Fitting piston rings

Actually that sounds like good advice, the "official" tool for compressing the piston rings and installing them looks a lot like a thin sheet of metal wrapped around the piston and then tightened "Strap / handle". and then the piston is pushed down. I did see something on TV the other day about setting the gap on piston rings, does anyone have any experience doing this???

============================================== Put some color in your cheeks...garden naked!

do not align the ring ends, stagger them around the piston follow any alignment instructions you got with the rings.

use a ring compressor coat the piston and rings and bore with gear oil like 80W put the compressor on the piston, tighten up the strap fairly tight line up the rod in the bore and have the piston facing the right direction tap it down carfully using the end of a wooden hammer

the ring end gap is fairly important, but if your just using std rings in a std bore, you have no problems. The ring end gap should be measured with the ring in the bore at the top of its travel and the bottom.

Fitting piston rings by hand is the easiest way. Just gently hook one end down onto the piston, and work your way around to get the complete ring onto the top off the piston. Then gently work it down the piston. Obivously you'll have to get the first ring past at least one groove, and the easiest way to do that, is to get the ring just above the groove, then hook one end down and over the groove, and work around the piston just the same as getting the ring onto the piston.

Ooops, should off put removing them first. Removing them can be done by using a couple small screwdrivers. Just hook the end off the ring out with one, then with the other just work you're way around the ring with the other, gradually moving the end up the piston and out off the groove.

Unless you're extremely harsh, you won't do any damage to the piston. To get an idea off how strong the rings are, once you get one off the old ones off, break it. Personally I think handling piston rings is just like handling a sheet off glass. You've got to be firm but gentle.

Also, one of the important tests during a ring job is to measure the ring gap at the top and bottom of the cylinder (slip a ring into the cylinder, and then measure the gap clearance with a feeler gauge set. Most engines will develop some taper over time (wider at the top where less oil gets), and this should be honed out during the ring job. If there is too much taper, the rings will "pump" oil, even if the cylinder walls have been cleaned up and new rings installed.

The last engine I did (79 Honda Civic CVCC) had over 0.040 taper (!) but I was just interested in getting it to pass inspection so that I could sell it as a car, rather than scrap. I just broke the glaze on the cylinders and put the new rings in without touching the taper. Worked fine, passed inspection, didn't smoke. I told the guy that bought it that it was an old engine, and would probably need a rebuild soon. I figure the $300 in parts enabled me to get $800 for the car instead of $50 for scrap, so I was money ahead. Boring out the cylinders would have cost more than the car was worth. I wonder how many miles the buyer got before the "ring job" died. My guess is he got well over $800 worth of driving out of the car.

-- Bob (Chief Pilot, White Knuckle Airways)

I highly recommend a ring expander to install the rings on the piston and a ring compressor to install the piston in the cylinder.

I tried to install rings on a small piston by hand and I promptly broke the ring. That was on a model engine with CI rings. Obviouly steel rings are tougher. On model engines I wrapped some thin brass around the piston and used a cable tie to compress the rings enough to slide them into the cylinder.

These are quite inexpensive for a good brand. You can also use a big hose clamp, but that adds some friction.

Maybe. Some rings REQUIRE fitting and are purposely made oversize

The old rule of thumb for automotive engines was .002" per inch of bore. Might not be valid for an air-cooled engine. If no specs are available from the Mfg or the ring maker, look for similar engines with similar bore and ring size, from the same era, and see what their end-gap was.

You definatley need a piston ring compressor to get the piston back in the cylinder.

I have never broke a piston ring, when removing or installing them on the piston. Only time (other when I've wanted to break an old ring to clean the grooves) i've broken a ring, is when I was rebuilding an engine that used the multi-part oil control rings with the two thin rings and a wavy ring inbetween (there is a proper name for them but I can't remember just now). The piston ring compressor slipped up from the top off the engine block, and one off the thin rings popped out. First I knew about it was when I seen the bit piston ring fall out onto the bench. Which just so happened to be the engine that I knocked the piston cooling oil jet off, when trying to get another piston in. I still shudder thinking about rebuilding that damn engine.

Thanks for all the advice so far. I just took another look at the piston rings tonight. My engine's got one of those oil control rings (it isn't the wavy type; it has slots cut in it) and all four rings are cast iron, so it looks like I need to be careful. I'll look for stores that sell ring compressors and expanders.

Best wishes,

Chris

Autozone will rent you the tools. You have to buy it, and then you simply bring it back for a full credit.

I always lightly honed the cylinders with a fine stone. Are you saying not to do this? The worry here is the rings wont seat properly and then the engine will use too much oil. What I have also found is engines that are well maintained on oil today, never seem to have a ridge. And I have also noticed the cylinders look very good. I resealed the heads on my 1993 350 with 170000 miles and there was no ridge, the cross marks were still there. I also like to use synthetic oil, but I think the oils today are really much better.

One other little trick nobody's mentioned.

When you check the gap, you need to have the ring in the cylinder absolutely square. The easy way to do it is to put the ring into the cylinder and then push it down a little using a piston (sans rings) as a tool. That way, your measurement of the gap (with a feeler guage) will be accurate.

Jerry

Two tools, two jobs.

You need a ring speader to put the ring on the piston, then you need a compressor to stuff them into the hole. Shim stock HAS been used for both jobs, but the right tool is available from KD (among others) for a very reasonable price - and you can usually borrow or rent them from most of the DIY autoparts suppliers (like AutoZone etc) Nothing beats having the right tool, and knowing how to use it.

Risky. They need to be DEAD ROUND and DEAD STRAIGHT - and then they cannot be too smooth. Todays engines are built with a high precision micro-inch finish on both the rings and the bores - and they still have to wear in - but only a tiny fraction of what was common only a few years ago. If the bore is too smoth, the rings will never seat, and you will have an engine that produces high HCs, uses oil, and is not as "good" as it should be.

When I pulled the engine from my TransSport just over 2 years ago at

275,000KM there was no cyl ridge, and the crosshatch could still be seen - but it had been massively overheated and the cyls were VERY glazed. Not a chance it would pass the Sniffer test. It had been so hot it tightened right up and quit - and started just fine after it cooled off - yet no scoring on the cyl walls. A bit of aluminum transferred to the cyl walls below the ring travel, but no gouging at all.

I tore down an engine that I rebuilt myself over 160,000 miles prior. NO ridge. Bearings looked awesome as well. Kendall 20W-50 changed regularly and cleaned by Wix filters. Not my point, though.

I looked for this article again and couldn't find it. The points made were is that if the bore isn't square when the old pistons come out, the rings will show it when you shove them in and check for gaps. Unless sludge trapped the rings in place, not allowing them to rotate, the bores where the rings will be will most likely already round enough for the rings to do their jobs again. You can hone them round if needed, but don't leave crosshatch behind. That crosshatch will get ground off by the rings. That crosshatch you just took off is now grit in your engine, and very fine grit indeed. All that effort to get the engine spotless before assembly and you just went and tossed in a pinch of iron dust, where it will be circulated among softer bearings, wearing everything else out along the way. Guess what? 500 miles later, after the rings are "seated," the cylinders are polished nice and shiny, just like you wanted to avoid! Skip the whole mess. Seen a 500 mile oil change on a new car lately? Don't need to, because the finish on the walls is very specific and extremely fine. Rings don't need to seat anymore because they're made a whole lot better than they used to be as well.

I reread it a few times because I was naturally skeptical. It all made perfect sense, though, in a much better manner than I tried.

I think it was not mentioned because honing is a 'given'. By all means, hone the cylinders so the new rings will break in.

- - Rex Burkheimer WM Automotive Fort Worth TX

snipped-for-privacy@msn.com wrote:

Thanks for the suggestions. I just took another look another look at my engine in the daylight. There is a small ridge at the top of the cylinder and a minor amount of corrosion on one side of the cylinder. Should I buy a honing tool to fit an electric drill and polish these out?

Best wishes,

Chris