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Broken pistons, only half the motor

CyberSniper

CyberSniper

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#2, #4, #6, and #8 pistons (driver's side) are broken on a fairly freshly built Cadillac 500. Like 700 miles and 18 hours.

Other side of the motor looks like brand new. Like only 3% leakdown with cold cylinders.

All of the non-broken rings I've checked have been spot on. Same for the bores.

I don't have the tools to measure the deck height for precision or accuracy. The pushrods are the same length but that doesn't mean much. I did measure the heads and they're within half a CC across all chambers between each head (they're the common 76cc heads). I was wondering if that side had a higher compression ratio from milling (I know one head is missing .015") but I calculated that in order for it to make a difference on a motor that size it'd have to be a lot of missing material.

It pretty much always had blowby (enough where the PCV valve couldn't keep up since day 1) but I was told it was because the rings hadn't seated but seemed strange to me. 10-15% leakdown depending on cylinder (#4 and #6 the worst) at hour 4. I never did check it for leakdown again as all plugs looked good and it's a PITA to check anything with the wheel liners in. I did scope it at hour 4 with a camera and the pistons still were fairly clean. Driver's side was worse but I didn't think much of it as that's the side that the PCV valve connects to.

First motor I paid someone else to assemble and I regret it now. Anyway, I kept running it. Blowby never got better. It was also better when the engine was cold than warm.

Crazy part is that it still ran fine right up to when it started pushing all the oil out the front of the motor due to so much blowby. Limped it 200 miles home pissing out a quart of engine oil every 15 miles didn't help the bearings any but it still held 40psi at idle but basically only stopped when the lifters didn't keep the valves open. Leakdown when I got it home was 80%.

I did have spark knock for a brief period (Davis Unified Ignition/DUI sent me a garbage distributor with 40 degrees of advance that went to 16 degrees of advance at idle and 40 by 3100rpm). Never seen all the pistons on only *one* side of the motor go from detonation. There is no pitting in the crowns or any cracks. Most of them aren't even broken between the two compression rings. It is always on the front of the piston below the oil control rings.

Dual plane intake so if it was running lean on one side (TBI motor) it should have taken out two pistons on each side of the motor. The side that ate itself is the side with the oxygen sensor.

If any of the pistons weren't all on the same side or all of the pistons on one side weren't broken I wouldn't have questioned it.

Ideas?

Cadillac500_Driver_S.jpg
 
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All broken ring lands one one bank? Almost have to be temperature issue.
 
Yeah, all broken on the same side in the same spot. Other side of motor looks intact.

Motor has a 180° thermostat and a very expensive Flowkooler pump. The radiator is ginormous, people often put ones out of our pickups in them but they're 8" shorter in height. Takes 8 gallons of coolant between the radiator and the engine.

Motor also has a 19 row stacked plate Derale engine oil cooler on it and an identical one for the transmission cooler. Neither use the tank cooler in the radiator.

Block is on its way to the machine shop. What pistons this time? Not buying the same ones again.
 
CyberSniper said:
Yeah, all broken on the same side in the same spot. Other side of motor looks intact.

Motor has a 180° thermostat and a very expensive Flowkooler pump. The radiator is ginormous, people often put ones out of our pickups in them but they're 8" shorter in height. Takes 8 gallons of coolant between the radiator and the engine.

Motor also has a 19 row stacked plate Derale engine oil cooler on it and an identical one for the transmission cooler. Neither use the tank cooler in the radiator.

Block is on its way to the machine shop. What pistons this time? Not buying the same ones again.
Click to expand...


It looks like the oil rings butted and broke the narrow ring land out of the bottom of the piston. There is nothing else that could cause a failure like that. I'll bet those rings were a little big and they butted tight and cracked the ring land on the first or second warm up cycle. I think that's a first for me, i usually see the top ring, and sometimes the second land broken from tight end gap. I wouldn't blame the pistons, blame the guy who put it together.

Make sure you check the end gap of ALL of the rings when you put it back together. I like the end gap to be on the big end of the spec, or even 4-5 thou bigger than the spec if there's nitrous or bigger horsepower in it's future. Also make sure the secondary ring gap is as big as the primary.
 
I was wondering if the oil control ring land was damaged on piston install. These ones are broken straight like they got blunt force trauma instead of past ones where spark knock destroyed them they had a "taper" or "angle" to the crack.

I was also wondering if the oil control rings were gapped properly. The "good" ones on the other side of the motor are on the tight side of the range.

The motor is already well on the side of being too much for the tires on the front of the GMC motorhome. Even with 4 busted pistons it made enough power to spin the tires. If it was mine I would be half tempted to put a Whipple on it...
 
So I got the block back from the machine shop/engine builder yesterday and was going down the road of buying new pistons and rings (already ordered rods/mains/cam and gaskets a couple weeks ago). I was like "well, I don't want to buy the same ones".

So I'm looking at my options knowing I want to stay south of 9.25:1 so I can run pump gas... Which is what I was aiming for the first time and either had the option of 10:1 or 8.5:1 according to the engine builder. I went with the 8.5:1. Or so I thought.

Not a lot of options in .040" overbore that don't require a call to Diamond or Probe. Kind of realized a 4.340" piston is a big one...

Well...

I looked at the old pistons from the last two motors for a starting point. The ones from the first engine failure (owner dropped a bolt down the throttle body) were the peculiar +30cc peanut shaped dish pistons. The ones that came out of the engine this time were Federal Mogul/Sealed Power 609P according to the machine shop's build sheet. Which have a tiny dish. When I bore scoped it it didn't really occur to me because I figured they were just sitting down in the bore a little bit more than normal...

So I got a little curious and measured the pistons, CCd them with a crappy medicine dropper I usually use for my chickens. I got +8cc or so on the dish. So then I get out my caliper to measure the compression height. The holy shit moment started.

While looking at the second failed set of pistons (the ones shown above) I notice they have Keith Black wrist pins in them. So I look at the pistons more carefully. The top have 609P engraved in them but on the inside of the piston skirt is 1817 cast in. They're actually UEM/Keith Black/Silv-o-Lite 1817 pistons. +9.5cc advertised effective dish. So Federal Mogul just reboxed them.

Do some math.

Old motor was about 9.8:1. New motor is at least 11.5:1.

The previous machine shop had milled off .015" also due to the previous engine failure (but did a rough cut) on the same head so that's why this machine shop did a fine cut. Passenger head hasn't been milled as far as I can tell. I never CCd them but I guess I should now.


Anyway, mystery solved. Engine builder put the wrong pistons in it. It was probably on the ragged edge of detonation all the time. Explains a lot of things like why the first starter on the engine lasted 40 years but when swapped it quickly ate the bendix.

What do you guys think my chance of the engine builder making it right is? The whole reason I paid someone else to build the motor was so it would save me time and I'm 200+ hours into assuming I did something wrong. I know I'm not getting my time back but I think they should pay for their work and the parts to make it right. Or am I way off base?
 
many story's i have heard just local from 3 shops around me is its all hit or miss on 2 of them the 1 guy tho is top notch but has a looooong wait time he is so busy .

and lots of shops will pass the buck on to you some way or another and not own up to there f-up .

you got nothing to loose so call him out with ALL the facts / info / specs you found and say i paid you to build this correctly and it is not or never was correct to start with .

and how can you mill 1 head and not the other and expect it to run smooth ? did they mill 1 side of the block also ? sounds like someone was slacking big time or dont know a darn thing .
 
Standard bore on a Mopar 400 is 4.342"...but yeah you're right that is pretty big.

You'll probably get some song and dance BS, but it doesn't hurt to present them with your findings and see what they have to say. I wouldn't expect anything, but you never know til you ask...
 
Heads were originally done by another builder. They didn't do a great job but they ran on the old engine just fine. The heads are fairly rare ones (76cc, no smog provisions) and have a lot of money into them. Howard full roller valvetrain with a custom grind cam among other things.

New machine shop went through the heads including milling one head .015" and grinding three valves.

New machine shop was shipped a complete and running engine directly from a salvage operation. They disassembled it. They ordered all the parts that I didn't provide (oil pan that I cleaned up as the one on the salvage motor was dented, distributor, camshaft, heads, intake, valve covers came from the original motor). There were no cheapness on this, I even paid them to buy and install ARP head studs and ARP main studs. Engine was handed over to me with everything on it except the throttle body, dipstick, and waterpump (engine won't fit in motorhome with the dipstick and waterpump on).

I'm ignoring some problems like having to beg to get most of the old parts back (like the unused heads) and never getting some back (like all the accessories or brackets or or or). Or a couple other things.


I talked to them today. They said they'd look into it. I told them what I think happened (blindly ordered pistons based on compression ratio and never looked at the heads they worked on).

I'm expecting them to cover the cost of the destroyed parts (cam/rod/main bearings, gasket set, pistons, rings) and this last bout of machining ($380). Or about $1100 +/-. Basically so I can get the motor I paid for.

I'm kind of pissed because this is one of the few times that I paid someone else to do something for me that I'm perfectly capable of doing and like pretty much all the times I've paid someone else to do something for me it's screwed me over. It is a fairly honest mistake but after literally calling them asking all sorts of weird questions from the get-go I'm kind of irritated. It has literally cost me a couple hundred hours of time chasing problem and countless ruined shit. Probably $2500 in the hole over this not including the extra $1200 I paid him in labor the first time to tear down the motor and assemble it.
 
So anyway, I ended up getting $380 back from them. Which is what the second set of machining cost me. So basically they paid nothing but labor for the machining the second time (which was inflated 10-20% over what I had done a year ago). Reichert Engines in Owosso, Michigan did the work. I won't ever take anything there ever again. Andy Reichert does nice work but I think he has a bunch of idiots working for him. Since he chose not to stand behind his work I have no use for them and will not recommend them for anything. He has cost me hundreds of hours of wasted time because I assumed they did a good job.

I ended up buying a new set of dished pistons. New rings, bearings, new gaskets, etc. Just about $1100 into it now in hard parts if I work for free. I ground out the divider between the valves to get all the combustion chambers to 71-22cc. I had CCd the heads back in November and found out that the side that blew up was at least 3cc smaller, which by math is .015", than the side that didn't. So one side was around 72cc and one side was closer to 69cc (smallest being 67.5cc). Keep in mind when I sent the heads to Reicherts for assembly they'd already been gone through by another shop and both the other shop and I had CCd the heads already and found them at 71-72cc. I still have no idea why Andy Reichert chose to mill just one head and take .015" off. Since he argued with me about it I'm guessing he has no idea why he only milled one head also.

So not only has Reichert Engines cost me hundreds of hours of wasted time now I'm hundreds of dollars of wasted money in.

I'm going to ignore the lost parts. Or the dented to shit intake pan (there is a piece of stamped tin that goes on the bottom of the intake that was dented to shit and full of oil inside because the dent caused a tear--this means the engine had a damaged tin put in it because it's not like it's going to fill with oil after I pull it out...). Or maybe I shouldn't ignore all the problems. I'm not sure. I sure as shit would never pay Reichert Engines to assemble a motor.
 
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Ready to go back in the motorhome. Added more ARP to it while I was at it.

Kind of wish I'd done a MPFI setup instead of the FITech TBI but it is dirt simple. I've set it up so it has a spare part of everything that is simple to change on the road. The guy it is for is a 70 year old retired marketing executive with a doctorate.

Cadillac500.jpg
 
Haha. I have more cylinders in front of the MM252. They're all in a line but so I can get in my truck I have the welder where the door is. That way when one gets knocked over they all go and hopefully I get blowed up. I need a mixer then I'd need less cylinders. Only really need two of everything that way so then I have a backup when one goes empty. Right now I have 3 of everything. Probably get rid of the propylene or the acetylene someday. The acetylene I only really use when brazing. The trimix and that helium cylinder on the end are so stupid expensive I only have one of each.

That S5 beam on the floor and its brother are the same age as the hoist and engine stand but has gotten very rusty. I have two 13' long S5 beams, two modular pairs of ends for the beams, two trolleys, and two chainfalls I use to move the motor in and out. It's kind of hillbilly when in use and I'm too embarrassed to share pictures because it's even more hillbilly than normal for me.
 
Finally got it in. Ran it today once up to operating temperature. Have a couple exhaust leaks even though my new ARP header bolts showed up today. Probably going to have to re-curve the distributor again. I don't think it has enough timing going by how red the exhaust is.

What's the process for breaking in a motor these days anyway? I've still done the same old thing where you don't let it go to idle and vary the RPM until operating temperature... shut it off... let it cool... repeat but bringing the peak RPM up higher a little at a time. After about 4 cycles of this/1 hour of run time change the oil. Then go drive it the same way with the goal of bumping up the cylinder pressure to get the rings to grind the cylinder walls smooth.

All new bearings, cast/moly rings, cast pistons, full roller/used valvetrain. So basically I'm trying to get the rings to seat.
 
CyberSniper said:
Finally got it in. Ran it today once up to operating temperature. Have a couple exhaust leaks even though my new ARP header bolts showed up today. Probably going to have to re-curve the distributor again. I don't think it has enough timing going by how red the exhaust is.

What's the process for breaking in a motor these days anyway? I've still done the same old thing where you don't let it go to idle and vary the RPM until operating temperature... shut it off... let it cool... repeat but bringing the peak RPM up higher a little at a time. After about 4 cycles of this/1 hour of run time change the oil. Then go drive it the same way with the goal of bumping up the cylinder pressure to get the rings to grind the cylinder walls smooth.

All new bearings, cast/moly rings, cast pistons, full roller/used valvetrain. So basically I'm trying to get the rings to seat.
Click to expand...
Roller or flat tappet
 
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