvania
    About a week ago my car started making this noise, and after some reseaching i found out it was rod knock, i took my oil pan off and found metal shavings in it. So i was wondering how the hell to fix this??
    #1
  2. tenn-gsx

    tenn-gsx Proven Member

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    Well you MIGHT get away with replacing the bearings if the crank isnt all scarred up. However if there is metal in the oil pan then there is probably metal in the rest of the block and head. I would sugguest atleast tear it down and get it cleand and hot tanked. Then have the rods and crank reconditioned.
    Last edited: Apr 22, 2010
    #2
    Locke likes this.
  3. jstgon

    jstgon Proven Member

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    All new bearings!! I would just go a head and do all four and be done with them all. But this is up to you. Maybe now would also be the time that you look into replacing the rods if you plan on doing it in the future at all.
    #3
  4. FLASH1970

    FLASH1970 Proven Member

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    To do it properly, pull the engine out and rebuild it. You might get away with putting new bearings in it but the proper way is to rebuild the engine.
    #4
  5. mha5055

    mha5055 Probationary Member

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    erie, Pennsylvania
    where can i get the rods and bearing from?? and what would be the easiest way of putting them in. this will be my first engine rebuild.
    #5
  6. DSM_PWR

    DSM_PWR Proven Member

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    Austin, Texas
    You can get rod bearings from any vendor on here.. just pull the oil pan off and loosen the rod bolts and slide off the old bearings and place in the new ones. Feel the crank journals for scoring with your fingernail. Torque back down to spec

    As suggested.. its definetly recommended to pull engine apart and get everything checked. Do things right the 1st time
    #6
  7. mha5055

    mha5055 Probationary Member

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    erie, Pennsylvania
    would it be better if i got new rods also? or just rod bearings? and what kind would be a good type if i need new rods?
    #7
  8. GPLaserRS

    GPLaserRS Proven Member

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    Grosse Pointe P, Michigan
    OP, I'm in the process of swapping in new bearings to eliminate my rod knock in the #4 cylinder. It's just until I can finish a build on another motor I plan on putting in this summer. I don't recommend changing the bearings, even though I'm in the same boat as you, but if you try this use tri-metal bearings like the ones ACL makes. You can order them from just about any vender on the forum. Try STM, I have had good luck with them. But don't be surprised if the problem is bigger than a simple bearing swap. IF you choose to change out the rods, stock 1G rods are pretty strong (that all depends on if you have a 6 bolt or a 7 bolt because in '92 they changed motors in May, so you could have either depending on your build date), but Eagle makes a good and low costing set of rods for our cars. Good luck!
    Last edited: Mar 15, 2010
    #8
  9. cookmeup272

    cookmeup272 Proven Member

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    Nooooo dont just replace the rod bearings. People that are telling you that, tsk tsk tsk. Obviously they spun for a reason and just putting new ones in will just be a band aid on a wound...actually it will be like putting a band aid on and then going in the shower. It won't last long at all. I spun rod bearings, put new ones in, and then they spun again after a few hours of driving. Take the crank out and get it sent to get checked and ground down if needed.
    #9
  10. BogusSVO

    BogusSVO DSM Wiseman

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    yes the engine should come out.. be pulled apart, cleaned, pull oil galley plugs and wsh the oil galleys

    have the crank checked and have the big end of the rods checked and resized as needed....

    install new bearings, gaskets and rings.. at thhis time you may want to install the BSE kit
    #10
  11. seattleshawn

    seattleshawn Proven Member

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    Edmonds, Washington
    +100000000


    99.9% chance you crank is tore up and going to need ground if it was bad enough to be making noise. I am in the process of a rebuild due to a spun bearing. My crank was tore up and it was makeing no noise. I found it by metal in the pan and knew exactly what was going on. Do it right and do a complete overhaul or your just going to be doing it again in a few months.
    #11
  12. mha5055

    mha5055 Probationary Member

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    erie, Pennsylvania
    i planned on getting my crank ground down and what not. but how do i kno if my rods are bad or not?
    #12
  13. seattleshawn

    seattleshawn Proven Member

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    Edmonds, Washington
    Take them in to the machine shop with you and they will tell you
    #13
  14. Locke

    Locke N/T DSM Wiseman

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    Houston, Texas
    You have to consider why your bearings got buggered up in the first place. The only time the crank should have direct contact with the bearings is when starting the motor, otherwise there should be an oil film between the bearing and the journal. Abnormal rod bearing wear most commonly is the result of poor oiling.

    Be sure that the pump is building pressure, and that the oil galleries are free of debris. Unfortunately, since the oiling system does not [cannot] serially connect the oiling points, building pressure at one point (pump housing, head, &c...) does not mean you will have pressure available at other places, so you can't assume that because your gauge shows that you're building pressure at the pump housing that there is flow at all of the crank journals. A proper rebuild should be in order.
    #14
  15. mha5055

    mha5055 Probationary Member

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    erie, Pennsylvania
    well the car is 92 with 171k on it. could it just be old age that caused it?
    #15
  16. cookmeup272

    cookmeup272 Proven Member

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    Utica, New_York
    Could be....but I wouldnt let that justify not doing it right
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  17. chardbox03

    chardbox03 Proven Member

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    Lake Orion, Michigan
    nows the best time to shell out for that stroker kit!!! stroker kits come with crank connecting rods and pistons... Its expensive but you get what u pay for.
    #17
  18. BogusSVO

    BogusSVO DSM Wiseman

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    Pensacola, Florida
    mine is a 1985 with 220k on it (but it is a FORD :D) and has not spun a rod bearing

    low oil pressure in the upper rpm or just trash in the oil , or streched rod bores cause most all spun bearings.

    the diffrence in rod bore specs from low to hig is .0007 or 7 tenths of one thousand of one inch , the tickness of a sheet of notebook paper is appox .003
    #18
  19. LiquidX

    LiquidX DSM Wiseman

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    New Cumberland, Pennsylvania
    It could be a multitude of things but from your statements right now I would strongly advise you to seek out a very good machine shop somewhere near you and/or garage with DSM experience. There is more to building an engine than just getting something honed and putting things back in. There is a lot of measurements involved pre machine shop and post machine shop during the build.

    You should just get a whole build done now if you every plan on making more power. At least get some stronger rods as they are fairly cheap in price. ARP internals, BSE, all new gaskets etc.

    Find and talk to the machine shop and they will tell you what you will need unless there is a local DSMer on here that is close to you willing to help you out that has done this before. I know people want to learn but there is a difference between wanting to do it and learn and doing it the right way while being guided.

    If you already know how to do the measurements and have all the proper tools that I would assume you would know that you will need to take the crank out to get checked and micro polished and then measured for the proper bearing sizes. Also if you have shavings in your pan then you more than likely have it through out the motor including inside the turbo as well. EVERYTHING needs cleaned out.
    #19
  20. beniger

    beniger Proven Member

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    are you sure it's at the bearing and not the wrist pin?
    #20
  21. mha5055

    mha5055 Probationary Member

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    erie, Pennsylvania
    how can i tell the difference?
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  22. beniger

    beniger Proven Member

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    Las cruces, New_Mexico
    is the knock subtle when the car is cold or once it warms up. you said you found metal shavings i would say remove the bearings when you get a chance and look for scarring of the crankshaft
    #22
  23. mha5055

    mha5055 Probationary Member

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    erie, Pennsylvania
    should i take the engine out or could i leave it in the car and do this?
    #23
  24. BogusSVO

    BogusSVO DSM Wiseman

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    Pensacola, Florida
    well it going to come out if you plan on pulling the crank....
    #24
  25. LiquidX

    LiquidX DSM Wiseman

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    Please take it to someone that knows how to rebuild engines properly. You can put a new bearing in, but it'll only last for so long and potentially damage the block and/or the crank even more.
    #25

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