CRG Discussion Forum
Camaro Research Group Discussion => General Discussion => Topic started by: 1stgen68 on June 30, 2019, 04:50:06 PM
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I’ve posted a few things this week because I have a few issues to this new to me 68 SS clone. After the engine warms up there is a faint knock and I cannot tell where it is coming from being the top end or bottom end. Almost sounds like something is knocking against something somewhere. I was going to post the video on YouTube but I’ve found that the resources on this forum are more valuable and I respect the responses from people that know way more than me about these 1st gens and engines. If anyone wants. I can e-mail this video to someone.
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solid or hydraulic lifters?
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I really don’t know what type of lifters are in it
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Once the car warms up and starts to knock, disconnect all the belts and see if the knock goes away. But DON'T run it too long or it'll overheat. Just long enough to see if the knock stays or goes.
I had a bad water pump once that sounded exactly like rod knock and luckily, before I pulled the engine, I tried this trick. Saved me a TON of money and time!!
Ed
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That's a great idea Ed!!
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Also, you might pick up a stethoscope from your local car parts dealer to see if you can isolate the noise. They don't cost very much and work like the ones doctors use to listen to your ticker. LOL
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I had a p/s pulley rocking on the p/s pump because of powder coating....Joe
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So i came across some youtube videos regarding water pump knocking due to bearings going bad and the knock that it makes is exactly like the knock i'm having which give me hope.
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I’ve posted a few things this week because I have a few issues to this new to me 68 SS clone. After the engine warms up there is a faint knock and I cannot tell where it is coming from being the top end or bottom end. Almost sounds like something is knocking against something somewhere. I was going to post the video on YouTube but I’ve found that the resources on this forum are more valuable and I respect the responses from people that know way more than me about these 1st gens and engines. If anyone wants. I can e-mail this video to someone.
You could still post the video to youtube, then we could hear what it sounds like. Good luck.
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I went ahead and did that last night. Sounds exactly like a water pump woble or bearing going out.
https://youtu.be/YopLO-cNMTY
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Sounds right for that that issue.
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To me that sounds more like something hitting sheet metal or similar. A water pump knock is more of a dull thud.
Pull the belt just to make sure, but I have a feeling the knock will still be there. If it is, feel the valve covers. If it's the rockers hitting the covers, you should be able to feel it.
Ed
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Ed, i was telling someone the same thing!! Sounds like the headers or something banging against something but it only does it when the engine start to warm up. I'll pull the belts and see how it goes.
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could be a bad fuel pump.
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It seems too intermittent to be a rocker arm, in my opinion.
Is it louder on one side? Louder in front?
Could be a bad or loose pulley.
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could be a bad fuel pump.
On other cars I am more familiar with the fuel pump or vacuum pump ROD gets cupped from not turning properly and thumps. If you remove the rod and grind the end flat it fixes it. I don't have near as much experience with Chevys as I do with some others. DO Chevys ever do that?
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Can’t tell which side it’s coming from. I’ll need to start with a stethoscope and pull the surp belt like others suggested.
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could be a bad fuel pump.
On other cars I am more familiar with the fuel pump or vacuum pump ROD gets cupped from not turning properly and thumps. If you remove the rod and grind the end flat it fixes it. I don't have near as much experience with Chevys as I do with some others. DO Chevys ever do that?
i have not seen that condition in a Chevy but a bad pump itself will sound like the noise in the video. could be other things too, of course.
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Before removing the surp belt i got under the car on both sides and could definitely tell that the knock is coming from the back side of the motor somewhere. I can hear it just as equally on the driver side too.
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Maybe we need some pictures?
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If you have an auto it might be the converter bolts. But I would do the belt and eliminate the others first.
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Yes Sir it's an automatic.
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That noise is a strange one for sure.......to me its sounds like a rattle in the exhaust when it gets warm and the metal expands. A friend of mine had a muffler that rattled when it got hot.
Another thought........could the teeth of the starter be real close to the flywheel? Maybe the starter gear is not retracting like it should.
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If you have an auto it might be the converter bolts. But I would do the belt and eliminate the others first.
+1. Also, maybe the flex plate/flywheel bolts are loose.
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That noise is a strange one for sure.......to me its sounds like a rattle in the exhaust when it gets warm and the metal expands. A friend of mine had a muffler that rattled when it got hot.
Another thought........could the teeth of the starter be real close to the flywheel? Maybe the starter gear is not retracting like it should.
Does your exhaust on the passenger side still retain its Heat Riser ? They always clattered on any big block I ever had and I always tied them wide open with some wire to get rid of the noise if I was keeping the stock exhaust system on any cars I had. The springs on them are supposed to open with the heat generated and often the spring either isn't strong sufficiently to hold the flap fully wide open once the housing gets warmed up and the flap inside the pipe just ends up fluttering around clattering with the various exhaust timing events and making quite a metallic clattering sound similar to what you have going on..
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OOPs I see from the video you have headers - which makes the Heat Riser theory mute.. but check the flange bolts at least for tightness just to make sure it isn't one of them rattling around loose..
Or your emergency cable or adjuster hook not hitting against the exhaust somewhere also!
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Loose flywheel to torque convertor bolts usually make an irregular knock at or just above idle especially when the engine idle is rough. Most of the serious engine problems have a regular beat to the knock. Loose or cracked pistons usually knock when engine is cold and idling. Wrist pin knock is most often heard with engine hot and idling. Connecting rod knock can be best heard when the engine is accelerated and the RPM goes over its peak. Main bearing knock can be heard when driving and under load, sounding like a heavy rumble. Valve train noise at the rocker arms is more of a tapping noise. Rocker arms hitting the valve covers is usually a lighter tapping noise. Yes there are many other sources for engine noises. These are some of the most common heard knocks when the fan belt is removed.
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Check the flexplate for cracks.
What does it do off idle or when revved? Or, when in gear, does the sound change?
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https://youtu.be/OyMoi1xAqak
This sounds like the same knock that I’m hearing under the car.
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Sounds like in the torque converter area if not the converter itself.
Is there a dust shield that is removable to see the flex plate?
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Beware of spun bearings in big blocks causing this kind of noise. I had a 402 do this, ran fine but knocked when warm, 2 spun bearings were the culprits. Loose torque converter bolts on another 402 before, too - loud "clank" on startup more than a knock. Better pull it down before it REALLY gets worse.
Regards,
Steve
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On cars with an automatic transmission when checking for an unusual noise. The flex plate [flywheel] should be checked as a possible source. Remove the flywheel bottom cover and look up at the flex plate with a good light. Look for red rust leaking out of possible cracks. Sometimes cracks cannot be detected till the flex plate is removed. Noise from this part may only occur only when hot or only when cold. The noise can sound like a knock, a snap, a click, a clunk, or a rattle. It is the go to area to check when you have an unusual noise.
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Thank you guys for all the info! Got up under the car today and quickly turned into a sissy to remove anything because the torq converter is really close to the flexplate and I can’t get a wrench up in there because of the space to try to tighten the bolts if loose so I gave up 1 man card put the dust shield back on and going to take it to a mechanic and explain where this knock is coming from.
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Mechanic said torque converter and flexplate are fine. Also removed the fuel pump as well, still had the knock. He said that it's in tho motor even after i bet him 20 bucks it was the flexplate.
Now to find someone that can pull the motor and check basically everything and go straight down into the financial rabbit hole and come out butt hurt.
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https://youtu.be/LONT1oboJrs (https://youtu.be/LONT1oboJrs)
Is this your mechanic?
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That was too funny man!!!! Geez i'm still laughing at that!!! I wish that was what the problem was!!
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Turns out that I have to have the motor rebuilt
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Sorry to hear, man.
Just curious, what was the failed component(s)?
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Would like to know what they said was bad and pics of the items. Main bearings?
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Oil pump was barely inside the oil pan. Crank was really marred everywhere. Cam was rounded off. Pistons looked like $hit. Hydrolic lifters cupped really bad. Lifters mushroomed out. Saw it today for the first time and was blown away with what I saw. Threw up in my mouth a little too.
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Spun bearings charred beyond belief too. I didn’t take any close up pics. Sorry about that
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Sounds like it really wasn't rebuilt or rebuilt poorly. Sorry for you! Fix it right then you will know and hopefully get some good from it.
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Amazing still that the engine ran with that much internal damage. Sounds like the builder didn't think much of oil pickup/screen clearances -
Regards,
Steve
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Did the car have an oil pressure gauge, factory.
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In my opinion, the sounds captured in the video do not seem to match up with the damage found in the engine at tear down. But that is just my opinion.
BUT, I will tell you it is surprising how long a big block will run with damage. A 427 WILL run with 3 rods shucked out the bottom end. And I mean OUT, like onto the road out. Obviously it didn't run well, and was only left to idle for a few seconds, but it did idle. Long story...
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My opinion also. With all that damage it should have had death rattles, at least while driven.
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It felt like it ran fine and all that was noticeable was the bottom end knock. It didn’t have but will in the future a kick down cable and I never had a chance to floor it and open up 4 barrels. Never felt like a wobble whatsoever. If the block comes back with good pressure and can be salvaged, we are painting the block black and heads black with chrome valve covers. Also getting the billet surpentine belt kit for dress up because it’s not a numbers matching car and we can pretty much. Keeping the block stock with all new parts and as fat of a cam I can that the tolerance allows. Sucks that we just got this car and had to turn around and hear that it was shot and or about to be shot.
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This car is solid black with gray racing stripes. We call her Black Betty and she’s not rock steady right now. She’s been a real bi*ch ever since I got her. Once she comes back solid, she’ll be bambalam and I’m gonna open her up and finally see what it can do.
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Do you completely trust the machine shop that tore it down to check it?
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I do trust them. The guy that tore it down does this weekly for someone that drag races on the weekends and rebuilds a 454 when needed. He’s also a Camaro guy himself and familiar with these firsts gens. Knowing this put me at ease a little going into this project.
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Do you completely trust the machine shop that tore it down to check it?
Thats a very good comment. You MUST have complete confidance in your machinist/engine builder! I for one would not take a Chevy engine to a Ford guy, or vise versa.