Looking for Community Input on Blown FA20: To replace or not to replace

[NoHaveMSG]

Originally Posted by EndlessAzure

I have no idea with regard to region.


I just know there are cam sensor differences between zenki (-2016) and kouki (2017+)

It's not just the cam sensors. The reluctor wheel for cam positioning is different as is the crank position sensor and reluctor wheel. Inny vs. Outy. Pre-facelift ECU can't read the signal on the crank sensor. There was a thread a while back where someone was running the facelift cam sensors/cam gears, or some combination of parts on a pre-facelift car and it was reading the cam position, BUT, he was having issues with cam correlation codes. Not totally sure the guy knew what he had though so am kind of skeptical. Can't remember exactly being smooth brained and all.

TLDR OP find a used engine and fix the car. Will be worth far more complete then with blown engine if you decide to go a different route down the road.

[vfrqqq]

Thank you everyone for the helpful feedback. I've decided to move forward with replacing the engine and, as a matter of giving back to the community, I'll try to document what I did and post up about it as I'm able.

[finch1750]

Originally Posted by EndlessAzure

Yes, I have provided the year ranges for reference on zenki and kouki

Upgraded coil packs on zenki don't matter if you source an engine that still has its harness attached. It's the same main connector between engine and body

Or just keep your 13-14 harness and use your 13-14 coil packs on the 15-16 engine

[e1_griego]

Last motor swap I did (which was a few years ago) took about 5 hours from driving one into the garage with rod knock to firing the new (used, ebay) motor up.

These things are stupid simple.

[demasrv]

Originally Posted by vfrqqq

I've pretty much ruled out swapping out the shortblock as that is just beyond my technical capability such that I don't want to risk spending all that effort and still have some non-trivial issue that will require even more money and time to solve. In particular, not having any idea whether metal debris circulated through the oil after the con rod punched through the engine case, I have no idea what state the heads are in.

I had your opinion here until a buddy pushed me to just go for it. How long did you drive it after it was blown? I shut my car down within a minute, and the heads were super clean. There aren't THAT many crevices metal bits can hide, and you really don't have to take apart as much as you think. Chances are the heads are just fine, and the new-ish subaru head gaskets Subaru uses now with multiple layers of metal mean head gasket failures aren't really a thing. The most annoying part is scraping off the RTV. The youtube content around a short block replacement has come a long way too since when I did mine ~3 years ago. You'll be freaking out about stuff because it's your first time, but you can do anything with the forum guidance/youtube. Just get a torque wrench and follow the manual.


You'll probably want to buy:
- full engine gasket kit. You won't need all of the gaskets in the kit. (map performance has a good priced one)
- Engine timing kit, this includes chains, tensioners and guides (ebay)
- crankshaft bolt (from subaru dealership)
- head bolts (from subaru dealership
- Right stuff grey gasket maker. Black works okay too, but it's not officially rated for "asian" vehicles.
- Good time to replace the clutch and maybe flywheel, throw out bearing too. If you do this, get some grease (brake grease is fine here)
- Good time to replace the spark plugs too.


Then you'll need to buy/rent an engine hoist.

[vfrqqq]

Originally Posted by demasrv

I had your opinion here until a buddy pushed me to just go for it. How long did you drive it after it was blown? I shut my car down within a minute, and the heads were super clean. There aren't THAT many crevices metal bits can hide, and you really don't have to take apart as much as you think. Chances are the heads are just fine, and the new-ish subaru head gaskets Subaru uses now with multiple layers of metal mean head gasket failures aren't really a thing. The most annoying part is scraping off the RTV. The youtube content around a short block replacement has come a long way too since when I did mine ~3 years ago. You'll be freaking out about stuff because it's your first time, but you can do anything with the forum guidance/youtube. Just get a torque wrench and follow the manual.


You'll probably want to buy:
- full engine gasket kit. You won't need all of the gaskets in the kit. (map performance has a good priced one)
- Engine timing kit, this includes chains, tensioners and guides (ebay)
- crankshaft bolt (from subaru dealership)
- head bolts (from subaru dealership
- Right stuff grey gasket maker. Black works okay too, but it's not officially rated for "asian" vehicles.
- Good time to replace the clutch and maybe flywheel, throw out bearing too. If you do this, get some grease (brake grease is fine here)
- Good time to replace the spark plugs too.


Then you'll need to buy/rent an engine hoist.

Thanks for the feedback. I ended up finding a used motor with about the same mileage as my blown motor that was only about 25 miles away, was compression and run tested, and came with a six month warranty. So whatever I end up doing with the blown motor (e.g., parting it out, rebuilding with an IAG short block, etc.), I can take my time. The points about the support from this forum and YouTube to do just about anything one could wish to a BRZ/FR-S are well taken as I've definitely benefited from that in past. For now though, I will have a working vehicle and I can final give back to my wife the other garage parking space

At this point, the replacement motor has been installed and I'm waiting on parts for the exhaust before I can begin the process of firing up the new motor.

[vfrqqq]

The engine replacement is all finish and my BRZ lives to see another day! I think I got lucky mating the engine to the transmission as it only took about 30 minutes of orienting the engine and transmission before they were fully together. I was fully expecting that part to take hours and at least a couple attempts!

I ended up removing all the old flex fuel from the tank and fuel lines all the way--working with flex fuel is so much nicer than gasoline. I also reinstalled the OEM fuel pump and ended up cleaning all port and direct fuel injectors and replaced the fuel delivery pipes for the direct injector system. Replacing the fuel pipes seems quite wasteful and not inexpensive, but I didn't want to take any chances give the high operating pressures of the DI system and not wanting to have to pull everything apart to deal with a potential fuel leak. Perhaps I made up for it by avoiding having to drop $$$ on the specialized tools for installing new DI seals as I'd improvised my own. I ended up using various different sized washers, the perfectly sized head of a mechanical pencil that I had to modify a little, and a small plastic block left over from some Ikea furniture. Turns out a 5/16" drill bit was perfect for making a hole in the plastic block that I could just slide over the DI seal after it was installed to restore its form after being stretched out. A delicate operation to be sure, but patience and a comfortable work area proved crucial for success.

I attempted to clean out as much gunk from the intake ports as I could but was only really able to work on the one side of the engine with closed intake valves. I wasn't able to fill up the other side with carburetor cleaner so I just wiped up as much as I could. I made the silly mistake of forgetting to reconnect the vacuum line for the brake booster before I'd attempted to start and idle the motor a few times for the first time after the install. After correcting that problem, the motor has been running very smoothly and the data logs seem to reflect as much.

All in all, given it was my first time replacing a motor and dismantling the fuel system, I figured there were easily about 25 or more opportunities for me to have substantially screwed something up that would take way more patience to troubleshoot than I was interested in, so it's quite nice that everything worked out (knocked on wood).

Thanks to all for feedback, thoughts, and discussion on this. I greatly appreciate it.