Do you guys think this is Rod Knock?

[Jrparadis]

Hey Guys i could use some help with identifying the most likely cause of the sounds my 454 is making. Ill give some background first. It started overheating and lost power on the highway. Temp got up 235 when i got it pulled over and shut it off. I never lost oil pressure during this and now it makes a ticking sound and seems to struggle at Idle. A buddy of mine who is a mechanic thinks maybe something timing related and he said it doesn't sound like Rod knock to him but I am wondering if any of you guys who have more experience with a BBC recognize the sound its making or have some ideas.

My list of things i want to look at before I tear the motor out are:
-Vacuum Leak
-Timing chain or distributor issues
-bent pushrod
-broken flexplate (I know i know but apparently it can mimic a knocking sound)

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[Big Chip]

Make sure all the bolts are tight on your flexplate before you tear into it too far. It seems like a lot of guys have had them back out around here.

 

[MisterB]

Definitely troubleshoot all that, but start simple and use a gas additive. I had a knock develop, and I bought one of those Lucas complete fuel system additives. I put it in my tank at NAPA, and by the time I went through the parking lot and made a right turn, the knock was gone and hasn't returned.

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[Bextreme04]

Start simple, take the valve covers off and see what it looks like while it's running. Its not unknown for people to find pieces laying under there that explain those weird noises and poor running engines.

 

[Bextreme04]

While you're at it, run a compression test and leakdown test. Chances are you'll find your problem somewhere in those three steps or at least be able to determine what it is.

 

[Big Chip]

Come to think of it, I thought I blew my 305 in my 86 and after I found a new 350 and another pile of parts I took the valve covers off and one of the rocker arms had come off the pushrod and was making a pretty bad racket too. Good call @Bextreme04

 

[Bextreme04]

Come to think of it, I thought I blew my 305 in my 86 and after I found a new 350 and another pile of parts I took the valve covers off and one of the rocker arms had come off the pushrod and was making a pretty bad racket too. Good call @Bextreme04

Its a thing, I banged my head against a wall trying to figure out why my engine suddenly ran like crap and was occasionally backfiring. Finally ran a compression test and found 0 compression on 1 cylinder(OH CRAP!!). I assumed the motor had just gone toes up and was thinking of looking for a replacement. Then I decided to see if I could find how it had actually failed just because I was curious. Took the valve cover off and low and behold the intake valve spring on the offending cylinder was broken into 3 pieces.

I bought a new set of comp cams factory replacement springs for $50 and new valve seals for $5 and replaced everything in an afternoon. Its been running like a champ ever since.

With a sound like that I'd be looking for broken/missing parts, uneven lifter movement(wiped cam lobe), or loose valvetrain(wiped cam lobe or collapsed lifter). It also kindof sounds like a slight exhaust leak so I'd be looking to see if overheating the engine also had high exhaust temps that might have broken an exhaust stud or cracked the header.

 

[Jrparadis]

Thanks for your help guys. I have the rest of the week off and ill have time to work on it. Cant wait to cruise around once i figure it out.

 

[Termite_Delight]

With a sound like that I'd be looking for broken/missing parts, uneven lifter movement(wiped cam lobe), or loose valvetrain(wiped cam lobe or collapsed lifter). It also kindof sounds like a slight exhaust leak so I'd be looking to see if overheating the engine also had high exhaust temps that might have broken an exhaust stud or cracked the header.

I agree, I'd say valve train related noise.

 

[clendon1]

Quick way to check for rodknock: with engine idling, pull off 1plug wire at a time, if the noise stops you got a rod bearing problem, if the noise continues, you have other problems.