Need some hints for getting piston into engine block

[PaulK]

I've swapped almost all the other parts of the engine but I've been hesitant to mess with the connecting rod because I knew it would give me trouble. Sure enough, I can't seem to get the piston into the engine block. I've tried at least 20 times and every time it gets hung up on the lowest set of rings.

Could anyone tell me what I'm doing wrong or give me any hints that could make it easier?

 

[itsid]

piston goes in from above, not below...

if the piston ring compressor sits flush with the deck, all you need to do is tap the piston into the bore with the hilt of your mallet

'sid

 

[landuse]

This is how I did it

I used my fingers to press the rings in and then my forehead to push the piston into the block

 

[mckutzy]

Oh that's gold......


Would like to see a factory tour......
Ladies and gentlemen, here we have the engine assembly room, an our technicians hard at work...
People, now don't be alarmed, our skilled crafts-men/woman... Have proudly earned there "dished dome" upon there forehead, as they refer to it as.... As the connection they feel to be wholly immersed with the creation of each engine.......

 

[Kartorbust]

Get a piston ring compressor and feed it through the top of the engine. The compressor is maybe $20 or less.

 

[PaulK]

I used the compressor and tried to feed it through the top but for some reason I can't seem to get the rings compressed enough to feed it in without getting hung up at the rim.

 

[ezcome-ezgo]

Gap is too small on the OC ring.

 

[PaulK]

Sorry. Could you explain that a bit further?

Dumb question I'm sure, but which is the OC ring?
The piston didn't come with directions so I just mimicked what I could from the piston I was replacing.

Which gap? Just the offset from the gap on one ring to the gap on the next? If so, I get that. I'll just spin it further around.
If not, what would I do about it?

In any case, that's probably not making it difficult to insert, though it's good that I address it.

Do others have difficulty with this or is it just me?

 

[ezcome-ezgo]

The bottom ring in the second picture. The gap in it is too small (the "space" in it's circumference), this space will not allow it to compress enough to sink into the piston and clear the bore.

 

[bob58o]

Isn't the tool upside down?
Put the Piston in the ring compressor from the other direction. Leave a bit of the Piston skirt out side of the compressor so it can sit inside the top of the cylinder.
Get it as tight as you can. Use oil on the Piston and cylinder and inside of tool. Set tool with Piston tightened inside on the top of the cylinder and push with the handle of a hammer.

 

[PaulK]

ezcome-ezgo

That makes sense and would certainly explain my problem.
What's my best solution? Could I maybe reuse those from my original piston?
The engine doesn't have a lot of wear.
If I have to reorder new ones I guess I question why they were off in the first place.
Might I have the order wrong? I was reasonably confident of the top two because they were marked similarly to the originals. But the bottom ones with the strange spring looking thing between them looked interchangeable.

---------- Post added at 10:51 AM ---------- Previous post was at 10:48 AM ----------


bob58o

I've tried it both ways. In fact, the two pictures show it one in either direction. Seems like the second one is probably better. right? I can't tell very well from your picture. you insert the wrench from the connecting rod side, not the flat side. Right?

 

[bob58o]

I added another pic to the last post. I use a 1/4" drive ratchet to tighten. If I understand the question properly, then the wrench is on the flat side of the piston, not the con rod side.

This looks correct as long as the bottom of the piston skirt is below the bottom of the compressor,

 

[bob58o]

I missed the part about the oil ring gap and have to leave for work now.

 

[PaulK]

Got it. You're right; that's the reverse of my description. Thanks.
I'm pretty sure I have, but I'll try it again that way.
What's the likelihood NR accidentally sent me rings that don't have enough room to compress fully. They've been pretty good to me generally but anyone can make a mistake. This seems an unlikely one though.

 

[bob58o]

Got it. You're right; that's the reverse of my description. Thanks.
I'm pretty sure I have, but I'll try it again that way.
What's the likelihood NR accidentally sent me rings that don't have enough room to compress fully. They've been pretty good to me generally but anyone can make a mistake. This seems an unlikely one though.

I have never replaced or gapped piston rings myself. Not sure if you need to gap those rings yourself or if they come pre-gapped.

Gapping piston rings means filing off the end of the ring so you get the appropriate gap when the piston/ ring is in the cylinder bore.

 

[Kentucky Boy]

I've always used a couple wood popsicle sticks. Never needed to use a ring compressor.

 

[bob58o]

And make sure the connecting rod is not hitting the crankshaft when you are attempting to push it in.

 

[Hellion]

Sometimes that last ring doesn't want to go in, or it always seems the piston needs a good slap to go in but I've never had much issue.

KB: how about a demonstration of the popsicle stick method?

 

[KartFab]

i had issues with a piston ring compressor because it wouldnt tighten all the way.

I went to autozone and did their free tool rental (10$ iirc, and you get it back when you bring the compressor back) and the quality of the compressor was better, and it worked 1st time.

crappy tools make for a crappy experience.

I kept the compressor from autozone and have used it a few times since then.

 

[Kentucky Boy]

Sometimes that last ring doesn't want to go in, or it always seems the piston needs a good slap to go in but I've never had much issue.

KB: how about a demonstration of the popsicle stick method?

No time for a demo. Putting the piston in from the top, start with the bottom ring. Press one end of the ring into the piston groove and hold it in with a popsickle stick Slowly work your way around the piston, pushing the ring in with the stick. Apply gentle downward pressure on top of the piston. Once you work all the way around the ring the piston will slide into the cylinder one ring at a time. Then repeat the process for all the rings until your piston slides home. Sounds crazy but has worked every time for me without fancy tools or headaches. The popsickle stick has nice flat surface that helps and it will not scratch or gouge anything.