Deglazing/honing
#1
Deglazing/honing
Building the bottom end of my engine which already has 'B' pistons in it from factory. Cylinders and pistons are within tolerances. Normally would give the cylinders a hone to give it a good crosshatch but was reading the factory manual and:
- The 1998 '3rd edition' of the 4.0 and 4.6L v8 engine overhaul manual says nothing about honing other than 'a' pistons can be replaced with B pistons and cylinder honed over-sized;
- The 2003 '4th edition' of the same book says under piston inspection "CAUTION: DO NOT attempt to de-glaze cylinder bores".
Wondering if anyone knows the details of this? I would think it would be fine as long as you didn't result in the cylinder spec going below the 93.986 mm required for B pistons and you didn't put the piston/cylinder gap out of spec but the book seems clear ... (well at least the new one)
Anyone have any advice?
Forgot to mention I have a 1996 4.0.
- The 1998 '3rd edition' of the 4.0 and 4.6L v8 engine overhaul manual says nothing about honing other than 'a' pistons can be replaced with B pistons and cylinder honed over-sized;
- The 2003 '4th edition' of the same book says under piston inspection "CAUTION: DO NOT attempt to de-glaze cylinder bores".
Wondering if anyone knows the details of this? I would think it would be fine as long as you didn't result in the cylinder spec going below the 93.986 mm required for B pistons and you didn't put the piston/cylinder gap out of spec but the book seems clear ... (well at least the new one)
Anyone have any advice?
Forgot to mention I have a 1996 4.0.
#2
#4
Agreed bore geometry is key. Everyone I talk to (most with no LR v8 experience) says it's fine. But I can't see why they would put it in the FSM for no reason. There must have been a reason to add it between editions sometime in 1998 and 2003.
The best I could find but was just speculation is this advice was put in due to the heat and friction from honing causing sleeves to slip or move enough that they became susceptible to slipping but aluminum engines with sleeves are not unique to LR v8s and haven't found this advice for other engines...
The best I could find but was just speculation is this advice was put in due to the heat and friction from honing causing sleeves to slip or move enough that they became susceptible to slipping but aluminum engines with sleeves are not unique to LR v8s and haven't found this advice for other engines...
#5
#7
#8
#9
Interesting - had another read today and the 3rd edition says "If only new piston rings are to be fitted, break cylinder bore glazing using a fine grit, to produce a 60° cross-hatch finish. Ensure all traces of grit are removed after above operation."
This directly contradicts what I read in the 4th edition which says not to deglaze ...
This directly contradicts what I read in the 4th edition which says not to deglaze ...