SOLVED - Engine knocking (video inside)

[Peachy Bronco]

Hi everyone, brand new here. Just bought a ‘72. Wasn’t able to find out a whole lot about it, but it’s in pretty good shape. New 302 engine that ran great right off the bat, but suddenly started making a horrible noise and loses power under heavier acceleration.

Here’s the video HERE. Any suggestions? Thanks all!

 

[hummerdan]

Is the noise in the bell housing? Torque converter bolts?

 

[Peachy Bronco]

I’m not quite sure to be honest. Sounds like it’s more up under the hood?

 

[1970 Palmer]

I’m not quite sure to be honest. Sounds like it’s more up under the hood?

Take a very long screwdriver (or metal pipe/rod) and hold one end against the engine, place the other end against your ear. It's just a stethoscope. Move it around the engine and bell housing and figure out where your noise is coming from first, then you can narrow your search down.

Does it have any oil pressure?

 

[nvrstuk]

It's LOUD for sure. What Palmer says works great to help track/locate the source.

Sounded like when you stepped on the throttle creating more load on the engine the noise got louder. Is that right???

 

[Peachy Bronco]

It's LOUD for sure. What Palmer says works great to help track/locate the source.

Sounded like when you stepped on the throttle creating more load on the engine the noise got louder. Is that right???

Yes, definitely right. At low rpm it’s almost gone, just will occasionally pop/clank. I’ll have to confirm tomorrow, but when I start it up and rev the engine a bit, there’s almost little to no issue. I’ll have to check the revving at a standstill again though to be sure. Hard to stethoscope while driving!

 

[nvrstuk]

The "lose power" thing is somewhat odd. Means there could be more than just something like a typical rod bearing noise -so hard getting accurate sound via cell phone thru to headphones here at home. Lose a lot in the recording.

So that CLANK is loud. Could be a variety of things but if you aren't trying to purposely grenade the engine then I wouldn't drive it but just try to replicate the noise in the driveway- maybe in gear (easy with an auto) then you can load the engine easier.

 

[Peachy Bronco]

The "lose power" thing is somewhat odd. Means there could be more than just something like a typical rod bearing noise -so hard getting accurate sound via cell phone thru to headphones here at home. Lose a lot in the recording.

So that CLANK is loud. Could be a variety of things but if you aren't trying to purposely grenade the engine then I wouldn't drive it but just try to replicate the noise in the driveway- maybe in gear (easy with an auto) then you can load the engine easier.

I agree, it’s loud and concerning. Going to keep it off the road until I figure it out. Thank you.

 

[1970 Palmer]

Repeat......does it have any oil pressure? It's really hammering, "don't drive it, or run it very long".

If it has oil pressure, (and is it an automatic transmission?) it could be as simple as a loose or broken converter drive plate.

Maybe check the vibration dampener for a loose outer ring.

It sounds like a rod knock, which gets heavier/louder under load. This would test as low oil pressure. You should always use a real oil pressure gauge when testing, not the OE dash gauge.

You realize that we are just shooting in the dark with guesses. The more back ground information on your engine/transmission might help us help you narrow it down.

 

[nvrstuk]

Like Palmer said we are just throwing ideas out till we know more about your engine/trans combo.

 

[EPB72]

You can also pull the oil filter and look for metalic ...

 

[Peachy Bronco]

Thanks everyone for the help so far. I'll have to check the oil pressure (or have it checked). As I mentioned, just bought this truck and I'm in the process of figuring out all of the specs and vehicle history:

- 302 engine, fairly new but I don't know when
- 4 speed manual, NP 435 trans
- Brawler 4 barrel carburetor
- MSD electronic ignition

Advance timing was set around 8 deg, I bumped it to 12 deg to test but that didn't help. Video from original post is with 12 deg.

 

[spap]

I have had the starter ring around the flex -plate gear starter ring slightly detach from the flex plate it was for a c4 and more a different sound, but imagine if it was hitting something when speeds increase the sound could be close
good luck

 

[Peachy Bronco]

I haven’t been able to obtain an oil pressure tool yet, but my gauge is reading properly and the nylon oil line to the gauge is visually filling up when the engine runs (for whatever that’s worth).

 

[Viperwolf1]

Kind of sounds like starter gear is hitting the flexplate.

 

[Peachy Bronco]

SOLVED! There were a few rockers that were totally backed off and loose. Initially we thought the cam went out, but after adjusting the rockers down properly everything started running great again. Not sure how or why it this happened under the previous ownership, but luckily no damage was done and it was a simple fix.

Probably going to go back in a replace all of the rockers soon. For some reason the previous owner had 3-4 mismatched rockers in there too.

 

[gnpenning]

The adjusting nuts don't like being reused to many times. Sounds like they had problems previously and just put whatever was at hand on.

Odds are high you will be doing this again. Order your new rockers and nuts as planned.

 

[Peachy Bronco]

Thank you for the additional information.