QuestionQUESTION: hi, i have a 06 cobalt with 2.2 over 100k, which lead up to no start condition one fine day, prior to which i had check engine light and rough idle and reduced engine power message, next time i went to start, two cranks and no start; so turns out timing chain has too much slack and likely timing is off enough to cause no start, so anyway at this point with valve cover off no damage to anything so far..so what might be best and economical way to salvage this engine...? get complete timing chain job done and if valve(s) have some minor damage that occurred during start up attempt and to just replace valve(s) with timing parts, or entire upper head along with timing job, or do a complete rebuild (overhaul)on the engine with a master engine rebuild, or swap with used junkyard engine all together? if you could break down the scenario individually and typical cost(s) associated with each? i realize that majority of cost is involved in labor, but still wondering what might make the best sense and value. thanks
ANSWER: HI JR, THIS HAS THE ECO TECH. YOU WILL NOT SEE ANY DAMAGE REMOVING THE VALVE COVER. IF THERE IS DAMAGE IT WILL BE ON THE VALVE SEATS [VALVE FACE WILL BE BENT] MORE THEN LIKELY THE CHAIN TENSIONER WENT SOUTH. THIS CREATED A LOT OF PLAY IN THE CHAIN..MORE THEN LIKELY IT BENT THE VALVES WHEN IT LET GO..SOUNDS LIKE YOU KNOW ABOUT THIS...IF YOU ARE GOING TO DO THE WORK YOURSELF I WOULD DO A CYLINDER LEAK DOWN TEST AND HOPE THAT MAYBE THE VALVES ARE OK 50 -50 SHOT. IF THEY ARE OK.. TEAR THE FRONT HALF OF THE ENG APART INSTALL NEW CHAIN, WATER PUMP AND TENSIONERS YOU COULD DO THIS FOR ABOUT $400.00. A SHOP WOULD CHARGE YOU ABOUT $1400.00. IF THE VALVES ARE BENT AND YOU DO THE WORK AS ABOVE PLUS VALVE JOB $800.00 TO $900.00 IF A SHOP DOES IT $2500.00. I DO NOT KNOW IF YOU COULD FIND ONE OF THESE ENGINES IN A BONE YARD. BUT I WOULD THINK ABOUT $1000.00 COMPLETE..THEY HAVE BEEN PRETTY MUCH TROUBLE FREE UNLESS YOU DO NOT CHANGE THE OIL IN THEM...I GUESS IF YOU COULD FIND A LOW MIL ENG AND YOU DID THIS YOURSELF THIS MAYBE THE BEST WAY OUT FOR YOU AND MAYBE THE BEST BET IF A SHOP DID IT FOR YOU AS WELL. YOU WILL NEED TO GET SOME PRICES FROM YOUR LOCAL BONE YARDS AROUND YOU AND CRUNCH SOME #'S..HOPE THIS HELPS YOU AND IF YOU NEED MORE INFO GET BACK TO ME.. GOOD LUCK TO YOU,,,TOM
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QUESTION: hi again Tom, well great advice you gave. on hunch, i decided to take the valve cover off and inspect it carefully looking for any signs of damage, i did notice that on 1st cylinder (furthest away from timing chain) the intake valve lifter was cracked but rocker arm was just fine, i wonder if this is the tell-tail sign of valve hitting the piston upon cranking it and some damage possibly occurred? but no other evidence of anything irregular, i am still hopeful in doing a pressure/leak down test to tell if valves are ok. anything that tells you about the valve with lifter having damage to it, or anything else you might be able to tell from this?? thanks and appreciate any feedback you can offer.
AnswerHI JR,,WELL THIS IS UNUSUAL, A CRACKED LIFTER..I HAVE NOT SEEN THIS BEFORE..THIS COULD BE JUST A FLUKE THING, OR IT WAS LIKE THIS FOR A LONG TIME.. I WOULD JUST REPLACE THIS AND DO A LEAK DOWN TEST AND HOPE THAT ALL IS GOOD WITH THE VALVES...DID YOU EVER FIND OUT WHAT CAUSED THE TIMING CHAIN TO GO BAD..OR IS THAT WHAT YOU SAID [GOOD HUNCH ABOUT ????.]GOOD LUCK TO YOU AND LET MEK NOW HOW IT GOES...TOM
