Piston rings

[aqmxv]

I was taking the rings off the piston on my 6/1 today so everything could go into the parts washer.  Since this one-cylinder has more piston rings than I've seen in several multi-cylinder engines I've rebuilt, I was taking careful note of which side was up and which ring went into which groove.  Now the problem:  The order I removed doesn't make sense to me given what I know about piston rings.

All five rings have the trademark GOE stamped/etched into them.  One's obviously an oil ring, and logically should go at the bottom where it was found.  One is marked top. It's a stepped profile ring and was found with "top" side up in the fourth ring groove, right above the wrist pin.  Is this a scraper, or the first ring?  Does it go in the fourth groove where I found it?

The other three rings (installed in grooves 1-3) appear to be identical and symmetrical (rectangular cross section) with no top and bottom.  Some had the trademark up, some down.

I looked in the original Lister 5/1 manual, and it makes reference to a ring set or a scraper ring, but no other discussion of which ring goes where.

So who goes where, in what orientation, and why? 

[mobile_bob]

hopefully you will get a difinitive answer on this.

based on my experience, the ring that is different should be on the top groove followed by the 3 others that are the same.

perhaps someone will say differently, but i see no reason to have a 4th ring that is different than those above it.

is it made of the same material?

bob g

[Doug]

I was expecting you to say the three the same would be compression rings, 1 scraper ring and finaly the oil ring Bob....

Was it not common practice years ago to have an "oil scraper ring" to pull down excess oil that got my the oil ring at one time?

Doug

[mobile_bob]

not on diesel engines that have been in production over the last half century that i know of.

bob g

[GuyFawkes]

oil control on the bottom, scraper on top, standard in between.

can't offhand think of any exceptions to this in any motor.

don't foeget standard rings take a lot of the torque.

[hotater]

Hastings has sets with a 'top' ring, three compression rings and an oil rirg.  Their top is a chromed, radiused, 'barrel-shaped' ring.

[Doug]

That settles that quick....

I believe I was thinking of gasoline engine rings ( of the smaller air cooled types ) or I'm just plane wrong.

Place works when you let it, question, answere, additional answeres. Perhaps we are finaly getting back to normal around here.

Doug

[bat outta hell]

set #7249

bat

[aqmxv]

I was kinda hoping that a real, normal, lister-related question would get eveyrbody out of the weird character-assasination rut.  Besides, I actually *do* need to know.

Thanks, in particular, to GuyFawkes, who I presume has re-ringed an actual Lister CS at some point.

If anybody else has an opinion - let me know!  I'm a ways away from running the engine, so it's no big deal for me to pull the head and piston and move the rings if information warrants.

After run-in, things will be different...

[cujet]

I do not understand what you mean by stepped profile.

If it is a scraper, I suspect it goes above the oil ring, as this is a typical setup. The word TOP may mean that this it the top side, not the top ring. I have never seen a ring marked top that was marked for position.

Chris

[aqmxv]

I do not understand what you mean by stepped profile.

If it is a scraper, I suspect it goes above the oil ring, as this is a typical setup. The word TOP may mean that this it the top side, not the top ring. I have never seen a ring marked top that was marked for position.

Chris

I have seen a top ring that was both marked for location and marked for position - it's common on engines that use a pressure-assisted top ring with asymmetrical trapezoidal or L - shaped cross section.

I'm going to try to describe this ring:  The three compression rings all have a rectangular cross-section.  That is, the contact (outside) face of the ring is the same height as the inside of the ring.  The "special" ring has a contact face about 1/2 of the height of the inside of the ring.  Since it was found in the position right above the wrist pin (first groove above the oil ring) I'm wondering if it's a first compression ring or a scraper. 

[mobile_bob]

i thought the step was on the inside, if it is on the outside, i would be hesitant to use it in the top position

i have seen the inner steps, but i have never seen one such as you describe used in modern diesels so i don't know

good luck
bob g

[XHoosier]

Hi,  I'm a newbie to the forum, but could not resist asking one question in regards to piston rings and their positioning on the piston.

Question is;  Does anyone have info regarding the ring gap position of any one ring relative to the position of the adjacent ring's gap on the circumference of the piston?

Mac 

[hotater]

XHoosier-- 

I've heard 90 degrees and 180 degrees.  I use 180, but rotate the third ring down just 90 so all sides of the cylinder wall has a gap riding in it somewhere.

[aqmxv]

Question is;  Does anyone have info regarding the ring gap position of any one ring relative to the position of the adjacent ring's gap on the circumference of the piston?

Mac 

This one I *can* answer.  You want the gaps as far as possible apart from each other, both to maximize labrynth effect for blow-by reduction, and to minimize uneven bore wear, which you can get if the gaps are lined up.

So for two compression rings, you put the gaps 180 degrees from each other, and then make sure the oil ring gap is somewhere else - probably 90^o from the other two gaps.  With three compression rings, you go to 120 degree separation for the compression rings, and then try to put the other rings (looks like a scraper and an oiler right now for listeroids) at something like 30 degree offsets to the compression rings to avoid gaps in the same places.

The other technique I've seen is to divide 360 degrees by the total number of rings, and then arrange them with that many degrees offset top to bottom.  I don't think this makes as much sense because the vast majority of bore wear is caused by the first and second compression ring.