Is this rod knock?

[CruiserTrash]

If sound is increasing when you're on the Bellhousing, it seems like sound is traveling through the block. BGarcia beat me to it, but I too would check the valve train, particularly the lifter/pushrods before tearing anything apart.

FWIW, if/when you get to that point of replacing the Pilot bearing, JimC sells a super-duper one I've been itching to try:

Pilot bearing, 1F/2F/3F series engines

There's nothing worse than having to drop the transmission & transfer case and pull off the clutch to change a dried out pilot bearing. That's a lot of backbreaking labor that could have been saved by installing this top quality made in EU by SKF aerospace bearing filled with synthetic grease...

tlcperformance.com

Interesting. So the sound would be emanating from the lifters down below, or the valves up top? Devil's advocate question: why wouldn't I hear that more loudly directly at the source? Why is it loudest at the bellhousing?

 

[Spike Strip]

The Physics of sound...

Things like this can be very tricky because vibrations (like electrons) will travel through the path of least resistance and the bellhousing may be acting like a diaphragm in a speaker, or like two tin cans with taunt string between them like a childhood walkie-talkie. You 'hear' the vibrations where they can move air, like the speaker.

The Cam shaft end is right up against the Bellhousing.

It may very well be that there is a bearing or other issue right at that point in the Bellhousing / Crank juxtaposition that doesn't involve the valve train, nobody is gonna know but you - but I'd sure want to be 100% sure before tearing stuff apart.

I hate to harp on this, but this is where a proper Stethoscope with a long rod will help you isolate where the sound is originating.

 

[Zjohnsonua]

We've had a few engines come through the shop with slipping cam gears that kind of sound like this. Cam gear starts walking off the cam and every time the cam loads up it bounces off the rear cup plug. Had a few new builds from other shops come in for the same noise caused by aftermarket cup plugs that got squeezed in further by the bell housing during reassembly.

One of these such noises was so severe that the fellow pulled the pan and found shavings...he assumed it was rod knock and did the swap he'd been planning...we got the engine, tore it down, and found a pristine lower end...the rear cup plug was nearly ground through. If it had run much longer he'd have ground through it and emptied the oil pan into the bell housing.

 

[CruiserTrash]

We've had a few engines come through the shop with slipping cam gears that kind of sound like this. Cam gear starts walking off the cam and every time the cam loads up it bounces off the rear cup plug. Had a few new builds from other shops come in for the same noise caused by aftermarket cup plugs that got squeezed in further by the bell housing during reassembly.

One of these such noises was so severe that the fellow pulled the pan and found shavings...he assumed it was rod knock and did the swap he'd been planning...we got the engine, tore it down, and found a pristine lower end...the rear cup plug was nearly ground through. If it had run much longer he'd have ground through it and emptied the oil pan into the bell housing.

this went way over my head because I’ve never torn an engine apart. You’re saying because the cam gear is loose on the shaft, the entire camshaft is bouncing fore and aft, repeatedly slamming into something behind it?

When you say the gear is walking off the shaft when it loads up, you mean when the engine’s under load?

 

[CruiserTrash]

@Zjohnsonua Also curious what would cause that scenario in an original motor. Just trying to wrap my head around it so I can be looking in the right places when I do some more diagnosis.

 

[Spike Strip]

There's a locking clip on the front of the Cam that holds the gear in place. If it breaks or wears away, the Camshaft tens to push on the Welsh plug at the rear of the block that is an oil seal. That plug is up against the Bell housing

Post in thread 'How not to build the 2F' How not to build the 2F - https://forum.ih8mud.com/threads/how-not-to-build-the-2f.563170/post-7377892

 

[CruiserTrash]

There's a locking clip on the front of the Cam that holds the gear in place. If it breaks or wears away, the Camshaft tens to push on the Welsh plug at the rear of the block that is an oil seal. That plug is up against the Bell housing

The C-clip makes sense. I assumed that’s under the cover plate on the front?

My front main does leak … might be an w cause to go in there. But everything’s an excuse. Go in to replace a vacuum line and end up rebuilding the motor haha.

 

[klinetime574]

This is an interesting noise. The videos with and without the inspection cover sound completely different. I’m thinking flywheel or pressure plate issue. Loose bolts, worn dowels, oblong holes, random failure, etc. Definitely will be watching to see your findings @CruiserTrash

 

[CruiserTrash]

This is an interesting noise. The videos with and without the inspection cover sound completely different. I’m thinking flywheel or pressure plate issue. Loose bolts, worn dowels, oblong holes, random failure, etc. Definitely will be watching to see your findings @CruiserTrash

I’m going to dig in more tonight. Worst case scenario I order some parts and use the rebuilt H42 sitting on my shop floor to swap new stuff in.

@RodrigzCrzr suggested that if I do that, to run the motor with the transmission out to potentially isolate the camshaft issue - or other engine issues versus transmission problems.

 

[LandoNick]

I’m going to dig in more tonight. Worst case scenario I order some parts and use the rebuilt H42 sitting on my shop floor to swap new stuff in.

@RodrigzCrzr suggested that if I do that, to run the motor with the transmission out to potentially isolate the camshaft issue - or other engine issues versus transmission problems.

So pull the Trans to see if anything looks funky? Then run motor to see if the noise still is there? have you pulled belts off one my one to see if the noise stops? and I think you did the pull each plug wire method, and no change?

 

[CruiserTrash]

So pull the Trans to see if anything looks funky? Then run motor to see if the noise still is there? have you pulled belts off one my one to see if the noise stops? and I think you did the pull each plug wire method, and no change?

Correct on plug wires one by one and belts. No change for those tests. Really don't want to be dropping a transmission, but maybe that's my weekend.

 

[CruiserTrash]

Finally absconded with some time to dig in more. This is kind of crazy but the noise is loudest at the power steering pump. Granted, it’s kind of all over: right side of oil pan, block on the left side by cylinder 3, bellhousing, quite a bit in the clutch fork. I am not getting it in the valve cover, head, anything pulley driven - except the PS pump - front cover, etc.

Took the fuel pump off. It’s a year old and looks good. Taking belts off now.

 

[matubrembrem]

Did you figure out the source of the noise? If not, next time you’re under the truck pull the flywheel inspection cover off and check out the shift fork. My truck was making a similar noise and it ended up being the shift fork rattling against the pivot pin on the bell housing.

 

[CruiserTrash]

Did you figure out the source of the noise? If not, next time you’re under the truck pull the flywheel inspection cover off and check out the shift fork. My truck was making a similar noise and it ended up being the shift fork rattling against the pivot pin on the bell housing.

Did the noise change when you pushed the clutch pedal in?

I honestly haven’t done anything yet. The truck was on jack stands for a week long knuckle job, and when I fired her up Wednesday the noise wasn’t there. Since then it’s been intermittent again, and low on volume. I got an oil pan gasket on hand so I’ll probably drop the pan and have a look in the next week or two.

 

[WILLD420]

Not sure what your sound is. Leaning toward broken piston skirt or bad wrist pin.

Fast forward to about 33 minutes. You'll hear him start this 4.3 V6 with a rod knock. Don't think that is your issue.


This is another one, hard to hear over the valvetrain noise. Unknown problem, but doesn't sound all that similar to yours via the video.


Bad wristpin is closer to your noise.
Bad wrist pin on SBC? - https://www.youtube.com/shorts/wWJJNAuI0sI

Another wristpin. Sounds pretty close to me.
1985 Honda CRX Wrist Pin Tick/Knock - https://www.youtube.com/watch?v=LBZeRZ3_kf0

Piston slap is similar.
WHAT PISTON SLAPS SOUNDS LIKE - https://www.youtube.com/watch?v=806MP_wDYZs

This is what rod bearing knock usually sounds like.
Chevy 5.3 engine knock troubleshooting - https://www.youtube.com/watch?v=Pk1zX_0mKjg

 

[matubrembrem]

Did the noise change when you pushed the clutch pedal in?

I honestly haven’t done anything yet. The truck was on jack stands for a week long knuckle job, and when I fired her up Wednesday the noise wasn’t there. Since then it’s been intermittent again, and low on volume. I got an oil pan gasket on hand so I’ll probably drop the pan and have a look in the next week or two.

Mine would come and go and it would change when pushing the clutch pedal in.

 

[CruiserTrash]

Not sure what your sound is. Leaning toward broken piston skirt or bad wrist pin.

Fast forward to about 33 minutes. You'll hear him start this 4.3 V6 with a rod knock. Don't think that is your issue.


This is another one, hard to hear over the valvetrain noise. Unknown problem, but doesn't sound all that similar to yours via the video.


Bad wristpin is closer to your noise.
Bad wrist pin on SBC? - https://www.youtube.com/shorts/wWJJNAuI0sI

Another wristpin. Sounds pretty close to me.
1985 Honda CRX Wrist Pin Tick/Knock - https://www.youtube.com/watch?v=LBZeRZ3_kf0

Piston slap is similar.
WHAT PISTON SLAPS SOUNDS LIKE - https://www.youtube.com/watch?v=806MP_wDYZs

This is what rod bearing knock usually sounds like.
Chevy 5.3 engine knock troubleshooting - https://www.youtube.com/watch?v=Pk1zX_0mKjg

Seems closest to the wrist pin noise to me. But my noise doesn't seem to get louder with rpms. If anything it seems like it gets quieter. Still won't have time to drop the oil pan for another 7-10 days.

 

[CruiserTrash]

that would be one way, have torqe wrench and then unbolt con rod end..push piston up in cylinded then widdle con rod up and down see if the wrist pin had large axial play. if so, time to remove head take it to a machine shop.

Why would that necessitate taking the head to a machine shop? If it is a wrist pin, could I “get away with” pulling the piston, replacing the wrist pin, and putting it back in?

 

[diesellibrarian]

Why would that necessitate taking the head to a machine shop? If it is a wrist pin, could I “get away with” pulling the piston, replacing the wrist pin, and putting it back in?

I think The Analyst might have been a few beers deep when he wrote that.

 

[HemiAlex]

I’m deeply intrigued by this