Individual main bearing damage 1HD-T

[jdlsantos]

This is a question for the Diesel Gurus,
It is ok, to replace only one main bearing shell to my 1HD-T?

A long short history, I am doing a diesel conversion (1HD-T) to my LX450 and I would like to refresh the engine before that.

I thought to do only the Rod bearing and minor leaks, but after have the engine on the stand; I thought that could be a good idea to do head gasket and all the seal around but after I opened the engine, I thought that may be is a good idea to do the seal between the engine block, uhhmm front here it changed completely my scope of work and also the refresh budget!, (cylinder rins, entire engine seal, etc)

When I open the crankshaft ladder, I saw a problem in one of the main bearing shell of the cylinder 2 (see picture), fortunately the rest of the shells and the crankshaft still perfect, so, my question is can I replace only this main bearing damage? Or I should replace all the bearings?

Some of the bearings are number 3 and other number 4, I already talk with Onur and he kindly is willing to find me the numbers 4, but not the number 3. The other option could be to machine the crankshaft and get the entire set of bearing for the new crankshaft size.
All the ideas are welcome!
Thanks

 

[IanB]

I would replace them all, as this is a recommended preventative maintenance item on all iHD-T's anyways.

 

[blis]

Agreed, I would replace all of them since you have it open already...

 

[ticoman]

I am a bit confused. Are we talking con rod bearings or are we talking main bearings? If it is the con bearings, then yes change em all out with ACL bearings. don't worry about the numbers on the bearings as the ACL's are standard size and 1 size fits all.

 

[jdlsantos]

I am talking about main bearings (crankshaft bearing).
I remove front the engine 3 toyota main bearings # 4 and 4 toyota main bearings # 3, so, it looks like even on standard size they are different, but only 1 is damage.
The problem is that there is not main bearing # 3 available to buy in USA and I am checking outside.

and yes I already got some ACL to replace the rod bearing.
thanks

I am a bit confused. Are we talking con rod bearings or are we talking main bearings? If it is the con bearings, then yes change em all out with ACL bearings. don't worry about the numbers on the bearings as the ACL's are standard size and 1 size fits all.

 

[ticoman]

OK i get it. It is interesting that your main bearing shows signs of cavitation as well as scoring. This is the first I have heard of this I thought it only applied to the con rods. I no that the con bearings are also #ed 1-4 and can all be replaced with after market standard shells. Is this not the case with the mains too? Are there after market main shells made?

 

[jdlsantos]

There is too few information regarding main bearings. Could be nice to know if i can install standard after market.

The shell damage showed in the picture is OEM Toyota.

I no that the con bearings are also #ed 1-4 and can all be replaced with after market standard shells. Is this not the case with the mains too? Are there after market main shells made?

 

[Wheelingnoob]

Do not have the crank machined ever. They are hard nitrated and the machining process removes that finish.

If you are doing a full rebuild now i would replaces all the bearings regardless of there condition.

 

[jdlsantos]

Good point!, i didn't machine the crankshaft, and I would like to keep as is it, may be i will ask for inspect in a machine shop.
thanks

Do not have the crank machined ever. They are hard nitrated and the machining process removes that finish.

If you are doing a full rebuild now i would replaces all the bearings regardless of there condition.

 

[ozwallaby]

Do not have the crank machined ever. They are hard nitrated and the machining process removes that finish.

I think the word you're looking for is "nitriding"... essentially a case hardening type process that leaves the surface of the crank tougher.... and yes grinding the crank will remove this surface...

WN are you sure these cranks are nitrided or is it just hearsay.... I've been trying to find out whether 12ht cranks are nitrided, but apart from 2nd hand info, I've not been able to track down any (pardon the pun) hard evidence...

 

[Jan-78FJ40]

I think the word you're looking for is "nitriding"... essentially a case hardening type process that leaves the surface of the crank tougher.... and yes grinding the crank will remove this surface...

WN are you sure these cranks are nitrided or is it just hearsay.... I've been trying to find out whether 12ht cranks are nitrided, but apart from 2nd hand info, I've not been able to track down any (pardon the pun) hard evidence...

I'd be surprised. Toyota sells factory oversized bearings and suggests in the FSM to machine the crank to 0.25 or 0.5 oversized bearings if necessary, without mentioning a hardening process or negative consequences to the crank.
cheers,
Jan

 

[SkidBro]

I'm going to bump this thread.. I have the same bearing damge on my main crank bearing, First main bearing on front of block (not Conrod). I just measured the crank and found the shaft that runs in this bearing to be 1 micron under bottom tolerance. Crank shaft regrind was going to be the next step but your mention of a coating has me questioning if this is a wise move. Can anyone confirm if these are surface hardened?

Cheers, Skid