Cowracer
04-25-2005, 04:13
I managed to sneak in a few hours on the truck engine this weekend and I know what happened to it now.
The problem was in the #3 cyl. I knew this even before I pulled the engine out of the truck. But I didnt know what the problem was. After getting the drivers side head off, the cause of the failure was clear.
The #3 piston had a longitudinal crack in it running from the 9 o'clock position to the 3 o' clock. It nearly transversed the entire piston, stopping only about 1/2" from the 3 o'clock side edge. The crack allowed combustion gasses to escape through the piston. This eroded a hole in the piston aprox the length and thickness of a quarter at the top of the 'fire slot' between the 'mikey mouse ears'.
The cylinder itself had minor scuffing on the 6 o'clock positon, probably due to some piston material getting lodged in the rings. It is not too bad and should clean up with a .030 overbore which I was going to do anyway. All the combustion chambers had the typical cracks between the valves. Nothing too serious.
Cause of the destruction of the #3 piston is probably due to high EGT's. I foolishly ignored the advice given time and time again to get gauges first off. I ran mine with higher boost and a chip for about 4 months before I got gauges. The first time I saw the EGT's I was getting just going hard up an onramp, I realized that I probably overcooked the engine on numerous occasions. Now that particular chicken has come home to roost
The $4500 Moral of the Story is:
GET GAUGES FIRST! If you are even thinking about a chip or boost control of ANY kind, get the gauges first! Don't be an ass like me! If you think you can't afford gauges, do you think you can afford a new engine?
Tim
The problem was in the #3 cyl. I knew this even before I pulled the engine out of the truck. But I didnt know what the problem was. After getting the drivers side head off, the cause of the failure was clear.
The #3 piston had a longitudinal crack in it running from the 9 o'clock position to the 3 o' clock. It nearly transversed the entire piston, stopping only about 1/2" from the 3 o'clock side edge. The crack allowed combustion gasses to escape through the piston. This eroded a hole in the piston aprox the length and thickness of a quarter at the top of the 'fire slot' between the 'mikey mouse ears'.
The cylinder itself had minor scuffing on the 6 o'clock positon, probably due to some piston material getting lodged in the rings. It is not too bad and should clean up with a .030 overbore which I was going to do anyway. All the combustion chambers had the typical cracks between the valves. Nothing too serious.
Cause of the destruction of the #3 piston is probably due to high EGT's. I foolishly ignored the advice given time and time again to get gauges first off. I ran mine with higher boost and a chip for about 4 months before I got gauges. The first time I saw the EGT's I was getting just going hard up an onramp, I realized that I probably overcooked the engine on numerous occasions. Now that particular chicken has come home to roost
The $4500 Moral of the Story is:
GET GAUGES FIRST! If you are even thinking about a chip or boost control of ANY kind, get the gauges first! Don't be an ass like me! If you think you can't afford gauges, do you think you can afford a new engine?
Tim