Engine and Transmission housing cracks - '22 GX

[Alex7]

Anyone else have what appear to be hair-line cracks on certain parts of their 1UR and on the transmission housing ? I was poking around and underneath the truck and found these cracks on the valve covers, front and side of the block, and on the transmission housing underneath. The only other threads I could find in history are more for the FJ Cruiser, where some owner found these, took pictures that look almost exactly what I found today - link here (hope it works)

Small cracks on surface of engine block

www.fjcruiserforums.com

The owners on the forum above seem to conclude that they are cosmetic defects from faulty casting. Does anyone else have this on their GX ? Made me think my truck had been a victim to PO buffoonery but if something smacked the truck hard enough to crack engine/transmission im sure my frame would show issues too - but then again, this is my first GX... thanks

 

[185]

Pictures of your powertrain would assist in this. That being said, as the FJ cruiserw pointed out, alu molds tends to display imperfections on their products if they have gone through many cycles.

Have you documented this issue with your local dealer?

 

[Alex7]

pic 1 is the transmission housing (from under - the DB probably gives that away since ive seen that on other GX before) pic 2 is the front cover (?) just beyond the upper hose. It looks comparable enough to those other pics I found. Apparently 4 runner guys have something similar, but thought I'd share here. I will be bringing the truck into a dealer to begin documentation of it, just annoying. My left valve cover also has a small amount, but none on the right side. There are more, but in less accessible sections of the engine.

 

[RJinVA]

They're not cracks, that is normal for most aluminum casting. I really hope you don't bother your dealer with this.....

 

[Rednexus]

I would imagine that the casting molds for the 1UR engine and A760F transmission were quite old when your rig was made in 2022. After all they started producing the GX460 with the identical drivetrain in 2009, so they could have been running for nearly 13 years with hundreds of thousands of components casted. That could certainly explain microcracks in the mold and the reflection of those cracks in your transmission/engine block.

If it really bothers you I'll take that '22 GX off your hands for cheap .

 

[Alex7]

They're not cracks, that is normal for most aluminum casting. I really hope you don't bother your dealer with this.....

Eh, those dealerships are there for us. It's our responsibility to remind them of that fact because often times, many are out for their own agenda. I plan to add it to the list while they investigate the vibrations I get when on throttle at 1600rpm to roughly 2000rpm. Thanks for your feedback.

@Rednexus - makes sense, I was against buying anything produced during the pandemic and totally forgot that I had that concern when my wife wanted me to check this one out - we'll deal with this one for a few years and see where it goes. Thanks for taking a look.

 

[BigSwede]

I don't think those are cracks, either... but I'm just sitting here on my couch so hard to say for sure.

 

[RJinVA]

I would imagine that the casting molds for the 1UR engine and A760F transmission were quite old when your rig was made in 2022. After all they started producing the GX460 with the identical drivetrain in 2009, so they could have been running for nearly 13 years with hundreds of thousands of components casted. That could certainly explain microcracks in the mold and the reflection of those cracks in your transmission/engine block.

If it really bothers you I'll take that '22 GX off your hands for cheap .

Has nothing to do with cracks in the mold, Toyota, or most manufacturers for that matter wouldn't be using molds with cracks, even "micro-cracks" as you refer to them. This has to do with how the aluminum cools after the casting process, they use a rapid cooling process to increase production rates which can give you interesting surface textures like this. You will see it on aluminum cast in brand new molds from all manufacturers, not just Toyota.

 

[ericm979]

Has nothing to do with cracks in the mold, Toyota, or most manufacturers for that matter wouldn't be using molds with cracks, even "micro-cracks" as you refer to them. This has to do with how the aluminum cools after the casting process, they use a rapid cooling process to increase production rates which can give you interesting surface textures like this. You will see it on aluminum cast in brand new molds from all manufacturers, not just Toyota.

I've seen similar on a lot of engine and trans castings. It's normal.

 

[Rednexus]

Has nothing to do with cracks in the mold, Toyota, or most manufacturers for that matter wouldn't be using molds with cracks, even "micro-cracks" as you refer to them. This has to do with how the aluminum cools after the casting process, they use a rapid cooling process to increase production rates which can give you interesting surface textures like this. You will see it on aluminum cast in brand new molds from all manufacturers, not just Toyota.

You obviously know more about metallurgy and casting processes than I do . I'm pretty sure that none of the cast aluminum components on my '07 have this texture on them but I'll double-check next time I'm underneath the rig, and do the same on a '23 Highlander. Not that it matters, but I am curious.

Question though: Wouldn't a mold have some kind of wear/degradation after having hundreds of thousands of components cast into it? Toyota must have some tolerance regarding the mold itself.

 

[RJinVA]

You obviously know more about metallurgy and casting processes than I do . I'm pretty sure that none of the cast aluminum components on my '07 have this texture on them but I'll double-check next time I'm underneath the rig, and do the same on a '23 Highlander. Not that it matters, but I am curious.

Question though: Wouldn't a mold have some kind of wear/degradation after having hundreds of thousands of components cast into it? Toyota must have some tolerance regarding the mold itself.

Save your dealer the trouble and just go look at any other GX out there and you'll see the same casting marks. Every car I've ever owned has had them, and they just get more pronounced when the aluminum inevitably oxidizes. Or, take it to the dealer for peace of mind but if you're not going to believe what forum members are telling you why bother asking at all?

 

[Rednexus]

Save your dealer the trouble and just go look at any other GX out there and you'll see the same casting marks. Every car I've ever owned has had them, and they just get more pronounced when the aluminum inevitably oxidizes. Or, take it to the dealer for peace of mind but if you're not going to believe what forum members are telling you why bother asking at all?

I think you're confusing me with the OP. My 2007 is never going to any dealer for anything and alin my post I said I'd check my other rig out of curiosity the next time I'm under it.

 

[ZIOI]

Has nothing to do with cracks in the mold, Toyota, or most manufacturers for that matter wouldn't be using molds with cracks, even "micro-cracks" as you refer to them. This has to do with how the aluminum cools after the casting process, they use a rapid cooling process to increase production rates which can give you interesting surface textures like this. You will see it on aluminum cast in brand new molds from all manufacturers, not just Toyota.

This^^. A "microcrack" in a casting die become a mega crack pretty fast and a very expensive die cast tool is scrap. They put a lot of effort into preventing tool cracking and failure, which is why the tooling is so expensive. (exotic alloys TONS of time into polishing and such).

These are die castings, not sand castings. Managing the die temps is a big part of tooling design. If the dies run too hot, they wear quickly and the resulting parts will have more shrinkage. If they run too cold, then the thermal shock of receiving hot metal can general accelerated fatigue that shortens tooling life.

The dies will have coolant passages plumbed in them and the tooling manages the coolant flow rate and temperature to regulate die temps for a given rate of squirt and shoot.

As such, the thing that's easiest on dies tends to be running them hot and then punching out parts that are barely solid. This minimizes thermal shock to the tools, while unfortunately placing that shrinkage stress in the ejected parts.

It looks to me like they got a bit carried away with "chill coat" or other die-prep sprays and treatments and it outgasses a bit when the liquid metal hit it.

 

[Alex7]

This^^. A "microcrack" in a casting die become a mega crack pretty fast and a very expensive die cast tool is scrap. They put a lot of effort into preventing tool cracking and failure, which is why the tooling is so expensive. (exotic alloys TONS of time into polishing and such).

These are die castings, not sand castings. Managing the die temps is a big part of tooling design. If the dies run too hot, they wear quickly and the resulting parts will have more shrinkage. If they run too cold, then the thermal shock of receiving hot metal can general accelerated fatigue that shortens tooling life.

The dies will have coolant passages plumbed in them and the tooling manages the coolant flow rate and temperature to regulate die temps for a given rate of squirt and shoot.

As such, the thing that's easiest on dies tends to be running them hot and then punching out parts that are barely solid. This minimizes thermal shock to the tools, while unfortunately placing that shrinkage stress in the ejected parts.

It looks to me like they got a bit carried away with "chill coat" or other die-prep sprays and treatments and it outgasses a bit when the liquid metal hit it.

Thanks for clarifying and the overall feedback.