Anyone have a rod bolt they could loan me or know their measurements?

4140 would be a high grade bolt. The final temper would probably be a treatment AFTER the threads were made... but most likely grade 8.

I don't think the issue is cheap bolts per se, but that they are under great stress due to the balance tolerance they were exposed to, age, and the fact they were re-used during rebuild(s).

Balancing the bottom end would be nice, but it's not in 99% of deuce owners budget/ability. Installing new rod bolts is.

Happens on cummins, too.

Engine & fuel engineering - Cummins 5.9 rod separation - root cause?

Heath_h49008 said:

4140 would be a high grade bolt. The final temper would probably be a treatment AFTER the threads were made... but most likely grade 8.

I don't think the issue is cheap bolts per se, but that they are under great stress due to the balance tolerance they were exposed to, age, and the fact they were re-used during rebuild(s).

Balancing the bottom end would be nice, but it's not in 99% of deuce owners budget/ability. Installing new rod bolts is.

Click to expand...

I agree. You can have custom rod bolts made here but they will be the same material as stock: Connecting Rod Bolts from Chandler Products

Simple test. Find a broken bolt and a good used bolt in the same engine and have a NDT check done for metal fatigue. Do the same for a non-rebuilt engine. I'm sure someone has one that lost a head gasket or was just spanked some other way.

If it is metal fatigue from something done in the rebuild process, new bolts will be a quick fix.

Looking at the spec sheet Patracy provided, it calls for "Casehardened", but no further details of that. Casehardening means that some or all of the surfaces of a component are selectively hardened to a higher hardness than the rest of the component. Common methods are carburizing, nitriding, induction hardening, flame hardening. I've been designing mining chains and bit holders for 38 years. In specifying case hardening, we always specify the method, the case hardness, the ECD (effective case depth - how deep into the part before the hardess drops below the specification), and the core hardness.
The hardness specified for these bolts is 32 - 37 Rockwell C, which is probably the core hardness, as that seems soft for case hardening.
A poorly done case hardening job could cause brittleness and failures. Measuring case hardening can be tricky. If the case is very shallow, the Rockwell C method might not be suitable. Our lab uses the Tukon method for that purpose. I'll again offer to get some bolts analyzed, ideally some that have failed and/or some from the same engine as failed bolts. Just need the bolts.

Can you just swap them out in the truck? Or, should the rods be resized?

Unless there is a clearance issue physically removing them while inside the crankcase, then there should be no issue.

Resizing compensates for wear on the rod, but it is not required.

Edit: While you're there you might as well drop in rod and main bearings if required.

Honestly, these engines are easier to work on in-chassis than most passenger car/truck engines.

JasonS said:

I have a hard time believing that anybody would spec grade 2 bolts for a con rod. Doing a quick google search yields this page which suggests that 4140 is grade 8.

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I did forget to factor in the case hardening but without testing it is an unknown quantity. If anyone has a bolt handy the head markings should indicate its grade.

testing a stock bolt is really the only way to solve this.

Here is a company that will make connecting rods, I'm sure there pricey but I bet you'll never break one..
rrconnectingrods.com

We could all build race/puller engines if we wanted.

I'm a bit more interested in finding out why the rebuilds are chunking rod bolts.

If the data works out that these bolts were damaged by re-use or something in the rebuild process, simply dropping in new bolts covers the bases for 99% of us.

I just looked at one from my LDS I'm rebuilding and the head just says 10935343

(Subscribed to this to keep track with progress and see if there might be something I can help with)

Can someone explain in a bit more detail what the rod bolts are used for?. I am a english speaker, but I must admit that my technical english skills in particular in regards to some kinds of engineering is a bit beyond me. Are the rod bolts used to secure the con rods in the engine, or what?

The "rod bolts" bolt the rod cap to the connecting rod.

So what ever happened with the ARP rod bolts ??
Did ARP make a few sets?

mark salanco said:

So what ever happened with the ARP rod bolts ??
Did ARP make a few sets?

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No

I think these were mentioned earlier in this thread, or maybe linked to in this thread. I don't remember. Its in some thread on here.
Don't know of anyone having reported using them.
http://www.agkits.com/hercules-478-diesel-connecting-rod-bolt-40-1091706.aspx#hometab
http://www.tractorjoe.com/parts/p/h...gco-white/m/2-144/?c=109&sc=2438#!prettyPhoto

mark salanco said:

So what ever happened with the ARP rod bolts ??
Did ARP make a few sets?

Click to expand...

Westy contacted arp about having them made. They said buy one or buy 200, the price is $27 per bolt. He said "thanks for your time".

I've seen lots of speculation about the rod bolts here, but never any data. I tried in vain on one of those threads to get someone to properly document a failure, provide samples for a blown engine, take measurements on the non-broken rods of the blown engine, etc. I'd like to see one or more of the of the White\Herc\Cont. pulled on a tensile test machine to see if there is an issue with the bolts themselves.

gimpyrobb said:

Westy contacted arp about having them made. They said buy one or buy 200, the price is $27 per bolt. He said "thanks for your time".

Click to expand...

Guess everybody is to busy to take the time.