Looks like I lost #7 piston
05-13-2008, 11:27 AM
#86
I am assuming that #7 is on the passenger side? Do you think your maxing out the factory exhaust manifold? They were designed for alot less airflow then what you putting threw it now... Since #7 is the last one and 1,3,5 have all ready maxed out the manifold then #7 would be holding in all the heat and could cause it to sieze? Just and idea...
I think it would be interesting to see a log with thermocouples in the #7 and #1 to see the difference in temps... I bet they are pretty different...
I think it would be interesting to see a log with thermocouples in the #7 and #1 to see the difference in temps... I bet they are pretty different...
Last edited by BlackGMC; 05-13-2008 at 11:37 AM.
05-13-2008, 11:48 AM
#87
I have my opinions as well however they have already been placed on the table. Not fun to kill a motor...for the cost reasons, the down time and the work it will take to get her back up and running.
FWIW, thank you for sharing this event and documenting it well with the pictures. That is the reason I spend so much time on sites like PT.net. Its the closest thing to experiencing issues one-on-one
FWIW, thank you for sharing this event and documenting it well with the pictures. That is the reason I spend so much time on sites like PT.net. Its the closest thing to experiencing issues one-on-one
05-13-2008, 12:00 PM
#88
i dont htink he maxed out the manifold since ohio boys are going 7s with unported ones
maybe you can hone that and just run that motor, also that would be your sign of oil burning in the motor. as for the plug it might of been a faulty plug that caused the motor to fail. or when assembled the one tolerance was off some and thus lead to your oil issue. oil got on electrode cause hot spot and just finally broke...thats a good **** in the wind on that guess.
try to see if you can clean that up with a ball hone if you look at bottom you can see some material that is caked on the wall.
out of curious what coolant tubing are you runing? the crossover or the ls6 style?
maybe you can hone that and just run that motor, also that would be your sign of oil burning in the motor. as for the plug it might of been a faulty plug that caused the motor to fail. or when assembled the one tolerance was off some and thus lead to your oil issue. oil got on electrode cause hot spot and just finally broke...thats a good **** in the wind on that guess.
try to see if you can clean that up with a ball hone if you look at bottom you can see some material that is caked on the wall.
out of curious what coolant tubing are you runing? the crossover or the ls6 style?
05-13-2008, 12:12 PM
#89
Just got off the phone with Rex. He thinks it was a lean issue causing the piston to run extremely hot (hence the absence of carbon buildup on #7, unlike 1/3/5), which caused it to expand into the cylinder wall. He said it looks like it's been occurring for awhile since there is no carbon on #7. I must have just finally gotten it hot enough to actually do some damage. I can't imagine how #7 would be so much leaner than the rest though, unless maybe it's a combination of a partially clogged injector and the stock intake manifold that favors airflow into #7. Either that, or like I said before the location of the wideband sensor was causing it to give false readings.
Hopefully the metal on the cylinder wall will just clean up. He also wants me to see if I can get ahold of a bore mic to make sure the cylinder is not out of round, and to check for cracks in the cylinder wall. Otherwise, the whole engine has to come apart again and it will go another .010 over and I'll have to buy another set of pistons, rings, bearings, etc etc.
I have the coolant crossover in the front and the plugs in the back.
Hopefully the metal on the cylinder wall will just clean up. He also wants me to see if I can get ahold of a bore mic to make sure the cylinder is not out of round, and to check for cracks in the cylinder wall. Otherwise, the whole engine has to come apart again and it will go another .010 over and I'll have to buy another set of pistons, rings, bearings, etc etc.
I have the coolant crossover in the front and the plugs in the back.
05-13-2008, 12:17 PM
#90
Just got off the phone with Rex. He thinks it was a lean issue causing the piston to run extremely hot (hence the absence of carbon buildup on #7, unlike 1/3/5), which caused it to expand into the cylinder wall. He said it looks like it's been occurring for awhile since there is no carbon on #7. I must have just finally gotten it hot enough to actually do some damage.
Hopefully the metal on the cylinder wall will just clean up. He also wants me to see if I can get ahold of a bore mic to make sure the cylinder is not out of round, and to check for cracks in the cylinder wall. Otherwise, the whole engine has to come apart again and it will go another .010 over and I'll have to buy another set of pistons, rings, bearings, etc etc.
I have the coolant crossover in the front and the plugs in the back.
Hopefully the metal on the cylinder wall will just clean up. He also wants me to see if I can get ahold of a bore mic to make sure the cylinder is not out of round, and to check for cracks in the cylinder wall. Otherwise, the whole engine has to come apart again and it will go another .010 over and I'll have to buy another set of pistons, rings, bearings, etc etc.
I have the coolant crossover in the front and the plugs in the back.
that would also make sense why you were denotating before the meth. what was your target A/F? what was actual A/F? what Tstat you running? by any chance would you have a weak injector for that cylinder?
his theory makes a lot of sense as for the heating up and expanding but in order to do that it would of been extremely hot. not to many ppl run .040 that would net you a custom piston...in that case a new block might be cheaper....figure price of machine work for bore and cost of pistons vs the cost of block and boring