Hi Car Analogy,
For a simple undersize regrind you are right. The shop I have suggested for damaged journals grind the journal undersize and weld it bigger with very hard rod, and then grind it to stock diameter. The journal surface that is produced this way is harder than a nitrided surface and lasts as long or longer than an original journal surface would. It isn't cheap but for a small number of damaged journals it is less expensive than replacing the entire crank.
Larry

 

If you buy a used engine, buy a factory sealed engine from a seller who tests and warranty's them. Find one that's 100% stock.

The F series is incredibly robust. Its typically killed by either low oil level, a mechanical over-rev, or internal modifications.

If you buy a F20, make all the updates while the engine is out. AP2 retainers and, depending on the engine's manufacturing date, oil banjo bolts.

Replace the heater hoses and coolant hoses, thermostat and water pump.

Never shop aftermarket. Shop a dealer. Hondaautomotiveparts.com or similar.

If you are doing all the labor, assume about $6-8K for a longblock, all maintenance items, fluids, clutch, etc.

 

Wow, amazing! I'd been researching hardening processes, wondering about weld and grind then heat treat, trying to find something that would be as hard as stock process. Didn't occur to me that welding itself could provide sufficient hardness.

Who does this sort of crank processing?

 

It's Eds Crankshafts in Hayward CA.

 

Thx! Website says they use Submerged Arc Welding, SAW.

Found this scientific paper on the process, testing its effectiveness for r repairing automotive crankshafts:

SAW for cranks

An excerpt:

The hardness test values reflect the structures obtained. The average hardness value of the Daihatsu-B crankshaft at the surface is about 311 Hv which is more than the hardness value before repairing by about 60 Hv units, while the average hardness value of the Defender TDI crankshaft at the surface is about 429 Hv which is again higher than the hardness value before welding by about 70 Hv units. These differences can be attributed to the chemical composition of the welding wires and to the cooling effect during moving the crankshafts from welding stage to the stress relieving furnace.

 

The SAW procedure is interesting. Any idea what the SAW repair costs? Labor cost can be prohibitive to repair parts compared to what they're available for new. I'm reminded of the time my lawn tractor engine failed and the repair shop quoted me a price to repair it. I innocently asked "What's the price for a new engine?" Duh.

-- Chuck

 

Prices listed on Eds website (link a few posts up). Not prohibitively expensive.

I'd still prefer new. I wonder how much of the issues with rebuilt cranks on our motors are related to windup. Deflection of crank under load. Makes me wonder how crank deflects and flexes after built up via welding vs original.

Maybe its not a factor. Maybe it all comes down to hardness.

 

I had Ed's repair one journal on an M3 crank for a cost of about $250. which included polishing all the others and it worked well. That was much less expensive than a new crank.
Larry

 

Hey everybody. I think I have made my decision. I'm going to pull the blown engine and replace it with a good used unit. It seems like it could be rebuildable, but I don't trust the longevity of the engine. Plus, I'm sick of looking at it on jackstands in the garage.

Its not the cheapest option, but in the long term, I think it makes the most sense. If I do ever decide to sell the car, I think the next owner would like to know that the engine was replaced vs rebuilt. Either way, I'm going to get my money back on the project if I sell it.

I will likely sell the good parts from the blown engine, and use the crank and block as decoration. Like an engine table or a crank lamp.

 

Check with LKQ, and Copart, for a used engine also.