Let's Play- Did it spin!?

[Tyeler18]

Just rebuilt my 6 bolt in one of my 90's. 5 miles into break-in I could hear a knocking sound. Put a screwdriver on the exhaust manifold runners and the sound was loudest on cylinder 1. Disabling injectors via Link the sound would ALMOST go away when disabling the #3 injector. Well I just pulled all the rod caps, all of them are nice and shiny except Cyl #1. What do you guys think of it? It was still tight in the rod, locked into place, but there are a few light scuff marks on the crank, oil starvation? Does this look normal to you?

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These are ACL tri-metal "race" bearings. I'm pulling the mains next, but wanted input on this rod. Everything plastigauged perfectly in spec.

 

[LiquidX]

It may be me but it looks like the upper right portion of the bearing in the cap is starting to show heat marks. Do you notice anything like that on the bearing?

 

[nfernotalon]

Can you feel the scuff marks with your fingernail? If you can you're better off getting another crank.

 

[Tyeler18]

I'm not real sure what I'm looking for as far as heat spots, etc. Here's pics of all 4 rod bearings and then the front girdle.

#1

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#2

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#3

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#4

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Girdle

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Most places it looks "black" in the pictures is where the bearing is really shiney on the outer edges. I can't for the life of me get the middle main cap off, and the back 2 bolts on the girdle (tranny side of the girdle) I can't even get a socket on.... The bolt heads are too close to the rear main seal housing, the only way I'm getting them off is by removing the rear main seal WTF

I apologize for the quality of the pictures, I'm taking them with my Evo and they look great until I transfer them, then for some reason they get all pixely.

Wow I'd say they're toast.

Rod #2

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Rod #3

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[BogusSVO]

Why did you rebuild it in the first place?
Did you have the big end of the con rods checked for round?

 

[Tyeler18]

Why did you rebuild it in the first place?
Did you have the big end of the con rods checked for round?

Compression was low (100psi) across the board.

I had ARP rod bolts installed, so the machine shop align honed the rods.

 

[LiquidX]

Did the crank spin freely when it was bolted to the mains?

 

[Tyeler18]

Yes, very easily.

 

[TexasTurbo]

How does a machine shop "align hone" a rod? I would be skeptical about a machine shop saying they align hone rods.

 

[BogusSVO]

How does a machine shop "align hone" a rod? I would be skeptical about a machine shop saying they align hone rods.

I think he means they resized or honed the rods after the ARP bolts were installed.

The princapal is the same, weather you align hone a block, mulitable bearing bores at once or resize or hone one rod at a time.

 

[JusMX141]

Did it spin?

No. Not even close.

The phrase "to spin a bearing" refers to a situation where the journal dries out from lack of lubrication or excessive heat, the bearing sticks to the crank, and "spins" within the rod. Occasionally the bearings will even stack on one side of the crank journal, causing major issues.

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[crash89]

No, Just like Justin said you werent even close.. Here is on from my old motor.. The bearings were actually fused together and were as one, I had to pry them apart!!

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[BogusSVO]

What was your oil pressure, cold and hot idle? and Cold and hot running down the road?

 

[Black'95]

Agreed. My Talon spun a bearing before and it was fugly!! I replaced the crank and bearings, and I've since checked the rod bearings a couple times. Mine have more scuff marks than yours, but they don't make noise or give me issues... My non-expert opinion is that they're just breaking in.

 

[Tyeler18]

How does a machine shop "align hone" a rod? I would be skeptical about a machine shop saying they align hone rods.

Wrong terminology, they were machined for the ARP rod bolts.

What was your oil pressure, cold and hot idle? and Cold and hot running down the road?

It was sitting right at 20 psi warm when I first let it warm up. After it got to 190 (dsmlink) I took it out for it's drive, but don't remember what it was reading. After a while I stopped looking at it as it was reading good and I was trying to figure out why my boost gauge was reading 16psi at idle/cruise. Then when I heard it start knocking and pulled over it was sitting at 5 psi at idle. The next day when I started it up again to check things it was idling at 20psi cold, so I'm thinking the pump failed.

Agreed. My Talon spun a bearing before and it was fugly!! I replaced the crank and bearings, and I've since checked the rod bearings a couple times. Mine have more scuff marks than yours, but they don't make noise or give me issues... My non-expert opinion is that they're just breaking in.

They're definitely not breaking in. It was knocking hard. And the outer coating of the bearings is almost completely worn off.

 

[Black'95]

Yea, somethings definitely not right, there... Mine had some wear, but after 35k on em . And 20psi cold is crazy low.