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Discussion and questions related to the course Practical Engine Building
Hi there. I have this Honda F23A crankshaft in my engine and it spun a bearing due to lack of oil on high rpm. I tried to repair it using metal spraying method, it didn't work and went bad after a very short while. It is only on conrod journal and others are fine. It is Cyl. No.4
The crank is hard to find and expensive if found!
I have heard of repairing the journal using hard chrome plating. It is an available option for me.
Note that the crankshaft is used in an Stroker H22 engine, high compression around 240-250psi and 8000 rpm.
I would appreciate your help.
Thanks in advance.
Done properly, metal spray deposit works well, but as you're still having issues, it seems like you're going to need to have it professionall MIG welded and then ground back to size.
If you're unsure of where to get it done, try contacting the heavy industry companies and dealers in your area - this is a not-uncommon process for them and they should be able to advise you where to get it done.
NOTE, there is still a risk of crank failure, or distortion, which may need to be addressed, but...
As for finding another crank, I'd suggest you research what vehicles sold in your area that use the engine, and keeping an eye out on the various sites that dispose of damaged vehicles, or call the various car wreckers around you - they may have the engine in vehicles you can either buy complete, or as a complete engine, respectively, for not too much money. Same with any trading sites like your equivalent of E-Bay, for people selling complete cars. Wrecked "parts" cars can often provide what you need, and you can sell on the rest to re-coup some of the cost.
Hi, thanks for the reply. I talked to a company repairing cranks using SAW but they did not recommend high rpm cranks to be repaired using that method. This Hard chrome plating company I talked to said there should be no problem and there would not be any distortion during the process. I have not seen anyone using MIG welding to repair a crank journal in my country.
As for the crank, there is no car with an engine using that crank imported to my country, I have to buy from other countries which makes it expensive and unreliable as I don't know the condition of it until I get my hands on it.
I wouldn't have expected SAW to be used, but I have limited experiance with that process. Ah, I see it's not uncommon - one is always learning.
As you say, buying s/h is a crap shoot - if you aren't in a hurry, you may be better looking at buying new, either from Honda, if available, or from a Honda tuning specialist? It's more expensive, but if you factor in the risk the repair doesn't work anyway, and the need to pay for the full gasket set and any other resultant damage, it may be close.
Whatever you do, don't forget to thoughly clean everything, including the oil pump and all the oil-ways, and at least carefully check the connecting rod - or preferably replace it, as it may be compromised as far as roundness and strength are concerned.
Let's see if someone here has experience with Hard Chrome Plating. It is said to be the best amongst all. Buying new is not an option. It is far more expensive than repairing. I can repair for less than 150$.
So I would prefer journal repair using either Hard Chrome Plating or SAW.
Where i live it's quite common thing to weld on some material on damaged crankshafts, camshafts and then re-grind it up to the specs. I have one 4g63 crank done that way for a customer and it works with no problem making 500+ hp...
Which welding method do you use? MIG/TIG/SAW?
I'm not sure how it's property called in English but it is explosion particles spraying...
I believe you mean Metal Spraying.
Yes, metal particles spraying caused by little explosion blast.
I haven't had experience with metal sprayed repair, or hard chrome plating so can't really comment on the validity or reliability of these methods. What I'd absolutely suggest considering if you haven't already, is having the journals ground undersize and then using an appropriate OS bearing shell. The limitation here is whether you're going to be able to clean up the damage with what is still a relatively minor amount of grinding. The other issue that almost always accompanies a bearing failure and journal damage is that the crankshaft will usually be bent. Sometimes this can be straightened so it might not be a deal breaker but it's important to check.
It is beyond the limit to grind and use undersize bearings.