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Thread: knocking 3sge - bearings?

  1. #1
    Junior Member Carport Converter Dale's Avatar
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    Default knocking 3sge - bearings?

    Engine is a gen 1 3sge, done 110,000km since a full rebuild, oil and filter have been changed every 5000km since the rebuild. Inside the engine looks like new with absolutely no sludge build up.

    A little history on the problem, car had been running fine when I drove into a shopping centre, when I came back to leave the car started as normal and I reversed about 1m before it stalled... started again and it was knocking quite loudly - I thought probably a big end so shut it down and got it towed home. Car still had oil pressure showing on the gauge much to my surprise.

    So assuming it was a bearing I decided to pull it down and see how bad the damage is, checked all the big ends and mains today and none of them seemed to have much if any wear, pics of two that had some wear are at the bottom. The oil I dropped out was <5000km old and didn't appear to have any metal in it.

    I don't have much experience with this sort of thing so I'm wondering, how bad does a bearing have to be before it will start knocking? Any help would be appreciated

    clicky - main bearing # 5

    clicky - big end # 3
    I am the sun

  2. #2
    Junior Member Automotive Encyclopaedia
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    Default Re: knocking 3sge - bearings?

    check your oil pump and releive valve and also oil pick up

  3. #3
    ......... Carport Converter jeffro ra28's Avatar
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    Default Re: knocking 3sge - bearings?

    In my experiences bearings with that appearance are a long way from "looking" like causing a knock.

    If you see large patches of copper coloured bearing metal then you may have a knocking issue.

  4. #4
    Junior Member Backyard Mechanic DrNick's Avatar
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    Default Re: knocking 3sge - bearings?

    Those look fine to me, but I've only pulled apart a couple of engines so I'm no expert.

    However, the last one I took apart that had a knock looked like this :


  5. #5
    Junior Member Grease Monkey
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    Default Re: knocking 3sge - bearings?

    If its the bearing knocking it doesn't take many knocks before it starts hammering the bearing wider so have a good look at width.

  6. #6
    Village Idiot Automotive Encyclopaedia
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    Default Re: knocking 3sge - bearings?

    dale
    i'd clean then up and put back together
    grab some plastigauge and check your clearances to see if they are within spec to begin with

  7. #7
    Junior Member Automotive Encyclopaedia
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    Default Re: knocking 3sge - bearings?

    Quote Originally Posted by Dale View Post
    reversed about 1m before it stalled... started again and it was knocking quite loudly
    Pics are fine, wish all mine had looked like that.
    Bearings just don't suddenly go bad & loud, especially at parking lot rpm/speed. At high rpm/load it still takes a while to get loud so it has to be something else.
    I'd look at/listen to the clutch & accessories & belts, then maybe too much lash from a stuck valve.
    Also, I don't know how, but many seem to have mistaken an exhaust leak for a metallic/mechanical sound.
    Good luck.
    'I've scrapped better.' John stated when asked what he thought about it.

  8. #8
    Junior Member Carport Converter Dale's Avatar
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    Default Re: knocking 3sge - bearings?

    That confirms my initial thoughts, I didn't think a bearing would suddenly start knocking at what was basically idling rpm.

    I will get some plastigage and check the clearances are all within spec just to be 100% certain all is good there before torquing everything back up. As for oil pump I still had oil pressure, all cam lobes and bearing shells were still coated in oil so I don't think lack of oil was a problem. I also spun the pump over by hand before draining and removing the sump and saw that it was pumping oil . The pick up was ok too.

    My next thought was valves, I guess I'll pull the head off and see what's going on with them. The cams turn over as normal and I can see each valve shim going up and down as it's meant to, but I guess that doesn't mean much.

    If all is OK with the head and valves what are the chances of it being a gudgeon pin? For the very limited time I ran it trying to diagnose the noise seemed to be high up in the engine but it was hard to tell.

    Thanks for the help so far everyone, this is sure to be a steep learning curve for me... my trusty haynes manual had been coming in handy!
    I am the sun

  9. #9
    Village Idiot Automotive Encyclopaedia
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    Default Re: knocking 3sge - bearings?

    Check that the oil holes are clear in your pistons you'll need to remove the lower expander ring and side rings if the 3sge pistons are anything like a 4AGE, make sure they are not blocked up. Are the gudgeons circlip or press fit? Does the piston rotate freely on the gudgeon and is there any play (there will be some side to side (depending on whether you are press fit or circlip)

  10. #10
    Junior Member Carport Converter Dale's Avatar
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    Default Re: knocking 3sge - bearings?

    Finally got around to doing some more work on this... pulled the head off to find the pistons to have a fair bit of carbon build up on them, so I pulled them out and cleaned them up a bit.

    Piston 1 I noticed appeared to have a few 'scratches on it' which after cleaning I realised was slightly more than scratches.

    image of piston 1
    image of cylinder head

    It was very hard to get a good photo of but you can sort of see it at the top of the first photo, and top of the second photo where the head has been damaged.

    So I'm assuming there was foreign material in the combustion chamber, but as to what it was and how it got there has me puzzled. All spark plugs were in tact when I pulled them out, and when I seperated the head from the block I didn't see any metal on the top of the piston, just carbon.

    Anyway my next question, does the head need machining and the piston need replacing or will it be ok if I put it back together now that the foreign material is gone?
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  11. #11
    Junior Member Carport Converter Dale's Avatar
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    Default Re: knocking 3sge - bearings?

    Quote Originally Posted by 3sgte View Post
    Gen 1 motors occasionally kill valve shims, wearing a huge dish in a shim. I have seen 2 motors do this.

    One was noisy, a new shim 'fixed' it (the cam lobe still had some damage, but the noise was gone).

    The other was a parts motor, not running. It had actually progressed to the point where it spit out the worn shim.

    As for weak big end bearings, they were never an issue in my experience, however I don't do track time.

    I have seen 3SG with toasted big end bearings, but in all those cases it was a lack of oil that killed the bearings.

    Is the crankcase vented properly?

    EDIT:

    Forgot to mention, I also saw more than a few 3SG, gen 1 where a TVIS plate screw would either come out, or the head would break off. If lucky, the screw would get spit out the exhaust without significant damage.
    It is possible that the screw would be embedded in either the piston or head though...
    That is a nasty noise!
    Found this while searching... makes sense this is what might have happened
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  12. #12
    Junior Member Carport Converter Dale's Avatar
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    Default Re: knocking 3sge - bearings?



    This answers everything...

    Still wondering if it's going to be OK to put back together with the damage where the screw had been hitting the head though
    Last edited by Dale; 07-12-2009 at 05:23 PM.
    I am the sun

  13. #13
    Village Idiot Automotive Encyclopaedia
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    Default Re: knocking 3sge - bearings?

    take to a machinist and ask for their opinion
    depends on how bad the damage is (the pic doesn't really show enough) and whether its going to be able to seal up again correctly (and whether fixing the damage will change the cc of your chamber ect)

  14. #14
    The Aberrational Chief Engine Builder Andrew162's Avatar
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    Default Re: knocking 3sge - bearings?

    To me it looks like a heap of gouges into one section of the piston and the head, I'd say you were lucky it didn't get as far as the valves. It really depends on how deep the gouges into the head/piston are and what kind of effort will be required to clean them up back to smooth, and as grega said, if it will change CC, etc.

    Will a Gen3 3S intake manifold fit onto the Gen1 3S? If so, piss off TVIS altogether and go ACIS. Roar baby...
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  15. #15
    Junior Member Carport Converter StuC's Avatar
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    Default Re: knocking 3sge - bearings?

    a gen 3 intake wont but a gen2 tem will, and it has ACIS also. can you grab the head and a piston out of the other block you have or is it completely borked?

  16. #16
    Junior Member Carport Converter Dale's Avatar
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    Default Re: knocking 3sge - bearings?

    Hmm I guess a piston out of it would be ok, the head looked pretty grubby though

    The damage really is pretty minor as the screws are only tiny, it basically just looks like a few scratches. I'm going to clean things up properly today and have a better look
    I am the sun

  17. #17
    Junior Member Automotive Encyclopaedia roadkill's Avatar
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    Default Re: knocking 3sge - bearings?

    Hi,

    i would probably be doing it all properly and make sure that nothing is bent/warped. Unless that screw was flattened on the first impact (which it clearly wasn't) it's going to have done some damage. Basically that screw has been squashed between the top of the piston and the flat part on your cylinder head. Then it's exited the engine through the valves. Potentially you could have a cracked piston, bent rod or even bent valves. At least get those checked before putting it back together. I also look at getting the head checked to make sure its nice and flat.

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