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

Ahhh. The old home brew in frame

Yank it apart after work
drive it to work the next morning


Good times

 

I agree with @squirrel . Those AMC flatheads are tougher than you might think.
Back in the 80s I bought a '65 American with a flathead 6 (the last year). It had developed a rod knock at about 30 MPH.
Just used 20W50 and added some "Motor Honey" every once in a while.
My wife drove it that way for over 2 years and almost 10,000 miles. It was still running fine when the NY winters rusted the already rusty uni-body unsafe to drive.

 

After all your work, an unexpected gut punch but you can get through it!
I always enjoy your posts but particularly have enjoyed following your "driveway" makeover of the loveable little Nash. Old school practical, budget minded resourcefulness, tackle it yourself spirit.
The rod bearings will be the same. There's lots of 'in car' bearing replacement videos on Youtube to get you comfortable with the process. Pull the pan with the goal of replacing the first rod bearing. Ratchet, torque wrench. No sweat! Now repeat 5 more times. Maybe consider rebuilding/replacing the oil pump while you're in there...

 

I can say all the stuff you’ve done already is way harder than replacing a bearing or two!
Dan

 

Double knock = rod knock. Before doing much else, try to isolate it to a specific cylinder.

 

I'm another who always reads your posts. You know you can fix it, just gotta carve out the time.

 

This is really the key. I have a lot of cars and this one isn't well suited to long road trips or highway driving anyway. It'll only be for puttering around town and lazy county highway trips to the post office/FedEx drop-off. If I managed to add 10k miles in my lifetime I'd be happy/impressed. I don't want to blow it up, but i don't need it to be perfect or to last forever. Looking for the minimum amount of effort to stop the clattering and have it safe for some occasional gentle drives.

 

If you are interested in trying a 20w50 motor oil, here's what I've been using. High in zinc. Increased my oil pressure at idle a measurable amount.
https://www.amazon.com/dp/B09QXWLY2Y/

 

Then try the thicker oil first. If that does it for a few hundred miles a year OK. If not then drop the pan and new bearings. Price of the bearings + pan hasket.

 

Do you have an automatic transmission? If you do you might check the torque converter to flex plate bolts a loose bolt will make a knocking noise. I can’t tell from the video if you have a double knock or not.
Dan

 

IIRC, the four bolt holes in the lower crossmember/brace are elongated or ovoid, so there is room for adjustment goin back on. Just make sure the bolts and washers line up in the position they were originally when you reinstall the crossmember. I want to say the washers were special, and extra thick, too, but it's been a few years since I pulled my '52's engine.

The unibody is surprisingly stiff, so don't sweat it too much. I want to say the engine weight is 600 lbs or so, so not exactly lightweight. I dropped the engine and trans as one out the bottom onto a dolly, then lifted the body (well, unibody, technically) up from the front and rolled out the drivetrain. I remember the legs of the engine hoist were very close to the front wheels, though-- I might've even had to remove them to allow the engine hoist to be moved around...darn envelope body design and narrow front track.

 

So, after a long weekend at the Iola car show/swap meet and the Sanford Field flathead races I talked to several people about doing this job and I realize that no matter what, at some point I'm going to need to tackle it. I've watched a few videos of guys doing it (most of whom didn't seem like they were being very careful) and it doesn't seem impossible. At the very least, it seems like I'd have to mess something up really bad in order to make it worse than it is now.

I was able to find and buy an oil pan gasket set for it, and I'm thinking about buying the bearings right away. I don't know when I'm going to take this on but if I get a good window of time I'd like to have the parts on hand. Also I have no idea how long it'll take to get them so I'd prefer to order them right away.

My question would be, is there any conceivable reason I would need anything other than standard sized bearings? The crank isn't coming out or getting cut, it's only going to get cleaned up with some 1000 grit sandpaper as best I can in the car so I can't see needing undersize bearings, if the crank is worn I kinda doubt it would be perfectly .001 under anyway.

Also, considering they're only 11 bucks each, I'm thinking about getting 7 or 8 pairs just in case I drop one or mark it up somehow. I don't want to drop the pan to have a look unless I have the parts ready to go. If it ends up being some other unrelated issue, I'll have much bigger worries than having wasted 90 bucks on parts.

Let me know. Unless there's something I'm not thinking of (which is very possible, as I don't really know **** about what I'm doing other than a few bad Youtube videos), I'd like to get the parts coming.

 

I would at the very least least wait on ordering bearings until youve pulled one out. Even if the crank is perfect you may find it’s had a re-grind previously and is already at 10 or 20 thou.

 

Agree100%! Could be a regrind. I'd recommend pulling all the rod bearings, mic the crank, (or at least, measure with a good caliper), and clean up with emery cloth, then buy matching bearings, maybe you can use .001/2 to take up some additional clearance.

 

Yes wait on the bearings you want to get as close as possible to the factory clearance spec.
Dan

 

Measure the crank multiple places on each throw. Chances are that it may be egg shaped. If you use the smaller measurement in that case, it will be too tight. I would probably put the same bearing back in it.
You need to get some emery cloth to polish the crank. The bad bearing may have left some babbit on the crank.
It is not a bad job to do. Take the oil pan off, End caps off and marked. Clean stuff up and check the old bearing will take a couple hours. The back side of the bearings should have the sizing on them.
Order the parts when you have the measurements. It will take you about the same time to put it together.
I would guess 2 evenings of work and it should be done.

 

Wait to purchase, but confirm a reliable source! If it's one place, shipped to you, it will take a few days. If it's local (shamrock emoji), even better. What you don't want is available now, but not when you need them. If that is the case, BUY!
Typical is STD, Ten under (0.010" thicker, due to smaller journal) and some have twenty under. In some cases, they did offer one or two thousandths undersize for polishing, but you gotta go with what is out there.
There are little tools to roll the main bearings out and back in. Hope you just require a couple rod bearings and do them all for ease of mind. It takes a lot of polishing to go one thou undersize.

When you are under there, everything is for the most part, big heavy metal that won't be upset by a bit of banging. The ends of the rods should not be beat on much (they can get out of round) and the crank journals should be treated as very fine tolerance machined sections. If you are thinking of hitting anything with a hammer, consider the hammer handle or a bit of wood instead. Clean where the parts meet (rods/crank, rod bolts/nuts oil pan/block) is very important, but you don't need to be surgical. Just remember the forces pushing down on each piston is moving the car, and oil is splashing all around in there. Do it once, carefully and it won't have to be repeated.

Note that each rod cap goes to that rod FACING one way. take pics, notes, whatever. Torque is provided for just about every fastener. It is required absolutely for rods and mains (if undone). You can skip the oil pan bolts and other light duty stuff if you are comfortable, but I'd strongly suggest torquing the crossmember stuff and suspension too.

 

As suggested, try removing one spark plug wire at a time and then give a quick rev each time. See if the noise goes away or gets a lot quieter. That is the cylinder where the rod is making noise since it is not firing and therefore not making as much pressure on the bearing.

You do need a micrometer set up to measure the rod journal once you get it apart, that will tell what size new bearings you need. The rod bearings you take out should be marked if they are undersize to help you understand if the cranks has been machined since originally built. Also need a good torque wrench to tighten the rod bolts back up. You can also pull a main cap or two and just verify the main bearings look OK when you have the pan off for the rod bearings. Not much extra work and gives you a bit of confidence in the condition of the main bearings.

 

BEFORE YOU REMOVE THE FIRST ROD CAP . . .

Check all the rods and caps to see if they have been number stamped 1 thru 6. If not, get some number stamps and mark them all now. The number should be stamped on one side of both the rod and cap on either side of the cap's parting surface. This will keep you from getting the caps mixed with the with the wrong rods. And it will also keep you from trying to put the caps on backwards.

 

Just take it apart, wrap a fatty piece of bacon around the journey, hit the road

 

Numbering with a stamp in the crankcase might be a bit tough. I don't know how shrouded the sides are, but that was common on pre-'60s. Great apart, but upside down and swinging a hammer I'd maybe avoid. You can wiggle each one, get a feel and see if the offending one is looser. Take them apart one at a time, maybe paint mark each on one side to orient them.

Do take the spark plugs out. You are going to be rotating things during this.

 

A now deceased buddy of mine said his dad did something similar with an old babbit 216 in a Chevy 2 ton, but he used a piece of oiled shoe leather, and took out the appropriate number of shims. Once in a while it would start knocking again because the leather “bearing” would slip out. Guess it hauled a lot of logs that way.

 

Squablow;
"crank isn't coming out or getting cut, it's only going to get cleaned up with some 1000 grit sandpaper as best I can".
KenC & oldolds:
"clean up with emery cloth" .

Do *not* use either of these things on a crank - polished or not.
What you want is: Crocus Cloth(may take a bit of effort to find it, but it's sooooo worth it). Looks n feels like fine sandpaper/emery cloth, but *won't* damage polished crank/etc (bearing) surfaces. Yeah & also don't use it on the actual bearing pieces, either. Sandpaper, emery cloth/etc *will* damage the surface. Crocus Cloth is designed to clean-up stuff off of a crank(read: machined) surface. Iirc, the "grit" is walnut shells. It'll take off stuck bearing material, burnt oil, et-al; w/o harming the bearing surface. I've used this stuff for years(read: decades), cleaning-up A/C crank snouts/etc, also cleaned-up the journals in my Stude(s) in-car. Works esp well w/forged cranks, as they're less susceptible to damage from spun bearings than cast cranks(material quality & hardness). Since it won't harm the journal-surfaces, it also won't remove scratches, but unless the journal is scored heavily, won't matter for your intended use. Can use it w/solvent, or dry, as I have. It does "load-up" fairly quickly, so have a few sheets avail, in increasing-fineness. I've used it wrapped around my finger-tip, then progressed to the "shoe-shine" effect w/strips. Could be also wrapped around the journal & a shoelace/cord wrapped over that & pulled back-n-forth to get rotation, as needed. It's been awhile, but iirc, I stopped at ~1500 grit, you can go finer if you wish, won't hurt at all. This'll give a nice shine - not quite mirror-level, but nice/useable.
Your mill, your choice - but no point in needlessly hurting it.
Marcus...

&, btw, if you do find a spun-bearing once you're in there, know it's gonna have dumped all that debris through the mills' oiling pathways. So at the min, cleaning as best you can from inside the mill(brush-scrubbing everything & brakecleaning spray, as you'll probably find a bunch of gunk-n-goo inside the mill), what you can get in the oil p***ageways(if you can), & a couple oil & oil-filter changes before you drive it again. Once back together, let the mill idle for abit, then dump that change, next one rev it a little harder & very light driving-loads for a short while(like iffen you're going to break-in the cam, but *no* hard engine loads), dump that change, & I'd still do one more after ~ 100-250 miles. & be listening for unhappy bearings during that time. I would change all the rod & main bearings, since you're in there - it's actually easy then, just takes a little care, time, effort - but it's not hard, nor very expensive. & gives the mill the best chance to survive w/o a rebuild. Trick, iffen there is one, is to either do *one at a time*, or mark everything prior to dis***embly, lay it all out so you know where exactly it goes, & then don't mess anything up. I like the 1st approach. Although I prefer to stamp/mark the rods n caps - mains. Like claymore mentioned. Also make notes on what you find, what you need, & what you've done - as you do it. So's you don't forget, or wonder later - "did I...??? ;( " . Esp iffen you haven't done it before. Good luck, I think you'll do well. & the mill'll be happy. .

 

Crocus cloth is essential. My dad would bring a roll home from Grumman when I needed it.

An old timer I worked with, he used women's sanitary napkins to get the crank spotlessly clean.

And measuring a crank inside the block while standing on your head, difficult for sure. You are looking at tenths measurements.

 

I've done this years ago with crocus cloth on a roll. Comes in various widths, IIRC. Tear off a strip long enough to wrap around the journal with enough to overlap the ends an inch or so. A long piece of leather boot lace works well. Wrap it several times around the crocus cloth and journal to spread the pressure over the surface of the journal. Give it a shot of solvent, then pull the lacing like back and forth in long strokes like a shoe shine rag. It should leave a surprisingly nice finish on the journal after a few treatments.

 

True, but for what he wants, & the mills' needs, properly-used Plasti-Gauge should be sufficient, since he's interested in what-size(?) replacement-sized bearings(which probably don't come in half-a-thousand size, so's that'll mean going up, or down, to the next thousandth. Or maybe two, idk - depends on literally, what is physically available{Try Kantor for a supplier, a**** others}) & that'll get close enough. Half a thousand or a thousand off, isn't a big deal here, as long as the clearance isn't too tight or too sloppy-loose. Plasti-Gauge will get him that close. He'll still want a mic, or at least a good vernier-dial-calipers for the general overall dia. Plasti-Gauge for quick verification & final +/- half-thousandth. &, most bearings, iirc, are stamped on the backside with the sizing - so's that's a good starting point. The factory(or equivalent) manual will give the size-range(s), so there is no need for the clearance(s) to be dead-nuts-on to the .0001, they weren't. Most likely, the orig factory size will work ok, although sometimes the factory would grind to the next size to save the crank - so's that'd mean bearing would be factory-undersized. Which is why you don't buy them ahead of time, unless you can get a complete range of sizes, time is of the essence, & you can return what you don't use for refund. Oh, & don't forget to measure the bearings also - they aren't always correctly-made/perfect/in-correctly-marked-boxes, etc. All the little checking here is just for Peace-of-Mind - & to make sure. It's all good. .

I got my crocus cloth in sheets, & just cut it into strips(widths needed) w/a scissors.
Marcus...

 

Yeah . . . It could be a bit crowded in there with something like a Y-block Ford. But who knows what the nether regions of a Nash flathead 6 look like . . ?

 

Kanter sells .001 and.002 bearings
Dan

 

Looks like 1000 grit crocus cloth is available on eBay and isn't all that expensive either so I could definitely use that, seems logical. Kanter has a really surprisingly good selection of rod bearing sizes so I'll have some choice there. The decision on size will have to be made after I get it apart, and it's 100 degrees here this week with many other projects being delayed for the hot weather so I'm not entirely sure when that'll be, but I will update with what I find, and I appreciate all of the tips and suggestions.

It's a bit of a hack fix no matter what, but I do want to give it the very best chance of working and I don't want to miss anything if I can avoid it.

 

The crocus cloth may be available locally if you have a decent machine shop or cutting tool supply house in your area.

You're looking at it the wrong way. You might consider it to be a "hack" rebuild or overhaul. But it's a legitimate repair or fix if you take the time to do it right.

Perfection ain't everything it's cracked up to be.