RB25DE Rebuild tolerances

[MinKer]

I recently tore down a low compression RB25DE I have.

I was wondering what the acceptable tolerances are for bore diameter?

The largest of the six meaasures 86.05mm

Is this too high for a rebuild? (without changing to a larger piston size)

Edited May 10, 2020 by MinKer

[trel]

I'm not sure about DE only DET. You can get 86.5mm oversize pistons so should be right? 

[GTSBoy]

1 hour ago, trel said:

I'm not sure about DE only DET. You can get 86.5mm oversize pistons so should be right? 

I'm not sure that's the question he's asking.

But there's a bigger question. How round are the bores? Any taper? Any lipping at the top? All of these things need to be considered before thinking you can just drop another piston into the hole, regardless of whether the major tolerance on diameter is good.

I am of the opinion that if the motor is apart, it deserves to be done properly.

[KiwiRS4T]

Tolerances are in the engine manual. If you don't have the necessary micrometers etc you can hire them.

[Ben C34]

What did you measure the bore with?

[MinKer]

6 hours ago, GTSBoy said:

I'm not sure that's the question he's asking.

But there's a bigger question. How round are the bores? Any taper? Any lipping at the top? All of these things need to be considered before thinking you can just drop another piston into the hole, regardless of whether the major tolerance on diameter is good.

I am of the opinion that if the motor is apart, it deserves to be done properly.

It seems that I got given an imcomplete manual, but for future reference 

Seems the bore is shot, i'll triple check later

[Lvonn1]

Hey MinKer,

Where abouts did you get that table from ? 

[Murray_Calavera]

3 hours ago, Lvonn1 said:

Hey MinKer,

Where abouts did you get that table from ? 

Workshop manual.