3.5L V6 or 4.0 V6 more reliable?

You strike me as the type that east mayo with a spoon.

 

whaaaaaaaat, thats it your dead to me. You must drive a truck with minivan motor

 

I have well over 40+ years in the repair and maintenance side of the industry, so I don’t say things lightly. I know what works and what doesn’t, what's true and not, and I act according to all the data I find. But you do you

 

Then you should know not to speculate on something like this unless you 100% know?

Not trying to break your balls but you keep telling everyone this is preventable, when you truly don't know.

 

Guys, if the 4.0 could speak, this is what it would say.

 

I do know the causes, and I've outlined them and reiterate, you do you, and let everyone else do the same

 

Anyone have any of that -- you know, that stuff -- actual hard data, statistics from credible sources -- on the failure rates (including typical causes) of the 4.0L vs. the 3rd gen's 3.5L? (Asking for a friend..)

 

Depending on the year of the FJ the debate is whether to use premium or regular. And no real answers anywhere

 

‘08 it’s always gotten 91 or higher, except for a few tanks early on
Mileage drops and it’s sluggish when 87 was tried

 

Yeah, we don't do that here.

 

My 07 FJ never saw anything but 87 octane and it's running flawlessly with 170K on the clock. I have been ignoring that little 91 octane sticker on the inside of the fuel door since I bought it.

 

If you go with a 2013-2015 4.0 or a 2019-23 3.5 AND the engine has been well maintained (and documented) with regular oil changes, I expect either will be equally reliable. If you want out of the box low down torque, get the 4.0. If you want updated tech and features, get the 3.5. You can also put an OTT tune on a 3.5 for better torque response. I had a 4 and now have a 3.5. With an OTT tune, I prefer the 3.5 and updated features/tech.

Regular maintenance is critical. Stay away from engines changed at 10k that are daily driven with short trips or run off-road more than 50% of the time. 10k oil changes are really for highway / longer distance driving where the engine is allowed warm up.

 

The Car Care Nut has a video explaining the oil leak issue on the 3.5L 2GR-FE in great detail. He starts off by calling it "A legend of an engine, very reliable with one issue". He removes one from a Lexus RX350 to fix the timing cover oil leak while describing and showing exactly what causes some of them to leak oil at the exact same failure point. Not all of them develop this leak and he also explains and demonstrates why this is so. It's more common on one side than the other, but can leak at the same spot on either side.

Putting it simply: it's a roll of the device. They can leak very early when the car is brand new, after a random number of miles, or never.

 

All due respect to "The Car Care Nut", there’s no such thing as luck, or roll of the dice, things happen for a reason.

Moreover, when you go to repair something, the first task is to find out why it failed in the first place, so you don’t have the same occurrence on your dime.

 

My experience with leaks is usually related to imperfect mating surfaces. I would guess there are some machining, or assembly variations between these component surfaces that a gasket or even a sealing agent doesn't always do the job well whether these leaks will show up sooner, or later.

 

Always 1 owner, 2013-2015 2nd gen with 40k or less miles, Off Road trim --GREEN-- imo

 

I watched the CarCareNut video of the 3.5 V6 timing chain cover repair. He said the leaks always occur at the joint where the head meets the block, either side of engine. But more prominently on the passenger side (above the power steering pump). So you have a horizontal joint of 2 vertically oriented pieces of metal, with the timing cover spanning over the top of both surfaces. When he was resealing them (after extensive cleaning) he ran the video at high speed. He was applying the black sealant with a caulking gun type application. Looks like a delicate selling job. You don’t want any sealant oozing inside the cover as foreign material that could clog an oil drain path. He said he has done hundreds of them. I guess with the multiple car engine application (this was a Lexus sedan) there are tens of thousands of these engines in service.

 

He is very specific on what, in his opinion, is the specific cause. It happens for a reason. In addition: if you don't perform the repair correctly, it's likely to occur again.

I'm not promoting his video any further than this, that or the next thing.