Piston Failure

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Charlesvolare

Charlesvolare

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I have a la 360, bored +0.060", kb pistons, Eagle H-beam rods, stock crank, retrofit roller cam, built Magnum heads, dual plane intake w/ holley 750, Fast E6 ignition. Timing set at 32 total. I've been tuning this setup for a few weeks now and took it to the dragstrip for the first time with everything last Friday. Runs mid 13.5's pretty repeatedly, with the best of the night being a 13.45. But I haven't touched the carb much and the secondaries are super rich it seems so it still has room to get better.

It's been running good so I decided to take it to see family on the 4th of July (the Thursday after the strip night). It's about an hour and a half drive down the interstate and if anything I could use the highway miles to figure out mpg (19.9 mpg, 93 octane pump gas!). The car cruised good, 3500 rpm @ 73 mph and the temp never went over 180* even with the 93+ degree day. The car cools down for a few hours and I drive another 45 minutes to visit with my friends and show off everything I've done to my car in the past few months. The car cools for about another hour and we decide to get fireworks (about a mile away). We take my car and I get on it pretty hard pulling out of the driveway, pulling trough the gears, shifting at ~6400 rpm. Start the car after buying a few snakes and sparklers and thought it was smoking, but it was a gravel parking lot so I figured it was gravel dust. We go to get ice cream (another mile away) and leaving from there there was definitely a smoke cloud following us, my heart immediately sank. I park the car and let it cool for a few hours while we shot fireworks and grilled and everything. Pulled it into their garage and pulled the plugs (#1,3,5,7- it was smoking from the drivers side exhaust):
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Pulled the valve cover, valve seal is still there. Started the engine with breather off:


It ran good still and idled fine, so I swapped #5 spark plug into #7 and trailered it the 80 miles back home.

Pulled it off the trailer and let it warm up a bit, but the smoke didn't go away. Didn't seem to misfire or be down on power. In fact, laid some nice tracks pulling it from the trailer to my driveway :)
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Pulled the #7 plug again (newish from cylinder 5) and this is what it looked like with the little time idling and pulling on/off the trailer:
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I did a compression test and that cylinder is down 40 psi from what I measured a few weeks ago, but it held it there for 1+ hour. I din't pull any other pugs however. I'll try to get to that tomorrow if i get the time, was just trying to see if there was a hole in the piston.

What I'm thinking is that all of the driving I did got everything hot, and running it hard like I did caused the rings to butt up and crack/break a piston ring land. I have a picture of the exact piston I have in my engine I'll attach to give an idea of ring location. What gets me is how compression dropped 40 psi but holds it at that. Could something else make more sense? Idle has no noticeable change, no noticeable/significant power loss. Lots of blow-by, smoking from drivers-side bank, #7 plug is oil-fouled. Everything started occurring suddenly after hard acceleration after a day of driving.
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IDK but a leak down is better than a compression test. There is certainly oil on the plug. IDK why you are only running 32 total. I can't see the plug well enough to see the timing mark on the ground wire. Also, can't see the plug number, but it looks rich at idle and a bit closer at cruise. Don't know what that ignition system is either.
 
yellow rose said:
IDK but a leak down is better than a compression test. There is certainly oil on the plug. IDK why you are only running 32 total. I can't see the plug well enough to see the timing mark on the ground wire. Also, can't see the plug number, but it looks rich at idle and a bit closer at cruise. Don't know what that ignition system is either.
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I'm running 32 because I was having problems with detonation under load and that was the most I felt safe with running. I think it was a combination of the cam, compression, and iron heads. The plugs are autolite 5224. The Fast ignition is a CD box, same as the msd stuff but made by comp/Fast. I work at comp cams so I got a pretty decent discount. I was still working on mixture tune, a wideband was gonna be the next purchase so I could dial it in. I'll try to pull all of the plugs tomorrow and take a better look and rerun the compression test and possibly a leak down. Definitely a lot of blow-by though.
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SLOPAR72 said:
Have you heard any detonation?

JW
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Nothing I noticed. I had a issues before and cranked the timing down to get rid of it. I haven't touched timing in a few weeks and haven't noticed anything, even at the strip. It would have to be extremely little, if any
 
Charlesvolare said:
Nothing I noticed. I had a issues before and cranked the timing down to get rid of it. I haven't touched timing in a few weeks and haven't noticed anything, even at the strip. It would have to be extremely little, if any
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Detonation can wipe out a Ring land in a jiffy. Just spit balling and not seeing the car don't be surprised if that's the problem. As for beating on the car at the track and having a ring issue, it could happen but that if the rings are properly gapped then that is not something I would put into the equation right now....

Pull it down and you will find out.

JW
 
SLOPAR72 said:
Detonation can wipe out a Ring land in a jiffy. Just spit balling and not seeing the car don't be surprised if that's the problem. As for beating on the car at the track and having a ring issue, it could happen but that if the rings are properly gapped then that is not something I would put into the equation right now....

Pull it down and you will find out.

JW
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I'm definitely suspecting ring problems, I put it together myself. First bottom end I built, right out of highschool. I don't remember the clearances, but I thought I had given them a little more than what was called for. It's been through a lot and lasted this long, but this was the first big summer drive with this top end combination.
 
Charlesvolare said:
I'm running 32 because I was having problems with detonation under load and that was the most I felt safe with running. I think it was a combination of the cam, compression, and iron heads. The plugs are autolite 5224. The Fast ignition is a CD box, same as the msd stuff but made by comp/Fast. I work at comp cams so I got a pretty decent discount. I was still working on mixture tune, a wideband was gonna be the next purchase so I could dial it in. I'll try to pull all of the plugs tomorrow and take a better look and rerun the compression test and possibly a leak down. Definitely a lot of blow-by though.View attachment 1715359563
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Ok, Fast. You said F3 or something and I didn't connect the dots.

What cam are you running? The plugs you posted don't show signs of detonation. But, it can be hard to see in pictures.
 
Lean tune. Imo
I like to tune on the lean side as well, but under harsh wot the temp spikes and hypers come apart.
Maybe you broke part of the ring land off, maybe you just pushed a head gasket into oil. Leakdown test is in order. The plugs look lean all around the base Circle and all I see is the fuel additive of the brand feel you use or put in which is reddish orange... but that's just what I see in that grainy pic.
Being 40 PSI down is substantial, would take a number of Cc's introduced to lose that much.
 
I'd just [pull the head and check that hole. I'd wager you need a piston. But it may be you "only" need a piston so do it sooner than later. It's already .060 over so if the bore gets damaged it needs more major work.
 
MOPAROFFICIAL said:
Lean tune. Imo
I like to tune on the lean side as well, but under harsh wot the temp spikes and hypers come apart.
Maybe you broke part of the ring land off, maybe you just pushed a head gasket into oil. Leakdown test is in order. The plugs look lean all around the base Circle and all I see is the fuel additive of the brand feel you use or put in which is reddish orange... but that's just what I see in that grainy pic.
Being 40 PSI down is substantial, would take a number of Cc's introduced to lose that much.
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That 19.9 mpg made me wonder the exact same thing. Dunno the rest of the car (trans, gearing, etc.) but that number stood out in my 1st read. Do you have an AFR gauge OP?
 
My magnum did the same thing! Smoking from the exhaust and blowing smoke out of the breather. It ended up only being a failed headgasket. The compression was leaking into the crankcase and blowing smoke out under throttle. And on decel it was pulling oil into the cylinder and smoking from the exhaust.
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OP, if not the piston .... what type if rings did you use? Listen real good to the rpm drop after a quick rev in neutral for a little chatter sound...maybe you justcracked/broke the top ring...but I'm leaning towards my 1st reply.
 
1994redram said:
My magnum did the same thing! Smoking from the exhaust and blowing smoke out of the breather. It ended up only being a failed headgasket. The compression was leaking into the crankcase and blowing smoke out under throttle. And on decel it was pulling oil into the cylinder and smoking from the exhaust.
View attachment 1715360132 View attachment 1715360133 View attachment 1715360134
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I don't see those plug being lean. I usually see that type of gaske failure as detonation, but those gaskets are junk. It's possible if the manifold isn't very good that one cylinder could be lean and that killed the gasket. Plus, it's hard to see things like that on plugs and gaskets in pictures.
 
AJ/FormS said:
What makes them so?
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That pressed together material won't take much punishment. Any little detonation will do that, and not show up anywhere else. Or, as I'm thinking, that one hole was a skosh lean under load and even a Fel Pro blue gasket wouldn't even blink at it. That gasket takes a dump.

When I worked in the production rebuilding shop (worst job ever) I eventually worked my way into the office. After looking over the warranty claims, the first order was stop using those head gaskets. Head gasket failure was reduced by 98%.

The second order was to teach the moron resizing the rods how to use the gauge, and then refinish about 800 rods he screwed up. Then I fired his ***.

Third order was tell the dick doing the heads to finish the guides BEFORE he cut the seats. He had about 100 heads to redo. I didn't fire him because he took his medicine and didn't *****. Plus, he was fun to work with. Reduced head department warranties by about 60%.

That's why I never use those gaskets. It's funny how a company rolls along and accepts things, pays out what I considered horrible money to fix crap we didn't need to have happen by some simple fixes in procedures and products. In fact, the new gaskets (Detroit at that time) were LESS money than the junk ones.

And setting up processes for every step of the operation to make sure things are done correctly. These guys were hired of the street, half assed trained and cut loose. That's a management issue.

That job made me lose hair in the shower every day. I hated that job.
 
yellow rose said:
I don't see those plug being lean. I usually see that type of gaske failure as detonation, but those gaskets are junk. It's possible if the manifold isn't very good that one cylinder could be lean and that killed the gasket. Plus, it's hard to see things like that on plugs and gaskets in pictures.
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Those were the OE installed gaskets. My grandpa bought the truck new. The intake is an edelbrock dual plane for the magnum engine, carb was a demon 625. The engine was running great... until the gasket popped.

Parts fail, stuff happens.
 
1994redram said:
Those were the OE installed gaskets. My grandpa bought the truck new. The intake is an edelbrock dual plane for the magnum engine, carb was a demon 625. The engine was running great... until the gasket popped.

Parts fail, stuff happens.
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Yeah, they used they cheapest vendor that can find.
 
yellow rose said:
That pressed together material won't take much punishment
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That was my experience as well, just wanted a second opinion.
And there ain't a lot of fire-ring support in that direction as well.

My FelPro 100xs are on their third install;" if you don't try it, then you'll never know"; I said to myself. The least amount of pressure they have seen is about 175psi, and they now have probably over 80,000 miles on them, but probably less than 100,000.
IMO, they are gold no matter how much they cost, and the cost per mile for me is so cheap right now, nothing else I have tried can touch them.

Thanks for responding in detail.
 
My last 360 had KB hypers and 10.5:1 true static compression. I put 25k miles on that thing over 6 years with lots of detonation; cam was mismatched for the compression and cubes and built way too much cylinder pressure at low RPMs. Didn't matter if I used the best premium gas I could find. I mean I pinged that thing almost every time I took it out and it held together for that long. Finally when it did let go it butted the top ring, busted a chunk off the top of one of the pistons and proceeded to trash the piston pin and put a huge crack in the cylinder wall.

I'd be surprised if you really broke a ring land because based on what happened to my engine I would think yours would have some serious internal damage from a chunk of aluminum getting repeatedly smashed up inside the cylinder up against the head... just my $0.02

Oh and now my current 360/5.9 is only 9:1 compression with aluminum heads and runs on regular gas with no pinging whatsoever lol. Learned my lesson with high compression on the street, it's a fine line to walk and oftentimes not worth it.
 
MopaR&D said:
My last 360 had KB hypers and 10.5:1 true static compression. I put 25k miles on that thing over 6 years with lots of detonation; cam was mismatched for the compression and cubes and built way too much cylinder pressure at low RPMs. Didn't matter if I used the best premium gas I could find. I mean I pinged that thing almost every time I took it out and it held together for that long. Finally when it did let go it butted the top ring, busted a chunk off the top of one of the pistons and proceeded to trash the piston pin and put a huge crack in the cylinder wall.

I'd be surprised if you really broke a ring land because based on what happened to my engine I would think yours would have some serious internal damage from a chunk of aluminum getting repeatedly smashed up inside the cylinder up against the head... just my $0.02

Oh and now my current 360/5.9 is only 9:1 compression with aluminum heads and runs on regular gas with no pinging whatsoever lol. Learned my lesson with high compression on the street, it's a fine line to walk and oftentimes not worth it.
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May I refer you to my thread...
When **** hits the fan


He could very well be driving still with part of the ring land missing... as in, the fractured bits went out the exhaust port.
 
MOPAROFFICIAL said:
May I refer you to my thread...
When **** hits the fan


He could very well be driving still with part of the ring land missing... as in, the fractured bits went out the exhaust port.
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I remember that thread... very true that could be the case, I know when I pulled mine apart the broken piece off the piston was nowhere to be found, pretty sure it got crushed and flew out the exhaust.
 
Used a borescope to look in the cylinder and saw oil pooling up on top of the piston, so I ended up pulling the head and it turned out to be the head gasket. #7 was blown completely through and #5 was a little ob-longed, probably close to failing. I was using Felpro 1008 which is supposed to be a performance gasket, so it wasn't a cheap stock gasket or anything. Would you guys just recommend just replacing the gasket (other head too possibly since it's already most of the way apart) and stay easy on it, get a wideband put on and see whats its doing? Flat-mill the heads? Any different gaskets that might do better?
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I'm just glad it was the head gasket and nothing else. I didn't even think about the head gasket blowing out into the lifter valley and there's not too many other ways to burn as much oil as it was doing. Huge relief to me :)
 
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