Scion xA block heater install
 

So, Toyota was smart. People might want block heaters, so in the 1NZ-FE engines in the Echo, Yaris, xA, xB, and sometimes the Prius have little pockets in the block. These pockets are designed to hold a little block heater, about the size of your finger. Because there's no physical break in the block wall, there's no extra chance of leakage, and you don't have to drain the coolant to add a heater. It should be easy as pie!

Well... that's the idea, at least. Right now I'm cursing Toyota and wishing that my dealership was open so I could go curse at them. It's not their fault, but dang was it a pain to install.

The install itself is a little tricky, but mostly involves digging into the engine.
I've chronicles the steps here.
Basically, you remove the wires from the top of the airbox, then two hoses in the front of the airbox lid and one in the rear. This allows you to remove the upper and lower parts of the airbox entirely, which gets you near the engine. From there, you need to remove some bolts holding a brake line in, as well as a bracket for coolant line.

Ironically, after all that, the best way to get the block heater in is to lower it in from the rear. You can't just skip all those steps though, because the brake line bracket blocks the hole.

The killer part of the install isn't getting to this tiny hole, hiding under a wire loom and coolant hard line. No, the fun part is that Toyota combined several different block heaters into one part, PU140-00900. The part that used to go with the xA and xB were -00855. The one difference I know about (from an install guide on an xB) is that the cord that plugs into the heater comes straight out. The connector I got does a right angle straight - straight into that coolant line. I was able to get it mostly on, and it's wedged in between the coolant line and wire harness, so it's not going anywhere I guess.

However, there is another problem with the part. The block heater is basically just a cylinder, with a c-ring clip on it (sort of like the clip that holds a pen in your pocket). The cylinder has a flat bottom on the outside edge that has to line up with the metal under the hole, roughly level with the ground. The clip has to be directly on the side of the cylinder facing the rear of the car. This puts one of the "ears" of the c-clip pointing about 15 degrees off from down - and interfering perfectly with the flat bottom portion. That clip is the only thing keeping the heater in, so you can't just toss it - I ended up grinding the ear off, although it definitely reduced the holding strength of the clip. Who knows if it will keep on?

That said, it's in, it's plugged in, and we will see what the weather tomorrow morning looks like. These last few days I've been heading to work much earlier, and the temperature is also dropping overnight, so I've noticed a pretty good drop in my morning economy - probably around 3-4MPG. I'm hoping the block heater reduces some of that. I need to find some time to put the grill block on too, since that will help cooling issues during the rest of the drive (and improve my aero, I hope).

Thanks for posting and hopefully you'll see a large and noticeable improvement right off the bat, at the beginning of each drive!

Sadly, today's test was a flop. No benefit. I don't think the plug was properly plugged into the heater, because the engine cold light was still on for the start of my drive. I'm going to plug it in again Monday and check with my hand before I start up just in case, but I think the issue is the right angle plug. I'm going to have to pull it out and figure out if I can either hack it to turn 90 degrees either to the side or straight out. The coolant hose that's in my way is a hard line, so I can't do much about it.

Still, I will persevere. I think the cable is just a straight through 110 volt cable, so I may be able to rig something up myself that just clips onto the pins, and then just flood the area with silicone.

I have the same heater in my Prius and it works great. ~2 hrs of preheating gets it up to a good temp. If you go much longer you really start using more power for less heat gain.

Do you have yours on a timer? Plugging it in 2 hours ahead of time is a fair bit of forethought.

Yep, checked this morning after being plugged in overnight. The engine block was cold. I messed with the plug today - the boot is a very soft rubber and I was able to cut the part that angles the wires up. This exposed a little more wire, which seems to be heatproof rubber, but I pulled the foil shield down a little more. Hopefully I can reach back there and plug it in without having to take everything out again. I think I can test to see if it's plugged in by checking resistance across the hot and neutral blades on the plug - at 400 watts, it should be about 30 ohms.