An FA20D failure / diagnosis & repair story...

[Eaton PSI]

Rod 1 is fed from 1st main bearing. Rod 4 is fed from 5th main bearing. Rods 2 and 3 are both fed from 3rd main bearing. It will always be 2 or 3 rod that fails first as they have to share oil.

Just guessing... Maybe the angled rod cap has something to do with it? The angle is different relative to rotation on 2 and 3 rods. When the oil disappears, maybe one orientation is more survivable than the other.

On a regular inline crank it is common for each rod to have its own feed from a main bearing, no sharing.

[Opie]

Well....now I know where this engine will be going once I finish rebuilding it....no accidents, hydrolocked motor!

[NoHaveMSG]

Originally Posted by Ultramaroon

Why always #3? Grrr...

solidsnake had a couple theories on it. I know he was slotting bearings and opening up feeds on the crank.

[Ultramaroon]

Originally Posted by NoHaveMSG

solidsnake had a couple theories on it. I know he was slotting bearings and opening up feeds on the crank.

I remember some of his stuff. One was the parting line and taper for the mains oil gallery. I didn't quite understand his work on the crank. Wish he hadn't thrown that tantrum and deleted all of it.

[NoHaveMSG]

Originally Posted by Ultramaroon

I remember some of his stuff. One was the parting line and taper for the mains oil gallery. I didn't quite understand his work on the crank. Wish he hadn't thrown that tantrum and deleted all of it.

Yeah, I still have some PM’s from him from 19’ for reference but none of it in what exactly he was doing.

[Opie]

Rod bearings and rings arrived today, so I started to install the pistons...got to #3, and as I was removing the old rings, part of the ringlang came with it...WTF? I guess it was cracked and being held together with the rings still installed. So now, 1 piston on order....meanwhile I did get the other three rods plastiguaged, all in spec. So three of the 4 pistons are installed. Think I can get the head installed on the side that has two while I wait on more parts...

[Ultramaroon]

Interesting result from the harsh vibration. I wonder how long it was operated with that spun bearing. Like you noticed, that rod end got hot!

[Opie]

Where I'm at...

And it looks like you can't buy pistons seperately, they come in a set for one side of the engine...so I'll be getting 2 right side "B" pistons....guess I'll have a spare...

[Eaton PSI]

Good opportunity to put a decent set of rods in there. The stock rods are made of chocolate. There's some pretty good value aftermarket stuff around these days.
With a good set of rods it'll be ready for whatever you can throw at it in the future.

[FR-S2GT86]

Originally Posted by Eaton PSI

Good opportunity to put a decent set of rods in there. The stock rods are made of chocolate. There's some pretty good value aftermarket stuff around these days.
With a good set of rods it'll be ready for whatever you can throw at it in the future.

I was thinking the same thing. Remove the one major weak link standing in the way of forced induction just in case. Or at least make it that much more reliable for the future if you want to stay au naturale.

[Ultramaroon]

Originally Posted by Eaton PSI

The stock rods are made of chocolate.

So's the gearbox. Leave it stock.

Besides, he's rescuing/flipping these.

[Opie]

New piston finally arrived, got it installed and completed the engine today. Tomorrow I'll pull the bad motor out of the White #19 and by Sunday afternoon the rebuilt motor should be fully installed and running in it. Then I'll tear down that one...

[Opie]

Some of you may be wondering, what was the final cost to rebuild this motor. I've included the parts spreadsheet below. $1,359.94 in parts + $100 machine shop. Total = $1,459.94

This engine also got a 2015 engine wiring harness, 2015 coil packs, water temp sensor and oil temp sensors installed, all of these I had sitting around from part outs.

Things to note;

• I buy "A LOT" of parts from my local dealership and get special pricing because of it.
• All parts prices include sales tax
• I don't include costs of "shop supplies", Three-bond, RTV remover, razor blades (plastic and metal), assembly lube, Plastiguage, etc.
• I do not include the costs of any tools
• I do not include my labor time as a cost

If you are undertaking a project like this, or any large repair project. Go to your local dealer and speak with the parts manager, explain the scope of your project and see if they will offer you better than list pricing on parts. Any little bit helps.

There were some additional parts that I happened to have already on hand left over from other projects. Their cost is not reflected on the spreadsheet.
Such as: Lower Oil Pan O-rings (2), Oil Pick Up O-ring

Remember that you may need some ancillary supplies to complete a rebuild. shop supplies and certain specialty tools come to mind. I work on more Subaru projects than your average enthusiast...but having the correct tools makes these jobs so much easier.

I figure this rebuild took me 10-15 hours total of actual work time. If I was charging labor, say doing it for someone else...figure that would've added another $600-$850 to the cost just for the rebuild...when I do it for myself, its just hobby time. Installing the motor would add even more time, say 2-6 hours plus fluids & filters

Next up, showing is up and running!

[Ultramaroon]

Excited to hear it run! Thanks for telling this story.