Twins with Twins, Anyone?
- Thread starter kidturbo
- Start date
Ok spoke with Swain again today.
Said no idea why it would be lifting besides fact pistons set for almost 2yrs before seeing any heat. No way to guarantee it doesn't repeat it next week. So my warm and fuzzy feeling on coatings has changed to the current outside tempature...
Suggested glass beads as removal medium, best of luck, thanks for your business.
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Said no idea why it would be lifting besides fact pistons set for almost 2yrs before seeing any heat. No way to guarantee it doesn't repeat it next week. So my warm and fuzzy feeling on coatings has changed to the current outside tempature...
Suggested glass beads as removal medium, best of luck, thanks for your business.
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Unfortunately like a lot of this industry, the failures are known only through word of mouth.. As I posted a few pages back, "Failure Is Always An Option!" Own it, learn from it, make it better..
Luckily I designed in some hardware features that makes such hiccups easier to deal with. Like a simple set of casters that bolt to the engine mounting plates. Sure come in handy when you need to roll you junk around while fixing F-up's..
Now how the heck to mount up these big S476 turbos when the boat has 4x5" thru-hull exhaust ports to hit, only 18" from the back of intake. Things are suppose to line up like my avatar photo... lol
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Luckily I designed in some hardware features that makes such hiccups easier to deal with. Like a simple set of casters that bolt to the engine mounting plates. Sure come in handy when you need to roll you junk around while fixing F-up's..
Now how the heck to mount up these big S476 turbos when the boat has 4x5" thru-hull exhaust ports to hit, only 18" from the back of intake. Things are suppose to line up like my avatar photo... lol
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Maybe I was a bit quick to call NO damage from the coating. Looks to have played havoc on the top rings and the crown in a few spots on several pistons.
Just noticed it while tearing em down to strip it.
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Just noticed it while tearing em down to strip it.
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Pistons
This is just my opinion but I don't think that is from the coating. Look at the ends of the rings and see if the were butting up against each other. You are missing molly in the face of the ring and the scaring looks to be something is to tight. Now I'm sure everyone is going to slam me and that's fine. BUT I have never lost a piston or hurt a motor like that. Loose is you friend. Your not driving that thing down a road or hooked to a sled for 20 seconds. That thing will see SUBSTAINED heat that most will never see. Performance engines are such fun.
This is just my opinion but I don't think that is from the coating. Look at the ends of the rings and see if the were butting up against each other. You are missing molly in the face of the ring and the scaring looks to be something is to tight. Now I'm sure everyone is going to slam me and that's fine. BUT I have never lost a piston or hurt a motor like that. Loose is you friend. Your not driving that thing down a road or hooked to a sled for 20 seconds. That thing will see SUBSTAINED heat that most will never see. Performance engines are such fun.
no one should slam you! different trains of thought and if it works, it works! we dont learn if we dont look outside the box every so often.
you dont think piston coating material was transferred to the cyl wall where the rings run then they ate it? id be curious if rings that butted would still allow the piston to then hit its top side against the cyl or not. usually by the time ive seen a ring gap that was too tight, the piston was toast :roflmao:. just seems interesting the scarring on the piston matches so well up to the rings. maybe im not looking at it right though.
Piston pictures are all upside down sting... LOL
I checked a couple of the top ring no sign of them touching. But I haven't pulled them off and pistons yet. From my observation, as the Piston starts up it is rocked in One Direction, coating touch the wall and rubbed off then gets caught between top and 2nd ring.
When we first got the Pistons, the TBC looked soft. So we heated one up with a torch and that coating turned very hard. Damage looks like grains of sand in that very particular area. Each piston has a matching spot on the upper and lower side of the cylinder bores. Without the coating I don't think it would have hurt being loose.
I'm driving to NC at the moment, maybe tomorrow I'll stop by with a couple for you to check out sting.
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I checked a couple of the top ring no sign of them touching. But I haven't pulled them off and pistons yet. From my observation, as the Piston starts up it is rocked in One Direction, coating touch the wall and rubbed off then gets caught between top and 2nd ring.
When we first got the Pistons, the TBC looked soft. So we heated one up with a torch and that coating turned very hard. Damage looks like grains of sand in that very particular area. Each piston has a matching spot on the upper and lower side of the cylinder bores. Without the coating I don't think it would have hurt being loose.
I'm driving to NC at the moment, maybe tomorrow I'll stop by with a couple for you to check out sting.
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Ok started pulling rings tonight and I can say for certain, they are not butting up or binding. Carbon on the ends, no sign of touching or anything out of the ordinary. See pic below where I scratched a ring end for contrast. With a .026 gap on top ring, and no real run time at load on engine #1, this is most revealing.
What I can say, should send Swain Tech these 16 pistons along with bill and letter from my attorney for blowing me off. Better yet, maybe I should just drive over and liquid nail these pistons to their front office window. With a note saying "reaearch adhesive properties..."
This is total BS. Shit bubbled up and started rolling UP at their tape line on land above top ring as pistons traveled downwards. Then the balled up material detached and went through the top ring as pistons traveled upwards. Pieces of it on top and behind second ring on 2 of the 3 sets I've pulled so far. Some damage to the piston lands also.
What's more interesting, most of the damage on this engine is near exhaust valves. Not seeing any on the intake side of this one due to low hours. So the whole PTW question is also useless. Only issue is their junk ass TBC that I questioned from day one. See how thick it was applied.
Fingers, call Mike over there and tell him your customer has a caulking gun and is headed to a hardware store.. Need 2 sets of new rings minimum, and likely 5 or 6 pistons to make it right. And I haven't even honed the block'S yet.
BS BS BS...
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What I can say, should send Swain Tech these 16 pistons along with bill and letter from my attorney for blowing me off. Better yet, maybe I should just drive over and liquid nail these pistons to their front office window. With a note saying "reaearch adhesive properties..."
This is total BS. Shit bubbled up and started rolling UP at their tape line on land above top ring as pistons traveled downwards. Then the balled up material detached and went through the top ring as pistons traveled upwards. Pieces of it on top and behind second ring on 2 of the 3 sets I've pulled so far. Some damage to the piston lands also.
What's more interesting, most of the damage on this engine is near exhaust valves. Not seeing any on the intake side of this one due to low hours. So the whole PTW question is also useless. Only issue is their junk ass TBC that I questioned from day one. See how thick it was applied.
Fingers, call Mike over there and tell him your customer has a caulking gun and is headed to a hardware store.. Need 2 sets of new rings minimum, and likely 5 or 6 pistons to make it right. And I haven't even honed the block'S yet.
BS BS BS...
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Yeah coated only about halfway down. This call also on the suggestion of swain to protect the crown. Zoom in on piston pic post 783.
NC, I ran down to Raleigh to check out an LT5 engine my buddy at Crawford Racing is doing. Little CANBUS and L5P throttle body hacking side project.
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No, from what I can tell the worst of it is related to the side coating. However on the other engine there is some scratches that don't Mach up. And flaking off the top is surely gonna cause hot spots where it's missing.
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On engine #1, 7 of 8 top rings show significant damage on the face. Mostly isolated to area matching the coating damage on top land. Being the short run time, the rings don't look to have rotated much from installed positions.
Only a couple of the second rings showed any marks where material passed them. However I found what looks to be some lost TBC on top and behind the second ring.
See comparison of the one good top ring to another where TBC was in bad shape. Last is pics of a second ring before wiped down to show the gritty left overs I found.
Open to alternative theories if anyone has something better to explain it.
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Only a couple of the second rings showed any marks where material passed them. However I found what looks to be some lost TBC on top and behind the second ring.
See comparison of the one good top ring to another where TBC was in bad shape. Last is pics of a second ring before wiped down to show the gritty left overs I found.
Open to alternative theories if anyone has something better to explain it.
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On a good note, the pressurized wrist pin bushings look to be running happy happy happy on both engines..
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Here is a PDF I found that examines many types of diesel piston damage, and offers known causes with detailed explanations.
Good read, with pictures..
https://cdn2.ms-motorservice.com/fi...n-damage-recognising-and-rectifying_51730.pdf
Mine seem to be closest to example #42.
Now that is funny... :spit:
Good read, with pictures..
https://cdn2.ms-motorservice.com/fi...n-damage-recognising-and-rectifying_51730.pdf
Mine seem to be closest to example #42.
- Pistons with an incorrectly shaped bowl or an incorrect bowl depth or diameter.
Now that is funny... :spit:
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I'm gonna have to go with 42 also, there was similar wear on Brett Duestch's pistons he was selling used, never saw the bores though just the piston pics. It appeared to me the injector spray area on the outer oval caused a hot spot due to the smaller amount of material there so there was more expansion in that area. It's been a while since I looked at those but I thought his marks lined up roughly with the injector spray pattern. I think the coating on yours made it worse since it closes the clearance even more.
I'm not dead set on this it's just a theory on my end and it's in no way of a no insult to John on his pistons, now would I rather have a few piston scuffs instead of a cracked piston and ruined cylinder yeah so you loose in a few areas to gain in others. Big injector pulse surely makes the problem worse, guys with huge injectors and smaller pulse width's with these pistons probably never see anything on the pistons.
I'm not dead set on this it's just a theory on my end and it's in no way of a no insult to John on his pistons, now would I rather have a few piston scuffs instead of a cracked piston and ruined cylinder yeah so you loose in a few areas to gain in others. Big injector pulse surely makes the problem worse, guys with huge injectors and smaller pulse width's with these pistons probably never see anything on the pistons.
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Yeah I'm gonna say while this set only made a few short pulls, they saw the biggest pulse width [2850us], most heat [1800f], with shortest break in period [has oil pressure, send it] ... :rofl:
Which all those points alone fall under several possible causes listed in that PDF. If you read each description matching where these show contact, none are definitive. Plus these piston tops were shaved an additional .010 to match block deck work. So it's totally possible they are deforming slightly, or oil film was getting washed down with fuel, allowing coating to touch the wall.
And while you won't find a picture anywhere, nor did Jon receive it back, I have seen a cracked "coated" oval bowl with my own eyes. The crack went right across the top half of the oval cut, not centered over wrist pin as is most common. So the weakest point has obviously moved with his design mod.
But how does all this play into the coating issue? To me, it doesn't change fact the coating is what damaged the rings and mauled the cyl walls. If we had started out with bigger injectors as switching to now would it still occurred, most likely yes. If they had only coated the tops and not over the edge, then some of the missing chips in set # 2 would likely have still made their way down into the rings. That I believe true. So TBC is still bad... MMKAY!!
The gold coating seems to be applied thinner, and adheres better than this TBC. I've spoke to several builders running on forged pistons in gas engines and none report any such issues. I can't find anyone who has used the TBC, but recall someone posting a pic on here from years back showing it cracked and lifted also. Maybe I'll do a search when have time.
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