Damaged rod bearings - reason

[Boother]

Originally Posted by GONIF

Did you ever data log it after the rebuild ????? I wish we could get 95 octane fuel at the pump her in Arizona ,we have pure weasel piss for fuel here in Phoenix.

95 octane in Europe is equivalent to 91 octane in North America. Europe is a RON rating only while we use a combination of RON/MON that results in a lower number.

I am with Russell on this one, something is up with the bad damage at the parting line.

I am not sure how anyone can say the wear looks worse on the top compared to the bottom bearing since there are no pictures showing a bottom half??

[Badbubba]

Originally Posted by GONIF

Did you ever data log it after the rebuild ????? I wish we could get 95 octane fuel at the pump her in Arizona ,we have pure weasel piss for fuel here in Phoenix.

Europe's octane number is derived RON, our's is R+M/2. Research + Measured. Their octane ratings do not equal ours.

[Irek]

Originally Posted by Russell James

The heavy damage at the parting line of the bearing can be a clue of excessive crush. If the bearing crush is excessive (bolts way over torqued), it causes the bearing to bow inward at the parting line.

Google....connecting rod bearing damage failure analysis excessive crush. There are some good example pics out there.

Other possibilities... dry start, not primed before first start. Debris. Insufficient oiling... very low oil pressure. Those however would also show as damaged main bearings.

Only the builder would know if the clearances were correct when built, assembly lube used, oil system primed, cleanliness.... were the rod bolts new and torqued correctly with a reliable tq wrench?

To me... that heavy damage right at the parting line is an interesting clue. Normally debris or lack of oil pressure would show worse towards one end of the engine.

When they all show that same damage like that... seems like an assembly error, way too much crush or little to no clearance. Possibly an oversized bearing meant for a honed out rod got smashed into a std size rod big end? Something caused the bearing to bow in.

A global oiling problem/debris... would show the same damage in the main and cam bearings. If that damage is only in the rod bearings... it's a con rod installation error in some fashion. I've see way over torqued rod bolts do that. Makes the bearing bow in at the parting line. If the main bearings look perfect... they screwed up the connecting rod assembly in some fashion.

Hi Russell

Thank you for your deep analyze. I was not considering the torque used during assembly of the bearings, but sound like a good explanation. This would also explain why all 8 bearings were damaged in a similar way – probably the same torque was used for all screws.

I gave the crankshaft and the bearing for measurement, after the weekend I would know if the bearings were adjusted correctly. But of course I would never find out the bearing crush was adjusted correctly.

Do you think that in case of the engine knocking (detonation) all bearings could be damaged in a similar way?

Best regards
Irek

[Irek]

Originally Posted by acammer

If you can hear audible knock, you're pretty deep into detonation. I'm surprised you had a bottom end failure and not a hurt piston. I'd take a real close look at those while it's apart.

Without a doubt you need to get on a good high octane fuel, and a nice safe tune once it's rebuilt. As to the cause of the failure I think Russell is on the right track. Detonation bad enough to really hurt the main bearings would have cracked the ringlands off the pistons long ago. Oiling would be all the bearings. Interested to hear how you make out - keep us posted.

All the pistons were removed and they are completely fine. I have examined all the parts including the heads, valves, lifters etc. It looks that the rod bearings are the only damaged parts.

As mentioned the engine did just 3k miles after renovation, so maybe some more damages would appear if I would keep driving. Difficult to say.

But for sure I will post the further information, when I learn something more.

[Irek]

Originally Posted by Boother

95 octane in Europe is equivalent to 91 octane in North America. Europe is a RON rating only while we use a combination of RON/MON that results in a lower number.

I am with Russell on this one, something is up with the bad damage at the parting line.

I am not sure how anyone can say the wear looks worse on the top compared to the bottom bearing since there are no pictures showing a bottom half??

That is right the rating is different. I believe your comparison is correct European 95 is around 91 in US.

[Irek]

Originally Posted by Boother

95 octane in Europe is equivalent to 91 octane in North America. Europe is a RON rating only while we use a combination of RON/MON that results in a lower number.

I am with Russell on this one, something is up with the bad damage at the parting line.

I am not sure how anyone can say the wear looks worse on the top compared to the bottom bearing since there are no pictures showing a bottom half??

I gave all the parts for mesurement, but I will put some more pictures of the bottom half as soon as I would get it back.

[JD555]

strange the damage looks worse on the top bearing.

[Badbubba]

I don't really see a picture of the bottom of the bearing. The little I see still has damage. Can you post a pic of the bottom?

[trw427ss]

Looks like rod bearing clearances were too tight!

[JLGO]

I dont think those bearings were getting enough oil. I think the mechanic messed up this time. Knock has nothing with scored rod bearings. How is the crankshaft?

[Badbubba]

Originally Posted by JLGO

I dont think those bearings were getting enough oil. I think the mechanic messed up this time. Knock has nothing with scored rod bearings. How is the crankshaft?

Imo, lack of oil should show some heating.

[Russell James]

Originally Posted by Irek

Hi Russell

Thank you for your deep analyze. I was not considering the torque used during assembly of the bearings, but sound like a good explanation. This would also explain why all 8 bearings were damaged in a similar way – probably the same torque was used for all screws.

I gave the crankshaft and the bearing for measurement, after the weekend I would know if the bearings were adjusted correctly. But of course I would never find out the bearing crush was adjusted correctly.

Do you think that in case of the engine knocking (detonation) all bearings could be damaged in a similar way?

Best regards
Irek

Just my opinion, but I think an assembly error is more likely than detonation damage.

A supercharged engine with cast piston that has severe detonation/knock...I'd think would show up first as a piston problem. Such as a broken ring land on the outer edge.

Seems more likely to be a lack of lubrication scoring problem. Which has several possible causes... wrong bearing clearance, not pre-lubed, way over torqued...

I'd think wrong bearings are the most likely. Either way too tight clearance. Or when tq'd, they bowed in...and were no longer round. When a rod bearing is properly torqued, the correct "crush" makes it round.

If the main bearings all look perfect, and all the rod bearings look horrible... I'd think the leading suspect is wrong rod bearings/assembly error.

[CGT]

My opinion would be dirty, contaminated assembly and possibly not enough rod bearing clearance. Most all bearing shells have more clearance at the parting lines.

I have torqued and measured rod bore size with LS3 rods and couldnt even find a measurable difference in size even using ARP 2000 bolts(sorry common internet wisdom).

Keep us posted. Would like to see some pics of the crank. Good luck. Wash everything to perfection before going back together!

[JLGO]

Originally Posted by Badbubba

Imo, lack of oil should show some heating.

You mean discoloration, its there.