What can cause rod knock in 5 miles?

[crash89]

All I got was a video at the moment.

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[laserspeeddemon]

Did you say you spun the bearing or no? Either way sounds like negligence.

No, it did not spin. Which leads me to believe that maybe it was not rod knock after all?

 

[ed1380]

How bad is the wear on the bearing

 

[laserspeeddemon]

I'd say bad. But have a look.

 

[donniekak]

For one, the crank journal is tapered, or the rod is bent.

 

[laserspeeddemon]

For one, the crank journal is tapered, or the rod is bent.

I don't understand...
Explain what you mean?

 

[twicks69]

I don't understand...
Explain what you mean?

There is side to side movement wear patterns on the bearing. You could have a rod that isn't perfectly straight, a damaged or unevenly worn crank rod journal or a crank that has runout (your crank is bent).

 

[ed1380]

Pretty much it's shop error

 

[crimsondragon]

That's pretty bad. You can actually see on the bearing where the wear pattern tapers off a little. How's the crank? Is there anything imbedded in the bearing? You said there was stuff imbedded in the back side. Was that debris on the side that is tapered? It's possible the bearing wasn't seated fully in the rods cause of the debris and caused it to have smaller clearances on one side versus the other.

 

[mattasi]

Pretty much it's shop error

I hope the engine builder will warranty this, because it was his fault.

 

[laserspeeddemon]

That's pretty bad. You can actually see on the bearing where the wear pattern tapers off a little. How's the crank? Is there anything imbedded in the bearing? You said there was stuff imbedded in the back side. Was that debris on the side that is tapered? It's possible the bearing wasn't seated fully in the rods cause of the debris and caused it to have smaller clearances on one side versus the other.

Yes there was debris on inside of the bearing. In the last picture where ot's dark is where the debris is located. I can actually feel it with my finger it's thick.

 

[laserspeeddemon]

Well pictures of the bearing has been passed around, a few people had physically looked at it and the general consensus is the same. Either the rod was bent or the crank was incorrectly machined and the journal was tapered out of spec. Since the rods came out of an engine that had suffered heavy knock, I asked the shop to check the rods for straightness; they knew the history of the engine. And obviously they machined the crank. So either way it was their fault.

The good news, the shop agreed to help me resolve this situation when I come back from Afghanistan, but I don't know what "help me resolve" means. It could mean they will charge me full labor in exchange for work.

 

[donniekak]

Why would you spend all that money, and use used rods? For less than $2,000 you can get new rods, pistons, head studs, valve springs, retainers, and cams.

 

[laserspeeddemon]

They were Manley H-beam rods with about 10,000 miles on them. If they were still straight there would no reason NOT to use them.

 

[YZFR1]

Don't use a cut crank! It's not worth the risk IMO

Go to bed knowing your crank was cut at the factory and sleep tighter!

 

[donniekak]

They were Manley H-beam rods with about 10,000 miles on them. If they were still straight there would no reason NOT to use them.

Please don't take this wrong, but your experience shows that used internals are a crap shoot. Not to mention the rods were from a knocking engine.

 

[Tyeler18]

Don't use a cut crank! It's not worth the risk IMO

Go to bed knowing your crank was cut at the factory and sleep tighter!

This as well, although lots of people get by with it, but the factory crank is nitride coated and shaving it removes this coating.

 

[TSITurbo95]

There have been PLENTY of people who run cut cranks, with absolutely no issues what so ever. I would not hesitate to run a cut crank, but I would only run one cut .010 no more (personal preference). Actually there is a thread somewhere about people running cut cranks. . .

 

[YZFR1]

It's not that there are people out there that are doing it with no problems.. it's that you are putting too much into the hands of whoever gets it cut for you. Even the same person on a bad day could destory your engine down the line..

 

[huafist]

It's not that there are people out there that are doing it with no problems.. it's that you are putting too much into the hands of whoever gets it cut for you. Even the same person on a bad day could destory your engine down the line..

That's a straw man argument at best - You could say the same about ANY machine work you have performed. Bottom line is, if you don't trust the machinist, then do it yourself. But in any case, you should ALWAYS double check machine work.

 

[bryanwheat]

This as well, although lots of people get by with it, but the factory crank is nitride coated and shaving it removes this coating.

The hardening goes over .020 into the crank. Cutting .010 from the crank will not remove all of it. I would much rather run a crank cut .010 that i know is 100 percent in spec than an old used bent crank with who knows how many miles on it.

 

[YZFR1]

I might be faced with the choice of having my crank cut in the future, only because g4cs cranks are hard to come by. And i'm all for double checking the machine work, however, checking and cleaning a cut crank is a lot more intense than just micing your bore or checking your deck surface. For most 2 liter guys it's going to cost just as much to get a nice good used crank then having to go through all that trouble. But, of course, it is certantly doable just depends on your goals and skills.

 

[donniekak]

I might be faced with the choice of having my crank cut in the future, only because g4cs cranks are hard to come by. And i'm all for double checking the machine work, however, checking and cleaning a cut crank is a lot more intense than just micing your bore or checking your deck surface. For most 2 liter guys it's going to cost just as much to get a nice good used crank then having to go through all that trouble. But, of course, it is certantly doable just depends on your goals and skills.

If you are getting a 100mm crank cut, make sure they cut a fillet, or it will break. It may break anyway, but a fillet will help.

 

[BogusSVO]

There have been PLENTY of people who run cut cranks, with absolutely no issues what so ever. I would not hesitate to run a cut crank, but I would only run one cut .010 no more (personal preference). Actually there is a thread somewhere about people running cut cranks. . .

http://www.dsmtuners.com/forums/articles-engine-fuel/431201-cut-crank-tested-theories.html

 

[NHerron]

That's an awesome read BogusSVO, nice find