LS7 titanium rod failure
 

There's been a few comments under some recent threads that have brought up OEM titanium rod failures due to the anti-friction coatings wearing thru, allowing the rod big ends to eat into one another causing both bearing failures and titanium "dust" debri to circulate throughout the oiling system.

I recently had such an event on my shortblock that was recently refreshed roughly 5K miles ago, for which I will share with everyone so they can keep an eye on their engines.

First, the particulars:

The shortblock had roughly 87K miles on it when it was refreshed with a set of forged pistons, new bearings throughout, ARP hardware, and Katech blue LS7 oil pump. The car sees frequent trips to the dragstrip, 1/2 mile events, and early morning shenanigans to blow the carbon out :) The rods were my originals that had been upgraded to APR bolts and a stronger wrist pin upgrade with my pistons. They were not rebushed, nor were they recoated.
The failure happened at the 92K mile mark, and while catastrophic with two rods being destroyed, the associated rod bearings being spun, crank journal being scored, etc. , the block cam thru unscathed, intact, and rebuildable.
Oil pressure at the time of failure was a solid 35+ psi idle hot , 55-65 psi at cruise and WOT. Amsoil 10W-30 Z-Rod.

#1 rod, crank journal, and associated rod bearing.....

https://cimg3.ibsrv.net/gimg/www.cor...9247239f9e.jpg
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The titanium, and ultimately the bearing material, destroyed my Katech oil pump (not surprised).

https://cimg3.ibsrv.net/gimg/www.cor...695b4790c8.jpg
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Below is a link to a video...hopefully it works

https://photos.app.goo.gl/dYR7vCWttt2hxLk3A


I believe Katech doesn't recommend any recoating services on OEM rods once the anti-friction coating wears off, and would rather see them replaced. That being said, several builders have shipped the OEM rods to Calico for a recoating of the anti-friction coating....I don't have any data to suggest this might be a long term solution or not.
This initial deterioration of the coatings would show up in an oil analysis as a higher concentration of titanium material, as the bare rod shoulders would begin to make contact with one another and grind titanium off the big ends.

I know there have been several of us who have suffered catastrophic rod failure in the last few months....I'll leave it up to them to share their experiences if they so choose. I don't know how many miles those engines had on them, but I believe all of them were in excess of 50K miles, were highly modified and are raced regularly, and were un-opened bottom ends (original bearings and rotating assemblies).

My engine is currently torn apart for a rebuild, which i will share with you once everything is together and running.
I'd also like to point out that I recently had my WCCH heads inspected after 18-20K miles of use during this tear down, and identified that the exhaust valve guides were out of spec. While there is no real conclusion on the guide wear issue on my heads, I can't rule out the possibility that the contaminated oil with the titanium material circulating throughout the engine could have also contributed to the wear of the guide material.

To those who are concerned with this type of failure who have higher mileage or are highly modified, I'd suggest an oil analysis at least every other oil change to give you a heads up to any impending rods issues.

In for rebuild details...

I think a few builders just recently had a set of rods recoated with Calico, but I could be wrong.
As most that have had this type of failure lose #1 and #2, I know that you find sets of 6 good rods for sale on a regular basis....that's the give away that the engine had a rod failure. :)

There...I just saved you like $360 :D

https://cimg0.ibsrv.net/gimg/www.cor...0be1934ffc.png

I feel ya .
I'm looking at a new combo for crank/rod/piston that hopefully won't weigh any more than the OEM setup.
Still in the preliminary stages :thumbs:

Thanks for the post, Victor and sorry for the failure. When I get more info on my rebuild, I will post it in my thread. The bottom end is being done because my last two oil samples tested 7-8 PPM Ti for the first time and lead doubled. I am hoping some of the rods may be available for resale (58K miles with 12K miles on the HCI build). https://www.corvetteforum.com/forums...post1597925121

I'm really new to all this. Are you guys saying there's no legit alternative aftermarket rods for these things? Or are you just saying the Ti rods are nice due to the weight and not wanting another alternative?

There are alternative steel rods, just not nice to have to replace these expensive rods. My build will have new forged crank, rods and pistons. see my build link above for the specifics.

There are alternatives, but it sucks that these rods are considered expendable after the anti-friction coatings wear off.
Having light weight rods is a plus :thumbs:

I'm not sure if it would be considered a weak link, but it being a consumable item during a rebuild sure could suck.

Sorry for your motor issues!!!:(
Were you doing oil samples and if so what were your titanium levels. Similar to Daves??

:cheers:
DH

No oil analysis were done prior to the failure.
In hind sight, it could have given me some warning, like what Dave had, but ultimately the rods would have had to be replaced regardless. The crank may be salvageable but I'm replacing the entire rotating assembly on this new build.
The block suffered no damage, but I'm moving forward with putting in new Darton sleeves while it's apart :thumbs:

Looked at that thread briefly and saw this:
But when I looked up those rods they spec them for 650hp. Hmmm. Just found that interesting.
I'm with ya there, I just wasn't sure if there were no other rod options due to fitment restraints or whatever. Again, I'm new to all this and trying to read because I suspect I'll have one of these threads soon. :(

Some of these threads are scary. :eek: Especially the wiped bearing pics with Ti smeared all through the wear parts. :willy:

I don't think you have anything to worry about :thumbs:
As I noted, my engine has in excess of 92K miles on it, with a lot of 1/4, 1/2, 1 mile, and HPDE runs on it. In it's last iteration, it was revved to speeds in excess of 7300 RPM and made over 600 RWHP.
If it wasn't for the coatings wearing off and allowing the big ends to grind on one another, they would still be usable. I didn't "break them" , and I'm sure with the upgraded ARP hardware and pistons, could have lived happily into the 700-800 RWHP area.
I wouldn't worry about it until you start getting some higher miles on it. Use high quality oil and filter, change it regularly, and sleep good at night. :thumbs:

The weather has broken a little here so it's my first day in quite a while without some rain. I might work outside with an automatic level on my porch after which I'm tempted to pull some valve covers to see about these heads. Thanks for the comforting words about the rods in my car. That's all I would need right about now.

What year is your Z. I believe that I read on this forum that there was a change to the chamfer on the LS7 rods to reduce this problem.