How does one get piston rings to play nice during installation?

[bunni]

I spent the better part of the last 2 hours trying to get ONE piston re-installed in my engine. I have new rings, an autozone compressor, and freshly oiled pistons and liners, a bloody engine block, and torn up knuckles. I couldn't get a single one in! Every time it came to the point where the rings were moving from the compressor to the liner, it stopped and the small ring popped right out.

I currently have the block upside down on my bench with the crankshaft set in place (just working back from how I got it apart). I cant really put it on a stand because it would have only two out of four support bolts, and I can't really put the bottom on since I cant get to the piston rods through the bottom half of the engine.

Can anyone suggest a less bloody and violent way of putting pistons back in? It would be much appreciated.

[DMC5180]

What style of Compressor do you have? Curtain types work better than others.

[Bitsyncmaster]

I've use a large hose clamp when I did not want to rent a ring compressor. But normally you just tap the piston down with the handle end of a wood handle hammer.

[bunni]

This guy: http://www.autozone.com/autozone/accessories/OEM-3-1-2-to-7-in-piston-ring-compressor/_/N-25mm?itemIdentifier=531947_0_0_

[Silverbullet]

There are a couple styles of ring compressors,,, One is smooth spring steel that winds up with a allen...I don't like that one... I have one that is kind of waffled and you put the split part where it it solid...Also it really helps if you have another set of hands, so the compressor can be held down tight on top of the liner, so you can do solid taps, I use a wooden hammer handle...

Ya.. you got the crap one...saw the pic, it adjusts from 3 1/2" to 7"... Mine has a red plastic handle, and was not a lot of money, it is only like and inch wide...

Here is mine:

http://i116.photobucket.com/albums/o19/AtHomeSoda/Ring_zpse74dc9e2.jpg (http://s116.photobucket.com/user/AtHomeSoda/media/Ring_zpse74dc9e2.jpg.html)
Craig

[DMC5180]

The waffle band type is a "Lisle" brand. Most AP stores carry them. Whether or not it is the better of the 2 can be debated. Not all applications are equal. I have one and it did not work the best for me.

Consider installing the Piston into liner out of the block. set the liner up on 2 wood blocks and drop the connecting rod between them. Pay attention the piston liner to piston orientation. once the piston is in the liner set it in the block.

[DMC5180]

Maybe we should back up here. You are following the WORK SHOP MANUAL right? See Page C:07:05 under re-assembling [ Refit " LINER-PISTON-CONROD" assembly] Then Page C:07:06 Assembling the "liner-piston-conrod" Assemblies. Which means you pre-assemble these out of the block then refit them following the proper procedures.

[dmc6960]

When I rebuilt my engine I inserted all the pistons into the liners on the bench. Used the smooth style compressor and had no problems at all. I then dropped each piston-liner assembly into the engine and everything worked great.

[David T]

When I rebuilt my engine I inserted all the pistons into the liners on the bench. Used the smooth style compressor and had no problems at all. I then dropped each piston-liner assembly into the engine and everything worked great.


Generously cover everything in motor oil, squeeze the compressor tight and bop in gently with a wooden dowel or butt end of a plastic mallet. Stagger the ring gaps. You should fit each ring into the liner and measure the gaps before putting the rings onto the pistons. You might have to file the gaps to get the proper spec.
David Teitelbaum

[Silverbullet]

Generously cover everything in motor oil, squeeze the compressor tight and bop in gently with a wooden dowel or butt end of a plastic mallet. Stagger the ring gaps. You should fit each ring into the liner and measure the gaps before putting the rings onto the pistons. You might have to file the gaps to get the proper spec.
David Teitelbaum

Good info here... Always fit just the rings into the liner, and make sure they have the proper gap....

Craig

[bunni]

All good info, thanks guys. I guess I missed the part of the manual that says to mate the piston to the liner before putting it in. When I had some friends helping, all of the gaps were checked for each piston/liner combo, but were pulled back out as the liners needed work to be cleaned up and shimmed properly before those were put back. I suppose it would have been easier to leave the pistons in however :banghead: I was also working at a stupidly awkward angle and started out in a bad mood, I will give this a try tomorrow!

[David T]

All good info, thanks guys. I guess I missed the part of the manual that says to mate the piston to the liner before putting it in. When I had some friends helping, all of the gaps were checked for each piston/liner combo, but were pulled back out as the liners needed work to be cleaned up and shimmed properly before those were put back. I suppose it would have been easier to leave the pistons in however :banghead: I was also working at a stupidly awkward angle and started out in a bad mood, I will give this a try tomorrow!

It is not a good idea to have a bunch of friends over to have an engine building party. One tiny mistake and all of the work is for naught. Engine assembly is for the anal obsessive/compulsive and is best done alone. You need to know in your head what you are doing, what has been done and what needs to be done. It should be done in a very clean environment and everything should be organized so you can keep mating parts together, ie, a box for each cylinder and labeled. If you have to stop for any reason it should be done at an appropriate place so when you restart you don't miss anything. You should have a count on everything and nothing is "left over". You check and recheck everything you can with micrometers and plastigauge. You have everything cleaned and ready for assembly. You check EVERY hole for threads and any dirt.
David Teitelbaum

[bunni]

It is not a good idea to have a bunch of friends over to have an engine building party...

I surround myself with various kinds engineers (I am personally EE and SE), all of us double and triple checked what we were doing against the manual, and the two helping have rebuilt multiple engines in the past. I very much trust what they did, however none of us had ever dealt with the odd beat that is the PRV haha.

I spent a solid day obsessing over the liners, getting them cleaned, leveled, and at the correct height working out of the PRV reconditioning manual. I just missed the tiny detail of "you should have put the damn piston heads in first."

[DMC5180]

I surround myself with various kinds engineers (I am personally EE and SE),

You know you just set yourself to be the :bootyshake: of a few jokes right.


How many engineers does it take too.................. :jk:

[bunni]

Rebuild a D? More than I can count ;)

I got a few pistons back in without much issue, other than continually slicing my hands. Oil covered hands + sharp metal object = blood everywhere. Once I heal up I will get the rest in.

[David T]

Rebuild a D? More than I can count ;)

I got a few pistons back in without much issue, other than continually slicing my hands. Oil covered hands + sharp metal object = blood everywhere. Once I heal up I will get the rest in.

The question still stands, did you check the gaps on the rings in the liners before putting them onto the pistons? If you got a ring that is too big, ie, no gap, no amount of compression with a ring compressor will get that ring to fit. And if the gaps are too small you are in for a big surprise when you get the motor up to operating temperature. I understand everyone was well qualified, the problem is who did what and where did one person end and another begin. I dislike many hands when hand building a motor unless there is a clear division of labor and everyone knows what they are responsible for. Even then I like to see for myself because ultimately I am responsible if it has a problem. The only things I delegate are the machining and then only because I do not have the machines. I still check over the work. If the motor blows up you will really get to see who your friends are!
David Teitelbaum

[DMC5180]

Page C:06:06 has a nice illustration for ring positioning too.

[bunni]

The question still stands, did you check the gaps on the rings in the liners before putting them onto the pistons?...

I appreciate your concern, everything was tested out and fit properly. Once person had the job of fitting. I very much agree on having a clear division of labor, and that is what we had set up.


DMC5180: Yeah, I got that, oddly enough that isnt in the recondition manual, that only seems to call out the scraper alignment.