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  1. #11
    Join Date
    Jun 2005
    Location
    Norton Cross
    Posts
    492
    I had a worn push rod on mine after only 150 miles. Had a professional rebuild (supposedly). Engine made a knocking noise but no blue smoke.
    One thing I’d do first is drop the oil and change the oil filter and check for any metal in it.

  2. #12
    Join Date
    Apr 2013
    Location
    Basingstoke, UK
    Age
    38
    Posts
    303
    Quote Originally Posted by peterj1974 View Post
    I had a worn push rod on mine after only 150 miles. Had a professional rebuild (supposedly). Engine made a knocking noise but no blue smoke.
    One thing I’d do first is drop the oil and change the oil filter and check for any metal in it.
    Thanks Peter,

    One of the first things is definitely to change the oil and filter first....although the engine has not really been run, it has sat with that oil in for quite a while.

  3. #13
    Join Date
    Nov 2012
    Location
    Lanarks
    Age
    63
    Posts
    131
    It sounds as if a lifter or two has gone.........

    Take off the valve covers
    Turn over the engine by hand and check the pushrods are all moving the rockers to the same angle.
    This would tell you if a cam lobe has gone, bent pushrod or lifter gone

    If the lifter is going/gone.......paint a thin vertical line on the 2 pushrods ( one cylinder at a time)
    Turn over the engine
    You should notice that the vertical line starts to revolve indicating that the lifter is doing its job on the cam lobe - ie it is now matched with the broken in cam.
    If the line just stays in view and doesn't revolve then the lifter is on its way out.

    I suspect you have lifter damage

  4. #14
    Join Date
    Apr 2013
    Location
    Basingstoke, UK
    Age
    38
    Posts
    303
    Quote Originally Posted by drammyboy View Post
    It sounds as if a lifter or two has gone.........

    Take off the valve covers
    Turn over the engine by hand and check the pushrods are all moving the rockers to the same angle.
    This would tell you if a cam lobe has gone, bent pushrod or lifter gone

    If the lifter is going/gone.......paint a thin vertical line on the 2 pushrods ( one cylinder at a time)
    Turn over the engine
    You should notice that the vertical line starts to revolve indicating that the lifter is doing its job on the cam lobe - ie it is now matched with the broken in cam.
    If the line just stays in view and doesn't revolve then the lifter is on its way out.

    I suspect you have lifter damage
    Thanks for the tips....will try that and see

  5. #15
    Join Date
    Dec 2017
    Location
    South Warwickshire
    Age
    57
    Posts
    10
    That must be gutting! Keep the faith though, it might be an easy fix yet. It's difficult to hear exactly what is going on but you could investigate things as follows -
    Take the plugs out - one looking very different to the others might point you to the cylinder with problems
    If they are all oily, it's worth checking your breathing and PCV if fitted. I have seen an engine running rough and smoking worse than yours purely down to a faulty pcv valve.
    Before getting too deep into other things, it's also worth checking the exhaust manifold by running your hand around them when the engine is running (before it gets too hot). A leaking manifold can make an engine sound poor and sometimes like a 'knock' but does not explain smoking.
    Check the tappets and pushrods as others have advised - from what i have read this does seem a likely cause
    If it's still not apparent what the problem is then I would do a compression test to eliminate any possible piston, ring or head gasket issues.
    Then get into your sump, check for any metal and signs of any 'bumping', particularly if you are running non standard components. I dropped an oil pan off once to find the dipstick wrapped around the crank - you never know! Also it is possible to hit the sump in enough to cause a problem with clearances (that could be done accidentally with a jack or a ramp etc)
    As far as the smoking goes, it doesn't look that bad in the video. If the builder used forged pistons with slightly larger piston to bore clearance you might get a bit of smoke on start up and until they hot up and expand. If that is the case make sure you have a thermostat fitted.
    Good luck!

  6. #16
    Join Date
    Apr 2013
    Location
    Basingstoke, UK
    Age
    38
    Posts
    303
    Quote Originally Posted by ChrisP459 View Post
    That must be gutting! Keep the faith though, it might be an easy fix yet. It's difficult to hear exactly what is going on but you could investigate things as follows -
    Take the plugs out - one looking very different to the others might point you to the cylinder with problems
    If they are all oily, it's worth checking your breathing and PCV if fitted. I have seen an engine running rough and smoking worse than yours purely down to a faulty pcv valve.
    Before getting too deep into other things, it's also worth checking the exhaust manifold by running your hand around them when the engine is running (before it gets too hot). A leaking manifold can make an engine sound poor and sometimes like a 'knock' but does not explain smoking.
    Check the tappets and pushrods as others have advised - from what i have read this does seem a likely cause
    If it's still not apparent what the problem is then I would do a compression test to eliminate any possible piston, ring or head gasket issues.
    Then get into your sump, check for any metal and signs of any 'bumping', particularly if you are running non standard components. I dropped an oil pan off once to find the dipstick wrapped around the crank - you never know! Also it is possible to hit the sump in enough to cause a problem with clearances (that could be done accidentally with a jack or a ramp etc)
    As far as the smoking goes, it doesn't look that bad in the video. If the builder used forged pistons with slightly larger piston to bore clearance you might get a bit of smoke on start up and until they hot up and expand. If that is the case make sure you have a thermostat fitted.
    Good luck!
    Thanks Chris,
    All good things to be checking out.

    Kit has arrived.....follow my progress here at my blog:
    http://marksak427.blogspot.co.uk

    AK 427 Gen II
    Chevy SB 350
    Tremec TKO 600

    Well.....that's the plan at the moment!

    Welcome to the money pit......

  7. #17
    Join Date
    Nov 2008
    Location
    Guildford
    Posts
    311
    I had a loud knocking sound on my SBC350 after changing the exhaust. It really sounded as though something significant was knocking. I used a mechanics stethoscope to try and pin point where the knocking was coming from, but couldn't really hear anything mechanical on the block , heads or exhaust.
    After posting on here, I was advised to check for a leaking exhaust header gasket with a thin piece of paper et voila. Put the paper underneath the drivers side header and it was blowing. Might be worth a try.
    All the best.

  8. #18
    Join Date
    Apr 2013
    Location
    Basingstoke, UK
    Age
    38
    Posts
    303
    Quote Originally Posted by Flykilla View Post
    I had a loud knocking sound on my SBC350 after changing the exhaust. It really sounded as though something significant was knocking. I used a mechanics stethoscope to try and pin point where the knocking was coming from, but couldn't really hear anything mechanical on the block , heads or exhaust.
    After posting on here, I was advised to check for a leaking exhaust header gasket with a thin piece of paper et voila. Put the paper underneath the drivers side header and it was blowing. Might be worth a try.
    All the best.
    Thanks for the suggestion....this is definitely something we will look at first, as the exhaust header has most likely been taken off whilst at AK to weld up a small hole, so maybe still leaking or the gasket is not sealing properly.

    I really hope it is something that simple!

  9. #19
    Join Date
    Dec 2017
    Location
    South Warwickshire
    Age
    57
    Posts
    10
    If you find an exhaust leak and you want to make sure that's the cause of the noise before you go to all the trouble of taking the manifold off you could get some of this https://www.amazon.co.uk/JB-Weld-HIG...omotive&sr=1-5 Clean up the area with a screwdriver as best you can, push some of this in/on, let it go off and then try the engine. It's a good emergency repair although not pretty, will last a while actually, at least confirming the problem and probably would even get you through the IVA if you run out of time to do the job properly. I carry a tube in mine all the while.
    When you take the manifold off eventually, you can clean it off.

  10. #20
    Join Date
    Apr 2013
    Location
    Basingstoke, UK
    Age
    38
    Posts
    303
    Quote Originally Posted by ChrisP459 View Post
    If you find an exhaust leak and you want to make sure that's the cause of the noise before you go to all the trouble of taking the manifold off you could get some of this https://www.amazon.co.uk/JB-Weld-HIG...omotive&sr=1-5 Clean up the area with a screwdriver as best you can, push some of this in/on, let it go off and then try the engine. It's a good emergency repair although not pretty, will last a while actually, at least confirming the problem and probably would even get you through the IVA if you run out of time to do the job properly. I carry a tube in mine all the while.
    When you take the manifold off eventually, you can clean it off.
    Cheers Chris, will keep this on my Amazon list!

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