I was checking the oil on my '21 IS 350 today, and decided to just have a look around the engine bay. I am a nerd, what can I say? Anyway, I happened to notice a particularly rusty-looking surface and took a closer look at it. Whatever these are, there are two of them, one on each side of the engine, just below the valve covers.



I have two questions - 1) what are these, anyway? 2) Should I be worried that my 13-month-old IS 350 has rust here already?

 

Edge of the exhaust manifolds peeking through? Pretty normal for those to look a bit rusty, no!? *shrug I dunno. I'm just guessing as it's late and I don't feel like going downstairs to pop my own hood to take a look.

 

Arentz07 - I know my engine is not the same as yours but I went to check anyway just in case but I don't see that piece on the V8 - Sorry but I tried That being said, I have no clue what it could be from the pic.

 

haha thanks anyway. I think you're onto something, as it seems like exhaust manifolds rusting is a common occurrence.

It makes sense, since they would be cast iron, right? 🤷‍♂️

 

No idea what it is but I can tell you mine is rusted too. At least yours is 13 months old. Mine is only 7 lol

 

Gotcha. Yeah I posted this in my local friends' group chat and they also suggested exhaust manifold/headers. The exhaust manifold is integrated into the head this time, so maybe that's why it looks a bit different.

I did a little Googling and stumbled across this image, which is from an article about how to install exhaust manifolds on a Tacoma from 2015-2018.



The part with the four fasteners with the arrows pointing to it closely resembles the rusty part of which I shot a photo. I will have to get out there again and see if I can see the manifold down tubes extending off of this or not if I want to be 100% certain, but at this point I'm almost fully convinced it is the exhaust manifold. Due to the high heat this part endures, it will rust relatively quickly.

 

Side question - Curious why Lexus changed the manifold design from 3 ports to 1?

 

I'm guessing since the exhaust manifold design is now integrated into the cylinder head, we're not seeing the full picture.

See here: https://toyota-club.net/files/faq/13...engine_eng.htm

The image they use is for a single-exhaust car, i.e., transversely-mounted engine.

 

From my experience in engine building/rebuilding, it looks like the edge of a metal gasket sticking out. Looks like those bolts go through it. maybe a closer pic would help.