Doing a head gasket/timing job on an Subaru EJ251. As I type this I have it down to heads on a bench and a short block on an engine stand... but now I'm wondering if I shouldn't just take it all the way?
I'm trying to talk myself out of doing the job, honestly. The blocks on these are a HUGE PITA to split, and there is a lot that can go wrong, but that would be required to go farther. That being said... there is nothing visibly wrong with any of this.
- The cylinders still show good hone marks.
- it had plenty of compression.
- Pistons are solid as can be.
- No rod knock that I can feel.
In theory, journal bearings operate as hydrodynamic bearings, so experience zero wear so long as lubrication has been 100% maintained to spec. Similarly, the same could be said about rings and cylinders. So long as the cylinders are maintaining a nice film of oil 100% of the time, all of that could last indefinitely too.
The critical thinking here is, "theory rarely holds up to practice." It would be a shame to put this thing together all clean and proper, just to have it die in < 10k miles because of the few things I didn't overhaul.
If anything is certain that could/should be fixed, it could use new rings. They work, there is just no way they still have all the meat on the bone.
Then again, if it ain't broke, don't fix it...
So... Does it make sense to replace the main bearings and rings? Is the cost and time put in going to tangibly improve the engine?