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Engine knock 71 350

 
Old 03-10-2019, 08:06 PM
  #21  
Beltran
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Can anyone link me to Lars? I can't anything with his name in the vendor directory.

NM I located him... found an old thread.

Last edited by Beltran; 03-11-2019 at 08:02 PM.
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Old 03-10-2019, 08:26 PM
  #22  
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I have noticed a pattern with the car.. things are not tightened down. a lot of loose bolts. I hope I can pull this pan without pulling the engine.
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Old 03-10-2019, 08:34 PM
  #23  
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Harmonic damper outer ring unbonded & loose ... banging against timing cover, bracket etc.
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Old 03-10-2019, 11:02 PM
  #24  
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its not wobbling at all. It spins true. all the pulleys and belts spin true.
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Old 03-11-2019, 07:22 AM
  #25  
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Originally Posted by L88Plus View Post
Fuel pump pushrod should always be checked before you decide it's a rod bearing knock.
Flexplates tend to act different when not loaded as compared to when it's dropped in gear and under load. Mine didn't knock, it was a clicking/clanging sound.
Good luck, hope it's one of the easier ones to fix.
X2 on the fuel pump pushrod.......order an ARP unit and stick it in there.......I have fixed more than one knock like this and it is right there at #2 cylinder.

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Old 03-11-2019, 07:58 PM
  #26  
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ordered arp unit and gaskets from summit... /sigh. I hope this works.
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Old 03-13-2019, 10:03 PM
  #27  
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Argh.. the new fuel pump rod did nothing to eliminate the knock. Oil pan is coming off now.
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Old 03-13-2019, 11:13 PM
  #28  
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Well, after the videos, I hate to think it but it sounds like a big end rod knock. Pretty solid clack going on there I think.
Just my lazy self but I would try yanking the fan/alternator belts and if that does nothing I would drop the pan.
Hope it's something simple!
Best of luck and let us know what you you find.
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Old 03-15-2019, 10:34 PM
  #29  
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I dropped the pan and found no obvious issues. No parts in the pan and the oil did not have a sheen to it. so it doesn't appear as if anything is getting damaged.

I check the caps and bolts and all seemed to be tight.

I removed the number 2 cap and noticed that the bearing stops were on the same side ! The bearings look good fortunately. But how to solve this?

What would you do?

a) flip the cap around so that the bearing tabs are opposite like they are supposed to be, but the 'heavy' side of the bearing will be facing inside instead of out.
b) turn the connecting rod and piston 180 degrees. This will allow the oil hole to be facing inward per the service manual, but the piston would be facing the wrong way. This is a flat top 350 piston so is it an issue?
c) Pull the head, the piston and rod. Reassemble correctly at a significant cost and time. (my least favorite option.)



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Old 03-15-2019, 11:04 PM
  #30  
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I cannot see well enough from your pics

But OE pistons and their OE-type replacements usually have a pin offset.

Those that do have offset usually have a dot or arrow etc in TOP of piston indicating which way to install ... for example pistons with dot must be installed with dot toward front of motor... all so offset pin is installed correct,

That offset is engineered in to reduce piston slap/knock.

Aye, but here's the rub: if that offset is installed backwards (e.g. dot to rear) the piston will slap/knock more than if its pin were not offset at all.

Is your piston installed wrong? I don't know

Does your motor knock because of incorrect offset? I don't know.
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Old 03-15-2019, 11:49 PM
  #31  
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I think you do not want to rotate the piston in the bore. Valve reliefs will be on the wrong side. I couldn't tell you what to do. Probably pull the head is what I'd do and check the piston. Pretty much almost ready to pull the piston and rod right now, just the head, intake and cover left.
Someone here will set you straight. Oh, maybe you can get a borescope down #2 plug hole and check the top of the piston for marks, etc.

Last edited by stumpshot; 03-15-2019 at 11:53 PM.
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Old 03-16-2019, 09:54 AM
  #32  
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I will try the borescope today. I have one. See if that piston is in correct.

I found this article online and it makes me wonder if I have to worry at all about the orientation of the cap. http://engineprofessional.com/articles/EPQ416_50-54.pdf per the pictures on page 53. (its a article from a magazine, so its not 53 pages long. ;D)

And this article suggests that the orientation of the rod is correct. Note that the chamfer on the rod is facing the correct direction. Perhaps this is not the issue at all?

Maybe a cap is crossed with another odd numbered rod? hmm.

I also used a torque wrench to unloosen the nuts on the rod cap. It only took 50lbs of pressure to do this. It should have taken upwards of 70lbs +. Maybe it just needed to be tightened down more.

Last edited by Beltran; 03-16-2019 at 09:56 AM.
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Old 03-16-2019, 09:55 AM
  #33  
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Many pistons with four valve reliefs (both flattop & dish) have a dot and offset pin.
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Old 03-16-2019, 10:18 AM
  #34  
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Bearing tangs are SUPPOSED to be on the same side.
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Old 03-16-2019, 10:42 AM
  #35  
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ok thanks L88. I can find it documented both ways.
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Old 03-16-2019, 01:33 PM
  #36  
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Take a look at some pics of new rods on ebay - search "connecting rods". On many, you can see inside the big end, you'll see that tangs always face each other on the same side of the rod. If it's on the other way, the cap was installed backwards. Same with main caps.
More important now is what the bearing looks like. Shiny is fine, even with a few shallow scratches. Deep scratches or visible copper means trouble.
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Old 03-16-2019, 07:33 PM
  #37  
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There was nothing wrong with the bearings. They were clean and perfect. I pulled number 1 and number 2 just to be sure. I put the oil pan back on and I am convinced now that it is probably the fuel pump and it's missing the tension spring or something. It's a new pump but have to believe it is something simpler than a lower end problem.
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Old 03-16-2019, 08:11 PM
  #38  
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#4 main and 7 & 8 rods are usually the first to show starvation problems. If you've checked those, you're probably good. A rod won't knock unless the bearing is junk.
It can be so frustrating locating the problem since sound is transmitted through the block. When you pull the fuel pump and pushrod, use a borescope or something similar to check that cam lobe.
I feel for you, man, I've chased noises before and it can drive you mad.
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Old Yesterday, 12:34 AM
  #39  
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Originally Posted by Beltran View Post
There was nothing wrong with the bearings. They were clean and perfect. I pulled number 1 and number 2 just to be sure. I put the oil pan back on and I am convinced now that it is probably the fuel pump and it's missing the tension spring or something. It's a new pump but have to believe it is something simpler than a lower end problem.
i would have used plastigage to see what’s what before putting the pan back on. You know check bearing clearances.

Last edited by REELAV8R; Yesterday at 12:35 AM.
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Old Yesterday, 09:04 AM
  #40  
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I'll start by saying that I am Not a mechanic. That being said, many years ago I had a similar issue with a 32K mileage '55 Chevy 265ci V-8. I did all that you have and did remove the piston/rod. The piston had a cracked skirt and it slapped in the cylinder.
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