Lower air intake gasket - Google Photos

I just did this over the holiday. It was easy until it was very, very hard. There's been a bit of antifreeze in the valley of the engine for years now (seriously, I know, I'm horrible.) Until a few months ago it was just a bit. It would all burn off once I got the engine up to temp. Then it started to pool up. Finally it was running down the front and back of the engine and I couldn't ignore it any longer.

Theoretically replacing the gaskets is pretty easy, but I busted a couple bolts off on the driver's side. I tried all the tricks but I don't own a welder so I towed it to a local shop that had agreed to take it on. They got both bolts out and saved the threads. So, no insert which was a relief.

A few comments: this is basically the same as changing head cover gaskets, but you keep going after you get the upper air intake off.

I took the fuel rail out in one piece, detaching both lines where they hook up to the hard lines that go back to the tank and then fishing them out with the rail and injectors. I replaced the o-rings and grommets for each injector, cleaned and replaced them. I haven’t been having any problems with them. I used Beck & Arnley injector kits. The one’s from Toyota are just too expensive, stupid expensive. You can pick the kit up for about $5 per injector, two o-rings and two grommets.

I was lucky that I'd already bought a replacement wiring harness for the knock sensors that are under the intake. The harness came apart in my hand as I was pulling it out. It just disintegrated. I have no idea how they were still working.

If you're needing to replace the knock sensors this is the time. They are insanely expensive from Toyota ($250/each, not a joke. I called my local dealership.) Yotaparts has them for $200 and you can find them on the internet for $150ish/each. There are eBay sellers offering "genuine" Toyota sensors for even less, caveat emptor. Also, you can go aftermarket for hella cheap, but…

The coolant crossover pipe was probably not leaking, but the valley in my engine was quite rusty so I decided to re-bed/re-seal it. Always a risk, I know, but the bolts came out easy. There are two bolts that hold it to the engine block and one nut that holds it down to a stud in the back. The pipe is riveted to the plate that closes off the back of the valley. You unscrew the bolts and nut and lift it out forward and up. It’s a bit fiddly but it all comes out together.

The end that connects to the block appears to take an o-ring. There’s a circular groove in it. It does not. I called Toyota. They do not sell an o-ring or gasket for it. I was told to use a small amount of high-temp sealant in the groove.

There are two sensors (one front and one rear) that are installed in the lower air intake. I busted both of them trying to get them out to clean the plenum. Toyota does not sell the sensors separate from the intake and a new one is about $600. I bought a used one, with sensors intact, for $65. I found out later that you can buy the sensors from Rockauto. I’m re-building my old intake now, as a backup, I guess?

Re-assembly was pretty easy. Everything in reverse order. The intake bolts come in two lengths and alternate side-to-side, short to long. I used some cardboard to keep track of what went where. They torque to 15 ft/lbs and I did it in a few stages, starting in the middle and working my way out. Probably overkill but I wanted to get it right.

Once I got it started back up it had some of the worst lifter/valve knock I’ve ever heard. Scared the shit out of me because I thought I’d left something inside the engine for a minute. After running it in short bursts a few times it started becoming intermittent. I changed the oil and added some engine oil treatment and it seems to have subsided for now. I’ve been getting little flutters of the knock every now and then. So, I guess checking valve clearance and possibly changing out some of the buckets may be in my future? Another project for another day.

Side note, I’m new to the dual-electrode spark plug thing. I’ve had this truck for years and never knew. I’ve always just used the single electrode kind. Anyway, I installed the “right” plugs this time. The old ones seemed fine though, no extra wear, they’re all gapped the same, so…meh…