To hone, or not to hone, on re-ring?
 

Hello all,

Been chasing something kind of elusive, that is very likely to get a bunch of people saying it's total hooey. :rolleyes: Doesn't belong in the Unicorn Corral, though, because there's some evidence. I just can't find the *original* source.

Ok, so I've got this old Explorer with ~160k miles on the OHV Cologne V6. The spare truck has about the same, on the same engine. The plan is to pull the spare engine and refurbish it - basically clean it off, new seals, etc. Nothing fancy. It isn't that much more money in parts to do a full rebuild. Trouble is, the cost of the machine work on the block makes it non-economical for a "cheap project".

So I started poking around looking for how to re-ring the engine, found the conventional wisdom about "breaking the glaze", dingle-ball hones, etc.

Then I found this: Careful with that hone, Eugene!

Basic premise: The engine has already reached the best possible surface finish for the rings against the cylinder bores, by running itself in. There's no such thing as a "glaze" in most engines. :eek:

Why would you mess with that, if the cylinders are still round/straight and show no signs of scuffing, nor a ridge?

It mentioned "reprints of articles covering actual lab research done by the SAE - Society of Automotive Engineers - to support these claims". The article was first written in 1999, and was a story about a class the author took "a number of years ago".

I cannot find those papers, and it is driving me up the wall! :mad:

I did find a lot of info about "Plateau honing".

Basic gist: it is the goal of a ring/cylinder pair to achieve a "Plateau" surface condition, where you have the cross-hatch pattern for oil holding, with smooth surfaces between the cross-hatch, on the cylinder bores. Your engine does this by running in, rubbing the rings on the cylinders. Most of the wear happens in the first hour, and it levels out at about 24 hours of running. Assuming no catastrophic issues, or other problems, you are left with the optimal surface finish on the bores.

Further searching found lots of anecdata about "certain manufacturer's recommendation to not hone when installing their rings". I found a source document for that: ACL Re-Ringing and Honing

Basic gist: An amateur doing a hone job is more likely than not to either get the wrong surface finish or to leave grit in the bores/engine, leading to early ring failure (and/or other worn-out engine parts in the case of excess grit) and a warranty claim. So the ring manufacturers just say "don't hone", as the odds are, you're more likely to get a good engine that way.

Seems legit, but has nothing to back it up in terms of "you'll get a better ring seal that way".

If you search around a bunch, you run across large marine diesel engine manufacturer tech bulletins, aircraft engine tech bulletins, GM LS engine tech bulletins, etc. that either mention re-ringing a non-honed cylinder, recommending not honing the cylinder unless it is damaged, or explicitly disallowing honing of the cylinder (in the case of the GM LS engine only the second ring was being replaced, and GM would not pay for any machine work, nor warranty said work, unless there was other damage that needed correcting.)

There's a lot of info from the Flex Hone company, with a ton of detail about the desired surface finish. Here are two pdf's:

Brush Research PDF 1

Brush Research PDF 2

In the second one, in particular, they basically lay out the case that the cylinder bore surface finish that an engine arrives at through proper break-in is the desired finish for a new engine, though they don't exactly say so outright, IIRC. They claim that their Flex Hone tools will produce that finish, of course.

So, can anyone else find those SAE papers about ring vs. cylinder surface finish, break-in period, etc. that concluded you should not do a "glaze breaker hone", contrary to all received wisdom to the contrary outside of the usual "I got away with it on an old engine I redid as a poor kid in my dirt-floor garage, ran great!" anecdotal stuff?

It's so tantalizing. The SEM micrographs, the friction research, the stuff about Plateau honing, all that points in the direction that the first article suggests: absent any damage/excessive wear, if the cross-hatch pattern is there, don't hone. Just toss in new rings, it'll break-in just fine relying on wearing the rings to match the cylinders, with the cylinders being worn a lot less this time around. :cool:

Sounds too good to be true. I want those SAE papers, and I cannot find them. Plenty of papers on how the break-in process happens, plenty of stuff on new ring tech, new honing tech, new cylinder liner tech, etc. Just not a specific study on run-in bores vs. honed/bored bores, etc. and their effect on break-in with new piston rings.

There's a lot of good info-diggers here on Ecomodder. What can y'all find?:D

I have taken a bit of 600 grit sand paper and hand honed bores before. It just takes a while.

Glazing is from cylinders being washed with gas or coolant.
So unless you were running eyes burning rich or lost a head gasket probably no glaze.

But a gasoline engine with 160,000 probably has a fair bit of cylinder taper and may need to be bored.

Maybe not the answer you're looking for, but...
How long do you expect the vehicle to last? Don't build the engine to outlast the car or you're wasting time, effort, and money.

I would not hone unless there was an obvious reason to do so.

Hello oil_pan_4 and ksa8907,

oil_pan_4 - that's one of the anecdote flavors I keep seeing. I see "I hand-sanded it, and it did OK/blew up!", "I didn't touch the bores, and it did OK/blew up!", "I ran a dingle-ball hone through it, and it did OK/blew up!" and "I had it professionally rebuilt, and it did OK/blew up!".

No idea how much taper or wear I'll find. This is all study in advance. If the bores are bad, it's moot anyway as I need to get a different donor engine to start with.

As for glazing, the article agrees on that point - glazing occurs when there's something to bake onto the surface getting glazed. Most cylinder walls don't get glazed, though. How would a glaze stay put with piston rings scraping back and forth across it? Unless, of course, the engine in question had a serious oil consumption/blow-by problem.

ksa8907 - Not exactly the answer I'm looking for, no, but it is a worthwhile comment.

Up here in the land of truck-eating road salt, it's hard to say how long this vehicle will last. Rust has a foothold in the rears of the rocker panels, the rears of the front fenderwells, and the upper arches of the rear wheelwells, plus the bottoms of the rear doors and hatch. It can be cosmetically treated and probably won't be a major issue for 2-5 years. If the off-roading I want to do happens, more than likely there'll be big dents in it anyway!

My goal is an engine that runs decently - as well or better than current - doesn't leak everywhere (like both do now), doesn't use coolant (like current engine does), and doesn't burn any more oil than the current one does now. Basically, I want this "weekend warrior trail rig" to be a reliable daily driver, but it is *not* worth putting an $1800 re-manufactured long block in it. It also should run well enough that if, by the time I get it back together and drive it a while, I absolutely *hate* it, I can sell it on for a reasonable price and not feel like I'm screwing someone over.

Once I have the engine stripped down to a bare short-block, it's only $30 more in parts to re-ring it vs. just putting it back together with new gaskets and any required replacement parts. If I send the block out for machining, I'd pretty much be committed to a full rebuild, with new oversize pistons, etc. Pretty quickly the price is close to a reman long block.

So, assuming the bores don't look terrible, I have these options, in ascending complexity/difficulty:

1.) Leave the pistons and rings in the bores.
2.) Pull the pistons and rings, clean everything, and re-install the used rings/pistons where they used to be.
3.) Pull the pistons and rings, clean everything, install new rings. What 2 turns into if I break, bend or lose a ring. Plus, if the research is good, this may be the best for engine oil usage and
4.) Pull the pistons and rings, hone the bores with a "flex hone", clean everything, install new rings.
5.) Find bad bores, start over with different used engine.

I'm really interested in finding those SAE papers for option 3. Realistically, I'm more likely to do 1 on the theory that it if it ain't broke, don't mess with it, but if I do get it all the way apart, I'd like to pick the "best" inexpensive option.

This is mostly research - I found a shiny, and I want to see if it is valuable or just neat.

To bore and hone cylinders is usually only 20 to 25 dollars per bore.
Then how ever much pistons are.
When I get an engine I just assume it's going to get bored and have over sized pistons.

Anyone know what a piston stretcher is ? If not, I doubt if anyone would believe how I rebuilt my 1st car engine. If anyone does, I can explain how I learned to rebuild probably 20 or so engines, very inexpensively.

The only engine I did any serious work on was the LSJ in my Ion Redline, and I had it down to a short block where I discovered the bores looked good so I left the factory bottom end intact and re-gasketed it and installed in the car... it ran great, though I missed that the Head coulda used valve seals, so it smoked for about five min from cold start but ran great otherwise...

Yup. Also sandblasting the inside to grow everything but the crown. Oversize rings in hand cut grooves. Oversize piston pins. BTDT. Ridge reamer to even out the bores.

You can hone the bores to reasonably close tolerances but not with a ball hone. DID that with a 1/2 inch hand drill and a spring hanging from the rafters. Drill press would have been better, but didn't have one.

My take: wornout engines have less hone marks.

Tried posting 3 times. Computer keeps backspacing and eating the text. ?????

I always hone lightly if replacing rings. If there is taper then it needs to be bored. Ball hones are for wheel cylinders only in my opinion.

Flathead Ford when I was in college. There was a ridge at the tops of the cylinders. When I started it up it broke the top rings. :(

oil_pan_4 wrote:
Hello oil_pan_4,

Huh. That's not a lot of money, about $150 for my V6. Does that include cleaning? What level of quality does that buy, from your experience, and from about what timeframe (was this the 80's/90's or more recently)? Do you get a "plateau" hone, for example, with the slightly rough (for break-in) but flat (to limit wear depth) tops with the ~45 degree crosshatch going deeper beneath it for oil-holding? A few of the links in my first post went into detail about the process.

Even if it is that inexpensive, adding all the new parts I'd want to "because I'm already in it this far and getting burned by a bad XYZ would suck" and new heads gets really close to just shelling out for a long block. If this was a truck I definitely wanted to drive for 5-10 years, it might be worth it. As it is, this is my "get back into it and learn" truck, essentially considered to be somewhat disposable. So I need to figure out if this is an engine I want to take apart and re-assemble more thoroughly or not.

I need to call around and find out how much it costs to clean and leak-check cylinder heads. If I'm just slapping it back together with new gaskets, no sense in spending $500 on new heads. I just have to not overheat it...

Anyways, anyone else have any luck in tracking down those SAE papers mentioned in the original article I linked? Hmm. I need to see if the library has them on their online service, which means I have to figure out what my library log-in number is, since IIRC it's different from my library card number.

From 1977 to 1987 I was outside salesman for an auto parts jobber with a machine shop. We sold parts for all types of engines. At that time an engine overhaul usually consisted of a valve job, and replacing rings and bearings. Perfect Circle sold iron or chrome piston rings. Ring wear is often measured by the gap between the ends of the ring. The bore should be clean and round top to bottom. Since the condition of an engine will vary based on use it use, is important to take measurements. I recommend getting a good shop manual for the vehicle. I tend to use Haynes manuals whenever I buy a vehicle. The manual will tell you the acceptable tolerances and step you through the procedures. Keep track of mating parts.

You will have to disassemble the engine to determine what needs done. Find a machine shop that is recommended by people you know and trust, then have them look at it. Most likely need a complete rebuild of engine, short block and heads, at 160k. Otherwise it's a crap shoot on whether the cheap rebuild will run or blow up.

From a machinists point of view.

Realistically you may or may not have to hone the cylinders.

First let me get this out of the way if there is any abnormal wearing like scoring or gouges or anything that looks like friction welded material in the bore honing is useless without a re sleeve.

Now let’s ask some questions.
Are you using the same piston/rods and the correct factory sized bearrings? If yes and just changing rings you only need to use som 600 sand paper and some brake clean to remove the carbon at the top of the bore.

If you are using new or aftermarket pistons rods or bearrings you might consider a mild hone but even then you likely won’t need it.

Now if this was a race car then I would say go for it but otherwise save your money.

I thought the rehone was to add friction to allow the rings to seat, but I don't know much about engines. I used to have a 1995 Geo Prizm(Toyota Corolla rebadge) with a Toyota 7AFE engine (1.8l) that burned about 1/2 quart every 1000 miles when I got it with 140k miles. At 200k miles I was on a cross country trip from Minnesota to San Francisco, CA and I was putting in 1/2 quart of oil every gas tank and it burned more oil when things were hot and at interstate speeds. I thought of dropping the oil pan and putting new rings on the pistons as a sort of hobo-rebuild because the rest of the engine was in great shape apart from what was likely worn rings. The reason I didn't was that I didn't want to hone from the bottom and not be able to get everything cleaned out. ..long story short, I didn't do it and around 230k miles, the blowby gasses was more than the PCV system could breathe and I had pushed out a camshaft seal on an out-of-state trip. I took care of the seal and it happened again in about 10k miles. Nearly 1/4 million miles, I sold the car for cheap to someone who needed a cheap car. Would a easy/hobo rering job from the bottom without a hone possibly have kept that engine in service?

How my father did many engines over his life was to first use a ridge reamer at the tops of the cylinders, if there was a ridge that needed to be cut away. Can't get the pistons out if there's a ridge bad enough to catch the top ring.

Then after completely stripping the block he'd use a 3 stone hone with a 1/2" drill, using diesel fuel for lube. Have to keep it moving in and out while spinning it, going just past the top and bottom ends of the cylinders. Hone until the surface is fully scuffed. You're only removing at most a thousandth of an inch while leaving behind a surface that will wear in the edges of the rings for a tight sealing fit.

If you remove the pistons and put them back with the old rings, you won't get the rings back in precisely the same rotations and may end up with leakage past the oil rings and uneven compression.

When you install new rings you have to stagger the end gaps. Put them every 120 or 90 degrees or whatever works to make the longest path from gap to gap.

Some newer vehicles have some crazy durable metal in their engine blocks. I put rebuilt heads on a 2004 Dodge Dakota V8 and at 140,000 miles the factory crosshatch honing marks were still visible in the cylinders. In a GM or Ford smallblock V8 with that kind of miles the bores would be worn smooth with fine vertical wear lines all around.

When you rebuild an engine with new rings, crank, rod and cam bearings, it will take a while to break in. No high RPM operation for a while! Let it idle for a couple of hours and monitor the coolant temp. If it starts to heat up, shut it off and let it cool down, then run it again.

Then take the vehicle for a leisurely drive, keep it at 55MPH or slower. Gently does it for the first 500 miles and you'll not have problems. Always used a non-detergent oil for break in then drained and replaced with detergent Valvoline oil and a new filter.

Never failed for the hundreds of engines dad rebuilt for his vehicles and other people, as long as they didn't hit the dragstrip or racing on back roads before the engine was properly broke in.

Put a fresh engine together then treat it like you're racing (or you actually do go racing) and you're likely to have something go bad.

'Course for the high level drag racing where they pull everything out of the engine between runs it doesn't matter because with superchargers and nitromethane they come close to melting the pistons. They shove so much air and fuel through that blowby doesn't really matter, and if a bearing spins the dragster will be through the trap before the engine comes apart (usually). If the teams were allowed to just swap the whole engine from a ready supply of ones that have been carefully run in, there'd be very few that blow up.

Hello again all,

Grant-53, I have the Haynes, and I've read several pieces on how to measure bore taper using a single ring and measuring the change in gap as it is pushed down the cylinder. Also the way to measure it right with snap gauges or similar. For what conditions did Perfect Circle recommend chrome vs iron? What bore surface finish did they require to honor the warranty? I've found one ring manufacturer, ACL, that did not recommend honing on a re-ring for their plain iron rings, on the theory that you're more likely to destroy the engine with leftover grit from a poor cleaning job than you are to get poor seating on the new rings in an old bore - when re-ringing on a DIY basis.

tscheerer, well, yes. I have to pull the heads anyway to do gaskets, so I'll be able to see most of the bore in each cylinder and be able to check for a ridge, and check for taper in what I can access. Visible damage will mean either scrapping or further dis-assembly of the engine. That 160k mark for needing a rebuild - what era of engines is that based on?

stockMKIVTDI, you mentioned that one "may or may not have to hone". What do you base the decision on? Can it be "eyeballed" with a reasonable degree of success (I see the cross-hatch, should be good to go), or does a particular surface finish need to be measured to? Obvious damage will be obvious, as will excessive taper and the presence of a ridge. My question is mostly aimed at modern-ish engines with fuel injection that don't wash the cylinder walls with gasoline on every cold start, use a good ring pack, all designed to minimize oil consumption and blowby to get better fuel economy and lower emissions.

MN Driver, no idea. If you were pulling the bottom end apart, pulling off the head to get to the rest of the bore isn't much more work. Plus, if you are pulling the pistons out, I'm not sure how you get a ring compressor to fit right for re-insertion from the bottom.

Galane, that's more good information about "how it's always been done", and generally good advice. I'm not disparaging your advice, just, it's basically the same stuff I've already found.

Generally:

I'm not disputing that the tried-and-true method works, and I'm not "trying to get away with it" by not doing something that "should" be done. (Well, maybe a little... :rolleyes: )

I ran across a claim that the properly worn-in surface finish on a cylinder wall is the "correct" one for best ring seal, oil consumption, friction and longevity, plus some more information about methods of honing to approach that surface finish as closely as possible, and have been having a hard time finding more information about how best to refurbish used engines that don't have a ridge worn in the cylinder. Lots of good testing on machined/honed surface finishes of varying types, lots of great characterization of the wearing-in period, all fascinating. The only thing I've found about "not touching the bores" was the GM LS engine oil consumption problem where the rings were installed upside down at the factory, and the warranty repair did *not* authorize machining the cylinders - and would void the warranty if such work was done without evidence of a damaged cylinder wall. Even then, several of the anecdotes I ran across mentioned the owner of such an engine convincing the tech at the dealership to do the honing "on the side" because it "had" to be done or it would never seat. Not exactly a good representative sample size. There were other bits from aero engines and large ship diesel engines about changing out rings without touching the bores as part of certain regularly scheduled services, but again no study data.

The links to a representative sample of what I found are in my original post.

I do wish I had access to good surface finish measurement devices that I could use on a cylinder wall. We have good devices at work, but I can't bring an engine block in and it won't fit in the device anyway. I can't imagine the labor charge for a good bore surface finish inspection by a good shop being much different from the labor charge to bore and hone the cylinders to the next size up.

Anyone else have any luck finding good testing done on the ring sealing efficiency/break in success of various surface finishes - including the "as-is" condition of a used cylinder that measures in spec - when doing a re-ring?

Realistically, if I see OK compression numbers that don't change much with a bit of oil in the spark plug holes, it'll just be new gaskets and not-cracked heads. Pulling the engine the rest of the way apart would take longer and give far more points of entry for damaging grit, grime, and mistakes. I need to draw up a budget to see how long I need to drive it to pay off new heads by avoiding car payments. Also need to weigh the pros and cons of an in-frame refurbish vs. an engine swap if the bores in the current engine are OK. If I swap in the rebuilt front axle with 4.11 gears to run larger tires I'll have the pan exposed, making a pan gasket, timing chain gasket and water pump replacement not nearly as painful. Heads are a bit of a pain in the truck having to work around the A/C and deal with the exhaust, but more or less than a full engine swap where I have to leave the A/C in anyway? The main benefit to "on a stand" is I can turn it upside down to clean the decks, keep gunk out of the innards better that way. Plus access to the core plugs. Oh, and I would be able to say I completed an engine swap, rather than yanking and replacing the same engine.

I'd pull the heads and inspect them and the bores before deciding to by rings etc. Where squirting oil in the cylinders makes no changes to compression, it's likely the rings are good.

Camshaft bearings in a pushrod engine can last a long time, when the engine is taken care of. If you can drop the pan with the engine in, it would be a good thing to inspect the crank and rod bearings. Any journal grooving you can catch a fingernail in, out with the engine so the crank can be ground or replaced.

If the wear is minimal a crank can be polished, as long as that would keep it over minimum diameter for stock. If not, grind it 10-thou. 'Course with labor costs these days it may be cheaper to buy a new crank.

The last engine dad and I did, it was way cheaper to buy a new cast steel Eagle crank for the 91 Chevy 350 than to have the original ground. Also upgraded from dish to flat top pistons and King racing bearings. King bearings have a much thicker Babbitt layer than other brands.