3.5L V6 or 4.0 V6 more reliable?

Bingo

 

Alright, I'll bite. How does a 5k OCI vs a 10k OCI prevent the timing cover from leaking?

 

If the sealant wasn’t applied correctly to that joint correctly, it will leak eventually. I suspect heating and cooling cycles, will promote the leak happening sooner rather than later. I could definitely believe a clogged PCV valve might promote a leak if it increased the pressure inside the cover. And when I get my next TRDOR I’ll pay more attention to the PCV valve. That sounds like a good preventative maintenance item. I didn’t see it in the Tacoma maintenance schedule.

If the engine is producing blow-by gases faster than the PCV system can dispose of them, an increasing surplus becomes trapped in the crankcase, causing excess pressure and, inevitably, oil leaks. Even the most carefully sealed gaskets leak when confronted by rising internal crankcase pressure.

 

A repair needs to be perform correctly yes, but only after it has been determined that it was poorly sealed at time of assembly. And I appreciate your input because this may affect all owners.
Moreover, I would need to see a failure rate of over 2% or about 3k leaking timing covers on Tacoma engines to suspect a factory assembly issue.

I didn’t specifically say the oil OCI did, but poor maintenance does contribute to the overall heath of all the engine components including gaskets and seals.
There are other contributors such as air filters, PCV valve and lower quality fuel too, which may contain a higher number of contaminants from the lack of filter changes at the pump that eventually make their way to the combustion chamber. Severe service interval may help here.

That’s why it is called “preventative maintenance” and you have severe and normal schedule and It works

That said, the biggest contributor to engine leaks and seeps in this instance IMO, maybe the neglected PCV valve that no one replaces any more.
I replace all the above, use only use top grade fuel and never have seeps or leaks on dozens of vehicles over many years dating back to...

 

Some of you guys are exhausting.

 

Just a minute, we still didn’t figure out if the leak is caused by 5k or 10k oil changes.

 

It doesn't: Unrelated to OCI: You can change the oil every thousand miles and still encounter this issue. According to the CCN: some cars arrive -brand new- at the dealership with this issue.

 

Jack: Oh man..... He scared me in "The Shining", worried me in "One Flew Over the Cuckoo's Nest", made me paranoid in "The Departed", "Batman", and "A Few Good Men"... "Easy Rider" "The Witches of Eastwick". Jeeze-Louise: Don't ever aggravate Jack. ( Thank you Jack. )

 

I never understood the gen to gen hate, it’s pretty ridiculous. I love my 1st gen for what it is, simple enough that I know every bolt and could take it down to the crank if I had the reason to do so. Tough as hell but a bit tinny, and that’s why I’ve kept it and beat the shit out of it for 20 years. The bed side is tearing from hauling way too much weight on a homemade lumber rack, the inner fenders are cracking, the engine is tired, but it just won’t die. I paid $9000 for it with a rebuilt title, never had any intention of selling it and still don’t.

I personally think all of you are fucking nuts who’ll take a $20,000-$50,000 truck and wheel it or cut bedsides and chop body mounts, but to each his own.

My thinking is definitely that of course people come here to talk about issues with their trucks. Kind of the point of a forum to exchange experiences and if you’ve got 200,000+ trucks sold a year, there’s gonna be some issues.

So far the new Tundra is one of the most reliable trucks ever built and it’s all new tech. There will be some people with issues. How could there not be?

 

If there’s one thing my grandpappy taught me, it’s that there is no heavier duty engine than a mini-van-duty engine. It’s where toyota’s toughest engines are sent to play. Truck motors can’t handle the strain and lack of maintenance common to
the minivan community. Toyota knew the 4.0L would not be tough enough with all the new Tacoma owners on the scene hitting the Rubicon in their tee-arhhh-deeez after 10K on the factory fill.

Thank you Toyota for putting your most durable engine in our 3G trucks! Much appreciated. We know what it’s designed to handle.



The other thing grandpappy taught me was 3K oil changes with 5W30 and I’m sticking with that too!

 

My grandpa ran 20w-50. A real man's oil.

 

That is a big bag of speculation man.

Please explain how low-quality fuel will make a timing cover leak?

You do realize you could maintain your same truck very poorly and it could not leak?

I have a dozen examples of this at work. Poor OCI and no PCV replacements 100k plus miles. No leaks. mix of 2017 and 2018.

 

There’s no speculation on my part, just facts man. Why do you even think there’s a thing called “preventative maintenance”? Hint, It’s not something made up out of thin air.

And how many at your work have over ten years with no oil seep or leaks?

 

Hard to find a 10 year old 3rd gen... Our last fleet vehicles were 4cy single cabs. Pretty much stayed bone dry past 200k miles. These trucks were maintained like shit and driven hard. None of them ever has a PCV done. Just 10-15k oil changes and brakes.

Yea but just because your timing cover doesn't leak doesn't mean it's from you over maintaining it. Chances are your same truck could have been poorly maintained and never leaked a drop of oil. This is why it's not a FACT that stronger Maintenace equals no timing cover leaks.

There is an issue with these timing covers Period. No modern engine should push oil out of the timing cover regardless of Maintenace.

My dealer has seen timing covers leak at 25k miles, and some not leak at 100k plus. This is with a Majority of people following factory scheduled maintenance.

I would also like to know how bad quality gas could contribute to a leaky timing cover as you claim. That makes zero sense.

 

Ah, now I see where the problem is. You believe these engines has a problem with the timing covers, period.

Well, all the previous TOYOTA 4.0l Iv’e ever had with same timing cover set up, as the 3.5l that I maintained have never had a leak or even so much as a seep.

So until I’m proven wrong on my current 10 yr old 4.0 and seven 7 yr old 3.5l, and thousands of other 3.5l out there that are without leaks, I’ll continue to believe that there’s nothing fundamentally wrong with these engines and maintenance works as is supposed to.

But look man, if no maintenance works well for you, you do you. But as for me, that doesn’t work in my book, but as I said, you do you.

 

Explain how the fuel has anything to do with it.

Any how do you explain the failures that happen with 5k OCI and less than 50k miles?

 

The fuel thing is self explanatory if can read my paragraph or have ever read any technical manuals that explain how contaminants attack internal engine components.

As for the failures that occur below the factory warranty thresh hold, I would suspect that is because no manufacturing is expected to have a zero failure rate that I know of, except maybe NASA, but even they have had a failure or two.

So I think you and I are done here, and good luck at work with the no maintenance schedule, we tried that many years ago and ended up with a lot of downtime issues and were forced us to implement very rigid preventative maintenance schedules that dramatically reduced our down times.

And with that, you & I, we’re done here