DOHC head torque specs question.. and a very confusing problem
#1
03-06-2010, 02:09 PM
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DOHC head torque specs question.. and a very confusing problem
My first question is, what is the proper torque sequence for this car? I've read several different accounts, some with 25ft-lbs on the corner bolts, some with them at 35-ftlbs, some equal to the rest of the bolts. If somebody who has some experience could clue me in on this, it would be great.
So yesterday I finished installing a new MLS head gasket in my '97 Neon (DOHC). I start the vehicle up, it purrs like a kitten for about 45 seconds, then starts bogging down and dies. I start it back up, needed to give it a little push on the accelerator pedal. At this point I know it's somehow jumped out of time, but before I can shut it off, a hear a bang. I shut it off nice a quick. Figured a valve hit a piston. At this point I'm fairly upset over whatever happened. New hydraulic tensioner installer, new water pump, timing belt, the whole shebang. So an hour or so later I've got the head back off. cylinder #1 is full of pink fluid, and so is the intake. It seems my brand new head gasket failed, allowing fluid to seep into a cylinder, which in turn created too much compression, stalling up the exhaust valve and forcing the thing out of time The hydraulic tensioner seemed to have moved down (the rod at the end was extended further than when I installed the thing) even though I needed a long handled ratchet and quite a bit of force to break the bolts loose.
The fluid as far as I could tell was whatever murky solution of old antifreeze that was still sitting in the block after doing the head job (also pulled the motor, did some polishing and painting, cleaned out my engine compartment, etc). So yeah, that sucked, but the head just got back from my machinist, he says the valve was fine. I wouldn't have even known which valve it was if it weren't for a shiny spot (not even a scratch) on one of the pistons. Had the head rechecked for straightness (it was milled the last time I had it off), it's still fine. Borrowed his straight edge and checked my block, it's fine (kinda figured it would be lol but it was his suggestion).
So on to my second question, does anybody have any other ideas as to what might have caused this? Yes I also put in new head bolts, before anyone asks.
So yesterday I finished installing a new MLS head gasket in my '97 Neon (DOHC). I start the vehicle up, it purrs like a kitten for about 45 seconds, then starts bogging down and dies. I start it back up, needed to give it a little push on the accelerator pedal. At this point I know it's somehow jumped out of time, but before I can shut it off, a hear a bang. I shut it off nice a quick. Figured a valve hit a piston. At this point I'm fairly upset over whatever happened. New hydraulic tensioner installer, new water pump, timing belt, the whole shebang. So an hour or so later I've got the head back off. cylinder #1 is full of pink fluid, and so is the intake. It seems my brand new head gasket failed, allowing fluid to seep into a cylinder, which in turn created too much compression, stalling up the exhaust valve and forcing the thing out of time The hydraulic tensioner seemed to have moved down (the rod at the end was extended further than when I installed the thing) even though I needed a long handled ratchet and quite a bit of force to break the bolts loose.
The fluid as far as I could tell was whatever murky solution of old antifreeze that was still sitting in the block after doing the head job (also pulled the motor, did some polishing and painting, cleaned out my engine compartment, etc). So yeah, that sucked, but the head just got back from my machinist, he says the valve was fine. I wouldn't have even known which valve it was if it weren't for a shiny spot (not even a scratch) on one of the pistons. Had the head rechecked for straightness (it was milled the last time I had it off), it's still fine. Borrowed his straight edge and checked my block, it's fine (kinda figured it would be lol but it was his suggestion).
So on to my second question, does anybody have any other ideas as to what might have caused this? Yes I also put in new head bolts, before anyone asks.
#2
03-06-2010, 11:55 PM
Here is the tightening sequence...
*First, Bolts 1 thru 6 to 25 ft. lbs and bolts 7 thru 10 to 20 ft. lbs
*Second, Bolts, 1 thru 6 to 50 ft. lbs and bolts 7 thru 10 to 20 ft. lbs
*Third, Bolts 1 thru 6 to 50 ft. lbs.) and bolts 7 thru 10 to 20 ft. lbs
*Fourth, Turn an additional 1/4 Turn, Do not use a torque wrench for this step.
Is it possible you put the HG on backwards? I have seen and heard people doing it.
*First, Bolts 1 thru 6 to 25 ft. lbs and bolts 7 thru 10 to 20 ft. lbs
*Second, Bolts, 1 thru 6 to 50 ft. lbs and bolts 7 thru 10 to 20 ft. lbs
*Third, Bolts 1 thru 6 to 50 ft. lbs.) and bolts 7 thru 10 to 20 ft. lbs
*Fourth, Turn an additional 1/4 Turn, Do not use a torque wrench for this step.
Is it possible you put the HG on backwards? I have seen and heard people doing it.
#3
03-07-2010, 10:06 AM
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I'm one of them. I put my engine back together and poured it full of antifreeze and had it come out of my oil filter hole (I had yet to put it on). I got extremely lucky that I caught the probem before I tried starting it up. I did have to take it back apart though. When I took out the oil plug - antifreeze came out of the oil pan.
You can easily see a misaligned MLS gasket if you put it on backward from front to back of the engine ( going from cyl 1 to cyl 4) as all of the holes will not align, but you CAN put it on upside down (car front to car back - which is what I did). There is a return on the front of the engine that does not get properly covered if that occurs, and you will get anti-freeze in the lower block and in the cylinders.
You can easily see a misaligned MLS gasket if you put it on backward from front to back of the engine ( going from cyl 1 to cyl 4) as all of the holes will not align, but you CAN put it on upside down (car front to car back - which is what I did). There is a return on the front of the engine that does not get properly covered if that occurs, and you will get anti-freeze in the lower block and in the cylinders.
Last edited by bg1995redneon; 03-07-2010 at 10:08 AM.
#4
03-08-2010, 02:24 PM
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I'm one of them. I put my engine back together and poured it full of antifreeze and had it come out of my oil filter hole (I had yet to put it on). I got extremely lucky that I caught the probem before I tried starting it up. I did have to take it back apart though. When I took out the oil plug - antifreeze came out of the oil pan.
You can easily see a misaligned MLS gasket if you put it on backward from front to back of the engine ( going from cyl 1 to cyl 4) as all of the holes will not align, but you CAN put it on upside down (car front to car back - which is what I did). There is a return on the front of the engine that does not get properly covered if that occurs, and you will get anti-freeze in the lower block and in the cylinders.
You can easily see a misaligned MLS gasket if you put it on backward from front to back of the engine ( going from cyl 1 to cyl 4) as all of the holes will not align, but you CAN put it on upside down (car front to car back - which is what I did). There is a return on the front of the engine that does not get properly covered if that occurs, and you will get anti-freeze in the lower block and in the cylinders.
