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

[cajunfj40]

Hello all,

Been chasing something kind of elusive, that is very likely to get a bunch of people saying it's total hooey. 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.

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!

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.

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?

[oil pan 4]

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.

[ksa8907]

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.

[cajunfj40]

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.

[oil pan 4]

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.

[HaroldinCR]

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.

[19bonestock88]

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...

[Piotrsko]

Originally Posted by HaroldinCR

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.

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.

[HaroldinCR]

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

[me and my metro]

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.