rebuilt 318 knock noise around 2500

[Geoff 2]

Why don't you try what I posted in post #3? It is soooooo simple.....

[1] If just one rod brg has worn, unlikely to see a change in oil pressure because the oil pump is made with excess capacity.
[2] Not so noisy when cold. Oil is thicker, cushions the load...

 

[Doorkicker]

If it was this would it hurt the motor? Again i've ran this like this since 2016 chasing the noise around with different things and the motor lives. Puzzles me. once i was across the river from a buddys house and did a burn out and he heard me. Before he saw it was me he thought there was a diesel over there doing a burn out. It sounds somewhat like a diesel when you hear the noise at the motor

If the crank is a bit "lose" fore and aft the engine will still last - in fact, some high horsepower motors will have a touch of extra clearance on the thrust bearing. But if too much eventually that thrust bearing will give in to the beating and it will progressively get louder. The engine will typically run quite good because the piston pins are taking up the "slack"... but only to a point. Eventually, the issue (assuming this is the case) will transfer stress throughout the rotating assembly. For example, if it happens too much you'll likely start to get side-wearing on the piston. In short, an engine can run very good and for a while with too much thrust clearance, but it will eventually bite you.

The one thing that is quite concerning is the point about sounding like a diesel... that may be a different animal altogether. I think @padam is on to something with that you could have way too much advance and you're detonating.

You said you checked your timing... but I think I missed what it was. What is the base, sweep and total?

 

[Darter6]

Just thinking, Had a car with a wrist pin slap/knock.Drove that thing for 5 more years next owner did too. ?

 

[72RobCharger]

Why don't you try what I posted in post #3? It is soooooo simple.....

[1] If just one rod brg has worn, unlikely to see a change in oil pressure because the oil pump is made with excess capacity.
[2] Not so noisy when cold. Oil is thicker, cushions the load..

I plan to do this. As my friend said if it is a rod bearing then it wouldn't be anything to pull the motor (again) and tear it down until we find the culprit.

 

[Sixpactogo]

I'm betting on the fuel pump. Had that same issue myself but with a 383. There should be no play in that arm.

 

[eldubb440]

 

[72RobCharger]

I'm betting on the fuel pump. Had that same issue myself but with a 383. There should be no play in that arm.

What were the symptoms of your bad fuel pump? Would your 383 run with the fuel pump like that? I dont appear to have any fueling issues its ran like this for 8 years. Not spun any bearins or anything. Thank you

 

[Sixpactogo]

What were the symptoms of your bad fuel pump? Would your 383 run with the fuel pump like that? I dont appear to have any fueling issues its ran like this for 8 years. Not spun any bearins or anything. Thank you

My car ran great. No noise at idle. only when cruising at light throttle. It sounded like a rod or wrist pin to me. I drove from Wisconsin to the Mopar Nats and back home with no problems except what was going on in my mind. I had another 383 that I swapped in and never figured out what was wrong with my original engine until I had a problem with my 440 powered truck fuel pump. I swapped in the fuel pump from that 383 and wouldn't you know, there was that same noise in my 440. That fuel pump had a weak spring in the actuator arm and that was what was rattling.

 

[72RobCharger]

My car ran great. No noise at idle. only when cruising at light throttle. It sounded like a rod or wrist pin to me. I drove from Wisconsin to the Mopar Nats and back home with no problems except what was going on in my mind. I had another 383 that I swapped in and never figured out what was wrong with my original engine until I had a problem with my 440 powered truck fuel pump. I swapped in the fuel pump from that 383 and wouldn't you know, there was that same noise in my 440. That fuel pump had a weak spring in the actuator arm and that was what was rattling.

Thank you for sharing. Was the end of your fuel pump arm banged up like mine as shown in the video? Im gonna try a new fuel pump. Its just crazy to think its been running this whole time with no trouble to the motor or fueling issues. The new pump i have has the same play but does feel stiffer. The old fuel pump is probably 10 years old or so.

 

[Sixpactogo]

Thank you for sharing. Was the end of your fuel pump arm banged up like mine as shown in the video? Im gonna try a new fuel pump. Its just crazy to think its been running this whole time with no trouble to the motor or fueling issues. The new pump i have has the same play but does feel stiffer. The old fuel pump is probably 10 years old or so.

I hear ya. I would not have guessed the fuel pump either. Like i said, I found it by accident. My engine ran great but it was messing with my mind big time. I was imagining being stranded in the middle of nowhere. I knew it was on the passenger side since my stethoscope showed it more prevalent there but I couldn't pin point it. I can't remember any issues with the arm being banged up but I do remember the weak spring as to the cause.
I sincerely hope it is your problem as well since it is an easy fix. Good Luck!
I don't recall if I tried my stethoscope probe on the fuel pump itself but I should have for sure.

 

[72RobCharger]

here everyone i just took a video for you. I also replaced fuel pump and that didn't help unfortunately. At least with this video you can hear what im talking about

 

[Doorkicker]

here everyone i just took a video for you. I also replaced fuel pump and that didn't help unfortunately. At least with this video you can hear what im talking about

wow... ok... you can definitely hear it.

If I was right there with you I would...

1) check timing to see what total is just to be sure.
2) start pulling plug wires cylinder by cylinder and reving to see if it goes away

There is a tiny part of me that thinks it's in the piston (wrist pin ware, side wall, etc.), or there is carbon build up and you're getting a weird pre-ignition on one of the cylinders. Anyway... I'm super curious.

 

[72RobCharger]

wow... ok... you can definitely hear it.

If I was right there with you I would...

1) check timing to see what total is just to be sure.
2) start pulling plug wires cylinder by cylinder and reving to see if it goes away

There is a tiny part of me that thinks it's in the piston (wrist pin ware, side wall, etc.), or there is carbon build up and you're getting a weird pre-ignition on one of the cylinders. Anyway... I'm super curious.

Ive Ran the timing many different ways. Right now its sitting about 16 initial probably 32 all in by 2,000. Ive ran less timing and i've ran more timing. No difference in the sound. The noise doesn't move up or down in the rpm range either when i adjust the timing. It doesn't really sound like its hitting hard enough to be a rod bearing a lil loose but im going to find out. Im really hoping for something simple. Its been this way forever and has not seemed to hurt the motor at all. for a .060 318 with aluminum head it runs pretty strong.

 

[72RobCharger]

Ok everyone, I pulled each plug wire 1 at a time and revved in between the noise is still there. No difference. I appreciate all your responses and help thru out this head scratcher of a problem. I will continue to try and figure it out. The internet is a lovely tool for situations like this. My lil town where im from Mopars are far few and inbetween. Mostly chevy and ford guys or just your straight up diesel guys. So i really do appreciate all of your responses! Cheers from Wv

 

[Sixpactogo]

here everyone i just took a video for you. I also replaced fuel pump and that didn't help unfortunately. At least with this video you can hear what im talking about

Wow. That is loud. Does not sound like the fuel pump. Way too fast of a rattle. I assume you have disconnected the belts to rule out any add-ons. How about an exhaust leak?

 

[72RobCharger]

Wow. That is loud. Does not sound like the fuel pump. Way too fast of a rattle. I assume you have disconnected the belts to rule out any add-ons. How about an exhaust leak?

not yet no. I'll try that tho. Its so weird because its not hurt the motor all these years. And yea the rattle goes will the rpm. I've ran the dog shat out of this motor too. everyone talks about how tough 318's are. They are very tough. I always thought this was a valve train problem. I saw a tech bulletin once that said sometimes the rockers need clearanced from the valve springs as the springs can sometimes hit them.

 

[72RobCharger]

Im Still researching. has anyone ever had a worn oil pump shaft bushing sound like this?

 

[RemCharger]

not yet no. I'll try that tho. Its so weird because its not hurt the motor all these years. And yea the rattle goes will the rpm. I've ran the dog shat out of this motor too. everyone talks about how tough 318's are. They are very tough. I always thought this was a valve train problem. I saw a tech bulletin once that said sometimes the rockers need clearanced from the valve springs as the springs can sometimes hit them.

If the valve springs are too big of a diameter yes.

 

[72RobCharger]

If the valve springs are too big of a diameter yes.

Im running the comp cams 906 springs. Single Outer Valve Spring: 1.355" O.D., 1.011" I.D.

 

[Doorkicker]

@72RobCharger ... ok... I'm going crazy over here

In summary... just generalizing where we're at...

- timing is ok and no change if advanced or retarded (seems to "reduce" the pre-ignition concern)
- no change when pulling plug wires one at a time (seems to eliminate rod or piston problems - as well as pre-ignition, assuming it's a single cylinder)
- doesn't appear to be a fuel pump issue

Things I'm not sure were covered...
- Pulley interference (I doubt this a little more after watching the vid, but still a possibility)
- Has the flywheel/converter bolts been checked?
- I know I mentioned crank fore and aft movement before... have you gotten under the car and used a pry tool to see how far forward and rear the crank is moving?

General thoughts now...
- Bad / loose oil pump?
- bad distributor drive bushing (inside the block)? Doubtful.. but easy to check.