Replacing rings on 1 piston on 8ba
- Thread starter AnthonyG
- Start date
AnthonyG
Well-known member
Thx Ggmac & kjvma131, I'll let u know but right now I haven't got far enough to check. I know its an 8ba w a Merc crank so think it's 255ci which should put bores at min 3.1875"-Max 3.2775. I had head off recently to check right bank top side bore condition and scaled them rough at 3 3/16" Getting ready to pull engine and put on indexing stand to pull piston & replace rings on #2.
Thx A bones & Ronnie, I'll check with both Hastings and VP JIC.
Thx A bones & Ronnie, I'll check with both Hastings and VP JIC.
mrtexas
Well-known member
Can replace rings without removing engine. I've done it on a 37 engine. A little hard to get the pan off but it can be done.
Bored&Stroked
Well-known member
Hey Anthony - just to ask a question: When was this engine built and what do you think happened to it? Rings are not that expensive - and you're already pulling the engine and putting a lot of time into it.
If it was mine, I'd probably plan to pull all the pistons, check the bores and maybe hone and re-ring the whole thing?
It kind of depends on what you find when you pull the one cylinder (like a broken ring) . . . but do keep in mind whether or not to do all 8 of them. Also, I'd measure the bores accurately to see if they are worn, tapered or too "loose" for the pistons. Sometimes folks throw these engines back together with the "least amount possible" of work . . . so check it all out.
If it was mine, I'd probably plan to pull all the pistons, check the bores and maybe hone and re-ring the whole thing?
It kind of depends on what you find when you pull the one cylinder (like a broken ring) . . . but do keep in mind whether or not to do all 8 of them. Also, I'd measure the bores accurately to see if they are worn, tapered or too "loose" for the pistons. Sometimes folks throw these engines back together with the "least amount possible" of work . . . so check it all out.
Frank Miller
Well-known member
I re ringed and put new bearings in a 72 K10 that was blowing oil. It needed more but that was all I had. Drove it for about 5 years after that and sold it to a guy who did a little work and said it ran mint. He drove it for a few years too. I plowed with it too.
AnthonyG
Well-known member
Here’s the story on the engine, purchased from United Specialists Engines in Wichita Ka. In 2013 w 12,000 2yr warranty. I have approx 2000 miles on it, I know a lot of u guys drive’em a lot more but gotta believe I’m in the average for a cruise nite toy. Anyway had problems when first bought & under warranty which should’ve been a clue. Had wrong pressure plate on FW that busted case on my ‘35 ****** ( had to rebuild w good case), Fly Wheel drilled for pressure plate .090 out of concentric, E-distributor bad. United Speciaists sent new parts 4 all but damage & labor for their mistakes was on my time & $. Fast forward to now, before putting away for season I usually take out for long ride bring revs up to blow carbon out from slow driving all season. Did this yr in early Oct as was leaving for long Vacation in Nov. When I got home noticed smoke from engine, it was puffing ( in Rhythmic puffs see other post) coming from oil fill neck. No smoke from tail pipes! Checked compression good all cyl’s except #2. Pulled that head to see if any cyl damage could see none but could tell water had gotten into cyl 4 at some point (cyl had water stains but bore smooth & compression ok. Changed head gasket rechecked compression w same results as before. Tried to drive a few times based on suggestions from previous post. Rhythmic puffing from oil Fill neck got worse & heard odd lower end noise but still no smoke from tail pipes. Arrived @ Current decision to check lower end (think it's a cracked oil wipe ring or possible compression ring letting compression get to crankcase on cyl #2) so change rings on bad compression cyl 2, but will give all a good look. Rational is, engine has so few miles on it and only has the compression issue on the #2 cyl so seems that's probly the issue.
Last edited:
frnkeore
Well-known member
I agree with your solution but, I would have tried to isolate the "odd lower end noise" before pulling it out.
Did the oil pressure drop, at all, after the puffing started? The other thing that I'd check out is the wrist pin and piston.
Can you describe the odd noise?
AnthonyG
Well-known member
Initially thought it was spark plug knock as engine runs rough when it occurred. Increase revs a bit it diminishes. Comes & goes. When audible engine puffing smoke increased. Didn’t want to keep going was afraid of cyl damage. So far no smoke from tail pipes so think cylinders still OK, I hope. Will not run again till I see in side the bottom end. All has to b related. Pretty hard to diagnose w specificity
AnthonyG
Well-known member
Frank nailed it in post #15, broken piston, no broken rings. Makes more sense as Frank said. Once piston removed could see crack between top 2 ring grooves. Piston skirts & top of one side dragging on cyl, w piston out can see aluminum marks in cyl. Feels fine to touch. Can’t feel any cyl damage, aluminum against iron the iron won. 100% sure cyl is good & light hone will remove marks. See pics of piston, couldn’t get a shot of inside cyl that showed anything.
