[Va68goat]

Grivera,
If I wasn't confused before, I sure am now.

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[ta man]

I've followed this thread..great thread with a great end. Finally!

[MXTex]

Originally Posted by MXTex

If I understand correctly; when the motor let go on the dyno, the crankshaft and two connecting rods were damaged. If/when this motor gets disassembled (which I think is inevitable), I'd recommend looking very closely at the pistons that were on the connecting rods that were damaged on motor #1. A failed connecting rod could apply some very strong and abnormal forces on a piston. Assuming that the piston locations from motor #1 were duplicated in motor #2, I'd look very closely at these two holes.

[72projectbird]

Originally Posted by Va68goat

72projectbird,

I appreciate that. I don't quit too easily and I follow through with everything that I start and everything that I say I'm going to do. I'm already thinking about what else I could do to this car. The two things that I'm thinking about is suspension and A/C. I love this car. It's not going anywhere!

Good to hear!

You've certainly been a good sport throughout this fiasco. I hope you enjoy your ride, and put many miles on it!

[Va68goat]

So, I'm going to have to go through this whole thread to see who guessed the piston slap first so we can determine the winner. I will send the winner a Pontiac sign like I said I would. Hell, I'll even throw in some local Virginia beer. Hopefully we can all agree on the winner! Hahahaha!

I do have a question though. There seems to be some confusion if the bearing spun or not when it failed on the dyno. After reading the recent post, I do remember that it was discussed about the spun bearing. Has anyone heard of a piston skirt collapsing when a bearing is spun? Is that normal? What happens when a bearing is spun that could or would cause the piston to hit the head. Is that even possible? Considering that the knocking noise has been the same since when I first received the motor and stopped when that one piston was replaced, I would just like to get a better understanding of what happens when you have a spun bearing.

[promptcritical]

I thought it was determined that it didn’t spin a bearing???

[MidnightAuto]

Finally victory. Enjoy the ride.

[tooski]

I've been tuning in just about every day. Even made a post. Glad for everyone involved. I didn't know piston slap would sound that bad.

[HWYSTR455]

Just to say, the usual piston slap is different than what happened here, this was a collapsed skirt. And that would be why it didn't sound like piston slap, this was a knock. Slap is generally cause by loose piston to wall clearances, this was a gross clearance issue.


.

[455GRIN]

It seems there is some conflicting comments from the engine builder about the bearing failure. The damaged piston was from the same cylinder as the bearing issue on dyno before Joe received it. Coincidence? only if your from Iowa.

[hurryinhoosier62]

Originally Posted by 68 461 Bird

I don't see it quite like you do but I do agree with your opening statement and I am also happy this is resolved and Joe is driving and enjoying his GTO like he should have been able to do a long time ago.
As I see it Paul made two mistakes here, 1st with the oil pump and second with the repair. When he replaced the rod on the #5 piston, he should have noticed the damage on the piston and took measurements there. Extra care should have been taken with this engine since Joe's friends convinced him to send the engine all the way across country to Paul who was highly recommended. He could have taken it to other reputable Pontiac engine builders on the east coast but he went with Paul. I came across this thread a few months ago and Paul was blaming it on bad gas. I have been around the Pontiac hobby for almost 40 years and I knew it was internal.
I also believe with this story being aired on this forum it put pressure on Paul to make it right. Without social media, I would expect the typical engine builder response you mentioned above and blame the customer. Times have changed and social media is now a factor . Paul did admit he made a mistake on the oil pump and he should own up to the fact he missed the damaged piston and pay the $2,575 and the additional $1,900 chasing the knock. He also should have worked it out an amount with Joe before leaving his home, I would have..
I also have never met Joe and never heard of Paul until this thread so my opinion is not biased either way either. Joe paid out an additional $4,500 he shouldn't have. I hope he is compensated to his satisfaction, time he lost he can never get back. my2 cents.

Quick question: how many engines have YOU machined or built? As a retired ASE Master Engine Machinist I’ve seen problems like this. IF you have never machined or built an engine you are making assumptions based on ignorance, NOT experience.

[hurryinhoosier62]

Originally Posted by mgarblik

Paul, In my attempted explanation of what caused a piston skirt to collapse, I didn't know anything about something getting into the #5 cylinder. That could have been in the nearly 1400 posts somewhere, but I missed it. I also thought the bearing failure somewhere along the line was more serious and since I know you like a tight quench, I could see the piston contacting the head in a failure situation and collapsing a skirt. Your explanation makes just as much sense and you were there! When I began building engines decades ago, pistons came in a box with the nominal size on the box only, not actual measured sizes. It was up to the builder 100% to measure each piston in several places, do all kinds of math and averages and either hone each cylinder to the piston or hone to an average. Cast pistons were usually +- .0015 through a set and forged .003. As you know even today, forged custom pistons are still kind of all over the map. It's very unfortunate you guys and the engine owner got bit by this series of events. There are always a few rock throwers, experts chiming in from the sidelines as other's struggle. It's just more public with the internet and message boards. I doubt very seriously you would be in business for decades and have a reputation where people are willing to send their engines from all over the country to have your shop work on them. So to implicate that without a public forum you would have washed your hands of this engine is unfair IMO. Again, WE ALL MAKE MISTAKES. The shop I have worked out of for 30 years 5 years ago had 8 of the 10 top qualifiers in NHRA Stock and Super Stock at the US Nationals and is a builder of Australian Pro Stock engines they ship back and forth all year. 2 man shop. Mistakes are still made, few and far between. When they happen, just like this Pontiac, the problem is eventually found and corrected.
One of the worst I had happen that relates to this Pontiac, happened on the dyno. We had the jam nut that holds the air temperature sensor in the Superflow air hat vibrate loose and fall through the carburetor of a new engine on it's 3rd. or 4th pull. It bounced all through the engine, breaking 2 sleeves, bending valves and cracked a head. Lots of time and money lost because of a small jam nut. It was about the size of a car radio stem nut.
Personally, this whole drama should do more positive good for your business in the long run. If I didn't do all my own work, your shop would be on my short list. Take care.

Well said, Mike.

[chiphead]

Originally Posted by Va68goat

So, I'm going to have to go through this whole thread to see who guessed the piston slap first so we can determine the winner. I will send the winner a Pontiac sign like I said I would. Hell, I'll even throw in some local Virginia beer. Hopefully we can all agree on the winner! Hahahaha!

I do have a question though. There seems to be some confusion if the bearing spun or not when it failed on the dyno. After reading the recent post, I do remember that it was discussed about the spun bearing. Has anyone heard of a piston skirt collapsing when a bearing is spun? Is that normal? What happens when a bearing is spun that could or would cause the piston to hit the head. Is that even possible? Considering that the knocking noise has been the same since when I first received the motor and stopped when that one piston was replaced, I would just like to get a better understanding of what happens when you have a spun bearing.

If I don't win, I want a framed picture of the piston as a consolation prize. LOL

As far as collateral damage from a spun bearing, that's a theoretical debate that could keep this thread going forever. When a rod bearing spins inside the connecting rod, it rapidly self destructs due to friction and heat. During normal operation, the inside diameter of the rod's big end clamps the bearing halves in place (bearing crush). When bearing crush is lost for whatever reason, the inserts will spin inside the rod's big end. Loss of lubrication will also cause a spun bearing, when the friction wanting to turn the bearing insert overcomes the bearing crush keeping it stationary in the rod. Usually it makes a hell of a racket and the damage is limited to the rod and the crankshaft, unless the rod comes apart (thrown rod).

Since this engine didn't throw a rod, the rod bearing would have had to do one of two things to damage a piston:

1: Rod bearing is destroyed enough that the excess slack between rod's big end and crank journal allows piston to hit the head during TDC. That would have left witness marks on chamber and top of piston. Should result in damaged piston crown and pinched #1 ring land.

2: Rod bearing gets hot enough to friction weld itself between crank and big end of rod. Rod is then effectively welded to crankshaft. Rod tries to whip around with crank, restrained only by piston. The piston is damaged from the abnormal forces. However, this typically tears the rod cap off or breaks the rod, resulting in total carnage. Motor would have had to be shut down just before it chucks a rod across the room, to damage a piston like this but not chuck a rod.

[Va68goat]

promptcritica,
The bearing was spun on rod #5.

MidnightAuto,
Thanks. I've driven that car for the last two days. It's great. I'm already thinking about what to do next to the car.

tooski,
I'm glad it worked out as well. It was great when Paul found the problem. When he disassembled the motor, he put one thumb at the top of the piston and another thumb at the bottom and when he rocked that piston back and forth, that sound was exactly what I have been listening to for almost 2 years. No better feeling when we installed the motor and started it and heard no knocking sound!

455GRIN,
The #5 bearing spun on the original failed dyno which was the same cylinder as the damaged piston.

hurryinhoosier62,
It was great that Paul came here and fixed this motor. There is no doubt that there are plenty of shops that wouldn't have done that. As for what mgarblik said in his post about something getting into cylinder #5, that is just a possibility amongst a few other theories. Nothing has been confirmed that something fell into cylinder #5. I know there's a chance that it occurred but nothing has been confirmed. All that has been confirmed is that the bearing spun on #5 and the bearing was eaten up. Rod 5 and 6 were replaced along with the bearings. # 5 piston skirt collapsed, it was discovered, fixed and the motor is strong and knock free.

[Gator67]

The engine sure sounds great now, congrats.

Any theories as to what would have happened if the engine was run with the damaged piston?

[Va68goat]

Gator67,
Thank you. Paul inspected and measured the #5 cylinder walls. He said it was fine. I had only driven the car for less than 250 miles since I received it. It was never driven hard during that time.

[mgarblik]

Originally Posted by Gator67

The engine sure sounds great now, congrats.

Any theories as to what would have happened if the engine was run with the damaged piston?

Theory only! It could have run like that for a very long time pissing off the owner every time he drove the car. Not the way to enjoy a great car like a GTO. I drove a Jeep 4.0L with the skirt actually broken off below the oil ring land. Found the entire half of the skirt in the oil pan when I finally took it apart after 2 years and 30K miles of hearing it knock. So the answer is we will really never know. Forged pistons are so soft and pliable, it may have just hung on there and operated indefinitely.

[Formulajones]

Some of you guys need to read post 1400 again. Paul goes into detail what he found and it will answer all of these questions.

He states right in there, the bearing wasn't spun. It was over heated and discolored the journal and the rod next to it but it did not spin inside the rod.

The piston also never smacked the head and he explains why that never happened and couldn't have happened given the circumstances of this failure. He goes on to say that something entered the engine through the intake system and that's where the damage started.

After all that Paul has done to make this right maybe it's about time some of you actually listen to what Paul has to say and drop the conspiracy theory crap.

Bottom line is it's now fixed, Joe is happy and the engine runs as strong as ever.

[grivera]

FJ, this is where Paul previously said the bearing spun (Post 784):

Originally Posted by gtofreek

First off, Joe did NOT get charged for fixing the engine after the bearing spun.

[Va68goat]

Originally Posted by Formulajones

Some of you guys need to read post 1400 again. Paul goes into detail what he found and it will answer all of these questions.



He states right in there, the bearing wasn't spun. It was over heated and discolored the journal and the rod next to it but it did not spin inside the rod.



The piston also never smacked the head and he explains why that never happened and couldn't have happened given the circumstances of this failure. He goes on to say that something entered the engine through the intake system and that's where the damage started.



After all that Paul has done to make this right maybe it's about time some of you actually listen to what Paul has to say and drop the conspiracy theory crap.



Bottom line is it's now fixed, Joe is happy and the engine runs as strong as ever.

Formulajones, nobody is throwing Paul under the bus here. I really do appreciate that Paul came out here and fixed the problem. Paul posted that the bearing spun and it was eaten up but for some reason his last post said it didn't. Maybe he forgot because it's been a while. Paul and I are still communicating regarding business. I wont share that here. He's a stand up guy. Read the post #784.

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