Technical What is this engine sound? More '54 Nash Rambler diagnosis, things are looking bad...

The groove won’t be an issue, ***uming the groove is the only displaced material.
Ie, spin a rod on a lathe and take a light cut. Only thing you will feel would be the depression of the cut.
But take a center punch and hammer it on metal, the outside of the punched depression is raised higher than the parent metal.
My initial thought is the debris acted like a lathe cut.

 

I appreciate all the votes of confidence. We're going to give her a try and see what happens. I know I probably should have looked at the main bearings too but I don't want to dig into this any deeper, I'm not even sure if this is going to cure the sound or not. I stayed up late tonight to get the oil pan on (not too terrible of a job, surprisingly) and that way I can let the silicone in the corners set up until tomorrow (it's a 4 piece gasket) and then I'll fill it up with oil, put the crossmember and steering link back on and we'll see what it sounds like. Praying for a quiet runner without any surprises.

 

Crank polishing, I didn't see the practice of using a shoe lace or heavy string wrapped on the outside of the paper twice around the journal. This keeps the paper/crocus as round as the crank and in full contact. Feels clumsy at 1st but once you get your mojo goin it makes the job easy. Yes, 320 thru 500 grit wet paper will polish and remove minor high spots but won't take metal down very far. I polish the insides of master and wheel cylinders with 400 and it works well. Just sayin, from 1 "mud slinger" to another...

 

Like others have said. Run it. If the knock is still there it could be piston pin slop. That will require a complete tear down. So, run it to see if it is knocking at all. if so then proceed with the continued search. Went back and listened again. Sounds like a deep knock so you probably got it. Run it and see.

 

Old school vernier reading caliper mic's are a bit of an art. Not surprised that they weren't as reliable as the PlastiGauge. Many scoff at the PlastiGauge but it's a reliable, repeatable double check. Thanks for taking us along for the ride. Several guys here did yeoman's duty on this thread, which is awesome. Best of luck. My guess is the sound will be gone and this gem will run just as you need for years and years. In the words of Ant Knee, "I'd drive it."

 

Well I got it all back together today and I took it for a ride into town to put some gas in it. Initial impression was good, driving it around town 25-30 mph made no noise and sounded great, I was thinking I had it licked. But driving on the county road, the noise is back, seems like once you get to 40+ mph in 3rd it's still making noise. I maybe hit 50 tops and I didn't want to push it any further.

Pretty disappointed. I feel like I could drive it around town and but there's a 4 mile stretch between my house and shop that's 55 mph and the only route between the two (I got honked at for going 45 on my way to the gas station by some ***hole in a hurry) and if I can't make that short trip confidently, the car is kind of useless as-is. Not really sure what to do here.

I suppose I'm glad I didn't make it any worse, it definitely sounds better than it did before. I could hear it knocking very clearly driving it around town before, now it's only at higher speeds under more load, and maybe not quite as loud as in that video but definitely still uncomfortable.

I'm not quite sure what to do with it now, at this point. I'm getting married in about a year and I have two houses to fix up that we're gonna sell so I really don't have time to tear into it even deeper, nor do I have the knowledge or confidence to do that. For now, it's parked back in the big garage and it can sit there while I ponder my next move.

 

My only other thought is that it would be nice to know what temperature it was running at once it was warmed up. It didn't boil over, but it felt plenty warm, I didn't want to pull the dipstick out to check the oil because it was hot (it is also the breather however, so that kinda makes sense). My fantasy being that I could put a giant aluminum radiator in it to keep it cool and maybe that would help keep the oil thicker or keep something or other from expanding a bit too much, although typing that out it sounds pretty far-fetched.

 

What weight oil are you running? Like Mark said it could be detonating.
Dan

 

I had already reset the timing (according to the book, initial is 4 degrees after TDC) but I could retard it a couple of degrees more just to try it. I kinda doubt that's what it is, but I suppose it wouldn't cost me anything to try that. Not sure how much advance the vacuum advance gives this distributor, might look in the book and see if they list that out of curiosity. I am running non-ethanol 91 octane in it which I would think would help prevent spark knock but it's not impossible.

15w40 plus a quart of Lucas for good measure, since that seemed to have helped it previously. I would think that would be plenty thick enough but who knows.

 

My book is for 1952 but shows 24 degrees full advance at 2800 rpm. Not sure if that means anything but I looked and figured I'd make a note of it.

 

Your oil is plenty thick I believe, maybe set timing at 8* After TDC and see what happens. I don’t know if your harmonic damper has a rubber ring or not. If it does it’s not uncommon for the outer ring to slip on older units causing an erroneous timing reading. The rubber dries out.
Man I thought you had this thing fixed for sure.
Dan

 

Well poo

 

Me too, at first I thought for sure I was set. At some point, I will experiment with the timing, why not, it's free, and also it is bizarre that this car calls for 4 degrees after TDC for initial timing anyway, when virtually every other engine starts out advanced and just goes more from there. Odd design? Everything on this car is odd.

Changing the rod bearings definitely did something, and clearly the old ones had some wear and odd clearances, so I can't say it was a total waste. But then, was there multiple things wrong at the same time, all making similar noises? I suppose it's possible. I don't know what to think.

The car drove so nicely too, tracks straight and rides nice, starts super easy now, zero other issues. It felt very dialed in, other than the noise.

 

Couple things I thought of:
1. Is the car an automatic? Could be a loose torque converter bolt or two
2. Could be piston slap which you may be able to live with for a long time. I had Ford 300 six with piston slap I put a lot of miles on it after it started making noise.
Dan

 

You need to see how hot hot is. Those laser temperature probes are a great thing to have in your toolbox if you don’t already have one. It might be detonating from heat instead of timing. Those old engines were usually cold runners 160-180. They don’t like 210-215+ unless they are built for it.
Like Sharpone said, it could also be piston slap or a loose wrist pin, both will probably go a long time. Does it rattle when you accelerate and quiet down under low-load cruise?
BTW, it sure looks purty in the gas station.

 

1. It is a stick.

2. Very possible, although isn't piston slap usually at startup/cold temps? A buddy of mine had a truck that did that really bad but only when starting it cold, seems odd to only do it at higher temps and under load.

I do think I need one of those temp probes, that would be super useful and they're cheap, I might get one of those just to have it around, and I would be curious to see what temp this car is running at. I also need to have a look at the thermostat and housing which is crusty looking anyway. If it is running a bit too warm, a little less temperature in this car definitely wouldn't hurt.

Yes, it rattles when I accelerate and quiets down under low-load cruise, that's exactly what it's doing now. There are some mild hills between my shop and the gas station and going up the hills when I had to give it a bit more power it was noisy, when I let off or coast a bit down the hills it was basically gone. Even when warm, it makes no noise at all at idle or at low speeds/low load. Does that point to anything in particular?

If I was fairly confident it was piston slap or something that isn't imminent damage, I probably would drive it, what would I have to lose? My two main concerns are I don't want to break anything/damage it worse, and I hate to drive it if there's any chance I can fix it outside of a total rebuild.

 

Since you're doing "free" experiments here's something to try. When it makes noise try gently pushing on the clutch pedal. If the noise reduces it could be crank thrust or mains. The pressure on the pedal, not heavy enough to slip the clutch, could theoretically take up play in the crank. Might take a few tries to sort it out and it would tell a story. It may be exactly the same. But again its free. You might even feel the noise in your foot. Piston slap is pretty fast and distinctive.

When I had the Clipper it was more noisy than I expect a Packard to be. The prior owner was running 10W 30 oil, and after extended running various hydraulic tappet made intermittent noises, 1 or 2 louder than others. I ran a pint of ATF mixed with the oil for about 20 miles then let it sit a week. New filter and 20W 50 oil. No more lifter clatter even after a 35 mile freeway cruise to an event. Oil pressure rose about 10 more at idle. The engine had almost 90K on it. While sophisticated for its time the 356 was still based on 30s tech and knowledge. An engine today is a more like a precision appliance, back then more like a fancy farm implement. Raw thoughts...

 

Well, that is a kick.
I would suggest trying a bit less timing. I know the flathead is not as efficient as OHVs. I don't have a bunch of timing specs for those memorized, and what the gas was then is not what it is now.

Another thing is that as a worn engine, it could have carbon build up. Various methods to address this, but the water down the carb has worked for me. We can talk you thru this. Also various fuel treatments (Seafoam, BG44) to try there.

I know how it's frustrating and disappointing at this point. We all had great hopes for you. Take a step back but don't give up.
If it's going to sit in a corner, I'd make sure the antifreeze is good and perhaps drain the fuel and start fresh later.

 

And maybe dig into the distributor a little deeper. Make sure the centrifugal and vacuum advances are working properly. Possibly something gunked up that's not allowing the advance to return correctly at lower speed and load conditions. Or a broken spring on the advance weights or a failed or sticking vacuum advance canister.

 

Can you post up another video with the sound so we can listen to it after the new bearings.

 

Not sure if you engine has solid or hydraulic lifters you might inspect the lifters and valve train. There should be covers on the side of the block
-hopefully easy to remove- if you have solid lifters they may need adjustment, just thinking of anything that might make noise. However lifters that need adjustment should make noise at all RPMs
Dan

 

Rod knocks tend to happen on decell and go away under power. Free reving the engine will bring out a rod knock as the rpm comes back down. Bearing knocks on acceleration under load could well be main bearings. I'm fairly sure they were as worn as the rod bearings. You really should have dropped one to take a look.

 

Given the evidence of abrasive **** in the old rod bearings as well as the rod journal grooved by a substantial particle - my guess is the main bearings were damaged by the same stuff....

 

@jaracer you seem to be a smart cookie, but in the times I've heard a rod knock, it's always been when revved or under load, not the opposite.

 

I agree with the revved because free revving is light load changing to coast, but if a rod knocks under load it's really bad and probably about to leave the crank. A buddy of mine bought a 53 Studebaker with a rod knock (it was only a 10 year old car at the time). The previous owner had "overhauled" it, but put a couple of rod caps on backwards. When the starter wouldn't turn the engine over, they pulled it around with a chain. Eventually they put the rod caps on correctly then sold it to my friend. That's the first time I heard the cl***ic rod knock. It would knock when you let up to shift and go away under load. It's also the first time I was introduced to tapered shims to put behind the bearing shell. They worked for a couple of months, but it was his daily driver and the rod knock would slowly come back. I think I helped him shim the bearings a couple of times.

 

Olds engine (no autopsy), A BBC, spun rods no noise - dis***embled due to oil burning, A flathead 6 revived and had rod knock (confirmed with tear down) and a Toyota 4 the tech torqued the rod bolts to ft. lb. not Nm. noisy, replaced rods and bearings. These are personal experience, a few others I've heard but did not dig into myself.

 

I'll try that. Any data is good data, and that's easy, which is a plus.

I am going to try retarding the timing a bit, can't hurt, we'll see what it does. I did the water down the carb thing before I dug into the bearings, didn't seem to change anything. I've seen it done on cars that were really carbon'd up and created plumes of black smoke as things freed up, but this one seemed pretty darn clean.

I think you guys are right, and now I do regret not pulling a main bearing cap. I was so sure that #1 was cut wrong and was the smoking gun and I got a little over-eager to ****on it back up. Now that I know how everything comes apart, it'll only cost me a gasket and an afternoon to open it back up, which really isn't the worst. And if changing timing and whatnot doesn't affect it, that's probably what I'll end up doing. It's just that it'll probably have to sit a while until I have time to do that.

For now, it's safe, it looks nice in the garage, and it is all back together and can move itself around easily. Next opportunity I get I'll play with it a little more, check temp, try different timing, etc. 10 or 20 more miles on it as-is isn't going to wreck it. If that doesn't do it, the pan will have to come off again and we'll be looking at main bearings. I shoulda done that right away but live-and-learn I guess. Not giving up on it, just setting it aside for a little while until I have a bit more free time.

 

Also just wanted to mention I realize I didn't go through this thread and "like" all the comments and whatnot as they were being posted (was a little preoccupied) but I really, truly do appreciate all of the feedback and comments and suggestions, they've been a tremendous help and I wouldn't have gotten nearly this far if I hadn't had all the support. Not just with the knocking but earlier with the timing and the carb and a bunch of other issues I had to work through. If nothing else, I've learned a ton from working on this car.

 

I think many of has have learned from the constructive information sharing in this thread.