Xu10J2Te Rebuild Help Needed

[stuart1298 6]

Right had my crank polished and new big end and main end bearings/shells, as the engine over fuelled and suffered bore wash I thought it would make sense to change the piston rings, fitted the new ones and put it all back together, turning the bottom end over and there was a lot of resistance, I took the pistons out and moves freely, there was no wear on the bearing/shells, turns out there is meant to be a small gap between the joins of the rings around the pistons, can anyone tell the size of the gap should be? I managed to snap one of the rings so gonna stick a new set in and have the block honed

[DamirGTI 342]

Definitely , the gap must be present .

 

Top compression ring - 0.2 to 0.4 mm

Second compression ring - 0.15 to 0.35 mm

Oil control ring - n/a (??)

 

Personally , i wouldn't do honing (if the bores are in otherwise good state - need to measure with bore gauge) , but just deglazing cylinder walls .

If the gaps of the piston rings are too tight - file the piston ring ends until the gaps suit the listed specs.

 

Out of curiosity , with which brand of the piston ring set you've been working had that where gaped too tight ?

 

D

[DamirGTI 342]

Have you actually checked the big end bearing shell clearances ?

 

Torqued big end bearing cap bolts properly ?

 

D

[stuart1298 6]

I can't remember in all honesty, I'm not 100% that what's caused the engine to be a bit tight, I need to order a new set as broke one when I tried to remover em, will i do any damage if in stick the pistons in with out the rings just to turn by hand to make sure that I haven't got the stiffness I had before, when i say stiff it took one hell of a lot if effort to move it, once it was moving it seemed ok, it was just the initial getting it to turn

[stuart1298 6]

Yup, everything it torqued up. What tollarence's should I get? I let the engine ship source the shells so they should be correct

[DamirGTI 342]

Well , if you want to check just the turning resistance again , fit at least one (better still two) used piston ring on each piston before running them into the bores .. otherwise you might scratch the piston skirts , and also the pistons will "wobble" around a bit on the insides of the bores without the rings while spinning the assembly via crankshaft .

 

Torque specs. for the big end bearing cap bolts/nuts are :

1. stage : 20Nm

2. stage : + 70 deg.

 

Big end clearances : 0.025 to 0.050 mm - you'll need "Plastigauge" to check that .

 

D

[stuart1298 6]

Old piston rings are long gone. Yeah got the torque settings the same as that. Will it be ok fitting 2 pistons give that a try, if no resistance remove them fit the other 2 and try it that way, I assume it's the rings as the main end bearings run perfect, so assume the big ends will be correct

[stuart1298 6]

Old piston rings are long gone. Yeah got the torque settings the same as that. Will it be ok fitting 2 pistons give that a try, if no resistance remove them fit the other 2 and try it that way, I assume it's the rings as the main end bearings run perfect, so assume the big ends will be correct

[DamirGTI 342]

Maybe that'll be better choice .. aside from said , running the pistons trough the bores without the rings may fool you by creating even more resistance while turning the crank .

 

But , why not check the rings themselves inside the bores as this should be done ?

Arrange/mark the rings per each cylinder in which they where in (or chosen to be fitted in ..) , mark them so that you don't mix the order , compress the ring with fingers and slide it into the bore - use the piston up side down (with the piston crown facing down pushing on the piston ring) and push into the bore till the piston crown contacts the piston ring , push further up to the middle of the bore (middle of the piston rings travel inside the bore) to even out/level the ring inside the bore , slide the piston out and measure the ring gap with feeler gauges (per specs. written above) .

 

Edit : just understood now that you've binned the rings ! .. but do check the ring gaps when you buy new ones as described above .. after deglazing or honing the cylinders with thoroughly cleaned cylinder surfaces .

 

D

Edited September 24, 2013 by DamirGTI

[stuart1298 6]

Yeah found out how to do it, and even why it's important, with you giving me the gaps at the top of here I now know what I'm aiming for, cheers

[DamirGTI 342]

Need to do a lot of measuring when rebuilding an engine ! .. and thus having all the fancy measuring tools (which most of us don't ..) , also torque specs for bolt on engine components are critically important .

 

Sadly , i can't find any figures in my data for oil control rings .. but as a rule of a thumb , aim for 0.30 to 0.40 mm value (bigger gap wont hurt much here so can go a little bit bigger up to 0.50 mm)

 

Have fun !

 

D

[stuart1298 6]

Cheers mate, can only get 2 lots of piston rings at the mo, gotta wait a week for the other 2

[stuart1298 6]

The rings are gorzette or something along that lines, got cylinders 1 & 4 in tonight, still a little resistance, but I no it shouldn't be to easy to move, other 2 should turn up tomorrow and all be ok,