2.0 rough idle, hi NOX

neilh2o · 4-10-08, 17:59

i found one collapsed lifter and one cracked exhaust valve..a 2.0 liter Probe head (identical to a 2.0 Mazda 626)...anyways while i have the lifters out they are all getting taken apart and cleaned in carburator cleaner (great engine parts cleaner) and then lightly oiled ....to disassemble knock the lifter on a piece of wood cam side up..the collapsed lifter had a ton of carbon blocking the check valve ...the check valve is just a tiny ball thats spring loaded at the oil port on one of the small pistons.. when oil flows in thru the lifter fill hole the ball lifts off its seat and the lifter fills with oil.....i had some trouble with the cams getting cocked on disassembly so when that happens you have to reinstall all the cam caps and slowly tighten the bolts down in proper sequence 1/4 turn at a time till all the caps are tight and the cam is straight again..i found the best way to prevent that from happening again was to slightly rotate the cam as the cam caps are loosened up in 1/4 turn increments..the cam lobes must not rest on any of the lifters..its impossible to get equal compression on all the lifters so the cams can get cocked and jammed up very easily...you need a special valve spring compressor to compress the valve springs and remove the valves..i bought one on Ebay for about $70...the exhaust ports in the head were loaded up heavy with carbon deposits...there was absolutely no wear in the cylinder bores not even at the top of the block..the bores dont show wear probably because there are oil jets pressed into the block at the lower end of the cylinder bores ... the jets spray oil onto the cylinder bores underneath the pistons..after cleaning im going to lap in the valves lightly with a fine lapping compound

4-10-08, 17:59	#1 (permalink)
neilh2o Join Date: Jul 2006 Location: iTrader: (0)	2.0 rough idle, hi NOX i found one collapsed lifter and one cracked exhaust valve..a 2.0 liter Probe head (identical to a 2.0 Mazda 626)...anyways while i have the lifters out they are all getting taken apart and cleaned in carburator cleaner (great engine parts cleaner) and then lightly oiled ....to disassemble knock the lifter on a piece of wood cam side up..the collapsed lifter had a ton of carbon blocking the check valve ...the check valve is just a tiny ball thats spring loaded at the oil port on one of the small pistons.. when oil flows in thru the lifter fill hole the ball lifts off its seat and the lifter fills with oil.....i had some trouble with the cams getting cocked on disassembly so when that happens you have to reinstall all the cam caps and slowly tighten the bolts down in proper sequence 1/4 turn at a time till all the caps are tight and the cam is straight again..i found the best way to prevent that from happening again was to slightly rotate the cam as the cam caps are loosened up in 1/4 turn increments..the cam lobes must not rest on any of the lifters..its impossible to get equal compression on all the lifters so the cams can get cocked and jammed up very easily...you need a special valve spring compressor to compress the valve springs and remove the valves..i bought one on Ebay for about $70...the exhaust ports in the head were loaded up heavy with carbon deposits...there was absolutely no wear in the cylinder bores not even at the top of the block..the bores dont show wear probably because there are oil jets pressed into the block at the lower end of the cylinder bores ... the jets spray oil onto the cylinder bores underneath the pistons..after cleaning im going to lap in the valves lightly with a fine lapping compound
neilh2o Join Date: Jul 2006 Location: iTrader: (0)