What actually causes timing chain tensioner failure?

Hey guys! Just curious what are you thoughts in what causes timing chain tensioner failure?

I had the dreaded tensioner rattle for a few hundred miles (I was due for an oil change but on vacation) I changed it with fresh oil, filter, and 8oz of seafoam, the noise went away, and I plan on changing the oil again in a few hundred miles, just to clean the engine, then change it again. And no, it's not a waste of an oil change for me, I have other uses for the oil once it's drained.

The internals of my engine looks good from the filler tube, but the noise didn't start till I had around 9500 miles on the oil, I've towed 8k for several thousand miles, ramped my truck one time (fun stuff!) Was in the mountains using sequential shift to slow down to save my brakes, and did tons of off roading and some mild rock crawling, so the oil was used hard, im sending sending sample to blackstone on Monday.

My thoughts on the cause of failure or intermittent failure
Lack of maintenance, as seen by almost every photo of someone changing their tensioner, their engine if gunked up pretty bad

Old and heavily used oil, which is my scenario

Let me hear your thoughts on what you believe, or know, causes this failure. I haven't heard a concrete answer despite all of my research.

My truck has 224k if you're curious

 

You may have seen my engine around here. I think 8k is too long. Stick with 5k. I also believe the tensioner mounting position contributes to the failure and also (just now thinking this) perhaps the valve cover gaskets for the ports that feed the tensioner wear out and leak (little oring washers) which could cause too low of pressure to the tensioner. Also, I noticed the hole in the new tensioner was a little bigger than they old one. And, another thing is that some people may opt to just change the oil and not the filter when the have a bad experience with the filter housing and can’t get it off.

 

Wrong oil, long oil change intervals, engine overheating are operator/owner items that can exacerbate the issue.

Other sources of failure:
leak-by of oil pressure from loss of seal.
ratchet mechanism failure

 

Oil viscosity is a big factor.

 

What viscosity should it be? It's well documented that Tundra "officially" takes a huge range of oils depending on what country you bought it.

 

Depends on many factors, there is no one size fits all even in one country. For me it's currently synthetic 5 30, but if I was in Phoenix Summer it'd be 10 40, North Dakota Winter I'd run 0 20. Every case is different.

 

All are good points, I run 5w30 because I'm in the south, and its pretty much hot year round. My last oil change I had around 9k and sent the sample to blackstone, it came back great. @Dalandshark I also noticed in some photos the oil port is bigger in the new tensioner, I wonder if the new design doesn't fail as often. They had to have known this was an issue to increase the size of the port.

After 100 miles today so far, no noise with the new oil and seafoam. I'll keep everyone updated on the outcome. Might change my intervals to 7500 depending on the oil analysis. I put alot of miles on my truck so I don't really want to do that, but will do it if necessary.

Thanks again for the replies guys!