What is the probability of getting the timing chain cover oil leak on the 3.5 liter V6?

There’s enough threads about people complaining about the 3rd gens. Now we’re doing imaginary problems with the trucks?

 

it's not imaginary but admittedly it is hard to assign a failure rate. seems rare thank goodness.

the OP had the issue on his '16 and was asking about the probability of it happening on newer models. fair question, especially since others have reported the issue and it's been known to occur on other models.

it's nice to have input from folks that work on these trucks, like Bishop84.

 

Everything eventually leaks.

 

The need for Depends proves that point well.

 

It would be funny if my Toyota leaks more than my Harley did.

 

The whole timing cover leaks are over blown. Toyota has made millions of the 3.5l V6's. Think of all the Camry's, Highlanders, Siena's, Lexuses, etc running around. We are talking about a small percentage of them that are leaking. Toyota has recalled vehicles for issues that have gotten far less "forum notoriety". So if this iwas a problem effecting upwards of 20% of vehicles, you would have seen something and a change in the manufacturer process years and years ago.

The 4.0 on my 2012 started leaking around 80k. It occasionally left a drip on the floor, but it was more a seepage on the block. I ran it to 200k without ever repairing. Every 2500 miles I would top off 1/4-1/2 of a quart. Unless my 3.5 starts pouring oil out and making a real mess, I will not be fixing it. So far at 84k my '21 is bone dry all around.

 

There is a 3.141592653% chance that it will happen randomly

 

What's the time basis for that number? 8.521% per year? Every 5 years? Every 10?

Maybe it's a chi-squared distribution

 

I think it’s safe to infer there are not enough failures within the 60 month, 60,000 mile warranty to cost justify a change in the joint design. So if it happens outside of warranty expect to pay for the repair out of pocket. My $2900 repair (under warranty) involved 25 hours of labor. The dealer labor rate is $145.50 per hour. That’s $3638 for labor alone. The cost to me out of warranty would have been much more. The shop told me warranty repairs under Toyota Financial extended warranty gets a discount for labor charges. They replaced my water pump, serpentine belt, oil, filter and coolant. It would have easily cost me over $4000. So I got lucky having the extended warranty Toyota gave me for free due to under-filling my front diff 40%. So if it happens after warranty, it’s just an expensive repair. It’s not any worse than the GM V8s that have the defective valve train design due to cylinder deactivation. My 3.4 liter V6 on my 1999 Tacoma SR5 4WD Access Cab is still running strong. Frame has rust but no engine repairs ever. Just maintenance per the manual. 24 years and still going. My grand-daughter is learning to drive at our farm (off road) in that 1999 Tacoma. I’m getting a 2023 TRDOR so it’s not a deal-breaker to me. Already sold my 2016.

 

https://www.youtube.com/watch?v=KX5jNnDMfxA

 

Personally, I give it one chance in three

 

It's not really a rare issue, just rarely reported through a dealer for Toyota's records, and rarely leaks enough to be a real concern. The 3.5L V6 has always had this problem.
Here's a great video covering it in detail from The Car Care Nut on YT.
https://youtu.be/RMvjhUVjyc0?si=Wz_gc9elTDzzYH-j