Briggs 3HP with piston scoring

[creia]

I guess that I (incorrectly) thought that reinstalling the same rings (with the relatively limited ring and bore wear) would be a "plug and play" procedure. Had I known that the engine would now smoke and I'd have to break it in again, I would have taken the block to my machine shop and have them freshen up the bore with a nice honing to provide a nice healthy cross hatching. (They charge $ 40.00 which I think is pretty reasonable). If I did that, I might as well put in a new set of rings at the same time as well- no? That would probably have had everything seat in better and faster. We'll see what happens with continued break in. I have a set of OEM Briggs Chrome rings I might try if the continued break in does not correct things...
Michael

[bgsengine]

Yep. It's why I pretty much never re-used piston rings - even if they only had a relatively low hours on them - Back when I actually would do overhauls/rebuilds, rings were relatively cheap, so if I had the piston out, it always got new rings.

[creia]

Yep. It's why I pretty much never re-used piston rings - even if they only had a relatively low hours on them - Back when I actually would do overhauls/rebuilds, rings were relatively cheap, so if I had the piston out, it always got new rings.

Brian- When you put in new rings did you always hone the bore as well? Or did it matter how much of the previous cross hatching was still visible? It is my understanding that when installing new rings your are ALWAYS supposed to hone the bore?
Michael

[bgsengine]

Brian- When you put in new rings did you always hone the bore as well?

Only in the case of:
A) Cross Hatch gone (Cast Iron/Steel Bore only) - Never honed an aluminum bore. (Well, I did once, but never again - that engine lasted all of 10 minutes...), or
B) To touch up light scoring or after reaming out a ridge (Which USUALLY was just heavy carbon crust , if there was still cross hatch visible)

Or did it matter how much of the previous cross hatching was still visible? It is my understanding that when installing new rings your are ALWAYS supposed to hone the bore?
Michael

If there's visible cross hatching in the bore, chances are the bore is close to original spec anyway, no? The primary purpose of the cross hatching is to help the rings rotate and seat, which helps with oil control... If I could see cross hatch all the way around, no reason to hone (Unless it appeared to be glazed - which meant a mirror-like surface with cross hatch pattern UNDER a glassy cover - I'm talking appearance, not actual glass)

- If I could see where spots of cross hatching were worn away, I might do some bore measuring, and from there it was a judgement call based on the particular engine, application, and customer wallet - I'd usually recommend reboring and OS piston & rings in those cases where warranted , but sometimes customer wanted it to last just another year or two, which again depending on the actual situation, I might agree with them but not offer any warranty on my work. Often enough the engine lasted them better than 5 years down the road (and I know of one that is still running on a regular seasonal basis 30 years later! - runs a hay elevator)

With Aluminum or Kool-Bore, I would NEVER hone - with cast iron or steel sleeve, I'd only hone if it looked like it needed a cross hatch touch-up (as in the aforementioned 30 year engine)

- often enough a honing could correct a slightly worn/tapered bore (with a little more honing on the small end and less on the big end, and a final cross hatching final pass) and always washed bores (Even aluminum/kool-bore) with hot soapy water and rinsed and dried - Hot water opens up pores of metal so soap can flush out any small tiny particles of dirt/carbon/debris/honing dust/etc.. then scrub out with a clean oiled rag.

So, if there was cross hatching present , and bore and block otherwise clean, good piston and stuff still in spec, I'd have no problem with just throwing in a new ring set with no honing needed.

[creia]

Update 2/13/24:
Some good news....
I have ran the engine using the "break-in" procedure for a total of about 40 minutes now. The previous smoking has been reduced by about 75%!! In addition, compression is good at 90 PSI!!
I am hoping some continued running will completely eliminate the smoking. Is it time for an oil change yet or is it too soon?
Thank you,
Michael

[bgsengine]

Oil change after 5 hours or so of break-in , so 40 minutes isn't a whole lot in reality - maybe another tankful of gas - I'd only just check oil and be sure it stays at full level , run another 40 minutes to an hour run time (maybe hook a load to it and give it a little work to do?) and once satisfied with performance and/or smoking issue, then change your oil, and save it , pour some out in a nice flat pan with a painted black bottom to get a good layer and let it sit , then tilt it a bit and let gravity pull any particles to the low side , give you an idea how much metal war has occurred (I'd guess around a thimbleful if that)

[creia]

Another update:
I have run the engine about 2 hours now and all previous smoking has stopped. I would call this a success!!
I have not drained the oil yet to look for particles. I will report back after doing so...
Michael

[Merkava_4]

UPDATE: The bore ended up having only .0005-.001 wear.

With such low wear, I'd install a standard size chrome ring kit. I've had huge success with chrome ring kits. No honing needed with chrome ring kits. They bite their own way into the cylinder bore. The chrome ring kit for model 81200 is part# 297201.

The chrome ring kit has eight piston rings and they are arranged like this:

Ringland 1
- Thick Ring By Itself

Ringland 2
- Medium Thick Ring + Narrow Expander Ring*
- Thin Ring

Ringland 3
- Thin Ring
- Oil Ring + Wide Expander Ring*
- Thin Ring

*The expander ring goes on first and then the solid ring goes over the outside of the expander ring.

All ring gaps are placed 120 degrees in rotation away from each other.

[KE4AVB]

Part Info extracted and stored under the given pn.

[creia]

UPDATE: The bore ended up having only .0005-.001 wear.

With such low wear, I'd install a standard size chrome ring kit. I've had huge success with chrome ring kits. No honing needed with chrome ring kits. They bite their own way into the cylinder bore. The chrome ring kit for model 81200 is part# 297201.

The chrome ring kit has eight piston rings and they are arranged like this:

Ringland 1
- Thick Ring By Itself

Ringland 2
- Medium Thick Ring + Narrow Expander Ring*
- Thin Ring

Oh- I am WELL aware of the chrome ring sets. I used them MANY times over the years on both the Briggs 3 HP and 5 HP engines. In this particular case, with only .0005"-.001" bore wear I did not think that was enough to justify/warrant their use. I THOUGHT I could just put the original rings back in (also very minimal wear based on the ring gap I measured). I know better now...
Michael

Ringland 3
- Thin Ring
- Oil Ring + Wide Expander Ring*
- Thin Ring

*The expander ring goes on first and then the solid ring goes over the outside of the expander ring.

All ring gaps are placed 120 degrees in rotation away from each other.