Piston ring question

SW EM · Aug 31, 2015

I am working on a International 240 with a C-123 engine. I am replacing the piston rings because there was lots of blow-by out the crankcase. I have not ordered new rings
yet. I placed the old rings back in the sleeves to see what the end gap was ( to check how much wear). The gap was .070

My question is this: If I buy new rings from here (YT), will they have a much smaller end gap than .070? I would prefer to file them down a bit rather than having them
with a end gap of .020 or .030 out of the box. But I suppose that would be better than what I have now! The sleeves have very little wear(can't catch a finger nail), but
I will still find a ridge reamer to use on them. (Don't know where to find one of those yet...)

I would be disappointed if I spent $100 on new rings and the end gap was close to the same as before.

Thanks for your help and opinions!

kub6040 · Aug 31, 2015

Check the measurements up and down the bore and see how egged it is I have saw several with wear that wasn't detectable with my eyes , also don't know that the sleeves are standard or oversize .

old · Aug 31, 2015

How much of a ridge did you have to ream off the cylinder sleeve to pull the pistons out. That would be a good gauge to go by as for sleeve wear. Ring wear at the same rate as rings so replacing only one of the 2 maybe a waste of time and $$. Only by doing a good bit of mic of thing is the only way one will know for sure

Bob · Aug 31, 2015

In reality, piston ring end mgap is only a minor contributor to low compression or oil usage. We are NOT dealing with a racing engine here!

Bore taper and piston ring groove wear are WAY higher on the list of what you need to obsess over. Check out the link below.
Check out Daves whole web site not just this link

Deutz Lover · Sep 1, 2015

You can usually get a loaner ridge reamer from one of the many auto parts stores. They will require a deposit which you get back when you bring the reamer back. Make sure to check if they have an end date. They might keep your deposit if kept too long. A recent article I read said that the worn spot below the ridge is the result of ring reversal scraping and occurs during the transition in direction.

I. Check for cross hatching wear in the middle third of the cylinder. This is where a lot of wear can occur.

2 I presume you are using feeler gauges to determine the gap when the ring is in the cylinder. Check the gap near the top, in the middle and near the bottom of the liner. Differences will tell the taper.

3. Remember, Every increase of .003 inches of gap is equal to .oo1 inch increase of cylinder diameter. It's actually .00314 inch increase of gap, but who is counting. This is easier than using a T type bore gauge, But the T type gauge can tell you if your cylinder is oval.
Normal ring gap in a fresh cylinder of this size should be over .015 inch but less than 0.020 inch.

After you hone your new or used cylinder it is now recommended to plateau finish the cylinder by using a finer hone (about 400 grit or finer to flatten the ridges left by the coarse stone (usually 220 grit). Make sure you don't polish away the deep valleys. Be sure to fanatically clean after honing to avoid leaving any grit or dust. Rings break in much faster and have less wear when the cylinder is plateau honed. Look it up.

CenTex Farmall · Sep 1, 2015

Good point about plateau honing. The OEM's have been using it for a long time now and has contributed greatly to long life of
modern engines.

Deutz Lover · Sep 1, 2015

One thing I forgot to add is this. With plateau honing the engine should be immediately put under load by hauling or pulling something to help seat the rings. I do not know just how much of a load or for how long. According to some sources if this is not done it can lead to cylinder glazing and will undo your hard work.

I do recollect doing something like this to a ferguson continnental engine about 1997 before I knew industry was going to do it. We fired up the engine and drove the tractor around with it belching smoke for about an hour. I was beginning to be concerned when at about ten minutes later the smoke began to dissipate and less and less came out. Obviously, most of this was due to the oil left in the cylinder assembly, but the rest was the rings seating. I think the rings probably finished seating over the course of a day, and the tractor ran well after that.

Deutz Lover · Sep 1, 2015

SW EM,

Good morning. After a nights sleep and reading other posts I think you need to do something very important and that is to see what is going on with your rings.

1. If all of your top and second rings are reading around .070 and be sure they are in thousands.

2.You need to take a caliper and measure the piston skirt and mic the bore with a gauge.

It is very possible that your engine is .010 overbore maybe even 0.020 overbore as Old suggested.

Rational behind this. I don't think I have ever seen worn rings with a gap like this. They may have been std to begin with and the sleeves overbore. You need to see if the piston is std. or over size too. If you are absolutely sure your measurements are in thousandths then a gap of 0.070 means that your cylinders are at least .010-.020 over size not considering wear.

dimensions in thousandths of an inch
.070 measured ring gap
-.015 expected ring gap on new rings
-----------------
.055 resultant difference
translation is .018 greater than expected new bore diameter.

Okay take .008 thousandths for wear. That leaves .010 Which might indicate overbore sleeves and std rings in an overbore sleeve. This is just one possibility. Why a possible .020? Who ever put the rings in measured the gap with the rings in the cylinder so they looked ok. This was if they even measured them. Go figure?
:!:

I cannot get the numbers to line up properly after three tries.Sorry.

gene bender · Sep 1, 2015

That engine is a wet sleeve engine so it wouldnt have been bored nobody even makes pistons for a bored sleeve for that engine.

gene bender · Sep 1, 2015

Sleeves arent bored for that engine he doesent know that when he suggested overbore of course there are some who would try it but where would you get pistons then unless you spent big bucks and have them made but why when you just get new sleeves and pistons ct.

Deutz Lover · Sep 1, 2015

Yeah, I know, but when things are this wonky you don't know what people will try. Like boring out a sleeve and adapting pistons from a non sleeve engine overbore. It could happen, just not an OEM application.
I am familiar with what is available for a Super C with a C-123. but I don't know what is available for a 656. (Please excuse the farmall 656 reference. I was filling in information about that engine which is a c263. Early engines were sleeveless and had oversizes available.) Someone could fit these oversize pistons into the sleeved version, but I think the liner wall would be too thin to overbore much.

In the aftermarket anything is possible. Anything to save a buck. I actually considered boring out the sleeves on the Super C I am working on, but decided to stay with the original 3-1/8 inch bore as the sleeves are in good shape and don't have the wear that the op mentioned. That is what threw me. Mea culpa.

See comments on the web site of practical machinist where they describe just such an idea.

teddy52food · Sep 1, 2015

Put in new sleeves, pistons & rings & then you know what you got.

Deutz Lover · Sep 1, 2015

I forgot to ask one other question. Does your engine have the original flat head steel pistons, aluminum firecrater pistons or the 3-1/4 inch overbore sleeves with firecrater or stepped head pistons?

After looking at the production dates and horsepower it looks like they came with the aluminum fire crater pistons. I could not find the compression ratio.

dhermesc · Sep 1, 2015

Agreed.

SW EM · Sep 1, 2015

(quoted from post at 04:29:32 09/01/15) Check the measurements up and down the bore and see how egged it is I have saw several with wear that wasn't detectable with my eyes , also don't know that the sleeves are standard or oversize .

The sleeves are 3 1/8 I check the end gap on the pistons at the top of the cylinder where there's no wear, and in the middle of the sleeve. There is very little difference .001-.003 in the end gap. My question is if I buy new 3-1/8 rings will they have close to the correct end gap out of the box? If the sleeves aren't worn then this should be true. I just can't believe how much the rings wore then. The pistons are the original IH stepped head piston.

SW EM · Sep 1, 2015

I haven't reamed the sleeves yet. The pistons pushed right out the top of the cylinder without putting up a fight. So, the ridge isn't bad.

Deutz Lover · Sep 1, 2015

This may be a little difficult to do, but may answer your question about a new set of rings.

You need to measure the radial wall thickness of your rings. Set your ring on a flat surface. Keeping the caliper body parallel to the flat surface and the knife edges perpendicular to the surface measure the radial wall thickness near the ring gap.

I am holding a brand new Hastings chrome top ring for my C123 engine. The radial wall thickness measures 0.146 inch. Now I have steel pistons and I don't know if the radial wall thickness for the aluminum fire crater piston rings are the same, but at least you have an idea where to compare.

If they both use the same new radial thickness yours should read about 0.140 inch or less due to wear. This will tell you if a new set of rings will do any good.

Tell me what you get.

DL

CenTex Farmall · Sep 1, 2015

The new rings should be fine out of the box. You still want to check them but it's the high performance and
racing type rings that are file-to-fit. It sounds like someone put the wrong rings in to begin with, perhaps even
a factory screw-up.

You could measure lateral thickness of new vs. old rings and see how much difference there is.

Deutz Lover · Sep 1, 2015

I have not pulled the sleeves on my tractor yet so I am going to go put one of the rings in and measure the gap. Be back in a while.

DL

pete 23 · Sep 1, 2015

With a compression ring reading .070 end gap, I would be looking at the face of the ring for a dull finish from dusting from dirt entering. If by chance, the wrong rings were installed, and that being the cause of oil consumption, you will still see original machining on the face of the rings. I would double check the top ring groove for wear. Over .006 clearance on side of ring is too much. Then you can machine top groove, put spacer above it and forget about removing the ridge. Perfect circle always maintained a ridge less than .004 was not necessary to remove. More damage is done removing ridges than is gained from what I have seen over the years. If it needs ridge removed, it needs new sleeves. Not unusual to see .070 ring gap from wear. Heck, I have seen a lot more than that. Usually dirt or just a lot of long hours.

Andy Martin · Sep 1, 2015

As Pete alluded to, dust will wear the rings without wearing the cylinder. That does not make too much sense but it is true. I was on a construction project one time where we could not import air filters but we could import short blocks. So we ran lots of Ford pickups with inadequate filtration and threw away short blocks. I checked several of them and found absolutely no ridge in the cylinder. The rings would wear to where you could not pull start the engine, then the truck would get a new engine. It griped me that new rings would also have solved the problem, much less oil bath air cleaners, but I was told it was not my problem. Sounds like you just need new rings.

And end gap is not too important, as others have said, just check to make sure they are not too tight.

Deutz Lover · Sep 1, 2015

To SW EM ---and all others reading this topic.

I just returned from measuring the ring gap on a new top ring going on a Super C123 with 3.125 bore (ha ha not).

I measured the ring gap 3/8 inches down with the ring flat right on top of a piston.

The gap read .055 inch. So I am thinking they are all made a little loose because I had originally measured with calipers at the top of the cylinders and they read about 3.127 inch which was ok for me. But--But Just to be sure.

This time I got out my telescoping gauge set and measured down the bore. I got an average of about 3.136-3.137 inch diameter. This .012 inch increase makes up a .036 inch increase in gap.

Gentlemen I too will be buying a new set of sleeves to go with the rings I already have. Crap.

SW EM thanks for initiating this topic. I might not have found this out later and lost more time. That is if I had even bothered to check it at all. The ridge is almost undetectable??

John M · Sep 1, 2015

I can honestly say Ive never checked ring gap on any letter series engine Ive built. Nor have I ever put a "set of rings" in one. They all got sleeves! The very first M engine I built is just now starting to show signs of ring wear, but it should, that was 30 some odd years ago, and it gets ran at least twice a week.

pete 23 · Sep 1, 2015

Ridge almost undetectable, probably been rerung before and ridge was removed at that time.

SW EM · Sep 1, 2015

Are sleeves supposed to taper like that?

Deutz Lover · Sep 1, 2015

I think it is mainly the method of measuring. It is difficult getting calipers aligned on a block with studs still in.
I will go out later and do some more measuring with the telescoping bore gauge. I am going to put one of the rings at the bottom of the stroke and bring it up in increments, measure the gap and then use the telescoping gauge to check against the ring gap.

I wish I had a dial bore gauge so I could read directly and not have to measure and convert.

Allan in NE · Sep 1, 2015

I'm with you John,

All ya gotta do is build ONE engine with rings only and you'll never do it again.

Allan

David G · Sep 1, 2015

If I remember right. The "ideal" gap should be .003-.004 per inch of bore, or about .009-.012, the .070 seems really big to me. Cylinders will taper out at the bottom, so it should have the largest gap there.

teddy52food · Sep 1, 2015

You have that backwards. Most wear is on top just under the ridge.

cole in mo. · Sep 1, 2015

How much ring gap you will have with new rings will depend on how much the cyl is worn. The gap you have now, 070 is from worn rings as well as worn cyl.

Andy Martin · Sep 1, 2015

I know I'm in the minority here but I have had really good luck replacing only rings in A's, B's, C's, H's and M's. All low compression. I would re-ring it and not look back. It won't be like new but it will run lots of hours at minimum cost. I want my tractors to start good and pull loads.

caterpillar guy · Sep 2, 2015

Now that the ring and end gap has been beat to death. Check your piston clearance. I don't remember just what the specs are. I'll bet they are out of spec. If so then take the rings back and get the sleeve set with pistons and rings. Should come all together With the wrist pins in there too. Get bearings for it also. You will not need to do this again the rest of your life probably.

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