Jump to content

Nominations for Tractor of the Month
Garden Tractors and Parts on eBay



Photo
- - - - -

Problem Installing Piston on ONAN P216


  • Please log in to reply
13 replies to this topic

#1 SPECKER OFFLINE  

SPECKER

    Member

  • Member
  • Member No: 3794
  • 0 Thanks
  • 10 posts

Posted June 03, 2011 - 12:30 PM

Hey guys

I'm overhauling an ONAN Performer P216G gasoline engine. I ordered new rings for the engine and the oil ring is a wierd setup. The oil ring is a different type of ring than the one that was installed when I dissassembled. This new ring looks like corrugated-type center, with a spacer on the top and a spacer on the bottom. I'll try to get a picture on here of it if I can figure out how to do it. Lol. Anyways the problem i'm having is actually getting the piston in the engine with the new rings. One piston went in fine, and the 2nd is being an arse. I cleaned the ring lands, and the bore is the way it should be. But for some reason, the damn thing won't go in. I ordered new rings and I will get them on Monday, but until then, i'm looking for suggestions on installing this piston.

Just to let you guys know, i'm a diesel engine technician. This is my 1st gas engine overhaul. Real engines don't have spark plugs ;) hahaha

Thanks again!!

IMG_1080.jpg

#2 NUTNDUN OFFLINE  

NUTNDUN

    Lost in Cyber Space

  • Admin
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 3
  • 10,266 Thanks
  • 15,618 posts
  • Location: Pennsylvania

Posted June 03, 2011 - 01:07 PM

Did you happen to check the ring gap first? Usually the rings don't need sized but you might want to check them just in case. Looks like the typical oil ring/wiper setup.

#3 olcowhand OFFLINE  

olcowhand

    Red Tractor Nut & Diesel Addict

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Sponsor
  • Contributor
  • Member No: 20
  • 35,650 Thanks
  • 29,840 posts
  • Location: South Central Kentucky

Posted June 03, 2011 - 01:16 PM

You being a diesel Tech, then I have to assume you're using a ring compressor? Those oil ring rails will snag pretty good at times on the cylinder edge. I'd clamp that compressor down tight, make sure the compressor is seated square all round the cylinder, then thump the piston with the rubber handle of a hammer. They usually pop right on in this way.
You put the expander in the oil groove 1st, then do the lower ring, then the upper. Space the 2 rail rings 60 degrees apart & the mating ends of the expander opposite the rail gaps.

#4 SPECKER OFFLINE  

SPECKER

    Member

  • Member
  • Member No: 3794
  • 0 Thanks
  • 10 posts

Posted June 03, 2011 - 01:20 PM

Good point. I did check the gaps on the 1st and 2nd compression rings, and they were fine, within spec. But I did not check the oil ring. Like I said, I've never seen this type of oil ring before. I'm used to seeing the solid outside ring, and then a spring on the inside.

I just checked the gap for the oil scraper ring, and there is no gap. The two ends of the corrugated ring butt up to each other. On the two spacers that are above and below the corrugated ring, there is indeed a small gap, within spec as well.

It looks to me that the brass-looking piece in the middle is set up so that when you compress the rings before installation of the piston, that ring will actually compress against itself a little bit, and then expand onto the cylinder wall.

Again, inexperience in this type of ring setup isn't helping me haha.

#5 olcowhand OFFLINE  

olcowhand

    Red Tractor Nut & Diesel Addict

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Sponsor
  • Contributor
  • Member No: 20
  • 35,650 Thanks
  • 29,840 posts
  • Location: South Central Kentucky

Posted June 03, 2011 - 01:23 PM

The expander is supposed to butt up. To get these type oil rings to compress enough, you usually have to crank down on the ring compressor good & snug.

#6 SPECKER OFFLINE  

SPECKER

    Member

  • Member
  • Member No: 3794
  • 0 Thanks
  • 10 posts

Posted June 03, 2011 - 01:26 PM

@ olcowhand

I sure am using a ring compressor. I had the compressor pretty tight, and it was well seated against the top of the cylinder before i started smacking the top of the piston with my wooden handle on my hammer.

As i've mentioned, the first piston installation went in perfectly fine with little fuss. I've got a conventional set of rings (like im used to seeing) ordered for it and they will be here on monday. It's getting awfully close to beer....i mean...quitting time...

So i'll see what happens with the new rings and post back here on Monday.

Have a great weekend guys, appreciate all the advice.

Cheers!

#7 SPECKER OFFLINE  

SPECKER

    Member

  • Member
  • Member No: 3794
  • 0 Thanks
  • 10 posts

Posted June 08, 2011 - 12:20 PM

Hey guys,

So I got the rings all settled away and the pistons installed. Everything is al buttoned up and everything is connected.

Thing won't start.

I found out that I have no spark.

I am a diesel engine tech, I dont use spark plugs. lol

So my question is basically, what the heck did I do to eliminate the spark? I'm 99.4% sure that all my electricals are connected properly.

#8 olcowhand OFFLINE  

olcowhand

    Red Tractor Nut & Diesel Addict

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Sponsor
  • Contributor
  • Member No: 20
  • 35,650 Thanks
  • 29,840 posts
  • Location: South Central Kentucky

Posted June 08, 2011 - 12:25 PM

Did you get the trigger ring installed properly on the crank, behind the flywheel? It has to be right side facing flywheel & is marked. 12VDC is getting to the coil?
Being there is .6% chance of error, go back over the connections.
  • SPECKER said thank you

#9 SPECKER OFFLINE  

SPECKER

    Member

  • Member
  • Member No: 3794
  • 0 Thanks
  • 10 posts

Posted June 08, 2011 - 12:40 PM

Please tell me this is a trigger ring.

IMG_1109.jpg

#10 SPECKER OFFLINE  

SPECKER

    Member

  • Member
  • Member No: 3794
  • 0 Thanks
  • 10 posts

Posted June 08, 2011 - 02:06 PM

That must have been it! Thanks a bunch. I pulled off the flywheel, and slammed that ring in there, and we have spark, and she runs like a top!

Im sure my client will be quite satifsied.

THANKS!!

#11 olcowhand OFFLINE  

olcowhand

    Red Tractor Nut & Diesel Addict

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Sponsor
  • Contributor
  • Member No: 20
  • 35,650 Thanks
  • 29,840 posts
  • Location: South Central Kentucky

Posted June 08, 2011 - 03:26 PM

Please tell me this is a trigger ring.

[ATTACH=CONFIG]15666[/ATTACH]


That must have been it! Thanks a bunch. I pulled off the flywheel, and slammed that ring in there, and we have spark, and she runs like a top!

Im sure my client will be quite satifsied.

THANKS!!



Yep, as you now know, that's the trigger ring! Glad she's running!

#12 NUTNDUN OFFLINE  

NUTNDUN

    Lost in Cyber Space

  • Admin
  • Staff
  • -GTt Supporter-
  • Contributor
  • Member No: 3
  • 10,266 Thanks
  • 15,618 posts
  • Location: Pennsylvania

Posted June 08, 2011 - 08:21 PM

Good deal on getting it running. So what was the issue with the rings not going into the cylinder? Did you just have to clamp them a little tighter or gap them at all?

#13 SPECKER OFFLINE  

SPECKER

    Member

  • Member
  • Member No: 3794
  • 0 Thanks
  • 10 posts

Posted June 09, 2011 - 02:32 PM

@olcowhand
Thanks a bunch. Could you give me a basic explanation on what that trigger ring does? I'd appreciate it! I know that was my problem, but I'd like to know why. Lol

@nutndun
The problem with the rings was the spacer on top of my expander ring. It was bent ever so slightly which prevented me from getting it inside the cylinder. I just acquired another spacer and stuck it in and everything went smoothly. I was told that the 3 piece oil ring is a common gizmo in gasoline engines. That's why I was unfamiliar with it. But thanks for your help as well!

Glad I signed up. =)

#14 olcowhand OFFLINE  

olcowhand

    Red Tractor Nut & Diesel Addict

  • Staff Admin
  • Staff
  • -GTt Supporter-
  • Sponsor
  • Contributor
  • Member No: 20
  • 35,650 Thanks
  • 29,840 posts
  • Location: South Central Kentucky

Posted June 09, 2011 - 02:49 PM

Specker, inside the plastic ring is a piece of metal that sends a magnetic signal to the pickup, which in turns sends a signal to the coil to fire a spark. Basically it replaces points. Glad you signed up too!
  • SPECKER said thank you




Top